JPS58159350A - Manufacture of semiconductor device - Google Patents

Abstract

PURPOSE:To obtain the highly accurate mask pattern for the titled semiconductor device by a method wherein, after a CVD insulating film consisting of a PSG film had been formed, the surface of said insulating film is smoothed, and subsequently a CVD insulating film is formed again, thereby enabling to accomplish a high degree of smoothness of the surface of the CVD insulating film. CONSTITUTION:A photoresist film 7is formed slightly thin in thickness at the projected part 8 of the PSG film and slightly thick in thickness at the other part. Then, a dry etching is performed to the photoresist film 7 until the projected part 8 is exposed. A selective etching is performed on the above covexed part 8 using the photoresist film 7, whereon an etching was performed, as a mask and the smooth surface of the CVD insulating film 6 consisting of a PSG film is formed. Regarding the etching to be performed on the roughened part of said PSG film, when an over-etching is performed to some extent, a part 10 of the convexed section 8 only is somewhat overetched, and when the photoresist film 7 is removed, the smooth surface of a CVD insulating film 11, consisting of the first aluminum 6, can be formed on the region where the film is to be thickly formed.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method of manufacturing a semiconductor device by improving the formation of multilayer wiring in the semiconductor device.

Conventionally, in the formation of multilayer wiring for semiconductor devices, after forming a first metal wiring, an insulating film is deposited by a CVD method (fabric succession method) or the like to form a through hole, and then a second metal wiring is formed. However, this method has drawbacks such as the first metal wiring step being as large as s,ooo to 12,0OOA, and resulting in an overhang structure when depositing an insulating film using the XCVD method. However, if the second metal wiring is performed until that time, there is a problem in that a faulty situation such as wire breakage occurs due to poor step coverage at the stepped portion. As a solution to these problems, smooth multilayer wiring f5 is being considered.

Two conventional examples of forming multilayer wiring in a semiconductor device will be explained below with reference to FIGS. 1 and 2.

FIG. 1 shows a conventional example of multilayer wiring formation, in which 1 is a semiconductor substrate, 2 is an AI wiring, and 3 is an insulating film made of polyimide resin. In this method, A! A smooth surface of the polyimide resin 3 is formed by using the coating characteristics of the polyimide resin 3, which is applied so that the wiring 2 is attached and formed, and the convex part is thin and the other parts are thick. Although the number of processing steps is small, the accuracy of surface smoothing is not guaranteed.

FIG. 2 shows another conventional example of the multilayer wiring forming process, 1
2 is a semiconductor substrate, 2 is an A4 wiring, and 4 is a PSG film coated by the CVD method.The edges are made of photoresist or polyimide resin and are an organic coating. In this method, first, as shown in FIG. 2(a), Aj is placed on a semiconductor substrate 1.
After forming the wiring 2 and growing a thick CVD insulating film 4 thereon, an organic film 5 is applied, and then the organic film 5 and the insulating film 4 are etched at approximately the same rate. After plasma etching, as shown in Fig. 2(b),
The CVD insulating film 4 is slightly etched to smooth its surface, and the accuracy of surface smoothing is improved compared to the first conventional example mentioned above. However, the plasma etching method, which is performed at approximately the same speed f for both the organic film 5 and the CVD film 4 described above, does not change the etching rate due to variations in the quality of these films. In fact, it is technically difficult to maintain the same etching rate. That is, in this case, the insulating film 4 and the organic film 5 are subjected to pressure, gas, violet, front handle, 7 pieces, 8 degrees of change.
It is technically very difficult to control the etching speed so as not to obtain the etching pattern 4b.

Furthermore, in the two conventional examples mentioned above, when polyimide resin is used as the insulating film, impurities contained in the resin, such as chlorine, may deteriorate the device characteristics or corrode the metal wiring. also occurred.

The present invention has been made by focusing on the above-mentioned points, and is a method for manufacturing a semiconductor device that does not require impurity contamination or difficult etching techniques in the formation of multilayer wiring in a semiconductor device, and can smooth the surface with high precision. The purpose is to provide the following.

An embodiment of the present invention will be described below with reference to FIG.

FIG. 3 is an embodiment of the present invention, showing the process of forming multilayer wiring, where l is a semiconductor substrate, 2 is an AI wiring, and 6°11 is a PS
The G film is deposited by the CVD method described above to become a CVD insulating film. 7 is a photoresist film, 8 is a PSG film, and the convex film portion is P.
On the lower surface of the SG film, reference numeral 10 indicates an over-etched portion of the PSG film.

