JPH04180231A - Manufacture of semiconductor device provided with fine bump electrode - Google Patents

Abstract

PURPOSE:To manufacture a bump electrode whose accuracy is good and which is hardly stripped and, at the same time, to prevent an excess plated metal from adhering by a method wherein a fine bump electrode is constituted of a multilayer plated layer and a thick resist film is combined with a thin resist film. CONSTITUTION:Substratum metal films, 4, 5 are formed on a semiconductor substrate 1 in a part where a bump electrode is formed. They are coated with a thick resist film 6 as a photoresist film for electrolytic plating of the lowermost layer so that stepped parts in end parts of the metal films can be covered completely. An opening is formed in the thick resist film 6; the lowermost layer is plated; and a plated layer 7, at the lowermost layer, whose close contact property is good is precipitated and formed. Then, a thin resist film 8 as a photoresist film for plated-layer is applied; and an opening required to form a fine bump electrode is formed in the thin resist film. Then, the opening is plated electrolytically with a metal whose kind is the same as that of the lower layer; and the bump electrode 9 whose error is small and which is hardly stripped is precipitated and formed. Thereby, it is possible to prevent an excess plated metal from adhering and to obtain the fine bump electrode whose accuracy is good.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a method for manufacturing a semiconductor device having a fine bump electrode formed of multilayer plating layers.

[Conventional technology]

A conventional method for manufacturing bump electrodes on a semiconductor substrate will be explained with reference to FIG. 2 of the accompanying drawings.

First, as shown in FIG. 2(a), an aluminum electrode 3 formed on a substrate 1 is covered with a silicon nitride film 2 by a plasma CVD method or the like, and an opening is formed in a part of this silicon nitride film 2 by dry etching. do. Next, Figure 2(b)
As shown in the figure, a base metal film (adhesion barrier metal 4, diffusion barrier metal 5) is deposited on the opening of the silicon nitride film 2 on the aluminum electrode 3 by sputtering, and the diffusion barrier metal 5 is left only on the aluminum electrode 3 by selective etching. . Then, as shown in FIG. 2(C),
A photoresist film 6 (original resist film) having a thickness of 1.5 to 2.0 μm is applied to the base metal ridge to form a selection mask. Next, as shown in FIG. 2(d), the adhesive barrier metal 4
A bump electrode 10 is deposited and formed in the opening of the selection mask formed by the original resist film 6 by electrolytic plating using the resist film 6 as a cathode.

Next, as shown in FIG. 2(e), the photoresist film 6 is removed using a solvent, and the adhesive barrier metal 4 other than the portion where the bump electrode 10 is formed is removed by wet etching.

[Problem to be solved by the invention]

When manufacturing conventional fine bump electrodes, a photoresist film 6 (original resist film) is coated to a thickness of 1.5 to 2.0 μm, but as shown in FIG. 2(d), the edges of the photoresist film are not exposed to light or Processes such as post-baking cause deformation 11 and reduce the opening size. In a normal bump electrode, the opening size of the photoresist film is 50 to 100 μm, so a reduction in the opening size does not pose a big problem. However, when manufacturing fine bump electrodes on highly integrated semiconductor substrates, the required opening size of the photoresist film is 10 to 15 μm. For this reason, the deterioration of accuracy due to the reduction in opening size due to the deformation 11 is significant.

Further, since the opening size of the original resist film is required to be 10 to 15 .mu.m compared to the usual 50 to 100 .mu.m, photoresist tends to remain in the opening as a residual deposit during development when setting the opening.

This residual deposit exists between the bump electrode and the underlying metal film, and as shown in Figure 2 (d) due to the reduction in the opening size described above.
) The decrease in the connection portion 12 of the bump electrode leads to a state in which peeling is likely to occur.

On the other hand, as shown in FIG. 3, when a thin resist film 8 is used as the photoresist film to prevent the opening size from decreasing due to deformation of the photoresist film edge, and the thickness of the photoresist film is reduced relative to the opening size, electrolytic When a bump electrode is manufactured by a plating method, the photoresist layer may not be able to completely cover the unplanarized step portion at the end of the underlying metal film other than the opening for forming the bump electrode. In such a case, there is a problem in that extra plating metal 13 adheres not only to the bump electrode but also to the stepped portion that cannot be covered by the photoresist layer.

However, as shown in the table below, when using a thin resist film, the standard deviation is as small as 0°56, which is superior to when using a prototype resist film, regarding the accuracy of the dimensions of the opening required for fine bump electrodes. Therefore, it is suitable for forming fine bump electrodes.

Furthermore, since the thickness of the resist film is small relative to the opening size,
Another advantage is that there is no residual deposits that occur when using the original resist film, and there is little peeling of the fine bump electrodes.

Therefore, the present invention aims to solve each of the above-mentioned problems and apply the advantages of a thin resist film.The purpose of the present invention is to prevent the adhesion of excess plated metal, and at the same time, reduce peeling.
Another object of the present invention is to provide a method for manufacturing fine bump electrodes with high precision.

[Means to solve the problem]

In order to solve the above problems, the means taken by the present invention is to construct a fine bump electrode using multi-layered plating layers, and furthermore, use a deep resist film in the bottom layer and a thin resist film in the top layer. It's a method.

