Heater, wafer heating apparatus and method for manufacturing heater Number:7,417,206 from the United States Patent and Trademark Office (PTO) owispatent

Title: Heater, wafer heating apparatus and method for manufacturing heater

Abstract: A heater that is capable of heating an object to a desired temperature in a short period while minimizing the temperature difference the surface of the object is provided. The heater comprising a plate having a first surface and a second surface, the first surface being a mount surface whereon an object is placed and having a resistive heating member; wherein the resistive heating member is formed in a continuous band having arc bands located on one of two concentric circles of different radii, at least one arc band located on the other circle, and linkage arc band that connects the arc band located on the one circle and the arc band located on the other circle; while the distance between the adjacent linkage arc bands is smaller than the distance between the arc band located on the one circle and the arc band located on the other circle.

Patent Number: 7,417,206 Issued on 08/26/2008 to Nakamura

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Inventors:	Nakamura; Tsunehiko (Kokubu, JP)
Assignee:	Kyocera Corporation (Kyoto, JP)
Appl. No.:	11/238,641
Filed:	September 29, 2005

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Foreign Application Priority Data

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Oct 28, 2004 [JP]			P2004-313838
Mar 28, 2005 [JP]			P2005-092184

Current U.S. Class:	219/444.1 ; 219/544
Current International Class:	H05B 3/68 (20060101); H05B 3/50 (20060101)
Field of Search:	219/443.1-468.2,538-548 118/724,725

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References Cited [Referenced By]

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U.S. Patent Documents

2409244	October 1946	Bilan
5490228	February 1996	Soma et al.
5616024	April 1997	Nobori et al.
6080970	June 2000	Yoshida et al.
6437296	August 2002	Choi
6465763	October 2002	Ito et al.
6653603	November 2003	Yamaguchi
6686570	February 2004	Furukawa et al.
6746972	June 2004	Kim et al.
6753507	June 2004	Fure et al.
6849938	February 2005	Ito
6960743	November 2005	Hiramatsu et al.
7071551	July 2006	Hiramatsu et al.
2002/0043528	April 2002	Ito
2003/0183816	October 2003	Goto
2004/0108308	June 2004	Okajima
2004/0149718	August 2004	Ito et al.
2006/0000822	January 2006	Nakamura

Foreign Patent Documents

	1662105		Aug., 2005		CN
	1 089 593		Apr., 2001		EP
	1 109 423		Jun., 2001		EP
	04-101381		Apr., 1992		JP
	07-065935		Mar., 1995		JP
	07-220862		Aug., 1995		JP
	10-223642		Aug., 1998		JP
	10-229114		Aug., 1998		JP
	11-121385		Apr., 1999		JP
	11-191535		Jul., 1999		JP
	11-339939		Dec., 1999		JP
	11-354528		Dec., 1999		JP
	2000340343		Dec., 2000		JP
	2001-006852		Jan., 2001		JP
	2001-068407		Mar., 2001		JP
	2001-102157		Apr., 2001		JP
	2001-203156		Jul., 2001		JP
	2001-223257		Aug., 2001		JP
	2001-257200		Sep., 2001		JP
	2001-267043		Sep., 2001		JP
	2001-313249		Nov., 2001		JP
	2002-076102		Mar., 2002		JP
	2002-170655		Jun., 2002		JP
	2002-184683		Jun., 2002		JP
	2002-231421		Aug., 2002		JP
	2002-231793		Aug., 2002		JP
	2002-237375		Aug., 2002		JP
	2003077779		Mar., 2003		JP
	2004-006242		Jan., 2004		JP
	2004-111107		Apr., 2004		JP

Other References

Chinese language office action and its English translation for corresponding Chinese application No. 200510107141.4 lists the references above. cited by other.

Primary Examiner: Paik; Sang
Attorney, Agent or Firm: Hogan & Hartson LLP

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Claims

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What is claimed is:

1. A heater comprising a plate-shaped member having a first principal surface which is a mount surface whereon an object to be heated is placed, a second principal surface, a plurality of resistive heating members provided therein or on the second principal surface and a plurality of resistive heating member zones each having one of the resistive heating members, the resistive heating member zones further comprising a circular central resistive heating member zone, first resistive heating member zones in which a first ring-shaped resistive heating member zone positioned outermost and concentric with the circular central resistive heating member zone is divided equally by a plurality of first boundaries in the radial direction, and second resistive heating member zones in which a second ring-shaped resistive heating member zone positioned inside of the first ring-shaved resistive heating member zone is divided equally by a plurality of second boundaries in the radial direction, wherein, the first boundaries and the second boundaries are not aligned on one line; wherein one of the resistive heating members is formed in a continuous band having at least two arc bands located on one of two concentric circles of different radii, at least one arc band located on the other circle, and linkage arc bands each of which connects the arc band located on the one circle and the arc band located on the other circle, said linkage arc bands being located adjacent to each other; and wherein the distance between the adjacent linkage arc bands is smaller than the distance between the arc band located on the one circle described above and the arc band located on the other circle.

2. The heater according to claim 1; wherein the distance between the adjacent linkage arc bands is set in a range from 30% to 80% of the distance between the arc bands.

3. The heater according to claim 1; a third resistive heating member zone having one of the resistive heating members is formed between the second resisting heating member zone and the circular central resistive heating member zone.

4. The beater according to claim 1; wherein the number of divisions of the second ring-shaped resistive heating member zone and the number of divisions of the first ring-shaped resistive heating member zone are different.

