JPH05198687A - Multilayer wiring formation - Google Patents

Abstract

PURPOSE:To enable formation of a fine and arbitrary tapered through-hole and to provide a formation method of a multilayer wiring which can simplify a process by forming a through-hole in a layer insulating film consisting of polyimide resin by using a resist pattern. CONSTITUTION:A resist pattern with an inverted taper is formed of a resist 4 in a through-hole part on a first wiring 2 and is covered with polyimide resin 3. Then, a second wiring 5 is formed after the resist is removed by etching until an uppermost part of the resist pattern is exposed or after etching is performed until the entire resist is removed by using an etching rate of the polyimide resin 3 and the photoresist 4.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of forming a multi-layered wiring, which enables formation of a highly accurate through hole when forming a through hole in an insulating film made of a polyimide resin and enables miniaturization of a semiconductor device. Is.

[0002]

2. Description of the Related Art In recent years, due to miniaturization of semiconductor devices and multilayer wiring boards and multilayer wiring, insulators made of a polyimide resin having excellent film forming property, flattening property, and covering property on an interlayer insulating film or a surface protective film. Has come to be used.

A conventional method of forming a multilayer wiring will be described below. 3A to 3D are process cross-sectional views of a conventional multilayer wiring forming method, in which 1 is a semiconductor substrate, 2 is a first wiring,
3 is a polyimide resin, 4 is a photoresist, 5 is a second
Wiring.

When forming a through hole of a multilayer wiring,
First, the first wiring 2 formed on the surface of the semiconductor substrate 1 is covered with a polyimide resin 3, a resist pattern is formed thereon with a photoresist 4, and the exposed polyimide resin 3 is etched with a hydrazine etching solution. After that, the second wiring 5 is formed.

Another example of the conventional method for forming a multilayer wiring is shown in FIG.
It shows in (a)-(d). 1 is a semiconductor substrate, 2 is a first wiring, 3 is a polyimide resin, 6 is an inorganic film, 4 is a photoresist, and 5 is a second wiring.

When forming a through hole for multi-layer wiring,
First, the first wiring 2 formed on the surface of the semiconductor substrate 1 is covered with a polyimide resin 3, an inorganic film 6 such as a metal film, an oxide film, a nitride film or the like is covered thereon, and a photoresist 4 is further formed thereon. A resist pattern is formed. Then, the exposed inorganic film 6 is etched to remove the photoresist 4,
After the exposed polyimide resin 3 is etched by oxygen plasma or the like, the second wiring 5 is formed.

[0007]

However, in the conventional structure shown in FIG. 3, patterning with the photoresist 4 and wet etching with a hydrazine-based etching solution and bake conditions and etching conditions of the polyimide-based resin 3 cause a through hole. Since the taper angle changes, it is difficult to miniaturize the through holes and control the taper angle. Furthermore, the hydrazine-based etching solution is harmful to the human body and requires careful handling. It had the drawback.

Further, in the conventional structure shown in FIG. 4, since oxygen plasma or the like is used to etch the polyimide resin 3, the pattern of the inorganic film 6 such as a metal film, an oxide film or a nitride film is used as an etching mask. Must be formed, and the formation of the inorganic film 6, the resist patterning, the etching of the inorganic film 6, and the resist removal process are required for the formation, which increases the number of processes and the manufacturing cost.
Further, in etching with oxygen plasma or the like, it is difficult to form a taper angle of the through hole, the step coverage of the second wiring 5 deteriorates, and there is a drawback that disconnection may occur.

An object of the present invention is to solve the above-mentioned conventional problems, and an object thereof is to provide a multilayer wiring forming method capable of forming a highly accurate through hole and arbitrarily setting a taper angle.

[0010]

In order to achieve this object, a method of forming a multilayer wiring according to the present invention is designed such that a connection portion (through hole) to a wiring of an upper layer is formed on a wiring of a lower layer formed on a substrate by a negative type photo. Step of forming a convex resist pattern with reverse taper by appropriate overexposure using resist, step of covering lower layer wiring and resist pattern with polyimide resin with excellent coverage, polyimide resin surface Part of the convex resist pattern is etched with oxygen plasma or the like until the top is exposed, a step of removing the exposed convex resist pattern with a resist stripper, etc. There is a step of forming an upper wiring on the resin.

Another method of forming a multilayer wiring according to the present invention is
Using a negative photoresist in the through holes formed on the substrate, the process of forming a convex resist pattern with a reverse taper by appropriate overexposure, and covering the underlying wiring and the convex resist pattern Step of covering with a polyimide resin excellent in, a step of continuously etching a part of the polyimide resin surface and the entire convex resist pattern with oxygen plasma, etc., on the polyimide resin on which the through holes are formed. There is a step of forming an upper wiring.

