JPH0319344A - Manufacture of semiconductor device - Google Patents

Abstract

PURPOSE:To improve the yield and quality of a semiconductor device having a gold bump by a method wherein a plurality of resists, which respectively consist of a low first resist, which has a good accuracy of patterning and is easy to remove, and an upper second resist having a good plating resistance, are applied and patterned, a bump electrode is formed using these resists as masks, a plurality of the resists are removed and a barrier metal film is etched away. CONSTITUTION:A barrier metal film 4 is applied on a PSG film 3 including an opening part 6. Then, a ZPR first resist 11 is applied on the upper surface of the film 4 and moreover, an OFPR second resist 12 is formed. Here, the ZPR first resist 11 can be patterned with high precision, is easily removed and the OFPR second resist 12 is superior in a plating resistance. Then, a resist film mask 10, which has an opening part slightly wider than the opening part 6 and consists of the first and second resists 11 and 12, is formed at the position of the opening part 6. Then, a gold bump 15 is formed by plating in the opening part using the mask 10 as a protective film and using the film 4 as a plated electrode. Then, the mask 10 is dissolved and removed and the exposed film 4 is etched away.

Description

[Detailed Description of the Invention] [Summary] Regarding the method of forming metal bumps, for the purpose of improving yield and quality, an insulating film is deposited on a semiconductor substrate provided with a flat electrode L7, and the insulating film is patterned. Then, a step of depositing a barrier metal film on the entire surface of the flat electrode portion and the insulating film, and then a step of depositing a plurality of resists (for example, a resist film with a good Bakooning thickness and being removed). A resist consisting of a first resist (lower layer that is easy to resist) and a second resist (an upper layer that has good acetic acid resistance) is deposited, the flat electrode portion is opened to expose the barrier metal film, and the other portions are exposed. a step of forming a resist film mask made of the plurality of masked resists, a step of plating a metal bump on the barrier metal film in the opening using the barrier metal film as an electrode, and a step of plating the plurality of The method is characterized in that it includes a step of removing the resist film and etching away the exposed barrier metal film using the metal bump as a mask.

[Industrial application field]

The present invention relates to a method for manufacturing a semiconductor device, and particularly to a method for forming metal bumps.

Semiconductor devices equipped with metal bumps do not require wire bonding, so the thickness of the semiconductor container can be made thinner, and the bonding pads (electrode areas) of the semiconductor chip can also be made smaller, making it possible to flatten the semiconductor container. It can be built into an IC card in a different shape, or it can be used as a multi-pin IC.
This structure has the advantage that C can be highly integrated. Furthermore, since a plurality of semiconductor chips can be arranged on a circuit board to create a composite device, there is an advantage that electronic circuits can be mounted in high density.

Semiconductor devices provided with such metal bumps have recently been reconsidered and reconsidered due to their advantages in increasing density.

[Conventional technology]

Figure 2 shows a cross-sectional view of a metal bump electrode, where 1 is a semiconductor substrate, 2 is a flat electrode made of aluminum (aluminum electrode), and 3 is phosphorus silicate glass (PSG).
4 is a barrier metal film made of a composite film of Ti (titanium) and Pd (palladium), and 5 is gold (A).
It is a mushroom-shaped metal bump (gold bump) consisting of u).

Step-by-step sectional views of the conventional method for forming such metal bumps are shown in FIGS. 3(a) to 3('). To explain the outline of the process, as shown in FIG. 3 (see al; first, chemical vapor deposition (CV
D) A PSG film 3 (cover insulating film) is grown by method. Note that instead of the PSG film 3, silicon oxide (SiO
z) A membrane may be used in some cases.

FIG. 3 (see BL; see FIG. 3; next, the PSG film 3 is etched using a photo process to form an opening 6 on the aluminum electrode 2.

FIG. 3 (see Cl; then, after removing the mask, a barrier metal film 4 is deposited on the PSG film 3 including the opening 6 by vapor deposition.

Refer to FIG. 3(d); next, a resist film is applied, exposed and developed to form a resist film mask 8 having an opening 7 slightly wider than the opening 6 at the position of the opening 6.