5. The heater according to claim 3; wherein the resistive heating member provided in the central resistive heating member zone and the resistive heating member provided in the third ring-shaped resistive heating member zone are connected in parallel.

6. The heater according to claim 3; wherein a through hole is provided between the central resistive heating member zone and the first ring-shaped resistive heating member zone so as to penetrate the plate-shaped member.

7. The heater according to claim 1; comprising three or more peripheral protrusions provided along the periphery of the mount surface and inner protrusions that are lower than the peripheral protrusions in height, the inner protrusions being provided inside of the peripheral protrusions, wherein the peripheral protrusions are held so as to be movable at least in one of the radial direction of the plate-shaped member and a direction perpendicular thereto.

8. The heater according to claim 7; further comprising power terminals for supplying electric power to the resistive heating member, a cooling nozzle for cooling the plate-shaped member and an opening, a casing that covers the power terminals and the other surface of the plate-shaped member and clamp bolts that clamp the peripheral protrusions onto the plate-shaped member, wherein the clamp bolts penetrate through the plate-shaped member from one surface to the other surface so as to fasten the casing.

9. The heater according to claim 8; wherein a periphery of the plate-shaped member is pressed by clamp fittings.

10. A wafer heating apparatus having a heater according to claim 1.

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Description

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BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates mainly to a heater used in heating a wafer, a wafer heating apparatus and a method for manufacturing the heater.

2. Description of the Related Art

In a manufacturing process of semiconductor devices, a heater is used to heat a semiconductor wafer (hereinafter referred to simply as a wafer) during formation of thin semiconductor film, etching, baking of resist film and other steps.

For such heating purposes, for example, Patent Document 1, Patent Document 2 and Patent Document 3 disclose wafer heating apparatus as shown in FIG. 16.

A heater 771 comprises a plate-shaped ceramic member 772 and a metal casing 779 as major components, and is constituted by securing the plate-shaped ceramic member 772 made of a ceramic material of nitride or carbide on an opening of the bottomed metal casing 779, that is made of a metal such as aluminum, via an insulating contact member 774 made of a resin by means of bolts 780. The heater 771 uses the top surface of the plate-shaped ceramic member 772 as a heating surface 773 whereon a wafer W is to be mounted, so that the wafer W is heated by a resistive heating member 775 that is formed, for example, in concentric configuration as shown in FIG. 20, on the bottom surface of the plate-shaped ceramic member 772.

Power terminals 777 are connected by brazing to power feeder sections of the resistive heating member 775, with the power terminals 777 electrically connected to lead wires 778 that are passed through wiring holes 776 provided at a bottom 779a of the metal casing 779.

In order to form a uniform film over the entire surface of the wafer W or cause a resist film to react uniformly in heating reaction by using the heater 771, it is important to make uniform temperature distribution over the wafer. Accordingly, various measures have been employed as described below to keep the temperature difference across the wafer surface small.

One of the measures is to divide the resistive heating member 775 and independently control the temperatures of the divided sections.

Patent Document 4 discloses a heater that has a plurality of resistive heating member blocks. The resistive heating member of this heater is radially divided into four equal sections of fan-shaped block as shown in FIG. 17. A heater such as shown in FIG. 18 is also known that comprises four blocks of resistive heating member located along the periphery and a circular block of resistive heating member located at the center.

Patent Document 5 discloses a heater comprising a resistive heating member that is divided into identical rectangular regions 711 through 718 that can be controlled either independently or in groups each consisting of a plurality of regions, as shown in FIG. 19. In this heater, as shown in FIG. 19, four regions 715 through 718, among the regions 711 through 718, are located at positions that correspond to the arcs formed by dividing the peripheral portion of the wafer into four equal parts, and other four regions 711 through 714 are disposed inside of the four regions 715 through 718 in parallel thereto.

As to configuration of the resistive heating member, such a heater 500 (Patent Document 6) that comprises a plurality of resistive heatin members of which one located at the outermost position is formed in a sine curve, and heater 500 having outermost resistive heating member 750 formed in rectangular shape (Patent Document 7 and Patent Document 8) is also disclosed (FIGS. 21, 22, 23). In these heaters, a power feeder section 760 is disposed adjacent to the resistive heating member.

Patent Document 8 discloses a heater having a spiral-shaped resistive heating member.

Patent Document 9 discloses a heater where wafer W support pins (not shown) are provided on a mount surface 773 is provided so as to lift the wafer W from the mount surface 773 by a small distance, in order to achieve uniform temperature distribution over the wafer.

Patent Document 10 discloses a heater where a wall is provided along the periphery of the plate-shaped ceramic member 772 to surround the wafer W, so as to prevent the wafer W from moving laterally.

Patent Document 11 discloses a heater where a protrusion that engages with the wafer W is formed along the periphery of the plate-shaped ceramic member 772, and a multitude of projections that contact with the wafer W are formed inside of the protrusion, in order to achieve uniform temperature distribution.

Patent Document 12 discloses a heater where guide pins that locate the wafer W are provided around the plate-shaped ceramic member, thereby to achieve uniform temperature distribution over the wafer W.

Patent Document 13 discloses a heater where temperature distribution over the wafer W can be controlled by adjusting the height of support pins of the wafer W. A heater having guide pins engaged with the support pins is also disclosed.

