JPH02256251A - Semiconductor device and its manufacture - Google Patents

Abstract

PURPOSE:To obtain a high quality semiconductor device free from occurrence of bubbles and chip tilt by a method wherein semi-hardened thermosetting resin or thermoplastic resin adhesive of uniform thickness is used to adhere a chip to a die pad. CONSTITUTION:Adhesive 9 comprising semi-hardened resin or thermoplastic resin is used to make a chip 6 uniformly thick and adhere it to a die pad 2. That is, the adhesive 9 is screened on a tape-like release paper 10 with substantially uniform thickness, the adhesive 9 is heat-transferred to the die pad 2 of a leadframe 1, the chip 6 is press-fitted by a collet 7 while the adhesive 9 transferred to the die pad 2 is being heated, and heat treatment is performed for complete hardening if the adhesive 9 is semi-hardened resin so that the chip 6 is adhered to the die pad 2. Thus a high quality semiconductor device free from occurrence of bubbles and tilt of the chip 6 can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a semiconductor device and a method for manufacturing the same, and more particularly to the Guibond technology.

- Conventional technology In recent years, demands on the quality of semiconductor devices have become stricter, and even in die bonding methods for semiconductor devices, there are requirements such as the absence of air bubbles in the adhesive layer, the ability to control the thickness of the adhesive layer, and the ability to prevent chips from tilting. is being demanded.

Hereinafter, an example of the conventional bonding method for the semiconductor device described above will be described with reference to the drawings.

FIGS. 13 to 16 are diagrams for explaining an example of a conventional die bonding method for a semiconductor device. Figures 13 and 14
In the figure, 1 is a lead frame, 2 is a die pad which is a part of the lead frame on which the chip is placed, 3 is an adhesive such as silver paste for bonding the chip to the die pad 2, and 4 is the adhesive 3. 5 is a syringe which is a container for the adhesive 3; 6 is a semiconductor integrated circuit chip; 7 is a jig for transporting the chip 6 and press-bonding it to the die pad 2; This is a collet, which is a jig for doing this.

First, as shown in FIG. 13, pressure is applied to the syringe 5, and the adhesive 3 is discharged from the multi-nozzle 4 onto the die pad 2, which is a part of the lead frame 1. Next, as shown in FIG. 14, a collet 7 presses the chip 6 onto the die pad 2 coated with the adhesive 3. After this, if the adhesive 3 is cured, the chip 6 is fixed on the die pad 2.

Problems to be Solved by the Invention However, in the configuration of the conventional example described above, since the adhesive 3 is discharged onto the Guibad 2 by the multi-nozzle 4, the adhesive 3
are scattered, and after the chip 6 is crimped with the collet 7, the first
As shown in FIG. 5, air bubbles 8 remain in the adhesive 3, or as shown in FIG.
expands, causing the chip 6 to tilt, impairing the quality of the semiconductor device. This is because if the air bubbles 8 remain in the adhesive 3, the heat from the chip 6 cannot be released to the Gui pad 2, the strength of the adhesive 3 decreases, or the adhesive 3 is conductive. This is because, in some cases, electrical connections such as - on the back side of the chip 6 may be damaged. Also, chip 6
If the wire is tilted, too much or too little load will be applied when wire bonding is performed in the next step, which will impair good wire bond quality.

In addition, in the conventional bonding method, in order to sufficiently spread the adhesive 3 and obtain a stable bonding state, it is necessary to perform a so-called scribing operation in which the chip 6 is slightly vibrated in the horizontal direction while the chip 6 is being crimped. It is. For this reason 1
It usually takes nearly 4 seconds to bond two chips 6 together. For this reason, there is also the problem that the productivity (so-called throughput) of semiconductor devices does not increase.

The present invention solves the above-mentioned problems of the prior art, and aims to provide a semiconductor device and a method for manufacturing the same, which can supply adhesive to an even thickness without leaving any bubbles.