Refer to FIG. 3 (tel); Next, with the resist film mask 8 covered, gold bumps 5 are plated in the openings 7 using the barrier metal film 4 as a plating electrode by a plating method.

At this time, the portion covered with the resist film mask 8 is not plated.

Refer to FIG. 3(f); next, the resist film mask 8 is removed, and the exposed barrier metal film 4 is further etched away. In this way, the gold humb 5 is formed on the aluminum ξ electrode 2 with the barrier metal film 4 interposed therebetween.

The above is an overview of the conventional method for forming metal bumps.

[Problem to be solved by the invention]

However, in this method of forming metal bump electrodes, a manoshroom-type gold bump is formed by covering the resist film mask 8, and then the resist film mask 8 is removed.
Furthermore, since the method involves removing the barrier metal film 4 by etching, problems related to the resist film mask 8 occur. That is, in the plating process in which thick (approximately 50 μm in height) gold bumps are plated using the resist film mask 8 as a covering film, the resist film peels off, and the plating layer adheres to unnecessary areas. Defective products are produced due to plating abnormalities.

In addition, even if the resist film mask 8 and the barrier metal film 4 are removed by etching to form the mushroom-shaped gold bumps, they are not completely removed, and their residue remains under the mushroom-shaped mushroom, which may affect the device characteristics. may have a negative impact on.

In particular, in the case of large-diameter wafers with a diameter of about 6 inches φ, it is difficult to uniformly form the resist film mask 8 with a uniform film thickness over the entire surface, and the resist film thickness becomes non-uniform on the wafer surface. The thicker the resist is coated, the greater the non-uniformity of the film thickness across the wafer, which doubles the above problem.

The present invention proposes a manufacturing method for solving these problems and improving the yield and quality of semiconductor devices having metal bumps.

Next, a plurality of resists (for example, a plurality of resists consisting of a lower layer first resist that has good patterning accuracy and is easy to remove, and an upper layer second resist that has good mesoki resistance)
forming a resist film mask consisting of the plurality of resists, opening the flat electrode portion to expose the barrier metal film, and masking other portions; plating a metal bump on the barrier metal film in the opening, then removing the plurality of resist films, and etching away the exposed barrier metal film using the metal bump as a mask. is solved by a manufacturing method that includes

[A Thousand Steps to Solve the Problem] The problem is a step of depositing an insulating film on a semiconductor substrate provided with a flat electrode, patterning the insulating film to open the flat electrode portion, The step of depositing a barrier metal film on the flat electrode portion and the entire surface of the insulating film [Function] In other words, in the present invention, multi-layer coating is performed in which a plurality of resists are deposited. For example, the barrier metal film has good patterning accuracy and is easy to remove. A plurality of resists consisting of a first resist as a lower layer and a second resist as an upper layer with good plating resistance is deposited and patterned, this is used as a mask to form a bump electrode, and then the plurality of resists are removed. Then, the barrier metal film is removed by etching.

By applying multiple layers of resist in this way, it is possible to coat the entire wafer with a thick resist with a uniform thickness, and as a result, uniform bump electrodes are formed on the elements over the entire wafer, and the residue under the massoshroom is also reduced. , the yield and quality of semiconductor devices can be improved.

[Example] Hereinafter, embodiments will be described in detail with reference to the drawings.

FIGS. 1(a) to 1(e) show step-by-step cross-sectional views of the forming method according to the present invention. PSG is applied to the entire surface of the substrate including electrode 2 (film thickness around 1 μm).
A film 3 (film thickness of about 1 μm) is lengthened, the PSG film 3 is ethoched to form an opening 6 on the aluminum electrode 2, and a barrier metal film 4 is deposited on the PSG film 3 including the opening 6. do. Note that the barrier metal film 4 is a T film deposited by a vapor deposition method.
The film consists of two layers: an i film (thickness: 3,000 yen) and a Pd film (thickness: 2,000 yen). Further, the area of the aluminum electrode 2 is approximately 100 μm square.

