JP4598905B2 - Manufacturing method of semiconductor device - Google Patents

Description

[0001]
[Industrial application fields]
The present invention generally relates to the production how the semiconductor device, and more particularly relates to the production how a semiconductor device comprising a flip-chip bonding.
[0002]
[Prior art]
In recent years, with the development of process technology, the performance of semiconductor devices has improved remarkably, and as an interconnect technology that takes full advantage of its performance, the opportunity to apply flip chip bonding technology instead of wire bonding technology Has increased. Flip-chip bonding refers to a method in which an active element surface (main surface) of a chip is connected to a substrate.
[0003]
Usually, solder bumps are first formed on the main surface of the wafer. Next, the back surface of the wafer is back-ground (back surface grinding). Next, the wafer is diced into small pieces (chips). After turning the chip over and aligning with the position of the substrate, the solder is melted to obtain electrical connection, and finally the chip is sealed with a thermosetting resin.
[0004]
Since the bumps can be arranged not only around the chip but also at any position of the chip, for example, when a 100 × 100 matrix is used, 10,000 I / O numbers can be obtained. In the fields of small portable information electronic devices and IC cards, in addition to reducing the mounting area, a reduction in mounting volume is required, and the chip itself needs to be thinned.
[0005]
Wafer back grinding is an important process for thinning the chip. Conventionally, wafer backgrinding has been performed by using a thin adhesive layer and a two-layer or three-layer tape of a base film to reinforce the wafer and protect the main surface of the wafer.
Further, in the case of a wafer having a bump having a height of 15 to 30 μm, such as an electrolytic gold bump, back grinding is performed using a normal two-layer or three-layer tape after the bump formation.
[0006]
【task to solve】
A wafer having solder bumps with a height of 30 to 40 μm can be back-ground by a conventional method. However, in a back-grind of a wafer having bumps with a height of about 100 μm, the damage, thickness and unevenness of the bumps are reduced. It was difficult to control.
[0007]
On the other hand, it is advantageous to use high bumps to relieve stress between the chip and the substrate. In addition, the necessity of using high bumps is increasing in order to improve the ease of injection of the sealing resin. Therefore, it is an important problem to uniformly grind a wafer having high bumps of 40 μm or more to a predetermined thickness without damaging the wafer.
[0008]
In addition, if a large-diameter wafer having high bumps is back-ground using a multi-layered tape composed of a thin adhesive layer and a base film, the wafer thickness unevenness, thickness controllability, and bump damage may occur. there were.
[0009]
In order to avoid this problem of bump damage, there is a method of forming bumps after back grinding. However, there is a limit to the final thickness in consideration of wafer handling, and this method cannot reduce the thickness of the chip itself. There was a problem.
[0010]
Accordingly, an object of the present invention is 40μm or height, in particular uniformly and without damage to the wafer is a wafer having the above bumps 100 [mu] m, the manufacturing method of the semiconductor element capable of back grinding the thickness of the object Is to provide.
[0011]
Further an object of the present invention is to align the chip in the bonding step, just reflow, it is to provide a manufacturing how the semiconductor device to easily form the flip-chip bonding resin-sealed.
[0012]
Further an object of the present invention is also to provide a manufacturing how the semiconductor device above-mentioned object is achievable in a large-diameter wafer.
[0013]
[Means for Solving the Problems]
The above and other objects are a method for manufacturing a semiconductor device, comprising a step of preparing a wafer (11) having a main surface and a back surface, and a plurality of regions having a height of 100 μm or more in a predetermined region on the main surface of the wafer. A step (20) of forming a bump (21), and a step of applying a thermoplastic resin (31) which is plasticized below the melting point of each bump on the main surface of the wafer and between the plurality of bumps, The step of applying thermoplastic resin so that the top of the bump is exposed to 40 μm or less (30), the step of grinding the back surface of the wafer so that the thickness of the wafer is less than 350 μm (50), and the chip (71 ) Forming step (70), preparing the substrate (81), placing the chip at a predetermined position on the substrate, and sealing the chip, the plurality of bumps and the substrate with a thermoplastic resin (80). This is realized by a method for manufacturing a semiconductor device.
[0014]
【Example】
FIG. 1 shows a cross-sectional view of a wafer 11 according to one embodiment of the present application. The wafer 11 has an active element surface (main surface) and a back surface of the chip. The diameter of the wafer is not limited, but the present application can be applied even when the diameter is large (wafer of 8 inches or more).
[0015]
FIG. 2 is a cross-sectional view showing step 20 in which bumps 21 are formed on the main surface of wafer 11 in step 10 of FIG. The number of bumps is several for simplicity of explanation, but the number is not limited. The height of the bump is preferably 40 μm or more, more preferably 100 μm or more. The height of the bump is preferably as high as possible for stress relaxation, wafer reliability, and ease of resin injection. However, considering that the chip is thin and the number of bumps is limited, 120 to 130 μm is most preferable. It is. The material of the bump is generally Pb / Sn solder, but Au, Ni, Cu or the like can be used as a core and is not limited. Furthermore, the present invention can also be applied to lead-free solders such as Sn / Ag and Sn / Bi. As a method for connecting the solder bumps, a method called C4 (Controlled Collapse Chip Connection) or CCB (Controlled Collapse Bonding) is used, but the present invention is not limited thereto. The structure of the bump is not particularly limited in the present application. FIG. 3 is a cross-sectional view illustrating a step 30 in which a resin 31 is applied between the bumps on the main surface of the substrate in step 20 of FIG. When eutectic Pb / Sn solder is used for the resin application, a thermoplastic resin that is plasticized at 183 ° C. or lower, preferably about 150 ° C., is formed on the main surface of the substrate in step 20 with a bump head of 40 μm. Apply so that it is exposed to the following extent. The application is performed by heating the thermoplastic resin to a melting temperature of 240 ° C. to 250 ° C. and dropping it onto the main surface of the substrate in order to give the resin sufficient fluidity. At this time, it is desirable to keep the substrate below the melting point of the bump (183 ° C.) so that the bump does not melt. Next, the thermoplastic resin is allowed to stand for a while at a temperature higher than its plasticizing temperature and lower than the melting point of the bump (150 ° C. to 183 ° C.). By controlling the temperature in this way and leaving it at a high temperature, the thermoplastic resin can be uniformly applied on the main surface of the substrate without being coated on the bumps.
