Title: Susceptor supporting construction
Abstract: A susceptor supporting construction has a susceptor for heating a member to be processed and a supporting member, in which an inner space is arranged, connected to the susceptor. A chamber having an opening is connected to the supporting member, the opening of the chamber is communicated with the inner space of the supporting member, and the inner space of the supporting member is sealed in an airtight manner with respect to an inner space of the chamber. The supporting member further has a tubular main portion, a diameter extending portion arranged at an end portion thereof to which the susceptor is faced, and one or more continuous round portions arranged between the main portion and the diameter extending portion, when viewed by an outer profile of a longitudinal section of the supporting member.
Patent Number: 6,997,993 Issued on 02/14/2006 to Yamaguchi,   et al.
| Inventors:
|
Yamaguchi; Kazuaki (Nagoya, JP);
Goto; Yoshinobu (Nagoya, JP)
|
| Assignee:
|
NGK Insulators, Ltd. (Nagoya, JP)
|
| Appl. No.:
|
068791 |
| Filed:
|
February 6, 2002 |
Foreign Application Priority Data
| Feb 09, 2001[JP] | 2001-033809 |
| Current U.S. Class: |
118/728; 118/725; 118/500; 361/234; 219/444.1; 219/544; 156/345.51; 156/345.52; 279/128 |
| Current Intern'l Class: |
H01L 21/00 (20060101); C23C 16/00 (20060101) |
| Field of Search: |
118/728,725,500
156/345.51,345.52
361/234
279/128
219/444.1,544
|
References Cited [Referenced By]
U.S. Patent Documents
| 5688331 | Nov., 1997 | Aruga et al.
| |
| 6423949 | Jul., 2002 | Chen et al.
| |
| 2003/0183340 | Oct., 2003 | Yamaguchi et al.
| |
| 2003/0183341 | Oct., 2003 | Yamaguchi et al.
| |
| Foreign Patent Documents |
| 8-73280 | Mar., 1996 | JP.
| |
Primary Examiner: Hassanzadel; P.
Assistant Examiner: Kackar; Ram N
Attorney, Agent or Firm: Burr & Brown
Claims
What is claimed is:
1. A susceptor supporting construction comprising a susceptor for heating a member
to be processed and a supporting member, in which an inner space is arranged, connected
to one another, a chamber having an opening connected to the supporting member,
the opening of the chamber being in communication with the inner space of the supporting
member, and the inner space of the supporting member being sealed in an airtight
manner with respect to an inner space of the chamber, said supporting member further
comprising a first wall portion defining a tubular main portion, a second wall
portion defining a diameter extending portion arranged at an end portion thereof,
the entirety of said second wall portion being joined to the susceptor, and one
or more continuous round portions arranged between the main portion and the diameter
extending portion, when viewed by an outer profile of a longitudinal section of
the supporting member, wherein a portion of an outer surface of said second wall
portion is substantially parallel to a portion of an outer surface of said first
wall portion, the radial thickness of said first wall portion is less than the
radial thickness of said second wall portion, and an inner surface of the supporting
member has a substantially constant diameter along the entire length of the supporting
member and wherein said first wall portion, said second wall portion and said one
or more continuous round portions define a one-piece structure.
2. The susceptor supporting construction according to claim 1, wherein a curvature
radius of the round portion is not less than 3 mm and not more than 30 mm.
3. The susceptor supporting construction according to claim 1, wherein a straight
portion extending in a direction crossing to a center axis of the supporting member
is arranged between the diameter extending portion and the round portion, when
viewed by an outer profile of a longitudinal section of the supporting member.
4. The susceptor supporting construction according to claim 1, wherein an another
round portion is arranged between the diameter extending portion and a surface
of the susceptor, when viewed by an outer profile of a longitudinal section of
the supporting member.
5. The susceptor supporting construction according to claim 4, wherein at least
a part of the another round portion is formed to the susceptor.