Patent Document 14, Patent Document 15 and Patent Document 16 also disclose heater 850 made of ceramics where a coil-shaped resistive heating member 853 is embedded as shown in FIG. 24. The heater 850 consists of a plate-shaped ceramic member 851 made of a nitride ceramic material such as silicon nitride or aluminum nitride in which a coil-shaped resistive heating member 853 formed in spiral configuration is embedded, while the power feeder terminals 855 are connected to both ends of the resistive heating member 853. In order to decrease the temperature difference across the wafer surface, such measures are disclosed as increasing the density of the resistive heating member 853 in a region of 10% of the mount surface on the outside, restricting the variation in the number of windings per unit length of the coil-shaped resistive heating member 853 and 3-dimensional arrangement of the resistive heating member 853.

Patent Document 17 and Patent Document 18 also describe attempts to decrease the temperature difference across the wafer surface by connecting and embedding a resistive heating member having different coil diameter, or by providing a swelling portion at a turn-back portion of the resistive heating member.

Moreover, in a CVD film forming process, for example, such a wafer holding member is employed that supports a ceramic heater comprising a plate-shaped ceramic member by means of a cylindrical support member made of ceramics. Such a heater 850 made of ceramics is also known as one principal surface of the plate-shaped ceramic member 851 having resistive heating members 853, 854 embedded therein is used as mount surface 851a and a cylindrical support member 860 made of ceramics is joined onto the other principal surface, as shown in FIG. 25. In the heater 850, the power terminals 856, 857 are connected by brazing to the terminals of the resistive heating members 853, 854, and power terminals 856, 857 are lead through inside of the cylindrical support member 860 to the outside for connection.

In recent years, increasing number of semiconductor devices are manufactured with circuits having line width of 90 nm or 45 nm. Manufacturing such semiconductor devices requires a heater that can heat a wafer with more uniform temperature distribution.

[Patent Document 1]

Japanese Unexamined Patent Publication No. 2001-203156

[Patent Document 2]

Japanese Unexamined Patent Publication No. 2001-313249

[Patent Document 3]

Japanese Unexamined Patent Publication No. 2002-76102

[Patent Document 4]

Japanese Unexamined Patent Publication No. 11-121385

[Patent Document 5]

Japanese Unexamined Patent Publication No. 11-354528

[Patent Document 6]

Japanese Unexamined Patent Publication No. 2001-6852

[Patent Document 7]

Japanese Unexamined Patent Publication No. 2001-223257

[Patent Document 8]

Japanese Unexamined Patent Publication No. 2001-257200

[Patent Document 9]

Japanese Unexamined Patent Publication No. 10-223642

[Patent Document 10]

Japanese Unexamined Patent Publication No. 10-229114

[Patent Document 11]

Japanese Unexamined Patent Publication No. 2002-237375

[Patent Document 12]

Japanese Unexamined Patent Publication No. 2002-184683

[Patent Document 13]

Japanese Unexamined Patent Publication No. 2001-68407

[Patent Document 14]

Japanese Unexamined Patent Publication No. 4-101381

[Patent Document 15]

Japanese Unexamined Patent Publication No. 7-220862

[Patent Document 16]

Japanese Unexamined Patent Publication No. 7-65935

[Patent Document 17]

Japanese Unexamined Patent Publication No. 2004-6242

[Patent Document 18]

Japanese Unexamined Patent Publication No. 2004-111107

[Patent Document 19]

Japanese Unexamined Patent Publication No. 11-339939

[Patent Document 20]

Japanese Unexamined Patent Publication No. 2001-102157

[Patent Document 21]

Japanese Unexamined Patent Publication No. 2002-170655

There has been a demand for a heater that can heat a wafer with more uniform temperature distribution with a simpler structure, since it is difficult to achieve uniform temperature distribution with the conventional heater and it is necessary to carry out very complex and delicate control procedure to achieve a uniform temperature distribution.

In the case of the technology of chemically amplified resist that is being employed along with the trend toward smaller circuit line width of the semiconductor devices, emphasis is placed not only on the uniform temperature distribution over the wafer, but also on the temperature changes throughout the period from the time when the wafer is set in a heat treatment apparatus to the time when the heat treatment is completed and the wafer is taken out. Thus it is desired to stabilize the wafer temperature in uniform temperature distribution with about 60 seconds after placing the wafer on a heater, but the conventional heater cannot satisfy this requirement because it takes a long period of time to stabilize the temperature.

There has also been such a problem that a heater comprising a coil-shaped resistive heating member embedded therein has a tendency of the density of the heating member changing significantly between the outside and inside at a bending portion of the resistive heating member, which makes it difficult to decrease the radius of curvature. Accordingly, the methods described in Patent Document 17 and Patent Document 18 require it to connect the resistive heating members of different coil diameters within the plate-shaped ceramic member, or to form a swelling portion at a turn-back section of the resistive heating member. This results in a complex process that is not suitable for volume production, and it is very difficult to mass-produce products with stabilized quality and high level in the yield of production.

In addition, there has been such a problem that the heater having the cylindrical support member attached thereto allows heat to dissipate through the cylindrical support member, thus resulting in significant temperature difference across the wafer surface.

To counter this problem, Patent Document 19 discloses a heater having increased resistance density on the inside of the cylindrical support member 860 so as to keep the temperature difference across the wafer surface small even when the temperature is raised quickly and prevent the plate-shaped ceramic member 851 from breaking.

Patent Document 20 discloses a heater made of ceramics having a cylindrical support member attached thereto wherein temperature difference across the surface is decreased to prevent breakage, by increasing the resistance of a middle portion and an independent resistive heating member 854 is embedded at a position near the joint surface of the support member 860. Furthermore, Patent Document 21 discloses a heater having a resistive heating member embedded therein so as to heat the cylindrical support member 860.