First, a base metal film is formed on the semiconductor substrate at the location where the fine bump electrodes are to be installed. A deep resist film is applied as a resist film.

In this deep resist film, an opening having the same size as that used in a normal deep resist film is set using a photolithography technique. Next, the bottom layer is plated by electrolytic plating, and a bottom plating layer with good adhesion is deposited.

Next, in the step of manufacturing a fine bump electrode as the top layer of the multilayer plating layer, a thin resist film is applied as a photoresist film for the plating layer. In this thin resist film, the photolithography technique allows openings required for forming fine bump electrodes to be set with high precision, which is difficult to achieve with a deep resist film.

Next, this opening is electrolytically plated with the same type of metal as the underlying layer to deposit and form a fine bump electrode with less error and less peeling. Multilayer photoresist layers are removed using a resist stripper.

Through the above steps, a fine bump electrode with less peeling 2 and high precision is manufactured.

[Effect]

According to this method, a bump electrode is formed from a multilayer plating layer on the base metal crotch on a semiconductor substrate, and a deep resist film is applied to produce the bottom plating layer to set an opening. In the process, by applying a deep resist film as the bottom layer, the thickness of the photoresist film is sufficient to cover the stepped parts such as the edges of the underlying metal film, preventing excess plating metal from adhering to areas other than the set openings. be done.

Further, even in the electrolytic plating process for the second layer and subsequent layers, the deep resist film at the bottom layer prevents excess plating metal from adhering to areas other than the precipitated plating layer. .

Since the opening for the fine bump electrode is set in the thin resist film of the top layer, the opening is set in the pattern resist film applied to the bottom layer with the same opening size as that passed through the pattern resist film. By performing electrolytic plating, a lowermost plating layer is deposited that is not affected by residual deposits and deformation of the edges of the photoresist film, has a secured bonding area, and has little peeling.

Furthermore, the thickness of the plating layer is kept lower than the thickness of the original resist film, making it possible to manufacture the second and subsequent plating layers.

On the other hand, a thin resist film is applied as the top layer of the multilayer plating layer, and openings are set for manufacturing fine bump electrodes, but the thickness of the thin resist film is smaller than the original resist film and the opening required for fine bump electrodes. Since the resist film is sufficiently thin compared to the dimensions of the resist film, a highly accurate aperture can be set without any residual deposits and unaffected by deformation of the resist film.

By performing electrolytic plating on this opening using the same metal as the lower layer, a fine bump electrode is manufactured with a plated layer with high precision for the dimensions required for the fine hump electrode. Since it is made of the same metal, it is strongly bonded and manufactured with high precision, so there is no reduction in the area of the connection with the underlying plating layer, resulting in a fine bump electrode with less peeling.

〔Example〕

Next, embodiments of the present invention will be described based on the accompanying drawings.

FIG. 1 shows cross-sectional views of each step in manufacturing a fine bump electrode having two gold plating layers according to an embodiment of the present invention.

As shown in FIG. 1(a), a silicon nitride film 2 is formed as a protective film on an aluminum electrode 3 on a substrate 1 by plasma CVD method, etc., and then selective etching is performed to set an opening, and an adhesive barrier is formed as a base metal layer. Metal (T i ) layer 4
Then, a diffusion barrier metal (Pd) layer 5 is formed by sputtering.

Next, as shown in FIG. 1(b), a diffusion barrier metal layer 5
is set in the electrode forming part by selective etching, and then a master resist film 6 with a thickness of 1.5 to 2.0 μm is formed on the base metal layer (adhesion barrier metal layer 4 and diffusion barrier metal layer 5).
is applied as the bottom photoresist layer. This prototype resist film 6 completely protects stepped portions such as the edges of the base metal film during electrolytic plating, and prevents excess plating metal from adhering. Next, an opening of approximately 50 μm, which is equivalent to that normally set in the original resist film, is set by photolithography.

Next, as shown in FIG. 1(C), gold plating is applied to the fine bump electrode formation portion opened in the original resist film 6 by electrolytic plating using the adhesive barrier metal 4 as a cathode.
Produce a bottom gold plating layer 7 of ~1.4 μm. The thickness of this gold plating layer allows for the formation of a second layer, so
Adjust the plating time so that the thickness is within the thickness of the original resist film.

In addition, in order to reduce the number of peeled surfaces, the opening size of the original resist film 6 is set slightly wider than that of the diffusion barrier metal 5, as shown in FIG. In some cases, the diffusion barrier metal 5 is covered with a plating layer, and the end portion of the plating layer is bonded to the adhesive barrier metal.

Next, as shown in FIG. 1(d), a thin resist film 8 having a thickness of 0.5 to 0.9 μm is coated on the original resist film 6 and the lower gold plating layer 7 as the uppermost photoresist film. Openings for fine bump electrodes are set in this thin resist film 8 by photolithography, but the thickness of the thin resist film is 0.5 to 0.9 μm compared to the required opening size of about 10 μm. The opening is thinner than the resist film thickness of 1.5 to 2.0 μm, has high precision, and has no residual deposits.