[0012]

With this structure, since the through holes are formed by the photoresist pattern, the through holes can be miniaturized, an arbitrary taper angle can be provided, and the process can be simplified.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings.

1 (a) to 1 (d) are process cross-sectional views of a method for forming a multilayer wiring in an embodiment of the present invention. In FIG. 1, 1 is a semiconductor substrate, 2 is a first wiring, 4 is a negative photoresist, 7 is a photomask, 3 is a polyimide resin, and 5 is a second wiring.

First, a first wiring 2 is formed on a semiconductor substrate 1, a negative photoresist 4 is applied on the first wiring 2, and a through hole connecting portion between the first wiring 2 and the second wiring 5 is formed by using a photomask 7. Then, a resist pattern having an inverse taper is formed by appropriate overexposure. Next, the first wiring 2 and the resist pattern on the semiconductor substrate 1 are covered with a polyimide resin 3 and etched by oxygen plasma or the like until the uppermost part of the resist pattern is exposed, and then the exposed resist pattern is removed by a resist stripper. , The second wiring 5 is formed.

Further, FIGS. 2A to 2D are process cross-sectional views of a method for forming a multilayer wiring in another embodiment. In FIG. 2, similarly to the above, after covering the first wiring 2 and the resist pattern on the semiconductor substrate 1 with a polyimide resin 3 whose etching rate is slower than that of the negative photoresist 4, the etching rate of the etching rate is changed by oxygen plasma or the like. By utilizing the difference, a part of the surface of the polyimide resin 3 and the entire resist pattern are continuously etched, and the second wiring 5 is formed on the formed through hole.

As described above, according to the two embodiments, the first
A negative photoresist 4 is used in the through-hole portions of the wiring 2 and the second wiring 5 to form a resist pattern having a reverse taper by appropriate overexposure, and the resist pattern is used as it is for the through-hole. By adjusting the overexposure, it is possible to form a through hole that can have an arbitrary taper angle and simplify the process. Further, it is not necessary to form a hydrazine-based etching solution which is harmful to the human body for wet etching, or to form an inorganic film 6 pattern such as a metal film necessary for dry etching.

In this embodiment, the lower wiring is the first wiring and the upper wiring is the second wiring, but the lower wiring is the Nth wiring.
If the wiring and the wiring in the upper layer are the (N + 1) th wiring, an N-layer multi-layer wiring forming method can also be used.

[0019]

As described above, according to the present invention, a resist pattern having an inverse taper is formed on the through-hole portions of the lower layer wiring and the upper layer wiring by appropriate overexposure, and the resist pattern is used as it is for the through hole. Therefore, it is possible to realize an excellent multi-layer wiring formation method that can finely form a through hole in which an arbitrary taper angle can be provided by adjusting overexposure and simplify the process.

[Brief description of drawings]

FIG. 1 is a process sectional view of a method for forming a multi-layer wiring according to an embodiment of the present invention.

FIG. 2 is a process sectional view of a method for forming a multilayer wiring according to another embodiment of the present invention.

FIG. 3 is a process cross-sectional view of a conventional method for forming a multilayer wiring.

FIG. 4 is a process cross-sectional view of another conventional multilayer wiring forming method.

[Explanation of symbols]

 1 Semiconductor Substrate 2 First Wiring 3 Polyimide Resin 4 Photoresist 5 Second Wiring 6 Inorganic Film 7 Photomask

Claims (2)

[Claims] 1. A method of forming a wiring and a multilayer wiring made of a polyimide resin on a substrate, the method comprising forming a convex resist pattern at a connection portion with an upper wiring located on a lower wiring, A step of coating the lower wiring and a convex resist pattern with a polyimide resin, a step of etching a part of the polyimide resin surface until the uppermost part of the convex resist pattern is exposed, and the exposed connection portion A step of removing the convex resist pattern of
A method of forming a multi-layer wiring, comprising a step of forming an upper wiring on the polyimide resin on which the connection portion is formed. 2. A method of forming a wiring and a multilayer wiring made of a polyimide resin on a substrate, the method comprising forming a convex resist pattern at a connection portion with an upper wiring located on a lower wiring, The step of coating the lower wiring and the convex resist pattern with a polyimide resin, the step of continuously etching a part of the polyimide resin surface and the convex resist pattern, and the connection portion are formed. A method for forming a multilayer wiring, comprising a step of forming an upper layer wiring on the polyimide resin.