Recently, it has been called for to decrease the time taken to raise the temperature to a very short period. However, there is a possibility that the heater made of ceramics having the coil-shaped resistive heating member breaks when heated at a high rate. Particularly, heaters made of ceramics having cylindrical support members attached thereto designed for increasing wafer size of 300 mm in diameter were often broken due to the high thermal stress generated by quick heating.

SUMMARY OF THE INVENTION

Accordingly, an object of the present invention is to provide a heater that is capable of heating a wafer or other object to a desired temperature in a shorter period of time while minimizing the temperature difference across the surface of the object, and a wafer heating apparatus that uses the heater.

Another object of the present invention is to provide a heater comprising a plate-shaped ceramic member with a coil-shaped heating member embedded therein that is capable of quickly heating an object while minimizing the temperature difference across the surface of the object with high reliability, and a method for manufacturing the same.

In order to achieve the object described above, the present invention provides a first heater comprising a plate-shaped member having a first principal surface which is a mount surface whereon an object to be heated is placed, a second principal surface and a resistive heating member provided therein or on the second principal surface; wherein the resistive heating member is formed in a continuous band having at least two arc bands located on one of two concentric circles of different radii, at least one arc band located on the other circle, and linkage arc bands each of which connects the arc band located on the one circle and the arc band located on the other circle, said linkage arc bands being located adjacent to each other;

while the distance between the adjacent linkage arc bands is smaller than the distance between the arc band located on the one circle described above and the arc band located on the other circle.

The first heater of the present invention having the constitution described above is capable of heating a wafer or other object to a desired temperature in a shorter period of time while minimizing the temperature difference across the surface of the object, and a wafer heating apparatus that uses the heater.

The present invention also provides a second heater comprising a plate-shaped member having a first principal surface which is a mount surface whereon an object to be heated is placed, a second principal surface, a resistive heating member provided therein or on the second principal surface, and a temperature measuring element; wherein

the resistive heating member is formed in a continuous band comprising arc bands that are located on at least two concentric circles of different diameters and are connected with each other, with power feeder sections provided on both ends thereof,

the temperature measuring element is provided within a ring-shaped resistive heating member zone that is defined as a region interposed between a circle inscribed to an arc band located at the innermost position among the arc bands and a circle circumscribed to an arc band located at the outermost position among the arc bands; and

the power feeder section is provided outside of the ring-shaped resistive heating member zone.

The second heater of the present invention having the constitution described above is capable of heating a wafer or other object to a desired temperature in a shorter period of time while minimizing the temperature difference across the surface of the object, and a wafer heating apparatus that uses the heater.

In the second heater of the present invention, at least two arc bands are disposed on one of the adjacent circles and the arc bands are connected by the linkage arc band that is located adjacent to the arc band disposed on the other circle, while the distance between the adjacent linkage arc bands is smaller than the distance between the arc bands that are connected by the linkage arc band.

In the first and second heaters of the present invention, the distance between the adjacent linkage arc bands is preferably set in a range from 30 to 80% of the distance between the arcs.

It is preferable that the first heater of the present invention comprises a plurality of the resistive heating members, and the resistive heating members are provided within a ring-shaped resistive heating member zone that is defined as a region interposed between a circle inscribed to an arc band located at the innermost position among the arc bands and a circle circumscribed to an arc band located at the outermost position among the arc bands.

In the first and second heaters of the present invention, it is preferable that a plurality of the ring-shaped resistive heating member zones are disposed in a concentric arrangement, with the resistive heating member disposed in each of the ring-shaped resistive heating member zones.

In the heater described above, it is also preferable that the plurality of ring-shaped resistive heating member zone comprise a first ring-shaped resistive heating member zone, a second ring-shaped resistive heating member zone and a third ring-shaped resistive heating member zone disposed in this order from the inside, while a circular or ring-shaped central resistive heating member zone is provided inside of the first ring-shaped resistive heating member zone and an additional resistive heating member is provided in the central resistive heating member zone.

Further in the heater described above, it is preferable that outer diameter D1 of the central resistive heating member zone is in a range from 20 to 40% of the outer diameter D of the third ring-shaped resistive heating member zone, outer diameter D2 of the first ring-shaped resistive heating member zone is in a range from 40 to 55% of the outer diameter D, outer diameter D3 of the second ring-shaped resistive heating member zone is in a range from 55 to 85% of the outer diameter D, inner diameter D22 of the first ring-shaped resistive heating member zone is in a range from 34 to 45% of the outer diameter D, inner diameter D33 of the second ring-shaped resistive heating member zone is in a range from 55 to 65% of the outer diameter D, and inner diameter D0 of the third ring-shaped resistive heating member zone is in a range from 85 to 93% of the outer diameter D.

In the heater described above, it is also preferable that the second ring-shaped resistive heating member zone and the third ring-shaped resistive heating member zone are each divided into equal sections by a plurality of boundary zones provided in the radial direction, that the boundary zones that divide the second ring-shaped resistive heating member zone and the boundary zones that divide the third ring-shaped resistive heating member zone are located at staggered positions with respect to each other so as not to overlap in the radial direction, and it is more preferable that the number of divisions of the second ring-shaped resistive heating member zone and the number of divisions of the third ring-shaped resistive heating member zone are different.

In the heater described above, the resistive heating member provided in the central resistive heating member zone and the resistive heating member provided in the first ring-shaped resistive heating member zone may be connected either in series or in parallel.