6. The susceptor supporting construction according to claim 1, wherein an outer
side surface of the diameter extending portion is extended in a direction substantially
parallel to a center axis of the supporting member, when viewed by an outer profile
of a longitudinal section of the supporting member.
7. The susceptor supporting construction according to claim 1, wherein a material
of the susceptor or the supporting member is ceramics.
8. The susceptor supporting construction according to claim 1, wherein said supporting
member is an integral body including said first wall portion, said second wall
portion and said one or more continuous round portions.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a susceptor supporting construction used for
attaching a susceptor to a chamber.
2. Prior Art Statement
In a semiconductor manufacturing application and so on, as shown, for example,
in FIG. 6, it is necessary to attach a ceramic susceptor
2 to an inner wall
surface of a chamber
10. In order to achieve such an attachment, one end
21a of a tubular supporting member
21 made of ceramics is
attached to a contacting surface (rear surface)
2b of the ceramic
susceptor
2, and the other end
21c of the supporting member
21 is attached to an inner wall surface
10d of the chamber
10. The supporting member is formed by heat resistive ceramics such as alumina,
aluminum nitride and so on. An inner space
6 of the supporting member
21
is communicated with an opening
10a of the chamber
10. A portion
between the supporting member
21 and the chamber
10 is sealed in
an airtight manner by using an O-ring
20. In this manner, a portion between
the inner space
6 of the supporting member
21 and an inner space
5 of the chamber
10 can be sealed in an airtight manner, so that
a gas in the inner space
5 of the chamber
10 is not leaked outside
of the chamber
10. In the ceramic susceptor
2, for example, a resistant
heating member
4 is embedded.
A temperature of a mount surface (heating surface)
2a of the ceramic
susceptor
2 for mounting a semiconductor wafer
1 reaches to a temperature
for example, not less than 400° C. and sometimes not less than 600° C.
On the other hand, a sealing member made of rubber such as the O-ring
20
and so on is unendurable for high temperatures, and a heat-resistant temperature
of the sealing member is normally about 200° C. Therefore, it is preferred
to control a temperature near the O-ring
20 to be not more than 200°
C. by cooling a portion near the O-ring
20 by means of a cooling flange
8 arranged in the chamber
10.
However, in this embodiment, a temperature of the ceramic susceptor
2
becomes high as mentioned above, and a temperature of the one end
21a
of the supporting member
21 exceeds for example 400° C., while
a temperature of the other end
21c of the supporting member
21
is cooled to not more than 200° C. In this case, a temperature gradient in
an inner portion of the supporting member becomes not less than 200° C.
In order to improve a connection strength of the supporting member with respect
to the susceptor and to arrange gas holes and through holes for passing a terminal
or a thermocouple in a wall surface of the supporting member
21, it is necessary
to make a thickness of the supporting member
21 more thicker so as to increase
a contacting area of the supporting member
21 with respect to the susceptor.
However, if the supporting member becomes thicker, a heat conduction amount propagated
through the supporting member becomes larger due to a temperature gradient in the
supporting member mentioned above. As a result, a cold spot is generated to the
heating surface
2a by a heat conduction increase near the connecting
portion (one end)
21a of the supporting member. Therefore, it is
effective to make a main portion of the supporting member thin and to arrange a
thick extending portion (flange portion) to the supporting member at which a side
end portion of the susceptor is faced.
However, if such a thick flange portion is arranged to an end portion of
the supporting member, in the case that the susceptor is heated to high temperatures,
there is a tendency such that an inner stress concentrated at near the boundary
between the main portion and the flange portion becomes excessive. Therefore, in
order to prevent a failure of the supporting member, it is necessary to set an
upper limit temperature of the susceptor.
SUMMARY OF THE INVENTION
An object of the present invention is to provide a susceptor supporting construction
having a susceptor for heating a member to be processed and a supporting member,
in which an inner space is arranged, connected to the a susceptor. A chamber having
an opening is connected to the supporting member; and the opening of the chamber
is in communication with the inner space of the supporting member; In this manner,
the inner space of the supporting member is sealed in an airtight manner with respect
to the inner space of the chamber, which can suppress a heat conducted from the
susceptor to the support member and can reduce a stress concentrated to the susceptor
when the susceptor becomes heated to a high temperature.
