JPH0497532A - Manufacture of semiconductor device - Google Patents

Abstract

PURPOSE:To prevent electrical short-circuit due to the mutual contact of adjacent metallic plated films or unetched metallic conductive films which are current passage during plating by using first and second photoresist films as masks during plating. CONSTITUTION:In a case where a semiconductor substrate 1 is dipped in a gold plating solution and plating is performed by causing electric current to flow between the anode electrode plate of a plating apparatus with a titanium film 2 as a current passage, a gold plated wiring 7 does not grow in a direction perpendicular to the direction of the growth and adjacent gold plated wirings do not contact with each other as a result of using a first photoresist film 4A and a second photoresist film 4B as masks. Since there is no decrease in the plated region because of misalignment of patternings and fixed as a result of making a second opening portion 6B of the film 4B smaller than a first opening portion 6A of the film 4A, stable gold plating can be performed and electrical short-circuit can be prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method of manufacturing a semiconductor device, and particularly to a method of forming a metal plating film for wiring by plating.

[Conventional technology]

Conventionally, in the manufacturing method of semiconductor devices having this type of metal plating film, after the formation of the base wiring is completed, a metal conductive film is formed to serve as a current path during plating to strengthen the adhesion between the base wiring and the metal plating film. A barrier metal film is formed on the adhesion metal film to prevent the base metal film from reacting with the metal plating film, and then plating is performed using the photoresist film as a mask to form the barrier metal film. A metal plating film is formed on the film, and then the photoresist film is peeled off. Then, using the metal plating film as a mask, a part of the unnecessary metal conductive film is removed by etching, and each metal plating film is insulated and separated. was.

[Problem to be solved by the invention]

The conventional metal plating film manufacturing method described above uses a single photoresist film with a thickness similar to that of the metal plating film as a mask during plating. If there are variations in the growth rate, the metal plating film will easily enlarge in the direction perpendicular to the growth direction at the part where it is thicker than the photoresist film, causing adjacent metal plating films to come into contact with each other, or Another problem is that when a metal conductive film is removed by anisotropic dry etching, the enlarged portion acts as a mask and leaves etching residue, resulting in an electrical short circuit.

[Means to solve the problem]

The method for manufacturing a semiconductor device of the present invention includes a step of forming a base film consisting of a conductive film serving as a current path for plating, an adhesion metal film, and a barrier metal film on a semiconductor substrate on which elements and lower wiring are formed; A step of forming a first photoresist film on the entire surface including the base film and then patterning it to form a first opening in the metal plating layer forming area, and forming a polyimide resin film on the entire surface and forming the first opening. embedding and etching to expose the surface of the first photoresist film and leaving a polyimide resin film only in the first opening; forming a second photoresist film and then patterning it to form a second opening smaller than the first opening above the first opening; using a photoresist film as a mask to remove the polyimide resin film in the first opening to expose the base film; and using the first and second photoresist films as masks and exposing the base film by plating. and forming a metal plating layer thereon.

〔Example〕

Next, the present invention will be explained with reference to the drawings.

FIGS. 1(a) to (e) are cross-sectional views of a semiconductor chip shown in the order of steps for explaining the first embodiment of the present invention, in which the present invention is applied to gold-plated wiring of a tape carrier type integrated circuit. This is the case.

First, as shown in FIG. 1 (a), a metal conductive film with a film thickness of 0 is used as a metal conductive film that will serve as a current path when plating the entire surface of the semiconductor substrate 1 after completing the elements and lower layer wiring (not shown). .3
A titanium film 2 with a thickness of 0.2 μm is deposited on this titanium film 2 using a selective etching method or a lift-off method to form a base barrier film during plating.
Form IA3. This has a two-layer structure: a titanium film (thickness: 11 μm) to increase adhesion strength to the base, and a platinum film (thickness: 0.1 μm) to prevent gold diffusion.