A through hole may be provided between the central resistive heating member zone and the first ring-shaped resistive heating member zone so as to penetrate the plate-shaped member.

In the first and second heaters of the present invention, it is preferable that width of the resistive heating member provided in the ring-shaped resistive heating member zone located at the outermost position is smaller than the width of the resistive heating member provided in the other resistive heating member zones.

In the first and second heaters of the present invention, it is preferable that three or more peripheral protrusions are provided along the periphery of the mount surface and inner protrusions that are lower than the peripheral protrusions in height are provided inside of the peripheral protrusions, and the peripheral protrusions are held so as to be movable at least in one of the radial direction of the plate-shaped member and a direction perpendicular thereto.

The heater described above may have power terminals for supplying electric power to the resistive heating member, a cooling nozzle for cooling the plate-shaped member and an opening, and be further provided with a casing that covers the power terminals and the other surface of the plate-shaped member and clamp bolts that clamp the peripheral protrusions onto the plate-shaped member, with the clamp bolts penetrating through the plate-shaped member from one surface described above to the other surface, so as to fasten the casing.

The plate-shaped member may also be fastened onto the casing via a clamp fixture.

A third heater of the present invention comprises a plate-shaped ceramic member having a first principal surface which is a mount surface whereon an object to be heated is placed, a second principal surface and a resistive heating member embedded therein.

The third heater is characterized in that the resistive heating member is formed in a continuous electrically conductive wire having two spiral coils of which center is one of two concentric circles of different radii, at least one spiral coil of which center is the other circle, and connecting coils that connect the spiral coils of which center is one of two concentric circles and the spiral coil of which center is the other circle, said connecting coils being located adjacent to each other;

while the distance between the adjacent connecting coils is smaller than the distance between the spiral coil of which center is the one circle and the spiral coil of which center is the other circle.

The heater of the present invention having the constitution described above comprises the plate-shaped ceramic member wherein the coil-shaped resistive heating member is embedded that is capable of heating an object in a shorter period of time with high reliability while minimizing the temperature difference across the surface of the object to be heated.

In the third heater, it is preferable that the connecting distance is in a range from 30 to 80% of the distance between the coils.

In the third heater, it is also preferable that the spiral coil located at the outermost position has a coil pitch smaller than those of other spiral coils.

Moreover, it is preferable that the third coil has a cylindrical support member joined onto the second principal surface of the plate-shaped ceramic member, while the spiral coil located inside of the support member has a coil pitch smaller than those of the spiral coils located outside of the support member.

A wafer heating apparatus according to the present invention is characterized by having one of the first through the third heaters of the present invention.

A method for manufacturing the third heater of the present invention comprises the steps of:

forming a groove in a green compact that is made of ceramic powder in a plate shape;

inserting a coil-shaped resistive heating member in the groove;

filling a gap between the groove and the resistive heating member with a ceramic powder and applying a preliminary pressure to the ceramic powder; and

firing the preliminarily pressed green compact in a heat resistant mold while applying a pressure thereto.

According to the method for processing the wafer of the present invention, at least one of formation of a semiconductor film on the wafer, etching process and formation of resist film is carried out while heating the wafer by means of the heater, with the wafer being placed on a mount surface of the wafer heating apparatus of the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a sectional view showing the constitution of the heater according to the first embodiment of the present invention.

FIG. 2 is a plan view showing the configuration of the resistive heating member of the first embodiment.

FIG. 3A is a plan view showing a preferable example of ring-shaped resistive heating member zone according to the present invention.

FIG. 3B is a plan view showing an example of dividing the resistive heating member zone into a plurality of portions outside the ring-shaped resistive heating member zone of FIG. 3A.

FIG. 4 is a plan view showing a preferable example of configuration of the resistive heating member according to the present invention.

FIG. 5 is a plan view showing an example of constitution of the resistive heating member of the heater according to the second embodiment of the present invention.

FIG. 6 is a schematic diagram showing another example of constitution of the resistive heating member of the heater according to the second embodiment of the present invention.

FIG. 7A is a sectional view showing the constitution of the heater according to the third embodiment of the present invention.

FIG. 7B is a plan view of the heater of the third embodiment.

FIG. 8A is an enlarged sectional view of first example of the peripheral protrusion of the third embodiment.

FIG. 8B is an enlarged sectional view of second example of the peripheral protrusion of the third embodiment.

FIG. 8C is an enlarged sectional view of third example of the peripheral protrusion of the third embodiment.

FIG. 8D is an enlarged sectional view of fourth example of the peripheral protrusion of the third embodiment.

FIG. 9 is a sectional view taken along lines Y-Y of FIG. 7B.

FIG. 10A is a schematic plan view showing an example of the configuration of the resistive heating member zone of the heater according to the third embodiment.

FIG. 10B is a schematic plan view showing an example of the resistive heating member zone obtained by dividing the resistive heating member zone of FIG. 10A further.

FIG. 11A is a schematic perspective view showing the constitution of the ceramic heater according to the fourth embodiment of the present invention, b) being a schematic sectional view taken along lines X-X.

FIG. 11B is a schematic sectional view taken along lines X-X of FIG. 11A.

FIG. 12 is a schematic diagram showing the configuration of the resistive heating member of the heater according to the fourth embodiment.

FIG. 13A is a schematic perspective view showing the constitution of the ceramic heater according to the variation of the present invention.

FIG. 13B is a schematic sectional view taken along lines X-X of FIG. 13A.

FIG. 14 is a schematic diagram showing the resistive heating member of the fourth embodiment.

