JP2000223602A - Bonding structure of chip to substrate and manufacture of the structure - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a bonding structure of a chip to a substrate whereby the wafer having high bumps can be back ground to a desired thickness and the chip is sealed with a resin, without sealing with a thermosetting resin in a bonding step. SOLUTION: Semiconductor elements are obtained by a method comprising steps of forming bumps 21 on a main surface of a wafer, coating a thermoplastic resin 31 between the bumps on the main surface of the wafer, grinding the back surface of the wafer to a desired thickness, individualizing the wafer into chips 71, aligning the chips at specified positions on a substrate 81 and reflowing to seal them with a resin.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates generally to a semiconductor device and a method of manufacturing the same, and more particularly to a semiconductor device formed by flip chip bonding and a method of manufacturing the same.

[0002]

2. Description of the Related Art In recent years, with the development of process technology, the performance of semiconductor devices has been remarkably improved. As an interconnect technology that makes full use of the performance, instead of wire bonding technology, flip chip bonding technology has been adopted. The opportunities for application are increasing. Flip chip bonding refers to a method in which the active element surface (main surface) of a chip is connected to a substrate.

Usually, first, solder bumps are formed on the main surface of a wafer. Next, the back surface of the wafer is back ground (back surface grinding). Next, the wafer is cut into small pieces (chips) by dicing. After the chip is turned over and aligned with the position of the substrate, the solder is melted to obtain an electrical connection, and finally the chip is sealed with a thermosetting resin.

Since bumps can be arranged not only around the chip but also at any position on the chip, for example, 100 × 100
In the case of a matrix, 10,000 I / O numbers can be obtained.
In the fields of small portable information electronic devices and IC cards, the mounting area is required to be reduced, and the mounting volume is required to be reduced.

[0005] Back grinding of a wafer is an important step for thinning chips. Conventionally, back grinding of a wafer has been performed by using a tape having a two-layer or three-layer structure of a thin adhesive layer and a base film to reinforce the wafer and protect the main surface of the wafer. On a wafer having bumps of 15 to 30 μm in height, such as electrolytic gold bumps, back-grinding is performed using a normal two-layer or three-layer tape after bump formation.

[0006]

In a wafer having solder bumps having a height of 30 to 40 μm, back grinding can be performed by a conventional method. However, in a back grinding of a wafer having a bump having a height of about 100 μm, the back grinding can be performed. It was difficult to control the damage, thickness and thickness unevenness.

On the other hand, it is advantageous to use high bumps to reduce stress between the chip and the substrate. Also, in order to improve the ease of injecting the sealing resin, the necessity of using high bumps is increasing. Therefore, it is an important subject to back-grind a wafer having a high bump of 40 μm or more to a predetermined thickness uniformly and without damaging the wafer.

Further, when a large-diameter wafer having high bumps is back-ground using a multilayer tape composed of a thin adhesive layer and a base film, unevenness in the thickness of the wafer, reduction in thickness controllability, and damage to the bumps occur. There was a problem.

In order to avoid the problem of bump damage,
There is a method of forming bumps after back grinding,
Considering the handling of the wafer, the final thickness is limited, and this method has a problem that the chip itself cannot be made thin.

Therefore, one object of the present invention is to provide
An object of the present invention is to provide a semiconductor device capable of uniformly grinding a wafer having bumps of 0 μm or more, particularly 100 μm or more, without damaging the wafer, and capable of back grinding to a desired thickness, and a method of manufacturing the same.

It is still another object of the present invention to provide a semiconductor which can easily form a resin-sealed flip-chip junction simply by aligning and reflowing a chip in a bonding step, and a method of manufacturing the same.

It is still another object of the present invention to provide a semiconductor device capable of achieving the above object even with a large-diameter wafer, and a method of manufacturing the same.

[0013]

The above and other objects are to provide a semiconductor device having a wafer (11) having a main surface and a back surface, wherein a bump (21) is formed in a predetermined region on the main surface of the wafer. Forming a resin (31) between the bumps on the main surface of the wafer, wherein the resin is applied so that the tops of the bumps are exposed to a predetermined thickness (30); Grinding the back surface of the wafer to a desired thickness (50);
A semiconductor comprising: (1) a step (70), a step of preparing a substrate (81), and a step (80) of aligning a chip at a predetermined position on the substrate and reflow-sealing the chip. Implemented by elements.

[0014]

FIG. 1 shows a wafer 11 according to one embodiment of the present application.
FIG. The wafer 11 has a chip active element surface (main surface) and a back surface. The diameter of the wafer is not limited, but the present invention is applicable to a large diameter wafer (8 inch or larger wafer).

