JP2001223232A - Manufacturing method of semiconductor device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide the manufacturing method of a semiconductor device, by which product yield can be improved by preventing the damage of a semiconductor wafer. SOLUTION: In the manufacturing method of the semiconductor device by which conductive sections 7 are formed to electrodes 2 for the external connection of a semiconductor element, the reverse side of the circuit forming surface of the semiconductor wafer 1 under the state, in which a protective film 3 is formed onto the circuit forming surface, is removed and the circuit forming surface is thinned. Through-holes 3a penetrated to the protective film 3 are formed in response to the positions of the electrodes 2 in the protective film 3, and the conductive films 7 electrically conducted with the electrodes 2 are formed into the through-holes 3a and the protective film 3 is removed from the semiconductor wafer 1. Thus, the semiconductor wafer 1 in the case of the formation of the conductive sections is reinforced, and the damage of the semiconductor element can be prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a semiconductor device in which a conductive portion is formed on an electrode for external connection of a semiconductor element.

[0002]

2. Description of the Related Art In a process of manufacturing a silicon substrate used for a semiconductor device, a thinning process is performed to reduce the thickness of the substrate as the semiconductor device is thinned. This thinning is performed by forming a circuit pattern on the surface of the silicon substrate and then removing the back surface opposite to the circuit formation surface by mechanical grinding, wet etching, plasma processing, or the like. Conventionally, the thinning process is generally performed after forming a conductive portion such as a solder bump on an electrode.

[0003]

However, when thinning is performed after the formation of the solder bumps, stress concentration tends to occur at the discontinuity in the shape of the bump formation portion, so that the strength of this portion is reduced. Cracks sometimes occurred on the wafer. Further, the semiconductor wafer after the thinning processing has an extremely weak overall strength and is difficult to handle, so that the semiconductor wafer is likely to be damaged, which is a factor of lowering the product yield.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a method of manufacturing a semiconductor device capable of preventing a semiconductor wafer from being damaged and improving a product yield.

[0005]

According to a first aspect of the present invention, there is provided a semiconductor device manufacturing method for manufacturing a semiconductor device in which a conductive portion is formed on an external connection electrode of a semiconductor element. Forming a protective film on the circuit forming surface of the semiconductor wafer on which the semiconductor element is formed; removing the opposite side of the circuit forming surface of the semiconductor wafer on which the protective film is formed to thin the semiconductor wafer; A step of forming a through hole through the protective film corresponding to the position of the electrode in the protective film, a step of forming a conductive portion in conduction with the electrode in the through hole, and forming the protective film after forming the conductive portion. Removing from the semiconductor wafer.

According to a second aspect of the present invention, there is provided a method of manufacturing a semiconductor device.
2. The method for manufacturing a semiconductor device according to claim 1, wherein the conductive portion is formed by filling a conductive paste into the through hole.

According to a third aspect of the present invention, there is provided a method of manufacturing a semiconductor device.
2. The method for manufacturing a semiconductor device according to claim 1, wherein the conductive portion is formed by mounting a conductive ball in the through hole.

According to a fourth aspect of the present invention, there is provided a method of manufacturing a semiconductor device.
2. The method of manufacturing a semiconductor device according to claim 1, wherein the conductive portion is formed by forming a metal plating layer in the through hole.

According to the present invention, the semiconductor wafer is thinned by removing the side opposite to the circuit forming surface of the semiconductor wafer in a state where the protective film for protecting the circuit forming surface of the semiconductor wafer is formed, and thereafter, the protective film is penetrated. By forming a conductive portion in conduction with an electrode in the through hole provided as described above, the semiconductor wafer at the time of forming the conductive portion can be reinforced to prevent damage to the semiconductor element.

[0010]

Embodiments of the present invention will now be described with reference to the drawings. 1, 2, 3, and 4 are process explanatory views of a method for manufacturing a semiconductor device according to an embodiment of the present invention. 1 (a), (b), (c), FIG. 2 (a),
4B and 4C show a method of manufacturing a semiconductor device in the order of steps.