FIG. 15A is a schematic plan view explanatory of a preferable form of resistive heating member in the variation shown in FIG. 13A.

FIG. 15B is a schematic sectional view taken along lines X-X of FIG. 15A.

FIG. 16 is a sectional view showing an example of heater of the prior art.

FIG. 17 is a schematic diagram showing the configuration of a resistive heating member of the prior art.

FIG. 18 is a schematic diagram showing the configuration of another resistive heating member of the prior art.

FIG. 19 is a schematic diagram showing the configuration of another resistive heating member of the prior art.

FIG. 20 is a schematic diagram showing the configuration of another resistive heating member of the prior art.

FIG. 21 is a schematic diagram showing the configuration of another resistive heating member of the prior art.

FIG. 22 is a schematic diagram showing the configuration of another resistive heating member of the prior art.

FIG. 23 is a schematic diagram showing the configuration of another resistive heating member of the prior art.

FIG. 24 is a schematic diagram showing the configuration of resistive heating member of the prior art.

FIG. 25 is a schematic sectional view showing another ceramic heater of the prior art.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Embodiments of the present invention will now be described below.

Embodiment 1

FIG. 1 is a sectional view showing the constitution of a heater 1 according to a first embodiment of the present invention. The heater 1 of the first embodiment comprises a plate-shaped ceramic member 2, power feeder sections 6, power terminals 11 and a metal casing 19.

According to the first embodiment, the plate-shaped ceramic member 2 is made of a ceramic material consisting of silicon carbide or aluminum nitride as the main component, for example, and has one principal surface used as a mount surface 3 to place the wafer W thereon and a resistive heating member 5 is formed as described below on the other principal surface.

The power feeder sections 6 are electrically connected to the resistive heating member 5 that is formed on the other principal surface of the plate-shaped ceramic member 2, while the power terminals 11 are connected to the power feeder sections 6.

The metal casing 19 holds the power terminals 11 connected to the power feeder sections 6 and is fastened onto the periphery of the other principal surface of the plate-shaped ceramic member 2 via a contact member 17 so as to surround the power feeder sections 6.

The plate-shaped ceramic member 2 has a through hole 26 that penetrates therethrough in the direction of thickness. Wafer lift pins 25 are provided movably in the vertical direction in the through hole 26, so that the wafer W can be moved vertically and placed on the mount surface 3 and unloaded therefrom. With the constitution described above, electric power can be supplied from the outside through the power terminals 11 to the powder feeder sections 6, so as to heat the wafer W while measuring the temperature of the plate-shaped ceramic member 2 by means of a temperature measuring element 27.

The wafer W is held while being lifted by the wafer support pins 8 from the mount surface 3, so as to prevent the wafer W from being subjected to uneven distribution of temperature due to uneven bearing.

According to the present invention, it is preferable to divide the resistive heating member 5 into a plurality of zones each provided with a separate power feeder section and connected to the power terminals 11 so that electric power can be supplied independently to each of the power feeder sections 6. This constitution makes it possible to control the electric power supplied to the power terminals 11 so that each of the temperature measuring element 27 indicates a predetermined temperature and uniform temperature distribution over the surface of the wafer placed on the mount surface 3. In this case, while it is preferable to provide the temperature measuring element 27 in each zone, but one temperature measuring element 27 may be provided for every two or three zones.

The power feeder sections 6 are made of gold, silver, palladium, platinum or the like, for example, and is put into contact with the power terminals 11 thereby establishing electrical continuity. There is no restriction on the method of connecting the power terminals 11 and the power feeder sections 6, and soldering, brazing or the like may be employed as long as electrical continuity can be secured.

In the heater of the first embodiment, the band-shaped resistive heating member 5 formed inside of the plate-shaped ceramic member 2 or on the principal surface thereof comprises one continuous electrical conductor constituted from arc bands 5i through 5p that have substantially the same line width and formed in substantially concentric configuration and are connected by turn-back linkage arc bands 5q through 5v as shown in FIG. 2.

Specifically, the arc band 5i that has the power feeder section 6 at one end thereof is formed so as to constitute a part of circle that is located at the innermost position and has center located at the center of the plate-shaped ceramic member 2, with the other end of the arc band 5i connected to one end of the turn-back linkage arc band 5q. Connected to the other end of the turn-back linkage arc band 5q is one end of the arc band 5k that is formed so as to constitute a part of circle located at the second position from the inside (with the center located at the center of the plate-shaped ceramic member 2), with the other end of the arc band 5k being connected to one end of the turn-back linkage arc band 5t. Connected to the other end of the turn-back linkage arc band 5t is one end of the arc band 5n formed so as to constitute a part of circle located at the third position from the inside (with the center located at the center of the plate-shaped ceramic member 2), with the other end of the arc band 5n being connected to one end of the turn-back linkage arc band 5u. Connected to the other end of the turn-back linkage arc band 5u is one end of the arc band 5p that is formed so as to constitute a part of circle located at the fourth position from the inside (the outermost circle in the example shown in FIG. 2, with the center located at the center of the plate-shaped ceramic member 2), with the other end of the arc band 5p being connected to one end of the turn-back linkage arc band 5v. Connected to the other end of the turn-back linkage arc band 5v is one end of the arc band 5o that is formed so as to constitute a part of circle located at the third position from the inside, with the other end of the arc band 5o being connected to one end of the turn-back linkage arc band 5s. Connected to the other end of the turn-back linkage arc band 5s is one end of the arc band 5m that is formed so as to constitute a part of circle located at the second position from the inside, with the other end of the arc band 5m being connected to one end of the turn-back linkage arc band 5r. Connected to the other end of the turn-back linkage arc band 5r is the arc band 5j that is formed so as to constitute a part of the innermost circle, with the other end of the arc band 5j being formed as the power feeder section.