FIG. 2 is a sectional view showing a step 20 in which the bumps 21 are formed on the main surface of the wafer 11 in the step 10 in FIG. The number of bumps will be several for simplicity of explanation,
The number is not limited. The height of the bump is preferably at least 40 μm, more preferably at least 100 μm. The height of the bump is
The higher the value, the better the stress is, the reliability of the wafer, and the ease of resin injection. However, the thickness is most preferably 120 to 130 μm in consideration of the thinning of the chip and the limitation of the number of bumps. The material of the bump is generally a Pb / Sn-based solder, but Au, Ni, Cu or the like can be used as the core, and is not limited. Furthermore, Sn / A
It can be applied to lead-free solders such as g and Sn / Bi. The connection method of the solder bump is C4 (Controlle
d Collapse Chip Connection
n) or CCB (Controlled Coll)
A method called “apse bonding” is used, but the present invention is not limited to this method. The structure of the bump is not particularly limited in the present application. FIG. 3 is a cross-sectional view illustrating a step 30 of applying resin 31 between the bumps on the main surface of the substrate in step 20 of FIG. In the case of using eutectic Pb / Sn solder, the resin is applied at 183 ° C.
Hereinafter, a thermoplastic resin that is preferably plasticized at about 150 ° C. is applied so that the head of the bump is exposed to about 40 μm or less. The coating is performed by heating the thermoplastic resin to a melting temperature of 240 ° C. to 250 ° C. and dropping it on the main surface of the substrate so that the resin has sufficient fluidity. At this time, the substrate is set at the melting point of the bump (1
(83 ° C.). Next, the thermoplastic resin is left for a while at a high temperature that is equal to or higher than the plasticization 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, it is possible to apply the thermoplastic resin uniformly on the main surface of the substrate without coating the bumps. The thermoplastic resin refers to a resin that retains its external shape even after removing its external force after softening and molding by heating. Generally, it is a resin having a chemical structure of a linear or branched polymer and not causing an intermolecular chemical reaction by heating. In the present application, for example, polyethylene, polystyrene, polyvinyl chloride, polyadmi, and the like can be used. This resin functions as a reinforcing material at the time of wafer handling and back grinding, and also functions as a sealing material at the time of flip bonding. The upper limit of the plasticization 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 lower than the melting point of the material of the bump. The exposed height of the bump head is not limited to 40 μm as long as it is suitable for bonding the chip and the substrate in the bonding step described later.

FIG. 4 is a sectional view showing a step 40 in which a tape 41 is applied on the resin 31 and the bumps 21 in the step 30 in FIG. As the tape, a tape composed of the same base film and adhesive layer as in the related art can be used. It is not necessary to use a special multilayer tape for surface protection, fixing of bumps, and easy peeling of the tape. In the present application, since the resin has already been applied in step 30 and the resin functions as a reinforcing material, the tape is mainly applied to protect the surface during back grinding.

FIG. 5 is a cross-sectional view showing a step 50 in which the back surface of the wafer 11 in step 40 of FIG. 4 is back ground. In step 20, bumps have been formed, and step 4
At 0, the bumps are sufficiently fixed with resin and the wafer is reinforced, so that the wafer can be back ground to a desired thickness. In the prior art, even when a high bump is formed, the wafer is only reinforced with the base film layer of the tape, so that problems such as uneven thickness of the wafer, controllability of the thickness, damage to the bump, and even a thickness of 350 μm occur. Couldn't backgrind with good control. On the other hand, in one embodiment of the present application, even when solder bumps having a bump height of 130 μm are formed on an 8-inch wafer, the resin acts as a reinforcing material, so that the bumps are not damaged and a uniform thickness of about 100 μm. It is possible to back grind. As described above, even if a tall bump is used, the wafer can be back-ground thinner than before, so that the chip can be finally made thinner than before.

FIG. 6 is a cross-sectional view showing a step 60 in which the tape has been peeled in step 50 of FIG. In the present 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 light-sensitive layer, and to further facilitate peeling of the tape by irradiation with ultraviolet light (UV).

FIG. 7 is a sectional view showing a step 70 for dicing (slicing) the step 60 of FIG. 6 and an enlarged sectional view of the chip 71 after the dicing. Dicing is the process of separating wafers into individual chips. In FIG.
For the sake of explanation, only dicing in one direction is shown, but when dicing in the X direction is completed, the wafer is rotated by 90 °, dicing in the Y direction is performed, and individual chips are separated. The chip 71 is shown in a state in which the back surface of the chip 71 is turned upside down with respect to the wafer 11.

FIG. 8 is a 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 the environment such as external force, 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 liquid having a low viscosity, and is injected between the chip and the substrate by utilizing the capillary phenomenon, and then cured by heating. In the present application, a thermoplastic resin is applied in advance in step 30, and this thermoplastic resin functions as a reinforcing material during 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, so that resin-sealed flip chip bonding is easily formed. Furthermore, since a thermoplastic resin is used in the present application, at the time of reflow, not only the head of the bump exposed from the thermoplastic resin but also the thermoplastic resin itself is softened, and the resin can be sealed without applying stress to the bump. .

[0021]

The present invention has the following effects.

According to the present invention, the height is preferably 40 μm or more, particularly 10 μm.
It is possible to provide a semiconductor element capable of uniformly grinding a wafer having bumps of 0 μm or more without damage to the wafer and capable of back grinding to a desired thickness, and a method of manufacturing the same.