In the method of the present invention, first, as shown in FIG. 3(a), an AI wiring 2 is mounted and formed on a semiconductor substrate 1', and then a PSG film is deposited using the C method described above, which is almost the same as the An wiring 2. A CVD insulating film 6 is formed by depositing the same film thickness, and a photoresist film 7 is formed thereon. This photoresist film 7 is thinner on the PSG film convex portion 8 due to normal coating characteristics.
It is thicker in other parts. Next, as shown in FIG. 3(b), the photoresist film 7 is dry-etched until the convex portion 8 is exposed. Then, using this etched photoresist film 7 as a mask, the convex portion 8 is selectively etched to form a PSG film as shown in FIG. 3(c).
A smooth surface of the CVD insulating film 6 made of a film is formed. In this PEG film convex film portion 8 etching, even if some overetching is performed, the ht wiring 2 portion is not etched, so only a portion 10 where the convex portion 8 was previously etched is excessively overetched. As shown in FIG. 3(d), by removing the photoresist (M17) and re-depositing the PSG film, a PSG film as shown in FIG. 3(e) can be obtained. CVD insulating film 1 consisting of
A layer forming a smooth surface is formed.

In the above embodiments, a photoresist film was used as the organic film, but there is no problem in using other organic materials such as polyimide resin.

As explained above, in the embodiment of the present invention, the pattern of the photoresist film 7 can be pattern-aligned, and steps such as exposure can be omitted and the pattern can be formed only by etching. Moreover, this method is characterized by selectively etching only the convex film portions of the PSG film, and as in the above-mentioned conventional example shown in FIG. The above-mentioned technical difficulties encountered due to having to etch at approximately the same etching speed can be completely avoided. Furthermore, the CVD insulating film 60 is made of a PSG film.
Since over-etching is possible, there is an advantage that the etching conditions are considerably relaxed.

Furthermore, since the organic material used is ultimately removed, there is no need to worry about the semiconductor properties being affected by impurities in the organic material, as in the conventional example shown in Figure 111. There are also advantages.

Having explained the above, to my friend, the present invention involves plasma etching only the thin organic film on the convex portion of a semiconductor device.
By smoothing the surface of the VD insulating film and then growing the CVD insulating film again, it is possible to achieve a high degree of smoothing of the surface of the CVD insulating film without the need for technically difficult etching. This paper describes the effect of solving the problems of conventional impurity contamination and interlayer differences in metal wiring. Moreover, by using this advanced surface smoothing technique, the present invention can be widely used as a method for forming an interlayer insulating film in multilayer wiring of semiconductor devices. Since the photoresist film coated on the photoresist film can be obtained with a uniform film thickness without unevenness, the present invention has a remarkable technical effect that it can be widely applied as a technical means for obtaining a highly accurate mask pattern. .

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view of multilayer wiring of a semiconductor device showing a conventional example, FIG. 2 is a process diagram of forming multilayer wiring of a semiconductor device showing a conventional example, and FIG. 3 is a multilayer wiring of a semiconductor device showing an embodiment of the present invention. It is a process chart of formation. 1... Semiconductor substrate, 2... A) Wiring, 6, 11...
・CVD insulating film made of PSG film, 7... Photoresist film, 8... PSG film convex film portion Applicant: Oki Electric Industry Co., Ltd. Figure 1 Figure 2 Figure 3 Procedure amendment 1982 June 30th, Commissioner of the Patent Office, Mr. Kazuo San 1, Indication of the case, Showa S1, Tatami Permit Application No. 0417002, Preparation of conductor device, IF Act 3, Person making amendment, Relationship with the case Applicant (0!*) Kami Electric Co., Ltd. 4, agent 5, date of amendment order Showa year, month, day (Maro-
) 6. Subject of correction @llll book or ⑗moWIA umbrella theory @ J O column and “
1SO easy I! @JO 橢. (i) On page 2 of the specification, lines 18 to 20, ``The number of processing steps is small, but that is why the surface smoothing is done once.'' t - ``In order to use polyimide resin as an insulating film.'' , there have been problems such as impurities contained in the resin, such as chlorine, deteriorating the device characteristics or corroding the metal wiring.'' (2) - Book, page 3, lines 12 and 13. ``The accuracy of surface smoothing increases.'' is corrected to ``If the polyimide resin is completely removed, no deterioration will occur due to impurities contained in the resin.'' (3) Book 4, page 4 Lines 6 to 10: ``Furthermore, in the two conventional examples mentioned above, when polyimide resin is used as the insulating film, impurities and gags contained in the resin deteriorate the device characteristics due to chlorine, etc. , or there may be a problem of corrosion of the metal wiring, so delete J. (4) Correct line 10 of the same iFS image to "Pond part Jt-r other part 9". (5) Same book, page 8 11 rows of rPSG convex parts.”tr P
8 G@Convex 1[, e-P 8 Gl[Lower 1! surface,
10,... P8G film over-etched part" is corrected. that's all

Claims (1)

[Claims] In a method for manufacturing a semiconductor device in which a metal wiring is formed and an insulating film is deposited on the metal wiring in a multilayer wiring forming process of the semiconductor device, after the insulating film is deposited, a protrusion is formed on the surface of the insulating film. Applying an organic film thinly and thickly on other parts, uniformly etching the organic film until the convex portions of the insulating film are exposed, and etching the insulating film using the organic film as a mask. 1. A method of manufacturing a semiconductor device, comprising sequentially performing selective etching of the insulating film and re-deposition of the insulating film.