In FIG. 1A, reference numeral 1 denotes a semiconductor wafer on which a plurality of semiconductor elements are formed. The upper surface of the semiconductor wafer 1 is a circuit formation surface, on which electrodes 2 for external connection are formed. Next, as shown in FIG. 1B, a protective film 3 made of a heat-resistant resin material such as polyimide is formed on the circuit forming surface on the upper surface of the semiconductor wafer 1.
Has a function of protecting the circuit formation surface of the semiconductor wafer 1 and reinforcing the semiconductor wafer 1 that has become weak in the subsequent thinning process.

The protective film 3 not only protects the surface of the semiconductor wafer 1 but also has the role of reinforcing the semiconductor wafer 1 in the following steps of processing the semiconductor wafer 1 and manufacturing semiconductor devices. The protective film 3 is formed by using a method in which a resin film processed into a sheet shape is bonded to the circuit forming surface of the semiconductor wafer 1 with an adhesive, or a method in which a liquid resin is uniformly applied on the circuit forming surface. Can be.

Next, the semiconductor wafer 1 on which the protective film 3 is formed is sent to a thinning step. Here, as shown in FIG. 1C, the semiconductor wafer 1 is thinned by removing the side opposite to the circuit forming surface of the semiconductor wafer 1 (see the lower part shown by a broken line). Examples of the thinning method include mechanical grinding such as polishing, wet processing of chemically etching a semiconductor wafer with a chemical, plasma etching using a plasma processing apparatus, or a combination of these methods. For example, a method of performing chemical conversion can be used. Prior to this thinning step, the semiconductor wafer 1 is reinforced by the protective film 3, so that the semiconductor wafer 1 is not damaged in the thinning step, and product reliability and yield can be improved.

Next, the thinned semiconductor wafer 1 is sent to a through hole forming step. Here, as shown in FIG. 2A, through holes are formed in the protective film 3 formed on the upper surface of the semiconductor wafer 1. Laser processing is used to form this through-hole, and a through-hole 3 a penetrating through the protective film 3 is formed corresponding to the position of the electrode 2. By irradiating the predetermined position of the protective film 3 with the laser beam, the resin at the irradiation position sublimates, and a through hole 3 a reaching the surface of the electrode 2 is formed in the protective film 3.

Next, a process for forming the conductive portion 7 in the through hole 3a will be described. In the present invention, the conductive paste is filled into the through holes 3a, and the conductive paste is heated to form the conductive portions 7 that are electrically connected to the electrodes 2 as shown in FIG. 2B. As the conductive paste,
A metal paste such as cream solder 5 or a thermosetting conductive resin is used. In the case of a metal paste, the metal component is melted by heating and joined to the electrode 2 of the semiconductor wafer 1 to form a conductive portion 7. In the case of a conductive resin, the electrode 2 is electrically cured by being thermally cured in the through hole 3 a. The electrically conductive portion 7 becomes electrically conductive. Next, the conductive portion forming step will be specifically described with reference to the drawings.

FIG. 3 shows a step of forming a conductive portion using a metal paste. The metal paste is a paste made by mixing conductive metal particles and a liquid organic solvent, and cream solder is known as a typical example thereof. As shown in FIG. 3A, a screen mask 10 is mounted on the upper surface of the protective film 3 provided with the through holes 3a, and the screen mask 10 is formed through the pattern holes 10a provided corresponding to the positions of the through holes 3a. The cream solder 5 is filled in the holes 3a and the pattern holes 10a.

As a result, as shown in FIG. 3B, the cream solder 5 is supplied not only to the inside of the through hole 3a but also to the upper surface of the protective film 3. After that, the solder particles in the cream solder 5 are melted by heating. Since a sufficient amount of the cream solder 5 is supplied to the position of each through-hole 3a, the molten solder projects above the through-hole 3a. In a state where the through holes 3a are solidified as shown in FIG.
A conductive portion 7 integrally formed with a protruding portion that is electrically connected to the electrode 2 and protrudes above the upper surface of the protective film 3 is formed.