As described above, the resistive heating member 5 is a long band of heat generating member constituted from the plurality of arc bands 5i through 5p arranged to constitute concentric circles and the turn-back linkage arc bands 5q through 5v that connect adjacent ones of the arc bands 5i through 5p, that are disposed on circles of different radii, with each other in series, and both ends (arc bands 5i, 5j) form the power feeder sections 6.

In the first embodiment, since the resistive heating member 5 is formed by disposing each of the pairs of the arc band 5i and the arc band 5j, the arc band 5k and the arc band 5m and the arc band 5n and the arc band 5o so as to constitute a circle, with the arc band 5p also constituting a circle, while the circles are disposed concentrically, concentric temperature distribution patterns can be formed to repeat from the center of the mount surface 3 to the circumference by energizing the resistive heating member 5.

The first embodiment is characterized in that distances L1, L2 and L3 of the adjacent pair of the turn-back linkage arc band 5q and the turn-back linkage arc band 5r, the pair of the turn-back linkage arc band 5s and the turn-back linkage arc band 5t and the pair of the turn-back linkage arc band 5u and the turn-back linkage arc band 5v, respectively, are set to be smaller than the distances L4, L5 and L6 between the arc bands 5i through 5p that are located adjacent to each other in the radial direction.

This constitution enables it to generate the same amount of heat per unit volume from the turn-back linkage arc bands 5q through 5v as well as from the arc bands 5i through 5p, thereby to improve the uniformity of heating the mount surface 3 (uniform temperature distribution over the mount surface 3). In the prior art, the distances L1, L2 and L3 of the adjacent pairs of the turn-back linkage arc band 5q through the turn-back linkage arc band 5v are set to be equal to the distances L4, L5 and L6 between the turn-back arc bands 5i through 5p that are located adjacent to each other in the radial direction. With such a constitution, since heat is generated with lower density in the turn-back linkage portion (hereinafter referred to simply as the turn-back region) P5 that connect the arc bands 5i through 5p and the turn-back linkage arc band 5q through the turn-back linkage arc band 5v, temperature becomes lower in the outside of the turn-back region P5, resulting in larger temperature difference across the surface of the wafer W, thus impairing the uniform heating performance.

According to the present invention, in contrast, since the distances L1, L2 and L3 of the adjacent pair of the turn-back linkage arc bands 5q through 5v located on the same circle are made smaller than the distances L4, L5 and L6 between the arc bands 5i through 5p that are located adjacent to each other in the radial direction, shortage in heat generated from the turn-back region P5 is compensated for by the heat generated by the turn-back linkage arc bands 5q through 5v, thus enabling it to avoid temperature decrease in the turn-back region P5. As a result, temperature difference across the surface of the wafer W that is placed on the mount surface 3 can be decreased and uniformity of heating can be improved.

Highest uniformity of heating by the mount surface 3 can be achieved by setting the distances L1, L2 and L3 of the adjacent pair of the turn-back linkage arc bands 5q through 5v located on the same circle in a range from 30 to 80% of the distances L4, L5 and L6 between the arc bands 5i through 5p that are located adjacent to each other in the radial direction, more preferably setting L1, L2 and L3 in a range from 40 to 60% of L4, L5 and L6.

Also according to the present invention, since the resistive heating member 5 is constituted from the arc bands 5i through 5p and the turn-back linkage arc bands 5q through 5v, it is less probable that an excessive stress is generated in the edges than in the case of the rectangular turn-back resistive heating member of the prior art, and the heater 1 that has higher reliability can be provided wherein the plate-shaped ceramic member 2 and the resistive heating member 5 are less likely to break even when temperature of the heater 1 is raised or lowered at a high rate.

In the first embodiment, it is preferable for the form of the resistive heating member shown in FIG. 2 that the distance L4 between the innermost circle whereon the arc band 5i and the arc band 5j are disposed and the circle located at the second position from the inside whereon the arc band 5m and the arc band 5k are disposed, the distance L5 between the second circle and the circle located at the third position from the inside whereon the arc band 5n and the arc band 5o are disposed and the distance L6 between the third circle and the circle located at the outermost position whereon the arc band 5p is disposed are set substantially equal.

When the arc bands are disposed at substantially equal intervals in the radial direction as described above, it is made possible to generate the same amount of heat per unit volume from the arc bands 5i through 5p, thereby to suppress the unevenness of heating the mount surface 3 in the radial direction.

The effect of the constitution of the resistive heating member 5 described above is obtained, in addition to the case where the resistive heating member is embedded in the plate-shaped ceramic member, also in case the resistive heating member is provided on the other principal surface of the plate-shaped ceramic member 2. When the band-shaped resistive heating member 5 is provided on the other principal surface of the plate-shaped ceramic member 2, in particular, greater effect of preventing the plate-shaped ceramic member 2 and the resistive heating member 5 from breaking can be achieved by over-coating an insulation film on the resistive heating member 5.

The resistive heating member may also be constituted from a plurality of heating members that can be heated independently in a concentric configuration. In this case, it is preferable to set the distance between the outermost band of the resistive heating member and the band located inside thereof in the concentric configuration smaller than the distance of the band located inside thereof. The resistive heating member 5 having such a constitution makes it easier to replenish heat to the periphery of the plate-shaped ceramic member 2 from which heat is dissipated at a higher rate, thereby preventing the periphery of the wafer W from becoming lower in temperature.

