Laminating method of film-shaped organic die-bonding material, die-bonding method, laminating machine and die-bonding apparatus, semiconductor device, and fabrication process of semiconductor Number:6,825,249 from the United States Patent and Trademark Office (PTO) owispatent Provided are a laminating method and machine for successively heating and compression-bonding a film-shaped organic die-bonding material on a leadframe.leadframe 7 is placed on a travelling table 8 and is heated there. A film-shaped organic die-bonding material 2 is punched out and the resulting film is tack-bonded to a die pad on the leadframe. The leadframe with the film tack-bonded thereon is then moved to a position B by the travelling table. After the film is pressed by a compression-bonding element at the position B, a chip is mounted on the film-shaped organic die-bonding material 2.It is therefore possible to bond a film-shaped organic die-bonding material under compression on a leadframe with good productivity but without voids and further to avoid package cracking upon mounting a chip.<H semiconductor, fabrication, Laminating, meth, 6825249.html, Patent, pto, 6825249

Title: Laminating method of film-shaped organic die-bonding material, die-bonding method, laminating machine and die-bonding apparatus, semiconductor device, and fabrication process of semiconductor

Abstract: Provided are a laminating method and machine for successively heating and compression-bonding a film-shaped organic die-bonding material on a leadframe.leadframe 7 is placed on a travelling table 8 and is heated there. A film-shaped organic die-bonding material 2 is punched out and the resulting film is tack-bonded to a die pad on the leadframe. The leadframe with the film tack-bonded thereon is then moved to a position B by the travelling table. After the film is pressed by a compression-bonding element at the position B, a chip is mounted on the film-shaped organic die-bonding material 2.It is therefore possible to bond a film-shaped organic die-bonding material under compression on a leadframe with good productivity but without voids and further to avoid package cracking upon mounting a chip.

Patent Number: 6,825,249 Issued on 11/30/2004 to Takeda, et al.

Inventors: Takeda; Shinji (Tsukuba, JP); Masuko; Takashi (Tsukuba, JP); Yusa; Masami (Shimodate, JP); Miyadera; Yasuo (Tsukuba, JP); Yamasaki; Mituo (Takahagi, JP); Maekawa; Iwao (Hitachi, JP); Kotato; Akio (Mito, JP); Miyamae; Yuusuke (Hitachi, JP); Satou; Tadaji (Takahagi, JP); Saitou; Makoto (Hitachi, JP); Kikuchi; Tooru (Hitachi, JP); Kageyama; Akira (Niiza, JP); Kaneda; Aizou (Yokohama, JP)
Assignee: Hitachi Chemical Co., Ltd. (Tokyo, JP)

Appl. No.: 616943

Filed: July 14, 2000

Related U.S. Patent Documents


Application Number	Filing Date	Patent Number	Issue Date
875330		6099678

Foreign Application Priority Data


Dec 26, 1994 [JP]			6-322779
Apr 28, 1995 [JP]			7-106016
Jul 10, 1995 [JP]			7-173493

Current U.S. Class: 523/218 ; 524/439; 524/440

Field of Search: 523/218 524/439,440

References Cited [Referenced By]

U.S. Patent Documents


3608054	September 1971	Alvine
4358581	November 1982	Sutton, Jr.
4460718	July 1984	Tanaka et al.
4581096	April 1986	Sato
4604230	August 1986	Goswami et al.
4656238	April 1987	Kunimune et al.
4755415	July 1988	Iijima et al.
4875279	October 1989	Sakiadis
4933219	June 1990	Sakumoto et al.
4965331	October 1990	Jackson et al.
4985105	January 1991	Masuda
5141050	August 1992	Schuft
5145099	September 1992	Wood et al.
5177032	January 1993	Fogal et al.
5204399	April 1993	Edelman
5234522	August 1993	Suzuki et al.
5238730	August 1993	Hanawa et al.
5250637	October 1993	Shiobara et al.
5277972	January 1994	Sakumoto et al.
5296567	March 1994	Baumann et al.
5319005	June 1994	Hagiwara et al.
5360942	November 1994	Hoffman et al.
5406124	April 1995	Morita et al.
5432380	July 1995	Jin et al.
5476908	December 1995	Kishi et al.
5512628	April 1996	Sakumoto et al.
5528075	June 1996	Burns
5605763	February 1997	Yusa et al.
5635009	June 1997	Kawamura et al.
5659004	August 1997	Takigawa et al.
5667899	September 1997	Yusa et al.
5698891	December 1997	Tomita et al.
5728473	March 1998	Inoue et al.
5793099	August 1998	Murakami et al.
5827908	October 1998	Arai et al.
5837368	November 1998	Hiroe et al.
5985458	November 1999	Angelopoulos et al.
5989459	November 1999	Nguyen et al.
6046072	April 2000	Matsuura et al.
6201945	March 2001	Schlueter
6248613	June 2001	Matsuura et al.
6372080	April 2002	Matsuura et al.
2001/0015484	August 2001	Matsuura et al.