According to the invention, a susceptor supporting construction having
a susceptor for heating a member to be processed and a supporting member, in which
an inner space is arranged, are connected to one another. A chamber having an opening
is connected to the supporting member, and the opening of the chamber is in communication
with the inner space of the supporting member, and the inner space of the supporting
member is sealed in an airtight manner with respect to an inner space of the chamber.
The supporting member further includes a tubular main portion, a diameter extending
portion arranged at an end portion thereof to which the susceptor is faced, and
one or more continuous round portions arranged between the main portion and the
diameter extending portion, when viewed by an outer profile of a longitudinal section
of the supporting member.
The diameter extending portion means a portion at which an outer diameter is
larger than that of the main portion.
A phrase "one or more continuous round portions arranged between the main portion
and the diameter extending portion" means that at least one round portion is arranged
between the main portion and the diameter extending portion. The number of the
round portions is defined by the number of centers of curvature. If the center
of curvature is one, the round portion corresponding to the center of curvature
is also one. If the round portions are two, there are centers of curvature corresponding
to respective round portions.
Moreover, the present invention includes a case such that a plurality of
round portions are arranged continuously. Here, a term "a plurality of round portions"
means a plurality of round portions having different centers of curvature. Moreover,
a phrase "a plurality of round portions are arranged continuously" means that a
plurality of round portions are arranged continuously without arranging a portion
such as line portion, straight portion and step portion other than the round portion
between round portions. In this case, respective curvature radii of the round portions
may be different, and also they may be the same.
It should be noted that a case such that another round portions is arranged between
the diameter extending portion and the susceptor is not excluded.
BRIEF DESCRIPTION OF THE DRAWING
For a better understanding of the invention, reference is made to the attached
drawings, wherein:
FIG. 1 is a cross sectional view showing one embodiment of a susceptor supporting
construction according to the invention;
FIG. 2 is an enlarged cross sectional view illustrating a connection portion
between a supporting member 7 and a susceptor 2 in the construction
shown in FIG. 1;
FIG. 3 is a further enlarged cross sectional view depicting one part of the
construction shown in FIG. 2;
FIG. 4 is a cross sectional view showing another embodiment of a susceptor supporting
construction according to the invention;
FIG. 5 is a cross sectional view illustrating one embodiment of a susceptor
supporting construction without a scope of the invention; and
FIG. 6 is a cross sectional view depicting another embodiment of a susceptor
supporting construction without a scope of the invention.
DETAILED DESCRIPTION OF THE INVENTION
The present invention will be explained with reference to embodiments shown in
FIGS. 1-3. A diameter extending portion
7a is arranged at one end
of a tubular supporting member
7, and a diameter extending portion
7c
is arranged at the other end thereof. A connecting surface (end surface)
7e
of the diameter extending portion
7a is connected to a connecting
surface (rear surface)
2b of a susceptor
2. An end surface
7g of the diameter extending portion
7c is connected
to an inner wall surface
10d of a chamber
10. An inner space
6 of the supporting member
7 is communicated with an opening
10a
of the chamber
10. A portion between the supporting member
7
and the chamber
10 is sealed in an airtight manner by means of an O-ring
(sealing member)
20. A numeral
7d is an inner profile of a
longitudinal section of the supporting member
7, and numeral
7f
is an outer profile thereof.
A connecting method between the supporting member and the susceptor is not particularly
limited. For example, it is possible to connect them by means of a brazing material
or to connect them in a solid phase or a solid-liquid phase as shown in JP-A-8-73280.
An uppermost temperature of a heating surface
2a of the susceptor
2 reaches to. for example, not less than 400° C. sometimes not less
than 600° C. and not more than 1200° C.
