JPH04180229A - Manufacture of semiconductor device - Google Patents

Abstract

PURPOSE:To prevent a gas from escaping from an SOG film by a method wherein an insulating film is formed so as to cover an opening for through-hole use formed in the SOG film by removing a photoresist on metal wiring, a photoresist is formed on the insulating film and around the opening for through-hole use and, after that, a through hole is made. CONSTITUTION:A photoresist 7 for through-hole formation use is formed on an insulating film 4 formed so as to cover metal wiring 3. Then, an SOG film 5 is formed in the photoresist 7; the photoresist is removed. Thereby, an opening for through-hole use is formed in the SOG film. After that, an insulating film 6 is formed so as to cover the opening for through-hole use; and the sidewall in the opening for through-hole use in the SOG film is covered with the insulating film 6. Then, a positive photoresist whose opening is smaller than the opening is formed on the insulating film 6 and around the opening for through-hole use; after that, an etching operation is executed so as to reach the metal interconnection 3; and a through hole is formed. Thereby, it is possible to prevent the close-contact defect of the interconnection when a gas escapes from the sidewall part of the through hole.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a method of manufacturing a semiconductor device, and in particular, to a method for manufacturing a semiconductor device, in particular, a process using SOG (spin on glass) between multilayer interconnections.
This paper attempts to propose a simpler solution to the problem that occurs when an insulating layer containing a film is used to flatten a step caused by underlying metal wiring.

This SOG film is often used for planarizing interlayer insulating films in order to improve the yield and reliability of products with multilayer wiring.

(Prior art) As an example of multilayer wiring, SOG is used for two-layer wiring.
As shown in Figure 2, the general process using a film is to first form a first insulating layer on the main surface of a semiconductor substrate, and then form a first metal wiring on this first insulating layer. Part 2
Figure +a+), then an insulating film, an SOG film, and an insulating film are sequentially formed as a second insulating layer to cover this metal wiring (Figure (b)), and then on this second insulating layer. , After forming a photoresist around the through hole to be made (see figure (C)), etching was performed using this photoresist as a mask to form the through hole.
The photoresist is removed (FIG. 1(d)), and a second metal wiring is formed to fill this through hole (FIG. 2(e)).

In the manufacturing process as described above, the SOG film is inevitably exposed on the side wall of the through hole, as shown in FIG. 4(d). Gas such as moisture escapes from this exposed SOG film toward the through-holes, causing poor adhesion and reliability of the metal interconnects in the next process of forming the second metal interconnects. There was a problem.

In order to prevent such inconvenience from occurring, the following improved process has been proposed.

(Al 30 G film full surface etch hack method When forming the second insulating layer shown in FIG. The SOG film on the film is removed so that the SOG film is not exposed on the side wall of the through hole.

However, since this method involves etching the entire surface, it has the disadvantage that if excessive etching is performed, a new step will be created, reducing the effect of alleviating the step. Depending on the shape and difference in base level, even if the entire surface is etched back, the SOG film may remain on the insulating film formed on the first metal wiring, and SOG may not necessarily be exposed in all through holes. However, it was not very effective and could not be called a fundamental solution.

(b) Through-hole drilling method The process flow of this method is shown in Figure 3.
The first metal wiring is formed in the same way as in Figure 3.
n) Then, to cover this metal wiring, an SOG film is formed using an insulating film method (Fig. After forming the cyst around the SOG film (FIG. 2(C)), etching is performed using this photoresist as a mask to form a through hole, and this photoresist is removed to remove the cyst (FIG. 2(D)). An insulating film is formed to cover the (Fig.
), and then on this second insulating layer, a photoresist was formed around the through hole to be re-created (FIG. 1(f)), and then etching was performed using this photoresist as a mask to form the through hole. Later, this photoresist is removed (FIG. 6(g)).

In this manner, photoetching is performed when the insulating film and SOG are formed during the formation of the interlayer insulating film. The dimensions of the mask at this time are approximately 0.5 to 1 μm larger in through-hole diameter than those of the photoresist to be formed later. After this, an insulating film is formed, so that the side wall of the through hole is covered with this insulating film, so that the SOG is not exposed.

This double-drilling through-hole method is technically very effective and can solve the problem of scrap removal from the side wall of the through-hole. However, because two types of masks are required for through-hole patterning, and two photo-last processes and two etching processes are required, manufacturing becomes complicated and manufacturing costs increase. The problem is that it may end up being a problem.

(Problem to be solved by the invention) The problem of poor wiring adhesion and reduced reliability due to degassing from the side wall of the through hole as described above can be solved more reliably and more easily than the conventional method, and can also be achieved at low cost. It is an object of the present invention to propose a method of manufacturing a semiconductor device that can be manufactured at low cost.