Foreign Patent Documents


0 271 736	Jun., 1988	EP
0 285051	Oct., 1988	EP
0 618 614	Oct., 1994	EP
0 775 716	May., 1997	EP
0 837 498	Apr., 1998	EP
A-54-12266	Jan., 1979	JP
54-12266	Jan., 1979	JP
54-138371	Oct., 1979	JP
A-54-138371	Oct., 1979	JP
58-57730	Apr., 1983	JP
58-222530	Dec., 1983	JP
60-145630	Aug., 1985	JP
60-145630	Aug., 1985	JP
60-38825	Apr., 1986	JP
62-141038	Sep., 1987	JP
63-289822	Nov., 1988	JP
S64-9226	Jan., 1989	JP
64-22744	Feb., 1989	JP
1-165635	Nov., 1989	JP
H2-168636	Jun., 1990	JP
61-19735	Jun., 1990	JP
H2-246125	Oct., 1990	JP
2-256251	Oct., 1990	JP
02-256251	Oct., 1990	JP
A-2-256251	Oct., 1990	JP
3-228	Jan., 1991	JP
4-3438	Jan., 1992	JP
04-227782	Aug., 1992	JP
H5-117596	May., 1993	JP
5-125337	May., 1993	JP
H5-152355	Jun., 1993	JP
5-152386	Jun., 1993	JP
5-190022	Jul., 1993	JP
5-218107	Aug., 1993	JP
5-152466	Oct., 1993	JP
H5-331424	Dec., 1993	JP
5-331424	Dec., 1993	JP
H5-331425	Dec., 1993	JP
5-335379	Dec., 1993	JP
06-104300	Apr., 1994	JP
6-104300	Apr., 1994	JP
6-145639	May., 1994	JP
H6-151478	May., 1994	JP
H6-172714	Jun., 1994	JP
6-204264	Jul., 1994	JP
H6-218880	Aug., 1994	JP
6-218880	Aug., 1994	JP
H6-248241	Sep., 1994	JP
H6-256733	Sep., 1994	JP
H6-264035	Sep., 1994	JP
6-264035	Sep., 1994	JP
06-326240	Nov., 1994	JP
H7-22441	Jan., 1995	JP
7-90239	Apr., 1995	JP
H7-90244	Apr., 1995	JP
H7-171154	Jul., 1995	JP
H7-242820	Sep., 1995	JP
3117966	Oct., 2000	JP
3117971	Oct., 2000	JP
3117971	Oct., 2000	JP
3117972	Oct., 2000	JP
3215014	Jul., 2001	JP
WO 94/21744	Sep., 1994	WO

Other References

Y Sakamoto et al., "New Type Film-Adhesives for Microelectronics Application," 92 Proceedings of 42nd Electronic Components & Technology Conference, May 18-20, 1992 (New York: The Institute of Electrical and Electronics Engineers, Inc., 1992): pp. 215-218. .
Osaka City Industrial Research Institute et al. ed., Table: List of Properties of Major Thermosetting and Thermoplastic Resins, Plastic Reader 15th Edition (Japan: Plastic Age, Inc., 1987). .
Shinji Takeda et al., "Die Bonding Adhesive Film," Hitachi Chemical Technical Report No. 24 (Jan. 1995) (Tokyo: Hitachi Chemical Co. Ltd.). .
Fig. 1 (Water absorption (volume %), Saturation moisture absorption). .
Surface Energy, p. 538, Chemical Dictionary 7, Kyoritsu Publishing Co. .
Thermodynamic equibrium of wetting, p. 1235, Chemical Handbook Applied Chemistry II, Oct. 15, 1986, Maruzen Co. .
Japanese Appln. No. 2000-346979--Notice of Reason for Refusal mailed on Oct. 22, 2002 together with English Translation (Refs. X-AH Related). .
References cited in an opposition in Japanese Patent No. 3215014 (Refs. AI-AT and AU-AW and AZ). .
"Rubber Elastomer Utility Notes", relates to types of rubber and their chemical structure and properties, Jul. 20, 1991. .
Opposition raised against Japanese Patent No. 3187400..

Primary Examiner: Cain; Edward J.
Attorney, Agent or Firm: Griffin & Szipl, P.C.

Parent Case Text

The present application is a continuation of patent application Ser. No. 08/875,330, filed Jun. 25, 1997, now U.S. Pat. No. 6,099,678 which is a 371 of PCT/JP95/02691 filed Dec. 26, 1995.

Claims

What is claimed is:

1. A material comprising an organic die-bonding film having a surface energy of at least 40 erg/cm.sup.2 and a residual volatile component in an amount of not more than 3.0% by weight.

2. A material according to claim 1, said film having a water absorption of 1.5% by volume or less.

3. A material according to claim 1, said film having a saturation moisture absorption of 1.0% by volume or less.

4. A material according to claim 3, said film having a residual volatile component in an amount of not more than 3.0% by weight.

5. A material according to claim 1, said film having a peel strength of 0.5 kgf/5 mm.times.5 mm chip or higher when a semiconductor has been bonded to a support member using said material.

6. A material according to claim 3, said film having a peel strength of 0.5 kgf/5 mm.times.5 mm chip or higher when a semiconductor has been bonded to a support member with said material.

7. A material according to claim 1, said film having a peel strength of 0.5 kgf/5 mm.times.5 mm chip or higher when a semiconductor has been bonded to a support member with said material.

8. A material according to claim 4, said film having a peel strength of 0.5 kgf/5 mm.times.5 mm chip or higher when a semiconductor has been bonded to a support member with said material.

9. A material according to claim 1, said film having a void volume of 10% or less in terms of voids present in the material and at an interface between said material and a support member when a semiconductor has been bonded to said support member.

10. A material according to claim 1, said film comprising at least one component selected from an epoxy resin and a polyimide resin.

11. A material according to claim 1, further comprising a metal filler.

12. A material according to claim 11, said metal filler comprising a silver.

13. A material according to claim 1, further comprising an inorganic filler.

14. A semiconductor device, comprising: a semiconductor chip; a support; and an organic die bonding film having a surface energy of at least 40 erg/cm.sup.2 bonding the semiconductor chip to the support.

15. A semiconductor device according to claim 14, wherein said film has a water absorption of 1.5% by volume or less.

16. A semiconductor device according to claim 14, wherein said film has a saturation moisture absorption of 1.0% or less.

Description

TECHNICAL FIELD

This invention relates to a laminating method of a film-shaped organic die-bonding material, a die-bonding method, a laminating machine and a die-bonding apparatus for the bonding of a semiconductor element (hereinafter referred to as "chip") onto a support member such as a leadframe using the film-shaped organic die-bonding material.

BACKGROUND ART

As a method for bonding a chip on a leadframe, it has heretofore been the practice to feed a die-bonding material onto the leadframe and then to bond the chip onto the leadframe. As such die-bonding materials, Au--Si eutectic, solders, resin pastes and the like are known, for example. Among these, Au--Si eutectic has the problems that it is costly and has a high modulus of elasticity and requires vibrations at portions to be bonded. Solders involve the problems that they cannot withstand temperatures equal to and higher than their melting point and they have a high modulus of elasticity. Of resin pastes, silver paste is most common. Compared with other materials, silver paste is most inexpensive and has high heat-resistant reliability and a low modulus of elasticity, which means that silver paste is used most often as a bonding material for IC and LSI leadframes.

Reflecting the high densification and the move toward larger chips in recent years, it has however become increasingly difficult to evenly coat silver paste over an entire surface upon bonding. Unless resin paste can be coated evenly, voids occur in bonded parts and upon mounting, they cause package cracking during the course of soldering heat treatment. Occurrence of such voids has therefore become a problem.

Further, there has been an ever-increasing demand in recent years for high-density mounting to meet the move toward smaller and/or thinner electronic equipment. Replacing semiconductor packages of the conventional pin insertion type, surface-mount semiconductor packages suited for high-density mounting have come into mainstream use.

In the case of a surface-mount package, leads are directly soldered to a printed circuit board or the like. Therefore, using infrared reflowing, vapor phase reflowing, solder dipping or the like as a heating method, the package is heated in its entirety and is then mounted.

Here, the entire package is exposed to temperatures as high as 210 to 260.degree. C. If moisture exists inside the package, package cracking (hereinafter called "reflow cracking") occurs as a result of explosive vaporization of the moisture.

This reflow cracking significantly reduces the reliability of the semiconductor package to the extent that it has become a serious problem and the subject of technical attention.

The following is the mechanism of the occurrence of reflow cracking caused by a die-bonding material. In a semiconductor package, (1) the die-bonding material absorbs moisture during storage, (2) upon mounting the package by reflow soldering, the moisture is vaporized by heat, (3) destruction or separation of the die-bonding layer takes place due to the resulting vapor pressure, and (4) reflow cracking then occurs.

Under the current circumstances whereby sealing materials have been increasingly improved in reflow cracking resistance, reflow cracking which is caused by a die-bonding material has become a serious problem, especially in thin packages, leading to a strong demand for the improvement of reflow cracking resistance.

DISCLOSURE OF THE INVENTION

An object of the present invention is to provide a laminating method, a die-bonding method, a laminating machine and a die-bonding apparatus, which make it possible to fabricate, with good productivity, semiconductor packages which are free from package cracking and have excellent reliability.

Another object of the present invention is to provide a semiconductor device, which makes use of a film-shaped organic die-bonding material, is free from reflow cracking and has excellent reliability, and a fabrication process thereof.

In the present invention, a film-shaped organic die-bonding material is used. This is in the form of a film made primarily of an organic material such as an epoxy resin, silicone resin, acrylic resin or polyimide resin (including an organic material added with a metallic filler or an inorganic filler). On a support member such as a leadframe, the film-shaped organic die-boding material is compression-bonded in a heated state. Further, a chip is placed on the film-shaped organic die-bonding material, followed by heating and compression-bonding. Namely, a die-bonding material is evenly applied to a part, which is to be bonded, by forming a resin paste into a film. Such a film-shaped organic die-bonding material requires application of pressure so that the film-shaped die-bonding material is reliably provided with wettability to the chip and leadframe.

A film-shaped organic die-bonding material useful in the present invention can be produced, for example, by dissolving or dispersing an organic material such as a polyimide or epoxy resin and optionally, a material, for example, an additive such as a metallic filler in an organic solvent to form a coating varnish, coating the coating varnish onto a carrier film such as a biaxially-stretched polypropylene film, causing the solvent to evaporate to form a layer and then peeling off the layer from the carrier film. One side of the layer, the side having been in contact with the air in a drying step in which the solvent was caused to evaporate (i.e., the side being a side opposite to a side where the layer was in contact with the carrier film), will be referred to as the "side A", while the side at which the layer was in contact with the carrier film will be referred to as the "side B".

This invention provides a laminating method, die-bonding method, laminating machine and die-bonding apparatus for a film-shaped organic die-boding material, which are free from voids and feature good productivity and which are useful for applying the film-shaped organic die-bonding material to an actual assembly step for semiconductor devices.

The laminating method according to the present invention for a film-shaped organic die-bonding material comprises mounting and tack-bonding a film-shaped organic die-bonding material of a predetermined size on a chip-mounting support member at a predetermined position thereof and then pressing the die-bonding material against the support member, whereby the die-bonding material is compression-bonded on the support member.

The die-bonding method according to the present invention comprises mounting and tack-bonding a film-shaped organic die-bonding material of a predetermined size on a chip-mounting support member at a predetermined position thereof and then pressing the die-bonding material against the support member and compression-bonding the die-bonding material on the support member, thereby laminating the film-shaped organic die-bonding material of the predetermined size on the chip-mounting support member at the predetermined position thereof; and heating a chip and compression-bonding the chip on the film-shaped organic die-bonding material at a predetermined position thereof, the die-bonding material being located on the support member.

A first laminating machine according to the present invention comprises a feeder for feeding a film-shaped organic die-bonding material over a predetermined constant length, a punching device for punching out the film-shaped organic die-bonding material, a film tack-bonding device for placing and tack-bonding the punched-out film-shaped organic die-bonding material on the support member, and a film compression-bonding device for pressing the tack-bonded film-shaped organic die-bonding material against the support member so that the tack-bonded film-shaped organic die-bonding material is compression-bonded on the support member.

A second laminating machine according to the present invention comprises a feeder for feeding a film-shaped organic die-bonding material over a predetermined constant length, a cutter for cutting out the film-shaped organic die-bonding material, a film tack-bonding device for placing and tack-bonding the cut-out film-shaped organic die-bonding material on the support member at a predetermined position thereof, and a film compression-bonding device for pressing the tack-bonded film-shaped organic die-bonding material against the support member so that the tack-bonded film-shaped organic die-bonding material is compression-bonded on the support member.

The die-bonding apparatus according to the present invention comprises the above-described first or second laminating machine and a chip compression-bonding machine for heating a chip and compression-bonding the chip on a film-shaped organic die-bonding material at a predetermined position thereof, the die-bonding material being located on a support member.

An apparatus according to the present invention is constucted of a film feed-take-up unit for feeding a film-shaped organic die-bonding material over a predetermined constant length, a punching unit for accurately punching out the film-shaped organic die-bonding material, a provisional compression-bonding unit for provisionally compression-bonding the punched-out film-shaped organic die-bonding material on a leadframe (a film tack-bonding device for placing and tack-bonding the film-shaped organic die-bonding material on a support member at a predetermined position thereof), and a permanent compression-bonding unit for performing heating and compression-bonding subsequent to the provisional compression-bonding (a film compression-bonding device for pressing the tack-bonded film-shaped organic die-bonding material against the support member so that the die-bonding material is compression-bonded on the support member). As the film-shaped organic die-bonding material is supplied in a reeled form, the film feed-take-up unit is constructed of a mechanism for feeding the film from the reel and a mechanism for taking up the punched-out, remaining film. The punching unit is constructed of a die-punch mechanism for punching out the film. The provisional compression-bonding unit is constructed of a mechanism for holding the punched-out film-shaped organic die-bonding material on the leadframe at the predetermined position and tack-bonding it there (for placing the film-shaped organic die-bonding material on the support member at the predetermined position thereof and tack-bonding it there). The permanent compression-bonding unit is constructed of means for heating the leadframe and/or the film-shaped organic die-bonding material and a mechanism for permanently compression-bonding the film (for pressing the film-shaped organic die-bonding material against the support member and compression-bonding it there). Incidentally, these mechanisms and means may be arranged as an integrated apparatus. This means, for example, that the film punch could also act as a compression-bonding element for performing provisional compression-bonding. It is not particularly necessary to separate the mechanisms and means from one another insofar as the individual functions can be achieved.