An outer space
11 of the chamber
10, the opening
10a
of
the chamber
10 and the inner space
6 of the supporting member
7
are communicated, while they are apart from an inner space
5 of the chamber
10. A portion near the sealing member
20 is cooled by arranging a
cooling flange
8 in the chamber
10, and a temperature near the sealing
member
20 is controlled to be not more than 230° C.
The supporting member
7 comprises a tubular main portion
7b,
the diameter extending portion
7a of a susceptor side and the
diameter extending portion
7c of a chamber side. The present invention
relates to the outer profile
7f of a longitudinal section of the
supporting member
7 existing from the main portion
7b to the
diameter extending portion
7a.
In the present invention, as shown in FIGS. 2 and 3, an outer profile of the
main
portion is substantially straight and an outer side surface
16 of the diameter
extending portion
7a is also substantially straight, while they are
substantially parallel to a center axis A of the supporting member
7. When
viewing the outer profile of the supporting member
7, it is understood that
a round portion
13 (
13A and
13B), a straight portion
14,
an angle portion
15, the outer side surface
16 of the diameter extending
portion
7a, a round portion
17 and a rear surface
18
of the susceptor are arranged in this order from the main portion
7b
to the susceptor
2. In this embodiment, a symbol R shows a curvature
radius of the round portion
13 (
13A and
13B), and a symbol
RE shows a curvature radius of the round portion
17.
During investigations of a construction for reducing a stress concentration
near the diameter extending portion, the present inventors found that specific
shapes shown in, for example. FIGS. 1-3 are particularly effective for this purpose.
That is, in the case that one round portion
13(
13A and
13B)
is arranged between the main portion
7b and the diameter extending
portion
7a, it was found that a stress concentration of the supporting
member could be effectively reduced and a temperature of the diameter extending
portion
7c of the chamber
10 side can be suppressed most effectively.
The present inventors performed various detailed investigations for the other
plural shapes by means of a simulation of inner stress of the supporting member.
For example, a supporting member
7A having a shape shown in FIG. 5 was investigated.
In this example, a first round portion
21, a straight portion
22.
an angle portion
23, a straight portion
24, a second round portion
25, a straight portion
26 and the angle portion
15 are arranged
from the main portion
7f and the outer side surface
16 of
the diameter extending portion
7a. Symbols R
1 and R
2
show respective curvature radii of the first round portion
21 and the second
round portion
25. The present inventors tried to reduce an inner stress
of the supporting member by arranging a plurality of round portions between the
main portion
7f and the diameter extending portion
7a as
mentioned above and by varying a curvature radius of respective round portions
variously. However, from a result of actual simulation, it was found that an inner
stress maximum value of the supporting member was extraordinarily decreased by
arranging a single round portion between the main portion
7f and
the diameter extending portion
7a as compared with the case such
that a number of the round portions were arranged so as to disperse a stress. In
this manner, the present invention has been achieved.
A curvature radius of the round portion
13 is not limited, but it is preferred
from a point of view of reducing an inner stress of the supporting member to set
this curvature radius to not less than 3 mm, more preferably not less than 5 mm
and most preferably not less than 10 mm.
Moreover, there is a tendency such that, if a curvature radius of the round
portion is increased, a heat amount conducted through the supporting member is
also increased. For example, in the embodiment shown in FIG. 3, a curvature radius
R of the round portion
13A shown by a solid line is relatively small, and
a curvature radius R of the round portion
13B shown by a dotted line is
relatively large. From a point of view of reducing an inner stress of the supporting
member
7, the round portion
13B having a large curvature radius is
preferred. However, if a curvature radius of the round portion is large, there
is a tendency such that a cross sectional area of the supporting member becomes
larger correspondingly and a temperature near the diameter extending portion
7c
(refer to FIG. 1) is increased. From a point of view of decreasing a temperature
near the chamber side end portion of the supporting member, it is preferred to
set a curvature radius of the round portion
13 to not more than 30 mm, more
preferably not more than 25 mm and most preferably not more than 20 mm. A most
preferable range of a curvature radius of the round portion
13 is 14-16 mm.