Means for Solving the Problems In order to achieve this object, the semiconductor device and the method for manufacturing the same of the present invention use an adhesive made of semi-cured resin or thermoplastic resin and having a substantially uniform thickness. The chip is then bonded to the die pad.

Function: According to this configuration, the chip is bonded to the die pad using a semi-cured thermosetting resin or thermoplastic resin adhesive with a uniform thickness, resulting in high quality with no air bubbles or chip tilt. A semiconductor device can be realized. In addition, adhesives made of semi-cured resins and thermoplastic resins take less time to harden than conventional silver pastes, and do not require scribing, making it possible to significantly shorten bonding time. , the productivity of semiconductor devices can be dramatically increased.

EXAMPLE Hereinafter, an example of the present invention will be described with reference to the drawings. 1 and 2 are diagrams showing a method of manufacturing a semiconductor device according to an embodiment of the present invention. 1 and 2, 9 is an adhesive made of semi-cured resin or thermoplastic resin, 10 is a release paper for protecting the adhesive 9, and 11 is the adhesive 9 and the release paper 10. This is a reel for winding. The adhesive 9 is screen printed onto a tape-like release paper 10 to a substantially uniform thickness.

Further, 12 is a heater, and 13 is a heating transfer jig for applying heat from the heater to the adhesive 9 through the release paper 10. Note that 1 is a lead frame, 2 is a die pad, 6 is a chip, and 7 is a collet, which are the same as those of the conventional example.

First, from glue 11 in FIG. 1, adhesive 9 and release paper 1.
When you draw 0 and reach the top of Guipad 2, 80~
With a heating transfer jig 13 heated to 150°C, release paper 10 is
The adhesive 9 is pressed against the die pad 2 while transmitting heat to the adhesive 9 through.

Next, when the heat transfer jig 13 is pulled upward, the heated part of the adhesive 9 among the pressed parts is transferred to the surface of the die pad 2, and only the release paper 10 is lifted upward along with the heat transfer jig 13. go up to Furthermore, the adhesive 9 is newly supplied to the thermal transfer jig 13 by winding the reel on the right side of FIG. On the other hand, by moving the lead frame 1 so that a new die pad 2 is located below the heating transfer jig 13 and repeating the process of transferring the adhesive 9 described above, the adhesive can be easily applied to the die pad 2 of the lead frame 1. 9 can be thermally transferred.

Then, as shown in FIG. 2, while heating the adhesive 9 transferred to the die pad 2, the chip 6 is pressed by the collet 7, and if the adhesive 9 is a semi-cured resin, it is completely cured. The chip 6 is bonded to the die pad 2 by heat treatment.

As described above, according to this embodiment, the bubble-free adhesive 9 having a uniform thickness can be easily and continuously thermally transferred onto the die pad 2 using the thermal transfer jig 13, as shown in FIG. A bubble-free adhesive layer having a uniform thickness can be obtained, and the chip 6 can be prevented from tilting.

By the way, in the embodiments shown in FIGS. 1 to 3, the adhesive 9 was thermally transferred to the Gui pad 2 side in advance, but on the other hand, the adhesive 9
may be thermally transferred onto the back surface of the chip 6 in advance, and then the chip 6 may be bonded to the die pad 2 via the adhesive 9. When thermally transferring the adhesive 9 to the chip 6 side in this way, both ends of the chip 6 must be fixed by some means, and pressure must be applied to the tape-shaped release paper 10 and the adhesive 9 from the back side of the chip 6. This makes the work itself somewhat difficult.