A description will now be made with reference to FIGS. 1 to 4. At the film feed unit, a film-shaped organic die-bonding material (hereinafter abbreviated as the "film" in the description to be made with reference to FIGS. 1 to 4) 2 which has been supplied from a reel 1 is controlled so as to extend under a predetermined tension by a constant tension roller 10, a guide roller 12 and a feed roller 13, is intermittently fed at predetermined constant step pitches to pass through the punching unit, and is wound up on a take-up reel 3. The constant tension roller 10 can be constructed of an adjusting mechanism, which can control the tension of the film, and a powder brake, friction brake or the like, although it is not limited to such a construction. The feed roller 11 can be driven by a stepper motor or the like, which permits intermittent feeding of the film at predetermined constant step pitches, although the drive means for the feed roller is not limited thereto. The take-up reel 3 winds up the film which has been fed by the feed roller. As an appropriate tension upon feeding the film, a tension in a range of from 0.05 to 10 MPa is preferred. A tension lower than 0.05 MPa may result in slackness of on the film, thereby causing an offset in a transverse direction or a punching error. On the other hand, a tension higher than 10 MPa may stretch the film, so that a punching error may arise or, as the thickness of the film may become uneven due to its elongation, voids tend to occur. Further, the film will be broken if the tension exceeds the breaking strength of the film after its punching.

At the punching unit, the film 2 is punched out into a predetermined shape at the position of a die 6 when a punch 4 descends. It is preferred to adjust the tension of the film to 0.05 to 10 MPa before the film is punched out. A tension lower than 0.05 MPa is insufficient and may lower the accuracy at the time of punching. A tension higher than 10 MPa, on the other hand, may cause a deformation due to elongation of the film, so that the thickness of the film may become uneven and voids tend to occur.

The film 2 is held in place by a fixing punch 5 as needed. The punch 4 is provided with film suction-holding such as vacuum suction means. Owing to the provision of this means, the punched-out film is held under suction on the punch 4. It is preferred to provide two or more vacuum suction ports as the film suction-holding means, because use of only one vacuum suction port cannot hold the film still, leading to a reduction in positional accuracy. The size of each vacuum suction port may preferably be 2 mm or smaller in diameter. A diameter greater than 2 mm tends to leave a mark of the port on the film and also to form voids. At the provisional compression-bonding unit, a travelling table 8 with a leadframe 7 held thereon at a predetermined position thereof is kept stopped at a position A. After punching, the punch 4 with the film held thereon descends further to provisionally bond the film under compression on the leadframe. Provisional compression-bonding is performed as many times as needed in accordance with the number of patterns on the leadframe. A plan view of the leadframe is shown in FIG. 2.

Next, the travelling table is caused to move to a position B in the permanent compression-bonding unit. A heating unit is built in the travelling table to heat the leadframe at a predetermined temperature. Each film which has been provisionally compression-bonded on the leadframe is degasified and at the same time, permanently compression-bonded by a compression-bonding element 9 at the position B. To efficiently perform the degasification and the heating and compression-bonding, a surface of the compression-bonding element is preferably formed of a heat-resistant elastic piece, because the degasification cannot be achieved efficiently unless such an elastic piece is used. Further, it is preferred to configure the elastic piece so that its cross-sectional shape before compression-bonding centrally defines a curved convex surface, since the formation of the curved convex surface at the center makes it possible to carry out compression-bonding from the center so that each film can be compression-bonded without voids.

Examples of compression-bonding elements, which are each provided with such a curved convex surface, are shown in FIG. 3 and FIG. 4, respectively. In FIG. 3, an elastic piece 14 with a surface machined in a convex form is fixedly secured on a free end face of a compression-bonding element main body. In FIG. 4, a strip-shaped elastic piece 14 of a uniform thickness is fixedly secured extending from side walls of a compression-bonding element main body. Designated at numeral 15 is a fixing metal fitting. The compression-bonding element in FIG. 4 is constructed of the compression-bonding element main body having a smooth end face and the strip-shaped elastic piece covering a free end portion of the compression-bonding element main body. The strip-shaped elastic piece is pressed by the smooth end face of the core. The smooth end face of the compression-bonding element main body preferably has a profile irregularity of not greater than 15 .mu.m in terms of center line average height. Profile irregularity greater than 15 .mu.m in terms of center line average height may result in transfer of the ruggedness of the free end face of the compression-bonding element main body through the elastic piece so that voids may occur in some instances.