Next, as shown in FIG. 1(b), a first photoresist M4A exposing the titanium/platinum film 3 is formed in the first opening 6A by patterning using a conventional method. here the first
The photoresist film 4A has a relatively thin film thickness (approximately 3
．． 0 μm). Next, a polyimide resin with a film thickness of 8 μm is applied to the entire surface to fill the inside of the first opening 6A and flatten the substrate surface, and then the first
The polyimide resin is uniformly etched to the film thickness of the photoresist M4A of the first photoresist film M4A.
The polyimide resin film 5 is left only in the opening 6A.

Next, as shown in FIG. 1(c), using as a mask the second photoresist film 4B with a thickness of 3.0 μm, which has been patterned by a conventional method to form a second opening 6B, the polyimide resin film 5 is coated with a hydrazine-based film. All etching is removed with a solution to expose the titanium/platinum film 3. Here, the second opening 6B of the second photoresist film 4B is made smaller than the first opening 6A of the first photoresist film 4A. Therefore, its cross-sectional shape is overhanging.

Next, as shown in FIG. 1(d), plating is performed by immersing the semiconductor substrate 1 in a gold plating solution and passing a current through the titanium film 2 as a current path between it and the anode electrode plate on the plating apparatus side. , a gold plating layer on titanium/platinum M3, that is, a film thickness of 5.
A gold plating pattern 817 with a thickness of 0 μm is formed. At this time, since the growth rate of the gold plating within the semiconductor substrate 1 is not uniform, regions where the gold plating film is locally thick tend to occur. However, since the first photoresist film 4A and the second photoresist film 4B are used as masks during plating, the gold-plated wiring 7 does not grow perpendicular to the growth direction, and adjacent gold-plated wirings come into contact with each other. There's nothing to do. For example, when forming 5.0 μm gold-plated wiring using a 3.0 μm thick photoresist mask using the conventional method as in this embodiment, the interval between the gold-plated wires must be at least 4.0 μm; According to the above, a spacing of 1.0 μm is sufficient. Further, the second opening 6B of the second photoresist film 4B is connected to the first opening 6B of the first photoresist film 4A.
Since the opening 6A is smaller than the opening 6A, the plating area does not decrease due to positional deviation during patterning and remains constant, so stable gold plating can be performed.

Thereafter, as shown in FIG. 1(e), after sequentially removing the second photoresist film 4B and the first photoresist film 4A, the titanium film 2, which is a metal conductive film, is removed by etching, and each gold-plated wiring 7 is removed. By insulating and separating them, a semiconductor device having gold-plated wiring 7 is completed.

According to the first embodiment, gold plating is performed using the first and second photoresist films as masks, so even if the growth rate of the gold plating varies somewhat within the substrate, the gold plating wiring can be formed reliably. Can be formed stably. Here, other metals may be used for the titanium film as the current path during plating and the titanium/platinum film as the underlying barrier film, and metals other than all metals may be used for the metal plating wiring. I can do it.

FIGS. 2(a) to 2(e) are cross-sectional views of a semiconductor chip shown in the order of manufacturing steps for explaining a second embodiment of the present invention.

As shown in FIG. 2(a), a titanium film 22 with a thickness of 0.5 μm is applied to the entire surface of the semiconductor substrate 21 after completing the elements and lower wiring to strengthen the adhesion with the underlying layer. to adhere to. Next, a platinum film 23 with a thickness of 0.1 .mu.m is deposited on top of this to prevent reaction between the base and the gold-plated wiring. Since the titanium film 22 and the platinum film 23 are adhered to the entire surface of the substrate, they serve as current paths between the respective gold-plated wirings during plating. Furthermore, a first positive type photoresist film 24A with a film thickness of 3.0 μm is formed on top of the film to serve as a part of a mask during plating, and then patterned to form a first positive photoresist film 24A in the area where the gold-plated wiring is to be formed. Opening 26A
is formed to expose a part of the platinum film 23.

Next, as shown in FIG. 2(b), after applying a polyimide resin with a film thickness of 8.0 μm to fill the first opening 26A and flattening the substrate surface, the first positive type is formed by an etch-back method. The polyimide resin film is uniformly etched depending on the film thickness of the photoresist M24, and a first positive photoresist M24 is formed.
The polyimide resin film 25 is formed only within the first opening 26A of A.
leave.