In this regard, when thermally transferring the adhesive 9 to the die pad 2 as shown in FIGS. 1 to 3, the lead frame 1 is placed on a conventional die bonding device, and a conventional silver paste or other Since it is only necessary to replace the adhesive applying device with a thermal transfer device, there is an advantage that the conventional die bonding device can be used almost as is. Further, according to this method, the steps up to thermal transfer of the adhesive 9 can be carried out by the lead frame manufacturer. Sunawachi,
Lead frame manufacturers usually have equipment for applying polyimide support tape to fix lead frame leads, and can use this equipment as is to perform the thermal transfer shown in Figures 1 to 3. . Therefore, the semiconductor manufacturer can also deliver the lead frame with the adhesive 9 thermally transferred onto it from the lead frame manufacturer, making it possible to manufacture and deliver the lead frame in accordance with current business conditions.

Next, a method of transferring the adhesive 9 will be described.

As one of the transfer methods, there is a method in which a tape-shaped adhesive is cut into necessary dimensions in advance and then transferred onto the surface of the die pad 2. FIGS. 4 to 6 show an example thereof. As shown in FIG. 4, a part of the tape (adhesive 9 and release paper 10) pulled out from the reel 11 is cut by a cutter 14 to obtain a tape piece 15 of a required size. This tape piece 15 is attracted by a vacuum chuck 16 as shown in FIG. 5, and is pressed onto the die pad 2 of the lead frame 1 as shown in FIG. At this time, lead frame 1
If it is heated in advance, the adhesive 9 is thermally transferred to the surface of the die pad 2, and only the release paper 10 is attracted to the vacuum chuck 16 and removed.

On the other hand, as shown in FIG. 1, there is also a method in which a tape-shaped adhesive is fed in its tape form and the adhesive 9 is sequentially thermally transferred while peeling off the release paper 10. In the embodiment shown in Fig. 1, a reel system is shown in which winding is performed from reel to reel, but in Fig. 7,
A cassette system as shown in FIG. 8 may also be used.

In FIGS. 7 and 8, a supply reel 18 and a take-up reel 19 are provided in the cassette case 17, and guide pins 21 and 22 guide the reels 18 and 19 by rotation of the reel drive shaft 20. The tape 23 is fed in the direction of arrow A while being moved. A notch 17a is provided at the center of the lower end of the cassette case 17, and the tip of the heater plate 24 is inserted above the tape 23 within the notch 17a. The heater plate 24 is attached to a shaft 25 so as to be movable up and down, and is constantly pushed upward by a coil spring 26 fitted into the shaft 25, and normally remains stationary at a position where it hits a stopper 27.

From this state, when the heater plate 24 is pushed down against the urging force of the spring 26 by a driving means (not shown), the tip of the heater plate 24 pushes the tape 23 down from the notch 17a of the cassette 17. Therefore, if the lead frame is placed below the cassette case 17, the adhesive of the tape 23 is pressed onto the die pad surface of the lead frame, the adhesive is transferred to the die pad surface by the heat of the heater plate 24, and then peeled off. Only paper can be wound onto the winding wheel 19.

When using the cassette system shown in Figures 7 and 8, the first
The heating transfer device can be made smaller compared to the reel method shown in the figure.

Moreover, since the cassette can be easily replaced for each product type, there is an advantage that it is easy to handle high-mix low-volume production.

In both the reel method shown in FIG. 1 and the cassette method shown in FIGS. 7 and 8, two heater heating methods can be employed: a constant heat method and a pulse heat method.

The constant heat method is a method in which a portion of the heater is constantly heated. According to this method, a sufficient heating state can be obtained at all times, so there is an advantage that the transfer time can be shortened. On the other hand, in a thermal transfer device where a part of the heater is always close to the tape, the unbonded parts of the tape are heated to some extent, which accelerates the curing of the unbonded parts, which may be undesirable. It takes.

On the other hand, the pulse heating method is a method in which a portion of the heater is heated only during transfer. Although this method eliminates the drawbacks of the constant heat method, it takes some time to raise the transfer temperature to a sufficient level, so there is a drawback that the adhesion time is longer than that of the constant heat method.

Therefore, it is necessary to adopt either the constant heat method or the pulse heat method, taking various conditions such as the required quality of the die bond and the chip size into consideration.