Further, according to the present invention, by using a thermoplastic resin which also serves as a reinforcing material and a sealing material, alignment and reflow of a chip in a bonding step are performed.
It is possible to easily form a resin-sealed flip chip bonding.

Further, the present invention can achieve the above object even for a large-diameter wafer.

Although the structure of the invention has been described herein with reference to specific embodiments, those skilled in the art will recognize that the structure of the invention may be modified or changed. However, the structure of the present invention is not limited to the specific embodiments disclosed herein. For example, bump shapes such as mushroom type and straight wall type,
It is not intended to specify the type of the thermoplastic resin. Further, description of the steps of forming the solder resist layer and other protective layers and the like are omitted for simplification of description, but are not intended to limit the present application. The manufacturing process of the flip chip bonding without such description is 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.

FIG. 2 is a cross-sectional view showing a step 20 of forming bumps 21 on the main surface of the wafer 11 in step 10 of FIG.

3 is a cross-sectional view showing a step 30 of applying resin 31 between bumps on the main surface of the substrate in step 20 of FIG. 2;

FIG. 4 is a cross-sectional view illustrating a step 40 in which a tape 41 is applied on the solder resist layer in the step 30 of FIG. 3;

FIG. 5 is a cross-sectional view showing a step 50 in which the back surface of the wafer 11 is back-ground in step 40 of FIG.

FIG. 6 is a cross-sectional view showing a step 60 in which the tape is peeled in step 50 of FIG. 5;

FIG. 7 is a cross-sectional view showing a step 70 of dicing (slicing) the step 60 of FIG. 6 and the chip 7 after the dicing.
1 is an enlarged view of FIG.

FIG. 8 is a cross-sectional view showing a stage 80 in which a chip 71 is flip-chip bonded to a substrate 81.

[Explanation of symbols]

 11 Wafer 21 Bump 31 Thermoplastic Resin 41 Tape 71 Chip 81 Substrate

Claims (14)

[Claims] 1. A structure for joining a chip (71) to a substrate (81), comprising: a plurality of bumps (21) for forming electrical continuity between the chip and the substrate; A structure for joining a chip to a substrate, comprising: a thermoplastic resin (31) disposed between the substrate and the plurality of bumps. 2. The structure according to claim 1, wherein the chip has a main surface and a back surface, and the back surface is ground. 3. The structure for bonding a chip to a substrate according to claim 2, wherein said chip is ground to a thickness of less than 350 μm. 4. The structure for bonding a chip to a substrate according to claim 1, wherein the thermoplastic resin is plasticized at a melting point of the bump or lower. 5. A semiconductor device comprising: preparing a wafer (11) having a main surface and a back surface (10); and forming (20) a bump (21) in a predetermined region on the main surface of the wafer. Applying a thermoplastic resin (31) on the main surface of the wafer and between the bumps, wherein the thermoplastic resin is applied such that a top of the bump is exposed to a predetermined thickness (30). Grinding the back surface of the wafer to a desired thickness (50); slicing the wafer into chips (71) (70); preparing a substrate (81); A step of disposing the chip, the bumps and the substrate in a predetermined position and sealing the chip, the bumps and the substrate with the thermoplastic resin (80). 6. The semiconductor device according to claim 5, wherein the thermoplastic resin is plasticized at a melting point of the bump or lower. 7. A method for manufacturing a semiconductor device, comprising: providing a wafer (11) having a main surface and a back surface (1).
0); bumps (21) on predetermined areas on the main surface of the wafer
Forming (20); applying a resin (31) on the main surface of the wafer and between the bumps,
Applying the resin such that the tops of the bumps are exposed to a predetermined thickness (30); slicing the wafer into chips (71) (70); preparing a substrate (81); Disposing at a predetermined position on the substrate, and sealing the chip, the bumps, and the substrate with the resin (80). 8. Between a step (30) of applying a resin (31) on the main surface of the wafer and between the bumps, and a step (70) of fragmenting the wafer into chips (71). Grinding the back surface of the wafer to a desired thickness (5).
8. The method for manufacturing a semiconductor device according to claim 7, further comprising: 9. A step of applying a resin between the bumps (3).
9. The method for manufacturing a semiconductor device according to claim 7, wherein 0) includes a step of applying a thermoplastic resin. 10. The step of applying a resin between the bumps (30): heating the resin; dropping the resin on a main surface of the wafer; and holding the wafer at a high temperature; 10. The method for manufacturing a semiconductor device according to claim 7, comprising: 11. The method according to claim 7, wherein the thermoplastic resin is plasticized at a melting point of the bump or lower.
0. A method for manufacturing a semiconductor device according to item 0. 12. The step of grinding the back surface of the wafer (50).
12. The method according to claim 8, wherein the thickness of the wafer is ground to less than 350 μm. 13. The method according to claim 7, wherein the step (80) of sealing the chip, the bump and the substrate with the resin includes heating them. . 14. A semiconductor device comprising flip-chip bonding using a thermoplastic resin as a sealing material and / or as a reinforcing material for a wafer.