In the preferred embodiment of the present invention, as shown in, for examples
FIG. 3, a straight portion
14 extending in a direction crossing to the center
axis A of the supporting member
7 is arranged between the diameter extending
portion
7a and the round portion
13A (
13B) when viewing
the outer profile
7f of a longitudinal section of the supporting
member
7. By arranging the straight portion
14, it is possible to
make a thickness of the diameter extending portion
7a sufficiently
larger or to make a thickness of the main portion
7b sufficiently
smaller. For example, if the straight portion is not arranged in the embodiment
shown in FIG. 3, a thickness of the diameter extending portion
7a becomes
extraordinarily small.
An inclination angle θ of the straight portion
14 with respect to
the center axis A is not limited, but it is preferred from a point of view mentioned
above to set an inclination angle θ to 45-90 degrees.
Moreover, in the preferred embodiment, another round portion
17
is arranged between the diameter extending portion
7a and the surface
18 of the susceptor
2 when viewing the outer profile
7f
of a longitudinal section of the supporting member
7.
In this case, as shown in FIGS. 2 and 3, it is preferred to arrange at least a
part of another round portion
17 to the susceptor. In other words, it is
preferred to form a step (a) between the surface
18 of the susceptor
2
and the connecting surface
7e. Hereby, it is possible to reduce a
stress concentration of the connecting portion to the fullest extent.
In the present invention, as shown in FIG. 4, it is possible to arrange no step
portion between the connecting surface
7e and the surface (exposed
surface)
18 of the susceptor
2. In this case, if a round portion
17A is arranged, a thickness of the supporting member at the round portion
17A becomes extraordinarily small and irregular shape. Therefore, a stress
is easily concentrated near the round portion
17A or a film peeling easily
occurs from the round portion
17A.
The curvature radius RE of another round portion
17 (
17A) is preferably
set from a point of view of minimizing a stress at the connecting portion to not
less than 1 mm more preferably not less than 2 mm.
The step (a) is not limited, but it is preferred from a point of view of reducing
a stress at the connecting portion to set the step (a) to not less than 1 mm.
In the preferred embodiment, the outer profile
16 of the diameter extending
portion
7a is extended in a direction substantially parallel to the
center axis A of the supporting member
7. Increasing a length (b) of the
outer profile or outer surface
16 means increasing a thickness of the diameter
extending portion
7a. In this case, it was found that a stress near
the diameter extending portion could be further reduced by increasing the length
(b). From this point of view, it is preferred to set the length (b) to not less
than 2 mm, more preferably not less than 5 mm.
However, if the length (b) is made larger, there is a tendency such that
a heat conducted to the chamber through the supporting member
7 becomes
larger and a temperature of the chamber side end portion of the supporting member
is increased and sometimes exceeds a specified temperature (for example 200°
C.). Therefore, it is preferred to limit the length (b) to not more than 10 mm.
Materials of the susceptor and the supporting member are not limited, but
it is preferred to use ceramics. Moreover, it is preferred to use ceramics having
a corrosion resistance with respect to a halogen-series corrosive gas particularly
such as aluminum nitride or dense alumina, and further preferred to use aluminum
nitride ceramics or alumina having a relative density of not less than 95%.
The ceramic susceptor is heated by some kind of heating sources. In this case,
the heating sources are not limited, and use is made of the susceptor heated by
an external heating source (for example infrared lamp) and the susceptor heated
by an inner heating source (for example heater embedded in susceptor). In the susceptor,
it is possible to embed functional parts such as resistant heater, electrode for
electrostatic chuck, electrode for plasma generation and so on.
A material of the sealing member is not limited, but it is preferred to use O-ring
seal and metal-ring seal.