Figure 1 (see BL; Next, first resist 1.1) made of ZPR (Zeon Positive Resist) was applied to the top surface and cured to a film thickness of around 3 μm.
A second resist 12 made of PR (Tokyo Ohka Body Resist) is applied and cured to form a film having a thickness of approximately 3 μm. Although ZPR is prone to cracking, it is a resist that can be patterned with high precision and is easy to remove afterwards, and OFPR has excellent plating resistance. This resist is characterized by:

Refer to FIG. 1(C): Next, a first film having an opening 13 slightly wider than the opening 6 at the position of the opening 6 is exposed and developed.
A resist film mask 10 consisting of a resist 1) and a second resist 12 is formed.

Refer to FIG. 1(d); Next, the resist film mask 10 is used as a protective film, and the barrier metal film 4 is used as a blanking electrode to open the opening I.
3, gold bumps 15 (diameter 100 to 200 μmφ, height approximately 50 μm) are formed into a metal wood shape using a plating method. At that time,
The portion covered with the resist film mask 10 is not plated.

Refer to FIG. 1(e): Next, the resist film mask 10 consisting of the first resist 1) and the second resist 12 is dissolved and removed, and the exposed barrier metal film 3 is removed by etching. In this way, gold bumps 15 are formed on the aluminum electrode 2 with the barrier metal film 4 interposed therebetween.

If the above-described formation method is adopted, the second resist 12 has excellent plating resistance, so the resist film is less likely to peel off during the plating process, reducing the number of defective products and improving the manufacturing yield. Furthermore, the thickness of the resist film mask 10 can be made thicker for multi-layer coating, and the film thickness can be made uniform, and since the first resist 1) is a resist with little patterning residue, it is possible to make the resist film mask 10 thicker. There is no residue under the bumps, resulting in higher quality. Furthermore, since the resist is applied in multiple layers, it is possible to uniformly form the resist film mask 10 with a uniform thickness over the entire surface of a large-diameter wafer, which is particularly useful for improving yield and quality.

In addition, although the above embodiment has been described using a manufacturing method in which the metal bumps are gold bumps and the barrier metal film is a two-layer film of a Ti film and a Pd film, other members, for example, T can be used in the barrier metal film.
It goes without saying that a two-layer metal film of iW-8U, a two-layer metal film of Cr-Cu, etc. can be used, and a semiconductor device C in which solder bumps are formed can also be used.

[Effects of the Invention] As is clear from the above description, according to the present invention, in a semiconductor device having a metal bump electrode, the occurrence of defective products can be reduced when metal bumps are formed, and the residue under the hump electrode can be reduced. This has the great effect of improving yield and quality.

[Brief explanation of the drawing]

Figures 1 (al to el are step-by-step cross-sectional views of the forming method according to the present invention, Figure 2 is a cross-sectional view of a metal bump electrode, and Figure 3 ta+ to ff) are step-by-step cross-sectional views of a conventional forming method. In the figure, 1 is a semiconductor substrate, 2 is an aluminum electrode (flat electrode), 3 is a PSG film (insulating film), 4 is a barrier metal film, 5, 15 are gold humps, 6, 7, 13 are openings, 8.10 is a resist film mask, 1) is a first resist, and 12 is a second resist. All Genus Ha・>7・4 Dorukai Otke Shield I Edict No. 2 Figure 1 243

Claims (2)

[Claims] (1) A step of depositing an insulating film on a semiconductor substrate provided with a flat electrode, and patterning the insulating film to open the flat electrode portion. Next, a barrier is formed on the flat electrode portion and the entire surface of the insulating film. a step of depositing a metal film, then depositing a plurality of resists, opening the flat electrode portion to expose the barrier metal film, and forming a resist film mask made of the plurality of resists with other portions masked; Next, using the barrier metal film as an electrode, plating a metal bump on the barrier metal film in the opening; Next, removing the plurality of resist films and masking the metal bump. A method for manufacturing a semiconductor device, comprising the step of etching away the exposed barrier metal film. (2) The semiconductor according to claim 1, wherein the plurality of resists includes a first resist as a lower layer that has good patterning accuracy and is easy to remove, and a second resist as an upper layer that has good plating resistance. Method of manufacturing the device.