(Means for Solving the Problems) This invention obtains the same effect at a lower cost by producing the same through-hole side wall shape using a simpler method as in the double-drilling method of the through-hole described above. On the main surface, a first metal wiring, an insulating layer including an SOG film and covering the first metal wiring, and a second metal wiring formed on the insulating layer and electrically connected to the first metal wiring via a through hole. When forming the above-mentioned insulating layer in the manufacture of a semiconductor device having metal wiring, prior to forming the SOG film, a photoresist is formed on the through-hole portion to be created on the first metal wiring, and then the SOG film is formed. After that, this photoresist is removed to form a through-hole opening in the SOG film, an insulating film is formed to cover this through-hole opening, and then the above-mentioned through-hole is formed on this insulating film. This method of manufacturing a semiconductor device is characterized in that a photoresist is formed around an opening to form an opening smaller than the opening, and then etching is performed to reach the first metal wiring to form a through hole.

When forming a photoresist around the through-hole opening, it is more preferable to use the same photomask as that used to form the photoresist on the through-hole portion to be filled.

(Function) In this invention, the side wall of the through hole is covered with an insulating film to prevent the SOG film from being exposed to prevent connection failure and reliability degradation of the metal wiring due to degassing or release of adsorbed gas from the SOG. In order to achieve this, after applying SOG, an opening for a through hole is formed in the SOG film using a method such as a resist lift-off method.
Etching by etc. only needs to be done once. In addition, the side walls of the through hole are covered with an insulating film, and the same mask as the photoresist mask formed before applying SOG can be used as the photomask used when forming the photoresist for the subsequent through hole etching. Only one photomask is required.

When using the same photomask here, do you use a negative resist for the photoresist before applying S○G and a positive resist for the later photoresist? Since the difference in pattern conversion is different, it is possible to form an island-remaining pattern that is slightly larger (0.1 to 0.3 μm) than the hole size in the positive resist.

For this reason, when a SOG film is coated and formed by resist lift-off, patterning of the through-hole diameter is difficult.
This is done so that the OG film is not exposed.

(Example) The present invention will be explained in detail below with reference to the drawings.

FIG. 1 is a process diagram showing an example of the manufacturing method of the present invention. In the figure, 1 is a semiconductor substrate, 2 is a first insulating layer such as a Si oxide film, 3 is a metal wiring such as an AI wiring, and 4 and 6 are insulating films of the second insulating layer, such as S1.
There are oxide films, 5 is an SOG film, and 7 is a photoresist.

First, a metal wiring 3 is formed on the first insulating film 2 on the surface of the semiconductor substrate 2 as shown in FIG.
An insulating film 4 is formed by CVD so as to cover the
b)).

Next, on this insulating film, a photoresist 7 for forming a through hole to be made is formed (FIG. 3(C)). Is it preferable that this photoresist is a negative resist?If the same photomask is not used when forming the resist again in a subsequent process, it is not necessarily limited to a negative resist.

Next, SOGOsO4 is formed between the photoresists 7 (FIG. 4(d)). Even if this SOGOsO4 thickness becomes thicker than the photoresist 7, there is no problem since a resist lift-off method will be used later.

Next, this photoresist is removed using an asher method to form through-hole openings between the SOG films (
lift-off) ((e) in the same figure).

Thereafter, an insulating film 6 is further formed by CVD to cover this through-hole opening, and this insulating film 6 covers the side wall of the through-hole opening of the SOG film (see the same figure).
.

Next, on this insulating film 6, preferably using the photomask used before forming the SOG film, a positive photoresist with an opening smaller than this opening is formed around the above-mentioned through hole, and then a first Etching is performed to reach the metal wiring to form a through hole, thereby obtaining a semiconductor device in which the SOG film is not exposed on the side wall of the through hole, as shown in the same figure (g).

(Effects of the Invention) The semiconductor device manufacturing method of the present invention uses a resist lift-off method during SOG coating to prevent degassing from the SOG film, which conventionally required complicated manufacturing steps. ) To form through-holes, etching using RIE etc. can be performed only once (resist lift-off can be done using inexpensive equipment such as an asher), and (a) only one photomask is required for forming through-holes. Because it can be done easily, it can be manufactured more easily.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram showing the process flow of the manufacturing method according to the present invention, and FIGS. 2 and 3 are explanatory diagrams showing the process flow of the conventional manufacturing method. l...Semiconductor base 2...First insulating layer 3.
...Metal wiring 4...Insulating film 5...SOG
Film 6...Insulating film 7...Photoresist
8...Second metal wiring ■ ---1I --l
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Claims (1)

[Claims] 1. On the main surface of the semiconductor substrate, first metal wiring and SO
The above insulation in manufacturing a semiconductor device comprising an insulating layer containing a G film and covering a first metal wiring, and a second metal wiring formed on the insulating layer and electrically connected to the first metal wiring via a through hole. When forming the layer, prior to forming the SOG film, a photoresist is formed on the through hole part to be created on the first metal wiring, and then, after forming the SOG film, this photoresist is removed. A through-hole opening is formed in the SOG film, an insulating film is formed to cover this through-hole opening, and then an opening smaller than this opening is formed around the through-hole opening on this insulating film. 1. A method of manufacturing a semiconductor device, comprising: forming a photoresist, and then performing etching to reach the first metal wiring to form a through hole. 2. The method of manufacturing a semiconductor device according to claim 1, wherein the photoresist is formed around the through-hole opening using the same photomask used to form the photoresist in the through-hole portion to be formed.