A thermoplastic resin refers to a resin that retains its outer shape after being softened and molded by heating and then removing its external force. Generally, it is a resin that has a chemical structure composed of a linear or branched polymer and does not cause an intermolecular chemical reaction by heating. In the present application, for example, polyethylene, polystyrene, polyvinyl chloride, polyadomi and the like can be used. This resin functions as a reinforcing material during wafer handling and back grinding, and also functions as a sealing material during flip bonding. The upper limit of the plasticizing temperature of the resin can be changed depending on the material of the bump, and is not limited to 183 ° C. as long as it is not higher than the melting point of the material of the bump. The height at which the heads of the bumps are exposed is not limited to 40 μm as long as the thickness is suitable for bonding the chip and the substrate in the bonding stage described later.
[0016]
4 is a cross-sectional view showing a stage 40 in which a tape 41 is pasted on the resin 31 and the bump 21 in the stage 30 of FIG. As the tape, it is possible to use a tape made of the same base film and adhesive layer as in the past. There is no need to use special multi-layer tape for surface protection, bump fixing, and ease of tape peeling. In this application, since the resin has already been applied in step 30 and the resin functions as a reinforcing material, the tape is applied mainly for the purpose of protecting the surface during back grinding.
[0017]
FIG. 5 is a cross-sectional view showing a stage 50 in which the back surface of the wafer 11 in the stage 40 of FIG. 4 is back-ground. In step 20, bumps have been formed, and in step 40, the bumps are sufficiently fixed with resin, and the wafer is reinforced, so that it is possible to back grind the wafer to a desired thickness. Even when high bumps are formed with the conventional technology, the wafer is only reinforced with the base film layer of the tape, which causes problems such as uneven thickness of the wafer, controllability of the thickness, damage to the bumps, and even a thickness of 350 μm. Could not control, back grind well. On the other hand, in one embodiment of the present application, even when a solder bump having a bump height of 130 μm is formed on an 8-inch wafer, the resin acts as a reinforcing material, so that the bump is not damaged and the thickness is about 100 μm with a uniform thickness. It is possible to back grind up to. Thus, even if bumps having a high height are used, the wafer can be back-ground thinner than before, so that the chip can finally be made thinner than before.
[0018]
FIG. 6 is a cross-sectional view showing step 60 where the tape is peeled off at step 50 of FIG. In this application, even if the same tape as the conventional tape is used, since the resin is applied between the bumps, the tape can be easily peeled without damaging the bumps. However, it is also possible to use a tape having an ultraviolet photosensitive layer and further facilitate the peeling of the tape by ultraviolet (UV) irradiation.
[0019]
FIG. 7 is a cross-sectional view showing a step 70 of dicing (dividing) the step 60 of FIG. 6 and an enlarged cross-sectional view of the chip 71 after the dicing. Dicing is a step of separating the wafer into individual chips. In FIG. 7, only dicing in one direction is shown for explanation, but when dicing in the X direction is completed, the wafer is rotated by 90 °, and dicing in the Y direction is performed to separate individual chips. The chip 71 shows a state where the back surface is turned upside down with respect to the wafer 11.
[0020]
FIG. 8 is a cross-sectional view showing a stage 90 in which the chip 71 is flip-chip bonded to the substrate 81. After bonding, the chip is protected from external forces, moisture, and contaminants. In the prior art, a thermosetting resin is sealed on the chip surface at this stage. This thermosetting resin is generally a low-viscosity liquid, and is cured by heating after being injected between the chip and the substrate using capillary action. In the present application, a thermoplastic resin is preliminarily applied in step 30, and this thermoplastic resin functions as a reinforcing material in the process and also functions as a sealing material. Therefore, it is not necessary to seal the chip with a thermosetting resin at this stage. After transferring the solder paste to the tip of the bump or dispensing the flux on the substrate, the chip is aligned and reflowed to easily form a resin-sealed flip chip joint. Further, since a thermoplastic resin is used in the present application, not only the bump head exposed from the thermoplastic resin but also the thermoplastic resin itself becomes soft during reflow, and the resin can be sealed without applying stress to the bump. .
[0021]
【The invention's effect】
The present invention has the following effects.
[0022]
The present invention is 40μm or height, in particular no damage to uniformly and wafer wafer having the above bump 100 [mu] m, it is possible to provide a manufacturing how the back-grinding is possible semiconductor elements on the thickness of the object .
[0023]
Furthermore, the present invention can easily form a resin-sealed flip chip joint by simply aligning and reflowing the chip in the bonding process by using a thermoplastic resin that serves as both a reinforcing material and a sealing material. It is.
[0024]
Further, the present invention can achieve the above object even for a large-diameter wafer.
[0025]
Although the structure of the present invention has been described herein with reference to specific embodiments, modifications and variations of the structure of the present invention will occur to those skilled in the art. However, the structure of the present invention is not limited to the specific embodiments disclosed herein. For example, the shape of bumps such as mushroom type and straight wall type, and the type of thermoplastic resin are not intended to be specified. Further, description of the stage of forming the solder resist layer and other protective layers is omitted for simplification of description, but is not intended to limit the present application. The manufacturing process of flip chip bonding without such a description shall be performed by a normal method. Such modifications and changes are also within the scope of the technical idea of the present invention and are included in the scope of the claims.
[Brief description of the drawings]
FIG. 1 shows a cross-sectional view of a wafer 11 according to one embodiment of the present application.
2 is a cross-sectional view showing a step 20 in which bumps 21 are formed on the main surface of the wafer 11 in the step 10 of FIG. 1;
3 is a cross-sectional view showing a step 30 in which a resin 31 is applied between bumps on the main surface of the substrate in the step 20 of FIG. 2;
4 is a cross-sectional view showing a stage 40 in which a tape 41 is pasted on the solder resist layer in stage 30 of FIG. 3;
5 is a cross-sectional view showing a stage 50 in which the back surface of the wafer 11 in the stage 40 in FIG. 4 is back-ground. FIG.
6 is a cross-sectional view showing a step 60 where the tape is peeled off at a step 50 in FIG. 5;
7 is a cross-sectional view showing a step 70 of dicing (dividing) the step 60 of FIG. 6 and an enlarged view of a chip 71 after the dicing.
8 is a cross-sectional view showing a stage 80 in which a chip 71 is flip-chip bonded to a substrate 81. FIG.
[Explanation of symbols]
11 Wafer 21 Bump 31 Thermoplastic Resin 41 Tape 71 Chip 81 Substrate