Next, the shape of the heat transfer jig will be described.

The heating transfer jig 13 for the reel shown in the embodiment of FIG. 1 and the heater plate 24 for the cartridge shown in FIGS. 7 and 8 both have flat tips (tape pressing surfaces). In this case, the surface roughness (flatness) and parallelism of the tape pressing surface are strictly required. According to experiments conducted by the inventors, good thermal transfer can be performed if both the surface roughness and parallelism are within 2 to 3 μm.

By the way, when thermal transfer is performed using a thermal transfer jig with a flat tape pressing surface, as shown in Fig. 9 (al, lb).
As shown in FIG. 1, the cut surfaces of both ends of the adhesive 9 after being peeled off from the release paper 10 are jagged, which may be undesirable for improving die bonding quality.

To solve this problem, please refer to Figure 10 (a), fb)
As shown in FIG. 2, it is preferable to provide an adhesive cutting blade 28 at one or both ends of the tip of the thermal transfer jig 13 (or the heater plate 24 shown in FIGS. 7 and 8).

Figure 11 shows the single-edged thermal transfer jig 1 shown in Figure 10 (al).
This figure shows the state of thermal transfer using No. 3. By providing the blade 28 at the upstream end of the tape flow, appropriate cuts can be made in the adhesive 9, making it easier to cut after pressure transfer, resulting in a sharp cut surface without jagged edges, and making it easier to cut the adhesive 9. Bond quality can be improved. In addition,
The height of the blade 28 needs to be set to an optimum height depending on the softness of the adhesive 9 during heating, the pressure of the thermal transfer jig 13, etc., but according to experiments conducted by the inventors, the height of the tape (
When the total thickness of the adhesive 9 and the release paper 10 was 20 μm, good results were obtained when the height of the blade 28 was set to 5 to 15 μm.

Next, we will discuss the material of the tape.

First, the adhesive 9 will be described. The adhesive 9 is roughly divided into conductive adhesive and non-conductive adhesive.

The conductive adhesive is made to have conductivity by mixing silver powder (scaly or spherical). Because conductive adhesives use silver powder as a base material, they have less ``spread'' than non-conductive adhesives, making them so-called ``firm.'' For this reason, there are fewer variations and jaggies in the cut portion, and a sharp shape can be obtained.

On the other hand, the mainstream of non-conductive adhesives is epoxy adhesives, which have the advantage of being cheaper than conductive adhesives. However, since non-conductive adhesives do not contain anything that acts as a base material, they tend to "spread" and have weak so-called "stiffness", making it difficult to cut and the shape of the cut surface may be irregular. Prone. Therefore, when using a non-conductive adhesive, it is desirable to use a thermal transfer jig 13 having a blade 28 as shown in FIGS. 10(al) and 10(b).

Next, the release paper 10 will be described.

In the present invention, a tape with only adhesive 9 and no release paper as shown in FIG. Three types of tapes can be used, such as those shown in FIG. 12(C), in which release paper 10 is pasted on both sides of adhesive 10.

If the adhesive 9 itself has sufficient "firmness" and "tension", a tape made only of the adhesive 9 as shown in FIG. 12(a) may be used. However, although this tape can be used in the embodiment shown in FIGS. 4 to 6, that is, the method of adsorbing it with a vacuum chuck 16 and pressing it onto the preheated lead frame 1, It cannot be used for thermal transfer methods as shown in FIGS. 7 and 8. The tape shown in FIG. 12(a) is not covered with release paper on both sides, so it easily absorbs moisture. Therefore, sufficient care must be taken when storing tapes.

The tape shown in FIG. 12 tb+ with a release paper 10 pasted on one side of the adhesive 9 can be adsorbed using the vacuum chuck shown in FIGS. 4 to 6; It can be used in any of the thermal transfer methods shown. Moreover, if it is wound on a reel, it will not absorb moisture, making it easier to handle.