The Young's modulus of the elastic piece may preferably range from 0.2 to 50 MPa. A Young's modulus smaller than 0.2 MPa leads to an unduly soft elastic piece that may not fully press out voids. A Young's modulus greater than 50 MPa results in an excessively hard elastic piece that likewise may not fully press out voids. Usable for the elastic piece are rubbers such as silicone rubber, fluorine rubber, isobutylene-isoprene rubber and nitrile-butadiene rubber; plastic-modified rubbers each obtained by modifying with a plastic to control the modulus of elasticity; rubber-modified plastics each obtained by modifying with a rubber to control the modulus of elasticity; and the like. Other elastomers may also be used insofar as they are equipped with sufficient heat resistance. The elastic piece may preferably have surface smoothness not greater than 10 .mu.m in terms of center line average height. Surface smoothness greater than 10 .mu.m tends to result in the occurrence of voids.

As compression-bonding conditions for films, it is preferred to set the heating temperature and the compression-bonding force at 80 to 300.degree. C. and 0.03 to 2 MPa, respectively, so that necessary bonding strength can be obtained without allowing voids to remain. A heating temperature lower than 80.degree. C. may not permit successful heating and compression-bonding, while a heating temperature higher than 300.degree. C. is too high, and heating and compression-bonding cannot be performed well. Further, a compression-bonding force lower than 0.03 MPa is so low that voids may remain, while a compression-bonding force higher than 2 MPa is so high that the films may be deformed.

The leadframe with the film bonded thereon is passed to the next step, where a semiconductor element (chip) is heated, compression-bonded and then hardened so that the chip is firmly bonded. To perform this step, the same method as that commonly practiced using a resin paste can be adopted.

FIGS. 5 to 10 illustrate another apparatus according to the present invention, in which FIG. 5 is a front view, FIG. 6 is a plan view, FIG. 7 is a simplified plan view of a frame transporting rail unit, FIG. 8 is a simplified cross-sectional view of a feeder and a cutter, FIG. 9 is a simplified cross-sectional view of a film compression-bonding device for evenly pressing a film-shaped organic die-bonding material, and FIG. 10 is a plan view of a leadframe.

In FIGS. 5 through 10, there are shown a reel 21 of a film-shaped organic die-bonding material (hereinafter abbreviated as the "film"), a film-feeding pinch roller 22, a film-holding cylinder 23, a film-cutting cylinder 24, a frame-transporting actuator 25, frame-transporting rails 26, a film suction-holding pad feed cylinder 27, a preheater 28, a film-heating and bonding unit 29, a chip-heating and bonding unit 30, a heating and compression-bonding unit 31, a compression-bonded portion positioning device 32, a chip tray 33, a film suction-holding pad 34, a chip-bonding device 35, a film 36, a cutter 37, a heater block 38a for preheating each leadframe, a heater block 38b for heating and compression-bonding a film on each leadframe, a heater block 38c for heating and compression-bonding a chip on each film, a heater block 38d for heating each heated and compression-bonded chip again to achieve its permanent compression-bonding, a leadframe 39, a roller 40, and die pads 41 of the leadframe.

The film-shaped organic die-bonding material (film) is cut into a predetermined size by the cutter. The accuracy of machining steps such as cutting has been confirmed to be within .+-.200 .mu.m. If the cutting accuracy is lower than this level and the film is cut larger than the chip, the film is oversized and has a protrusion which becomes a starting point for the occurrence of cracks. A smaller film, on the other hand, results in reduced bonding properties.

The heater block (38a), which is provided to preheat the leadframe in the present invention, can heat the leadframe to an intended temperature in a short time when the leadframe has been moved to the heater block (38b) which serves to heat and bond the film-shaped organic die-bonding material under compression. In the present invention, the heater block (38a) for preheating the leadframe, the heater block (38b) for heating and compression-bonding the film-shaped organic die-bonding material on the leadframe, the heater block (38c) for heating and compression-bonding the chip on the film-shaped organic die-bonding material and the heater block (38d) for heating the heated and compression-bonded chip again and permanently compression-bonding the chip, the heater blocks being independently adjustable in temperature, can be independently set at different temperatures, whereby the film-shaped organic die-bonding material can be bonded under optimal temperature conditions.

The film compression-bonding device for evenly pressing the tack-bonded, film-shaped organic die-bonding material in the present invention, such as a roller device or the like, can prevent inclusion of bubbles or voids in a layer of the die-bonding material when the chip is bonded on the support member such as the leadframe, thereby making it possible to obtain uniform bonding properties of high reliability.

Preferred examples of the film compression-bonding device include rollers made of a metal, such as stainless steel, or TEFLON, and planar elastic bodies made of silicone rubber or the like. As the silicone rubber, heat-resistant silicone rubber of JIS-A 40 to 80 degrees in terms of the JIS hardness is preferred, with heat-resistant silicone rubber of JIS-A 45 to 55 degrees being more preferred.

The surface smoothness of the compression-bonding portion of the film compression-bonding device is important. It may not be greater than 10 .mu.m in terms of center line average height. It has been found that a value greater than this level may result in transfer of the ruggedness of the compression-bonding device onto the film and hence in reduced bonding properties.

