JPS6080226A - Manufacture of semiconductor device - Google Patents

Abstract

PURPOSE:To contrive improvement in covering of level differences and protection of a wiring film when performing deposition and etching alternately by performing only deposition to the predetermined film thickness and then etching after the thickness exceeds said predetermined value. CONSTITUTION:When SiO2 is vapor-deposited by bias spattering, a substrate bias is not applied while a film thickness is 500-1,000Angstrom (in such thickness, etching has virtually no influence on a base wiring film) and it is applied after the thickness exceeds this thickness. Next, deposition and etching are performed by spattering and ion milling respectively. At this time, while the film thickness is 50-1,000Angstrom , only deposition is done and when the thickness exceeds that thickness, etching is done. Consequently, covering of level differences is improved and damages in a wiring film can be prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION (1) Technical Field of the Invention The present invention relates to a method of depositing an insulating film over a wiring film deposited on a semiconductor substrate.

(2) Background of the technology Generally, thermal oxidation method, chemical vapor deposition (CVD)
) method, CVD method in plasma, etc., but in both cases, the semiconductor substrate is exposed to high temperatures, so currently physical sputtering methods are mainly used. In particular, sputtering of insulators uses radio frequency (RF) to prevent static electricity, and in Japan, 13
．． 56M11z is used. As sputtering methods for insulators, RF-diode sputtering and RF-magnetron sputtering, in which a magnetic field is applied to increase the ion concentration to increase the deposition rate, are widely used.

When a film is applied to a semiconductor substrate having a step by sputtering, the film does not adhere smoothly to the step, and deep folds are formed. In Fig. 1 fa), 1 is a semiconductor substrate, 2 is an aluminum (A1) film as a wiring film, and the figure shows an insulating film 3 that is deposited to cover the step caused by the AI film when sputtering is used. This indicates that deep cracks have formed at the step.

In order to obtain a smooth coating as shown in FIG. 1 fbl using the sputtering method, the following method is used.

(By applying a bias to the semiconductor substrate using the ALRF-diode sputtering method, the deposition and etching of the 1i film can be performed simultaneously to achieve the purpose. Figure 2+a) shows the main parts of the device, and 21.22 shows the main parts of the device. Pole plate, 23.24 is rf
A power source, 25 is a semiconductor substrate, and 26 is an insulator to be deposited on 25.

When the voltage of the power supply 24 is made higher than the voltage of the power supply #23, the insulator 26
is struck by argon ions (Ar) and deposited on the semiconductor substrate. Meanwhile, the semiconductor substrate 25 is struck by Δr+ by the bias power supply 23 and etched. Perform insulator deposition and etching.

(bl) As shown in Figure 2 (bl), an ion milling device 27 is added to an RF-sputtering device in which no bias is applied to the semiconductor substrate in the same device, and the substrate is moved and deposition and etching are applied alternately. .In Figure 2 Figure 1
The same numbers as 8) indicate the same objects. Alternatively, an ion gun of an ion milling device is added toward the semiconductor substrate in a sputtering device to simultaneously perform deposition and etching.

According to the sputtering method, insulating particles ejected by accelerated Ar ions fly in a straight line and are deposited, so if there is a step in the deposited material, the film deposited above the step may be slightly affected. However, if an overhang (4 in FIG. 1(a)) is formed, the overhang will be promoted as the deposition progresses, and as a result, cracks will occur at the stepped portion. Therefore, step coverage can be improved by performing deposition while removing overhangs by etching.

However, when the above method is carried out to improve the step coverage, a mechanically strong alumina (Δ
1zO,) film is damaged during the etching process, and the insulating film and AI react as shown in the following equation, causing wear on the AI, which not only fails to meet the designed capacitance, but is also extremely dangerous in terms of reliability. It is.

3StOz+4Al →2A1203 +3S 1(3
) Conventional technology and problems As mentioned above, improving the step covering and preventing wear on the wiring film is constrained by conflicting conditions, so methods such as making it thicker than the original in consideration of the wear on the AI can be considered. The amount is not constant, and once At is damaged, there is a problem in terms of reliability.

Therefore, it is desirable to provide a simple and complete manufacturing method that satisfies the above two requirements.

(4) Purpose of the invention The present invention improves the step covering in order to eliminate the above-mentioned conventional drawbacks,
Moreover, it is an object of the present invention to provide a manufacturing method that can prevent wear and tear on the wiring film.

(5) Constitution of the Invention When depositing an insulating film on at least a wiring film by sputtering, the wiring film is initially deposited only to a thickness that will not be substantially damaged by the following etching, It is characterized in that deposition and etching are then repeated simultaneously or alternately.

In the present invention, when depositing an insulating film, the wiring film is protected by only being deposited without etching to a thickness that does not substantially affect the underlying wiring film. After that, deposition and etching are performed simultaneously or alternately to obtain the desired step coverage.

(6) Embodiments of the invention Embodiments of the invention are described in 3.(2) Technical background (a)
.

(b) Regarding the two methods, silicon oxide (
S102), when using AI as the wiring film ゛ζ
explain.

(When depositing SiOz by the bias sputtering method, first do not apply a substrate bias until the film thickness is 500 to 1000 mm, and then apply it after this thickness is exceeded.

(bl) Even when deposition is performed by sputtering and etching is performed simultaneously or alternately by ion milling, the film thickness is 500 to 100 nm.
00, only deposition is performed, and etching is added after this thickness is exceeded.

Using the above method, the base layer is all! tI is protected.

In the present invention, SiO2 is used as the insulating film and AI is used as the wiring film, but changing these materials does not change the gist of the invention.

(7) As described in the detailed description of the invention, when an insulating film is deposited on a wiring film, it is possible to improve step coverage on the hour wheel and protect the wiring film;
It is extremely effective in achieving reliable productivity and improving reliability.

[Brief explanation of drawings]

FIG. 1 shows a cross-sectional view of a semiconductor substrate to explain step coverage, and FIG. 2 (al is bias type RF-diode-1'),
Batter Apparatus, FIG. 2(l)) shows a schematic diagram of an unbiased RF-diode-1 sputter apparatus with an ion-milling apparatus added. 1.25---semiconductor substrate, 2---one wire reflection, 3---
Insulating film, 21.22・--Polar plate, 23.24・-
r"Power supply, 26-Insulator, 27-- -Ion gun. 1st eye 2"1

Claims (1)

[Claims] When depositing an insulating film on at least a wiring film by a sputtering method, the wiring film is first deposited to a thickness that will not be substantially damaged by the following etching, and then deposited and etched. 1. A method for manufacturing a semiconductor device, characterized in that coating is repeatedly deposited simultaneously or alternately.