Next, as shown in FIG. 1(e), the openings for the fine bump electrodes set in the thin resist film 8 are plated with gold by electrolytic plating, and the top gold plating layer 9 with a thickness of 8 to 12 μm forms the fine bump electrodes. Manufactured as.

Next, as shown in FIG. 1(f), the thick resist film 6 and the thin resist film 8 are removed using a resist stripping solution, and then unnecessary portions of the adhesive barrier metal 4 are removed by wet etching.

As described above, a fine bump electrode with high precision and less peeling is manufactured on the base metal film (adhesion barrier metal 4 and diffusion barrier metal 5).

In this example, a fine bump electrode is constructed of two layers, the bottom plating layer 7 and the top plating layer 9, but one or multiple plating layers are provided between the bottom plating layer and the top plating layer. By forming it as an intermediate layer, a fine bump electrode of any height can be manufactured. This intermediate layer uses a thin resist film or a deep resist film, and is formed in the same process as the bottom plating layer.

〔Effect of the invention〕

As explained above, the present invention enables the production of fine bump electrodes with a multilayer structure using a plating method. It is characterized in that it is used to form the topmost plating layer, and has the following effects.

By using a deep resist film for the bottom plating layer, it is possible to prevent excess plating metal from adhering.

At the same time, by forming a fine bump electrode on the top plating layer, there is no residual deposit on the deep resist film, and it is possible to set an opening that is less affected by edge deformation, resulting in less peeling. This made it possible to form a plating layer.

Furthermore, by using a thin resist film as the top layer that forms the fine bump electrodes, it has become possible to manufacture fine bump electrodes with high precision. In addition, a multi-layer plating layer of the same metal, including a bottom plating layer with a guaranteed bonding area with the underlying metal film and a top plating layer of the fine bump electrode with a precise connection area. , it becomes a strong fine bump electrode.

As described above, by configuring a fine bump electrode with multiple plating layers and combining a deep resist film and a thin resist film, we have created a fine bump electrode with high precision and less peeling, which was impossible with conventional manufacturing methods. This makes it possible to manufacture electrodes, and at the same time prevents the adhesion of excess plating metal, which is a disadvantage of thin resist films.

[Brief explanation of the drawing]

FIGS. 1(a) to 1(f) are cross-sectional views of each step in manufacturing a fine bump electrode according to an embodiment of the present invention. FIGS. 2(a) to 2(e) are cross-sectional views of each step in manufacturing a conventional hump electrode using a deep resist film. FIG. 3 is a cross-sectional view showing a process for manufacturing a conventional bump electrode using a thin resist film, corresponding to FIG. 2(d). [Explanation of symbols] 1- Semiconductor substrate 2 - Silicon nitride film 3 - Aluminum electrode 4 - Adhesion barrier metal 5 - Diffusion barrier metal 6 - Deep resist film 7 - Bottom plating layer 8 - Thin resist Film 9 - Uppermost plating layer (fine hump electrode) 10 - Bump electrode 11 - Deformation of photoresist end 12 - Bump electrode connection 13 - Plated metal attached to one end. Figure 1 Figure 1 District 2 Figure 3 Procedural amendment (method) February 15, 1991 1, Indication of case 1990 Patent Application No. 30907
No. 5 No. 2, Name of the invention: Method for manufacturing a semiconductor device having fine bump electrodes Name of the person (523)
Fuji Electric Co., Ltd. 5. Date of amendment order
February 12, 1991 (all date of delivery) 6. Subject of amendment Description/Drawings (correction of Figure 1) 7. Amendment
Contents (1) On page 16, line 5 of the specification, “(
Correct the text “a) to (f)” to “(a) to (gl)”. Figure 1

Claims (4)

[Claims] (1) A method for manufacturing a fine bump electrode composed of multiple plating layers of the same type of electrolytic plating metal on a semiconductor substrate, the method comprising: forming a fine bump electrode on a base metal film on the semiconductor substrate; A process of applying a thick resist film as a photoresist film for the lower plating layer and setting an opening, a process of manufacturing the bottom plating layer by electrolytic plating in the opening, and a photoresist for the top plating layer. A fine bump characterized by comprising the steps of applying a thin resist film as a film and setting an opening for a fine bump electrode, and manufacturing a fine bump electrode as the uppermost plating layer in the opening by electrolytic plating. A method for manufacturing a semiconductor device having electrodes. (2) The bottom plating layer using the thick resist film is the first plating layer, and the top plating layer using the thin resist film is the second plating layer. A method for manufacturing a semiconductor device having a fine bump electrode according to claim (1). (3) The thickness of the thick resist film is 1.5 to 2.0 μm
Claim (1) or (2), wherein the thin resist film has a thickness of 0.5 to 0.9 μm.
A method for manufacturing a semiconductor device having a fine bump electrode according to 2. (4) Gold is used as the electrolytic plating metal, the thickness of the first plating layer is 1.0 to 1.4 μm, and the thickness of the second plating layer, which is the fine bump electrode, is 8 to 12 μm. A method for manufacturing a semiconductor device having a fine bump electrode according to any one of claims (1) to (3).