Experiment
EXAMPLES OF INVENTION 1-5
The susceptor supporting constructions explained with reference to FIGS. 1-3
were manufactured. As the susceptor 2, use was made of a disc made of aluminum
nitride sintered body having a diameter of 330 mm and a thickness of 15 mm. The
supporting member 7 was made of a dense aluminum nitride sintered body.
The supporting member 7 and the susceptor 2 were connected in solid
phase as described in JP-A-8-73280. The supporting member 7 and the chamber
10 were connected by means of screws. The O-ring 12 was made of fluorine rubber.
An overall length of the supporting member 7 was 180 mm and an inner diameter
of the supporting member 7 was 38 mm. A thickness of the main portion 7
b
was 8 mm and a thickness of the diameter extending portion 7
a was
8 mm. A curvature radius RE of the round portion 17 was 3 mm, the step (a)
was 2 mm, and a length (b) of the straight portion 16 was 15 mm. Curvature
radii R of the round portions 13 were shown in the following Table 1.
Under such a condition, assuming that a temperature of the mount surface 2
a
of the susceptor 2 was heated to about 600° C., a simulation was
performed. In this case, an inner stress of the supporting member 7 was
calculated along an overall portion thereof so as to obtain a maximum stress. In
addition, a temperature of the chamber side end portion 7
c of the
supporting member 7 was obtained.
| |
TABLE 1 |
| |
|
| |
|
|
Temperature of |
| |
Curvature radius R |
|
diameter extending |
| |
of round portion 13 |
Maximum stress |
portion 7c |
| |
(mm) |
(kgf/mm2) |
(° C.) |
| |
|
| |
| Example of invention 1 |
5 |
4.0 |
187 |
| Example of invention 2 |
10 |
3.0 |
192 |
| Example of invention 3 |
15 |
2.6 |
196 |
| Example of invention 4 |
20 |
2.3 |
200 |
| Example of invention 5 |
25 |
2.1 |
203 |
|
COMPARATIVE EXAMPLE 1
The susceptor supporting construction of the comparative example 1 shown in FIG.
5 was manufactured. The construction was basically same as that of the example
of invention 1, but round portions 21, 25, straight portions 22,
24, 26, and angle portions 23, 15 were arranged. A
curvature radius R1 of the round portion 21 was 5 mm and a curvature
radius R2 of the round portion 25 was 3 mm. As is the same as the
example of invention 1, a maximum stress and a temperature of the chamber side
end portion 7
c of the supporting member 7 were obtained. As
a result, the maximum stress was 3.2 kgf/mm
2 and the temperature of
the chamber side end portion 7
c was 180° C.
EXAMPLES OF INVENTION 6, 7
In the example of invention 6, the same construction as that of the example of
invention 1 was manufactured. However, a curvature radius RE of the round portion
17 was 3 mm, the step (a) was 2 mm, a length (b) of the straight portion
16 was 5 mm, and a curvature radius R of the round portion 13 was
15 mm. As a result, the maximum stress was 2.6 kgf/mm
2.
In the example of invention 7, the straight portion 16 was excluded from
the construction of the example of invention 6. As a result, the maximum stress
was 2.7 kgf/mm
2.
EXAMPLES OF INVENTION 8, 9
The same constructions as that of the example of invention 1 were constructed.
However, heights (b) of the straight portions 16 were varied as shown in
the following Table 2. With respect to respective constructions, a maximum stress
and a temperature of the end portion 7
c were calculated. The results
were shown in the following Table 2.
| |
TABLE 2 |
| |
|
| |
|
|
Temperature of |
| |
Height (b) of |
|
diameter extending |
| |
straight portion 16 |
Maximum stress |
portion 7c |
| |
(mm) |
(kgf/mm2) |
(° C.) |
| |
|
| |
| Example of invention 8 |
2 |
2.58 |
192 |
| Example of invention 9 |
12 |
2.48 |
207 |
|
As explained above, according to the invention, it is possible to suppress a
heat
conducted from the susceptor to the support member and to reduce a stress concentrated
to the susceptor when the susceptor becomes high temperatures.
*