Claims (5)

A method for manufacturing a semiconductor device comprising:
Providing a wafer (11) having a main surface and a back surface (10);
Forming a plurality of bumps (21) having a height of 100 μm or more in a predetermined region on the main surface of the wafer (20);
Applying a thermoplastic resin (31) that is plasticized below the melting point of each bump on the main surface of the wafer and between the plurality of bumps, the thermoplastic resin being applied to the top of each bump (30) which is applied so as to be exposed to 40 μm or less;
Grinding the back surface of the wafer so that the thickness of the wafer is less than 350 μm (50);
Crushing the wafer to form chips (71) (70);
Providing a substrate (81); and disposing the chip at a predetermined position of the substrate and sealing the chip, the plurality of bumps, and the substrate with the thermoplastic resin (80);
A method for manufacturing a semiconductor device, comprising: Applying a thermoplastic resin between the plurality of bumps (30),
Heating the thermoplastic resin;
Dropping the thermoplastic resin onto a major surface of the wafer; and holding the wafer at a high temperature;
The method of manufacturing a semiconductor device according to claim 1, comprising:   The step of sealing (80) the chip, the plurality of bumps, and the substrate with the thermoplastic resin includes heating the chip, the plurality of bumps, and the substrate. 3. A method for producing a semiconductor device according to 2.   4. The step (20) of forming the plurality of bumps (21) includes forming a plurality of bumps having a height of 120 [mu] m to 130 [mu] m. A method for manufacturing a semiconductor device.   The method for manufacturing a semiconductor element according to claim 1, wherein the thermoplastic resin includes plasticizing at 183 ° C. or lower.

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