In the heater 1 of the first embodiment, it is preferable to divide the resistive heating member into a plurality of ring-shaped resistive heating member zones disposed in a concentric configuration with the center located at the center axis of the wafer W that is placed on the mount surface 3. This is because, while heating of the surface of a disk-shaped wafer W is subjected to the influences of the atmosphere around the wafer W, wall surface that opposes the wafer W and the gas flow, the wall surface surrounding the wafer W, the surface that oppose the top surface of the wafer and the flow of the ambient gas are designed in centrally symmetric configuration so as to prevent the temperature from varying across the surface of the disk-shaped wafer W. Uniformly heating the wafer W requires the heater 1 to be designed to match the centrally symmetric environment with respect to the wafer W, and it is preferable to divide the mount surface 3 radially into resistive heating member zones 4 in centrally symmetric configuration.

In order to heat a wafer w of 300 mm or more in diameter with uniform temperature distribution across the surface, in particular, it is preferable to divide the mount surface 3 into three ring-shaped resistive heating member zones in concentric configuration.

FIG. 3A shows a preferable example of dividing into a plurality of resistive heating member zones 4. In this preferable example of zone division, the mount surface is divided into resistive heating member zone 4a of circular or ring shape located at the innermost position and three ring-shaped resistive heating member zones 4b, 4cd, 4eh located concentrically on the outside thereof. In this example, the resistive heating member 5 is divided into four resistive heating member zones so as to improve the performance of uniformly heating the wafer W.

In order to minimize the temperature difference across the surface of the wafer W, it is preferable to set the outer diameter D1 of the resistive heating member zone 4a located at the center of the heater 1 in a range from 20 to 40% of the outer diameter D of the ring-shaped resistive heating member zone 4eh located along the periphery, outer diameter D2 of the resistive heating member zone 4b located outside thereof in a range from 40 to 55% of the outer diameter D of the ring-shaped resistive heating member zone 4eh located along the periphery, and the inner diameter D0 of the ring-shaped resistive heating member zone 4eh located at the outermost position in a range from 55 to 85% of the outer diameter D of the ring-shaped resistive heating member zone 4eh located at the outermost position.

The outer diameter of the resistive heating member zone means the diameter of the circle that is circumscribed to the outermost arc band of the resistive heating member formed in the resistive heating member zone. The inner diameter of the resistive heating member zone means the diameter of the circle that is inscribed to the innermost arc band of the resistive heating member formed in the resistive heating member zone. Definition of the circumscribed circle and the inscribed circle is made by using the arc section excluding the protruding portions of the resistive heating member such as power feeder section.

When the outer diameter D1 is less than 20% of D, temperature of the mid portion of the resistive heating member zone 4a would not rise sufficiently even if the resistive heating member zone 4a is caused to generate more heat, due to the small outer diameter of the central resistive heating member zone 4a. When the outer diameter D1 is more than 40% of D, temperature of the resistive heating member zone 4a would become too high along the periphery thereof as the temperature of the mid portion of the resistive heating member zone 4a is raised, due to the large outer diameter of the resistive heating member zone 4a located at the center. The outer diameter D1 is preferably in a range from 20% to 30% of D, and more preferably from 23% to 27%, which makes it possible to further decrease the temperature difference across the surface of the wafer W.

When the outer diameter D2 is less than 40% of the outer diameter D, since the heater 1 tends to cool down along the periphery, an attempt to prevent temperature of the wafer W along the periphery thereof from decreasing by causing the ring-shaped resistive heating member zone 4cd to generate more heat would result in higher temperature of the ring-shaped resistive heating member zone 4cd in an inner portion thereof nearer to the center of the wafer W, thus increasing the temperature difference across the wafer surface. When the outer diameter D2 is more than 55% of the outer diameter D, an attempt to prevent the temperature of the wafer W along the periphery thereof from decreasing by causing the ring-shaped resistive heating member zone 4cd to generate more heat raises the temperature of the ring-shaped resistive heating member zone 4cd although the effect of decreasing the temperature of the wafer W along the periphery thereof reaches the ring-shaped resistive heating member zone 4b, thus resulting in lower temperature of the ring-shaped resistive heating member zone 4b along the periphery thereof. The outer diameter D2 is preferably in a range from 41% to 53% of the outer diameter D, and more preferably from 43% to 49%, which makes it possible to further decrease the temperature difference across the wafer surface.

When the outer diameter D3 is less than 55% of the outer diameter D, since the heater 1 tends to cool down along the periphery thereof, an attempt to prevent the temperature of the wafer W along the periphery thereof from decreasing by increasing heat generation from the ring-shaped resistive heating member zone 4eh would result in higher temperature of the ring-shaped resistive heating member zone 4eh in the inner portion thereof nearer to the center of the wafer W, thus increasing the temperature difference across the surface of the wafer W. When the outer diameter D3 is more than 85% of the outer diameter D, an attempt to prevent the temperature of the wafer W along the periphery thereof from decreasing by causing the ring-shaped resistive heating member zone 4eh to generate more heat raises the temperature of the ring-shaped resistive heating member zone 4eh although the effect of decreasing the temperature of the wafer W along the periphery thereof reaches the ring-shaped resistive heating member zone 4cd, thus resulting in lower temperature of the ring-shaped resistive heating member zone 4cd along the periphery thereof. The outer diameter D3 is preferably in a range from 65% to 85% of the outer