A load, at which the film placed on the support member such as the leadframe is compression-bonded by the permanent film compression-bonding device, may range from 50 g to 3000 g. A compression-bonding load lower than 50 g may lead to deteriorated bonding properties whereas a compression-bonding load higher than 3000 g may result in a distorted leadframe. A compression-bonding load outside the above range is therefore not preferred.

A temperature, at which the film-shaped die-bonding material (film) is compression-bonded on the support member such as the leadframe, is not lower than a glass transition temperature Tg (an .alpha. relaxation peak temperature in the measurement of kinematic viscoelasticity) of the film but not higher than a thermal decomposition temperature (a temperature at which a weight reduction begins to take place in a thermogravimetric analysis) of the film. A film compression-bonding temperature lower than Tg may result in a reduction in bonding properties whereas a film compression-bonding temperature higher than the thermal decomposition temperature may cause thermal decomposition of the film so that bonding properties may be reduced. A film compression-bonding temperature outside the above range is therefore not preferred.

A temperature, at which the chip is bonded to the film compression-bonded on the support member such as the leadframe, may be equal to or higher than Tg+70.degree. C. but not higher than the thermal decomposition temperature. If the bonding temperature of the chip is lower than Tg+70.degree. C., the bonding properties may be reduced. If the bonding temperature exceeds the thermal decomposition temperature, the film may undergo thermal decomposition so that the bonding properties may be reduced. A bonding temperature outside the above range is therefore not preferred.

The die-bonding apparatus according to the present invention may be preferably provided with a feeder for feeding a film-shaped organic die-bonding material over a predetermined constant length; a cutter for cutting out the film-shaped organic die-bonding material; a film tack-bonding device for suction-holding the film-shaped organic die-bonding material that has been cut out and heating and compression-bonding it on a leadframe, which has been preheated on a heater block, at a predetermined position thereof; a film compression-bonding device for eventually pressing the tack-bonded, film-shaped organic die-bonding material; a chip tack-compression-bonding device for heating and tack-bonding a chip on the film-shaped organic die-bonding material at a predetermined position thereof, the die-bonding material having been bonded on the leadframe heated on the heater block; and a chip, permanent compression-bonding device for heating the film-shaped organic die-bonding material, which has been bonded on the leadframe, and the chip again while heating them, and permanently compression-bonding the die-bonding material and the chip together.

The present invention has been described above with respect to the formation of the film-shaped organic die-bonding material of the predetermined size by the punching device or the cutter. It is to be noted, however, with respect to the method and device for placing and tack-bonding the film-shaped organic die-bonding material of the predetermined size on the chip-mounting support member at the predetermined position thereof and the method and device for pressing the film-shaped organic bonding martial against the support member and compression-bonding it there, that those described in association with the use of the punching device can be used likewise in the use of the cutter, and that those described in association with the use of the cutter can be employed similarly in the use of the punching device.

A semiconductor device can be fabricated by mounting a chip on a support member in accordance with the laminating method, die-bonding method, laminating machine or die-bonding apparatus of the present invention and conducting further steps employed for the fabrication of general semiconductor devices, such as wire-bonding and resin sealing of the chip.

FIG. 11 illustrates one example of a process according to the present invention for the fabrication of a semiconductor device.

A film-shaped organic die-bonding material 101 is unrolled and is cut into a predetermined size by a cutter 102 (FIG. 11(a)).

The film-shaped organic die-bonding material 101 is compression-bonded by a compression-bonding element 104 on a die pad 106 of a leadframe 105 on a heating platen 107 in accordance with the laminating method of the present invention (FIG. 11 (b)). As compression-bonding conditions, it is preferred to set the temperature at 100 to 250.degree. C., the time at 0.1 to 20 seconds and the pressure at 100 to 5000 g.

A chip 108 is placed on the film-shaped organic die-bonding material 101 bonded on the die pad 106 and is then heated and compression-bonded (die-bonded) (FIG. 11(c)). As die-bonding conditions, it is preferred to set the temperature at 150 to 350.degree. C., the time at 0.1 to 20 seconds and the pressure at 10 to 3000 g.

The process then proceeds through a wire-bonding step (FIG. 11(d)) and a resin-sealing step for the chip (FIG. 11(e), whereby the semiconductor device is fabricated. Designated at numeral 109 is a sealing resin.

In the present invention, examples of the support member on which the film-shaped organic die-bonding material is compression-bonded can include a die pad of a leadframe, and a chip mount of a padless leadframe portion (LOC), a ceramics-made printed board, a glass-epoxy printed board or a glass-polyimide printed board.

As the film-shaped organic die-bonding material, the description has been given of those having a single layer structure. In the present invention, those having a multi-layer structure such as a two-layer or three-layer structure can also be used.