Release paper 10 is pasted on both sides of the adhesive 9 shown in FIG. 12 (C1).The tape is most advantageous in that it is less likely to absorb moisture. However, it cannot be used in a vacuum chuck system or a cassette type thermal transfer system.

In the case of the reel method, the upper release paper 10 may be wound on a take-up reel as shown in FIG. 1, and the lower release paper 10 may be wound on another take-up reel on the upstream side of the thermal transfer jig. .

The embodiments of the present invention have been described above, but when a semi-cured resin or thermoplastic resin adhesive is used as in the present invention, the following effects are achieved compared to the conventional method using silver paste. I can't get it.

First, the curing time is short. The curing time of silver paste is 10 to 40 seconds on a hot plate, while the curing time of semi-cured resin or thermoplastic resin adhesive is 1 to 10 seconds on a hot plate, and 174 to 1/2 seconds. It can be shortened to 10.

Second, scribing is not necessary. When using silver paste, after the chip is crimped, it is necessary to sufficiently spread the silver paste while crushing air bubbles, so a so-called scribing process is required in which the chip is slightly vibrated. However, semi-cured resin or thermoplastic resin has sufficient "wettability" to the back surface of the chip or the surface of the pad, so there is no need to scribe it. According to experiments conducted by the inventors, the present invention can save approximately 0.3 seconds for a four-bore square chip compared to using conventional silver paste, and nearly 3 seconds for a 10n+m square chip. We have confirmed that it can save a lot of time.

In this way, when a semi-cured resin or thermoplastic resin adhesive is used, the curing time itself is short, and scribing is not required, so the total die bonding time can be significantly shortened and productivity ( Throughput) can be improved.

Furthermore, when silver paste is used, there is a problem that air bubbles are formed or the air bubbles expand during curing, causing the chip to tilt, deteriorating die bonding quality and subsequent wire bonding quality. For example, there are no air bubbles and the chip does not tilt. Therefore, both die bond quality and wire bond quality can be made good.

Effects of the Invention Since the present invention uses a semi-cured resin or thermoplastic resin adhesive to bond the chip to the Gui pad, no air bubbles are formed and the chip does not tilt.
A semiconductor device of extremely high quality can be obtained. Moreover, since the bonding time can be shortened compared to the conventional method using silver paste, productivity can be greatly increased.

[Brief explanation of drawings]

1, 2, and 3 are side views showing a method for manufacturing a semiconductor device according to a first embodiment of the present invention, and FIGS. 4, 5, and 6 are side views showing a method for manufacturing a semiconductor device according to a second embodiment of the present invention. The side view, FIGS. 7 and 8, showing the method for manufacturing a semiconductor device in the example, are the third embodiment of the present invention.
A front sectional view and a side sectional view showing the main parts of the thermal transfer device used in the fourth embodiment of the present invention, and FIGS. 9, 10, and 11 illustrate the thermal transfer jig used in the fourth embodiment of the present invention and its effects. Fig. 12 is a side view showing the tape used in each embodiment of the present invention, Fig. 13, Fig. 14, Fig. 15,
FIG. 16 is a side view for explaining a conventional method of manufacturing a semiconductor device. 1... Lead frame, 2... Die pad, 9... Adhesive, 10... Release paper,
11,18.19...Reel, 12...Heater 13...Heating transfer jig, 14...
... Cutter 15 ... Tape piece, 16 ...
...Vacuum chuck, 17...Cassette case,
17a...Notch, 24...Heater plate, 28...Blade. Name of agent: Patent attorney Shigetaka Awano et al. 18 No. 2 Figure 2 Figure Kashi Kasai J g/411 Board/Lee Luca/Tartapeh Figure 7 Figure 5 Figure 8 Figure 6ri! J 9 - Sho llL Shaved 10 - One peeled MJ & 11-M-Re - Cassette case reel Reel 5-piece glazed kite pin tape Jin-taped fine coil springst buckwheat. Figure 10 Figure 11 ■ IQ) (b) Figure 12