FIG. 4 shows another example of the formation of the conductive portion. First, as shown in FIG. 4A, a cream solder 5 which is a metal paste is filled. The cream solder 5 is filled using a spatula-shaped material such as a squeegee. Next, on the cream solder 5 filled in the through-hole 3a, FIG.
As shown in FIG. 7, a solder ball 6 as a conductive ball is mounted. The solder balls 6 are formed of the same solder as the cream solder 5. During the mounting of the ball, the protective film 3 around the through hole 3a functions as a guide for preventing the solder ball 6 from being displaced.

Thereafter, the semiconductor wafer 1 is sent to a reflow process, where it is heated. Thereby, the solder particles in the solder ball 6 and the cream solder 5 are melted, and are soldered to the upper surface of the electrode 2. As a result, as shown in FIG. 4C, a conductive portion 7 electrically connected to the electrode 2 is formed in the through hole 3a.

As a method of forming a conductive portion in the through hole 3a, a metal plating layer may be laminated on the surface of the electrode 2 by electroless plating or the like in addition to the above two examples.
A conductive portion may be formed in the through hole 3a. In this case, the protective film 3 functions as a resist for forming a plating film.

Thereafter, the semiconductor wafer 1 on which the conductive portions 7 are formed is sent to a protective film peeling step. Here, FIG.
As shown in (c), the protective film 3 is peeled off from the upper surface of the semiconductor wafer 1. Thus, a semiconductor device in which a conductive portion is formed on an external connection electrode of a semiconductor element is completed. The protective film 3 may be removed by etching using a chemical solution or plasma.

As described above, in the manufacturing process of the semiconductor device shown in the present embodiment, prior to the formation of the conductive portion 7 conducting to the electrode 2 of the semiconductor wafer 1, the protective film 3 is formed on the circuit formation surface of the semiconductor wafer 1. Is formed. Thereby, the circuit formation surface is protected in the conductive part forming process, and the fragile semiconductor wafer 1 is reinforced by the protective film. Therefore, the semiconductor wafer 1 is damaged in the manufacturing process of the semiconductor device including the conductive part forming step. Does not occur. Therefore, the quality of the completed semiconductor device can be ensured, and the product yield can be improved.

[0023]

According to the present invention, the semiconductor wafer is thinned by removing the side opposite to the circuit forming surface of the semiconductor wafer on which a protective film for protecting the circuit forming surface of the semiconductor wafer has been formed,
Thereafter, a conductive portion that is electrically connected to the electrode is formed in a through hole provided through the protective film, so that the semiconductor wafer at the time of forming the conductive portion can be reinforced to prevent damage to the semiconductor element. In addition, the quality of the completed semiconductor device can be ensured, and the product yield can be improved.

[Brief description of the drawings]

FIG. 1 is a process explanatory view of a method for manufacturing a semiconductor device according to an embodiment of the present invention;

FIG. 2 is a process explanatory view of a method for manufacturing a semiconductor device according to an embodiment of the present invention;

FIG. 3 is a process explanatory view of a method for manufacturing a semiconductor device according to an embodiment of the present invention;

FIG. 4 is a process explanatory view of a method for manufacturing a semiconductor device according to an embodiment of the present invention;

[Explanation of symbols]

 Reference Signs List 1 semiconductor wafer 2 electrode 3 protective film 3a through hole 5 cream solder 6 solder ball 7 conductive part

Claims (4)

[Claims] 1. A method of manufacturing a semiconductor device in which a conductive portion is formed on an electrode for external connection of the semiconductor device, comprising: forming a protective film on a circuit forming surface of a semiconductor wafer on which the semiconductor device is formed. A step of forming, a step of removing the opposite side of the circuit formation surface of the semiconductor wafer on which the protective film is formed, to thin the semiconductor wafer, and a step of penetrating the protective film through the protective film corresponding to the position of the electrode. A semiconductor device comprising: a step of forming a through hole; a step of forming a conductive portion in conduction with the electrode in the through hole; and a step of removing the protective film from the semiconductor wafer after the formation of the conductive portion. Manufacturing method. 2. The method according to claim 1, wherein the conductive portion is formed by filling a conductive paste into the through hole. 3. The method according to claim 1, wherein the conductive portion is formed by mounting a conductive ball in the through hole. 4. The method according to claim 1, wherein the conductive portion is formed by forming a metal plating layer in the through hole.