A film-shaped organic die-bonding material can be produced, for example, by dissolving or dispersing an organic material, such as a polyimide or epoxy resin and optionally, a material, for example, an additive such as a metallic filler, in an organic solvent to form a coating varnish, coating the coating varnish onto a carrier film such as a biaxially-stretched poly-propylene film, causing the solvent to evaporate to form a layer and then peeling off the layer from the carrier film. One side of the layer, the side having been in contact with the air in a drying step in which the solvent was caused to evaporate (i.e., the side being a side opposite to a side where the layer was in contact with the carrier film), will be referred to as the "side A", while the side at which the layer was in contact with the carrier film will be referred to as the "side B". If the film-shaped organic die-bonding material is laminated by the laminating method of the present invention so that the side A is brought into contact with the support member, a semiconductor device fabricated using the laminating method can avoid occurrence of reflow cracking, thereby making it possible to provide the thus-fabricated an extremely reliable semiconductor device.

In the invention, use of the following film-shaped organic die-bonding material can avoid occurrence of reflow cracking and is more preferred for the fabrication of an extremely reliable semiconductor device: (1) a film-shaped organic die-bonding material having a water absorption rate not greater than 1.5 vol. %; (2) a film-shaped organic die-bonding material having a saturation moisture absorption rate not greater than 1.0 vol. %; (3) a film-shaped organic die-bonding material having a residual volatile content not greater than 3.0 wt. %; (4) a film-shaped organic die-bonding material having surface energy of at least 40 erg/cm.sup.2 ; (5) a film-shaped organic die-bonding material containing voids in a void volume not greater than 10% within the die-bonding material and an interface between the die-bonding material and an associated support member in a stage of bonding a chip on the support member; or (6) a film-shaped organic die-bonding material having peeling strength of at least 0.5 kgf/5.times.5 mm chip at a stage when a chip has been bonded on an associated support member.

The following film-shaped organic die-bonding materials can be produced by adjusting the composition of a film-shaped organic die-bonding, for example, the structure of a polymer such as a polyimide or the content of a filler such as silver: (1) a film-shaped organic die-bonding material having a water absorption rate not greater than 1.5 vol. %; (2) a film-shaped organic die-bonding material having a saturation moisture absorption rate not greater than 1.0 vol. %; (4) a film-shaped organic die-bonding material having surface energy of at least 40 erg/cm.sup.2 ; and (6) a film-shaped organic die-bonding material having peeling strength of at least 0.5 kgf/5.times.5 mm chip at the stage when the chip has been bonded on an associated support member.

The following film-shaped organic die-bonding materials can be produced by adjusting their production conditions, for example, the drying temperature, the drying time and/or the like: (3) a film-shaped organic die-bonding material having a residual volatile content not greater than 3.0 wt. %; and (5) a film-shaped organic die-bonding material containing voids in the void volume not greater than 10% within the die-bonding material and the interface between the die-bonding material and the associated support member in the stage of bonding the chip on the support member.

According to the present invention, the film-shaped organic die-bonding material can be provided with two or more of the above-described physical properties and characteristic properties.

As physical properties or characteristic properties which are preferred to be provided, the followings can be mentioned by way of example: (A) a film-like organic die-bonding materials having a saturation moisture absorption rate not greater than 1.0 vol. % and a residual volatile content not greater than 3.0 wt. %; (B) a film-like organic die-bonding materials having a saturation moisture absorption rate not greater than 1.0 vol. % and peeling strength of at least 0.5 kgf/5.times.5 mm chip at a stage when a chip has been bonded on an associated support member; (C) a film-like organic die-bonding materials having a residual volatile content not greater than 3.0 wt. % and peeling strength of at least 0.5 kgf/5.times.5 mm chip at a stage when a chip has been bonded on an associated support member; and (D) a film-like organic die-bonding material having a saturation moisture absorption rate not greater than 1.0 vol. %, a residual volatile content not greater than 3.0 wt. % and peeling strength of at least 0.5 kgf/5.times.5 mm chip at a stage when a chip has been bonded on an associated support member.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a simplified front view of one embodiment of a laminating machine according to the present invention;

FIG. 2 is a plan view of a leadframe;

FIG. 3 is a cross-sectional view showing one example of compression-bonding elements;

FIG. 4 is a cross-sectional view illustrating another example of compression-bonding elements;

FIG. 5 is a front view of one embodiment of a die-bonding apparatus according to the present invention;

FIG. 6 is a plan view of the one embodiment of the die-bonding apparatus according to the present invention;

FIG. 7 is a simplified plan view of frame-transporting rails;

FIG. 8 is a simplified side view of a feeder and a cutter;

FIG. 9 is a simplified cross-sectional view of a film compression-bonding device;

FIG. 10 is a plan view of a leadframe;

FIG. 11 is a cross-sectional view showing one example of a process according to the present invention for the fabrication of a semiconductor device; and

FIG. 12 is a front view illustrating a method for measuring peeling strength by using a push-pull gauge.

BEST MODE FOR CARRYING OUT THE INVENTION

EXAMPLE 1