Claims (14)

[Claims] (1) Made of semi-cured resin or thermoplastic resin,
A semiconductor device characterized in that a chip is bonded to a die pad of a lead frame via an adhesive having a substantially uniform thickness. (2) Made of semi-cured resin or thermoplastic resin,
A method of manufacturing a semiconductor device, comprising bonding a chip to a die pad of a lead frame via an adhesive having a substantially uniform thickness. (3) A method for manufacturing a semiconductor device according to claim 2, characterized in that an adhesive is bonded to the die pad surface of the lead frame in advance, and then the chip is bonded to the adhesive. (4) A method for manufacturing a semiconductor device according to claim 2, characterized in that an adhesive is bonded to the back surface of the chip in advance, and then the adhesive is bonded to the die pad surface of the lead frame. (5) Made of semi-cured resin or thermoplastic resin,
A method for manufacturing a semiconductor device, comprising thermally transferring an adhesive having a substantially uniform thickness onto the back surface of a chip or the surface of a die pad of a lead frame, and then bonding the chip to the die pad via the adhesive. . (6) Made of semi-cured resin or thermoplastic resin,
A tape-shaped adhesive having a substantially uniform thickness is sequentially fed out, the fed-out tape-shaped adhesive is cut into predetermined dimensions, and the cut tape pieces are transferred to the die pad surface of a heated lead frame. After that, press the back side of the chip against the surface of the adhesive transferred to the die pad surface,
A method of manufacturing a semiconductor device, comprising bonding the chip to the die pad via the adhesive. (7) Claim 6, characterized in that an adhesive consisting only of a tape-shaped adhesive layer or an adhesive with a tape-shaped release paper pasted on only one side of the tape-shaped adhesive layer is used. A method for manufacturing a semiconductor device according to section 1. (8) A tape-like adhesive made of semi-cured resin or thermoplastic resin with a substantially uniform thickness and a tape-like release paper attached is placed along the die pad surface of the lead frame. Sequentially, the adhesive tape is transferred from the release paper side to the die pad surface using a heating transfer jig while being heated to transfer only the adhesive onto the die pad surface, and then the adhesive transferred onto the die pad surface. Press the back of the chip against the surface of the
A method of manufacturing a semiconductor device, comprising bonding the chip to the die pad via the adhesive. (9) Adhesive tape with a tape-like release paper pasted on only one side of the tape-like adhesive is sequentially fed out from a supply reel, and only the release paper after the adhesive has been transferred is sequentially wound onto a take-up reel. A method for manufacturing a semiconductor device according to claim 8, characterized in that: (10) Sequentially feed the adhesive tape with release paper pasted on both sides of the adhesive tape from the supply reel,
A first take-up reel provided on the upstream side of the thermal transfer position winds only one release paper, and the other release paper after transferring the adhesive is wound on a second reel provided on the downstream side of the thermal transfer position. 9. The method for manufacturing a semiconductor device according to claim 8, wherein the semiconductor device is wound on a take-up reel. (11) A supply reel and a take-up reel are housed in a cassette case, and the adhesive tape, which is sequentially fed from the supply reel toward the take-up reel, is passed through a notch provided in the cassette case and placed inside the notch. 10. The method of manufacturing a semiconductor device according to claim 9, wherein the adhesive of the adhesive tape is transferred onto the die pad surface by a heating transfer jig placed in the die pad. (12) The method for manufacturing a semiconductor device according to claim 8, wherein the heating transfer jig is constantly heated. (13) The method for manufacturing a semiconductor device according to claim 8, wherein the heating transfer jig is heated only when transferring the adhesive. (14) A blade for cutting adhesive is provided at the tape upstream end of the tape pressing surface of the heat transfer jig, or at both the tape upstream and downstream ends. A method for manufacturing a semiconductor device according to section 1.