Thereafter, as shown in FIG. 2(c), a second positive photoresist film 24B is formed by patterning using a conventional method. At this time, polyimide resin I! Utilizing the solubility of the positive type photoresist No. 25 in the phenomenon liquid, the polyimide resin film 25 is also etched away at the same time in the developing process during the formation of the second opening 26B of the second positive photoresist film 24B. The platinum film 23 is exposed. Also, here, the second opening 2 of the second positive photoresist film 24B
6B is smaller than the first opening 26A of the first positive photoresist M24A, and has an overhanging cross-sectional shape.

Thereafter, as shown in FIG. 2(d), the semiconductor substrate 21 is immersed in a gold plating solution, and a current is passed between the titanium film 22 and the platinum film 23 as current paths and the anode electrode plate on the plating apparatus side, thereby plating the semiconductor substrate 21. By doing this, a gold plating layer is formed on the exposed area of the platinum film 23, that is, the film thickness is 5. O), tm gold-plated wiring 27 is formed. Here, as in the first embodiment, the gold-plated wiring does not grow in a direction perpendicular to the growth direction, and the interval between the gold-plated wiring 27 does not decrease.

After that, as shown in FIG. 2(e), the second positive photoresist film 124B and the first positive photoresist film 2 are
After removing 4A, the platinum film 23 and the titanium film 22 are continuously etched by anisotropic dry etching using argon gas, and each gold plating layer is removed. By electrically insulating and separating wires 27, a semiconductor device having gold-plated wiring 27 is completed. At this time, since the gold plated interconnect 27 does not enlarge in the direction perpendicular to the growth direction, the platinum film 23 and the titanium film 22, which are conductive films, are etched away according to the pattern of the gold plated interconnect 27 by anisotropic dry etching. Therefore, there is no possibility of electrical short-circuiting between adjacent gold-plated wirings 27.

In the second embodiment, since the polyimide resin M25 can be removed at the same time as the patterning of the second positive photoresist M24B, there is an advantage over the first embodiment that the amount of burnout can be reduced.

〔Effect of the invention〕

As explained above, the present invention uses the first and second photoresist films as masks during plating, so
It has the effect of suppressing the enlargement of the metal plating film in the direction perpendicular to the growth direction and preventing electrical short circuits due to contact between adjacent metal plating films or etching residue of the metal conductive film, which is the current path during plating. be.

[Brief explanation of drawings]

1(a) to 1(e) are cross-sectional views of a semiconductor chip shown in the order of steps for explaining the first embodiment of the present invention, and FIG.
FIGS. 7A to 8E are cross-sectional views of a semiconductor chip shown in order of steps for explaining a second embodiment of the present invention. DESCRIPTION OF SYMBOLS 1... Semiconductor substrate, 2... Titanium film, 3... Titanium/platinum film, 4A... First photoresist film, 4B
...Second photoresist film, 5...Polyimide resin film, 6A...First opening, 6B...Second opening, 7...Gold plated wiring, 21...Semiconductor Substrate, 2
2...Titanium film, 23...Platinum film, 24A...First positive photoresist film, 24B...Second positive photoresist film, 25...Polyimide resin film, 2
6A...first opening, 26B...second opening,
27...Gold plated wiring.

Claims (1)

[Claims] A step of forming a base film consisting of a conductive film to serve as a current path for plating, a metal film for adhesion, and a metal film for barrier on the semiconductor substrate on which elements and lower layer wiring have been formed, and a step of forming a base film on the entire surface including the base film. A step of forming a photoresist film and patterning it to form a first opening in the metal plating layer formation area, forming a polyimide resin film on the entire surface, filling the first opening, etching it, and etching the first opening. exposing the surface of the first photoresist film and leaving a polyimide resin film only in the first opening, and forming a second photoresist film on the entire surface including the exposed first photoresist film. Thereafter, a step of patterning to form a second opening smaller than the first opening above the first opening, and using a second photoresist film having the second opening as a mask, a step of removing the polyimide resin film in the opening to expose the base film, and a step of forming a metal plating layer on the exposed base film by a plating method using the first and second photoresist films as masks. A method for manufacturing a semiconductor device, comprising: