JPS63192239A - Manufacture of semiconductor device - Google Patents

Abstract

PURPOSE:To remove bubbles, and to form insulating films having dense film quality by applying a plural layer of the insulating films including one layer of a borophosphosilicate glass film plural times, repeating melting every time the insulating films are applied and shaping the insulating films. CONSTITUTION:A plural layer of insulating films containing a borophosphosilicate glass film are applied, and melted at every application. That is, a plurality of wirings 2 are formed onto a substrate 1, and a phosphosilicate glass (PSG) film 11 is applied onto the wirings 2 through a CVD method. The PSG film 11 is melted through heating, a borophosphosilicate glass (BPSG) film 12 is applied onto the upper surface of the PSG film 11 again, and the BPSG film 12 is melted through heating again. Consequently, the insulating films in film thickness of 1mum are applied twice, and melted twice. Accordingly, bubbles are difficult to be generated, and the insulating films are made dense, thus shaping a multilayer interconnection layer having high reliability.

Description

DETAILED DESCRIPTION OF THE INVENTION [Summary] An insulating film containing at least one boron phosphorus silicate glass film is divided into a plurality of layers and deposited multiple times, and is melted each time it is deposited. This prevents bubbles from forming inside the insulating film.

[Industrial Field of Application] The present invention relates to a method of forming an insulating film among methods of manufacturing a semiconductor device.

BACKGROUND ART In semiconductor devices such as ICs and LSIs, multilayer wiring is provided on the upper surface of a miniaturized semiconductor element, and an insulating film (interlayer insulating film) is interposed between the wiring layers. However, it is desired that this interlayer insulating film can be melted at a low temperature and that it can be easily modified.

[Problems to be solved by conventional techniques and inventions] Conventionally,
As such an interlayer insulating film, a phosphorus silicate glass film (
However, recently, boron phosphorus silicate glass films (BPSG films) have been increasingly used. This is because the BPSG film can be melted at a lower temperature; the melting temperature of a PSG film containing 7 to 9% phosphorus is around 1000°C, whereas the melting temperature of a PSG film containing 7 to 9% phosphorus is about 1000°C. The melting temperature of the BPSG film containing about 5% is 900~
This is because it has a lower melting temperature of 950°C.

FIGS. 2(a) and 2(b) show cross-sectional views of the conventional method of depositing and melting a BPSG film.
Fig. a) is a process diagram in which a large number of wiring lines 2 are provided on a semiconductor substrate 1, and the upper surface including the wiring lines 2 is coated with a BPSG film 3 having a thickness of 0.7 to 1 μm. As described above, since the PSG film 3 is deposited by chemical vapor deposition (CVD), it has relatively good coverage, and the unevenness on the wiring surface is carried over to the upper surface as it is, and similar unevenness is Occurs on the surface.

Therefore, the coated BPSG film 4 is usually melted (reflowed) after being deposited in order to flatten the surface.

It is desirable to perform this reflow at as low a temperature as possible.
When it is reflowed at high temperature, impurity diffusion occurs,
This is because it affects the junction of the semiconductor element that has already been formed and deteriorates the element characteristics.

FIG. 2(b) shows a cross-sectional view of the process of melting the BPSG film, which is heated to 900 to 1000° C. in a neutral or reducing gas atmosphere.

However, as ICs have become increasingly finer in recent years, the gaps between interconnections have become narrower and the unevenness has become more pronounced, making it difficult to adhere the BPSG film densely to every corner of the recesses. Ta. Furthermore, when the BPSG film is melted, gas is generated from within the deposited film. Therefore, it has been found that when the BPSG film is melted, air bubbles H are included in the BPSG film in the recessed portions. These bubbles H impair the coverage of the insulating film, and from the viewpoint of reliability, it is important to form the insulating film so that it does not contain bubbles.

The present invention proposes a method for forming an insulating film that eliminates these drawbacks.

[Means for solving the problem] The purpose is to deposit multiple layers of insulating films, including at least one layer of boron phosphorus silicate glass film, in multiple steps, and repeat melting each time the insulating film is deposited. This is achieved by a semiconductor device manufacturing method that includes a step of forming an insulating film instead.

[Function] That is, in the present invention, an insulating film containing at least a boron phosphorus silicate glass film is deposited in plural layers and melted each time it is deposited. This will prevent air bubbles from forming in the insulating film.
The quality of the insulating film is improved.

[Example] Hereinafter, it will be explained in detail using examples.

1(a) to 1(d) show step-by-step cross-sectional views of the forming method according to the present invention, and FIG. 1(a) shows a plurality of wirings 2 provided on a semiconductor substrate 1, and a film Thickness 0.3~0
．． It is a process diagram in which a 5 μm thick PSG film 11 is deposited by the CVD method.

Next, as shown in FIG. 1(b), the PSG film 11 is melted by heating to 900 to 1000[deg.] C. in a neutral or reducing gas atmosphere.

Next, as shown in FIG. 1(C), a film with a thickness of 0
．． The BPSG film 12 with a thickness of 3 to 0.5 pm was deposited by the CVD method, and then heated again to 900 to 1000°C in a neutral or reducing gas atmosphere, as shown in FIG. 1(d). Then, the entire BPSG film 12 is formed.

In this way, an insulating film with a thickness of 1 μm is deposited in two steps and melted in two steps. This makes it difficult for bubbles to occur. Although this formation method slightly increases the number of man-hours, the insulating film becomes denser and a highly reliable multilayer wiring layer can be formed.

In the above embodiment, the PSG film 11 is deposited as the first layer of the insulating film, and the BPSG film 12 is deposited as the second layer. and a BPSG film is deposited as the first layer,
A similar effect of eliminating air bubbles can be obtained by depositing a PSG film as the second layer.

[Effects of the Invention] Therefore, according to the present invention, air bubbles are removed and an insulating film with dense film quality is formed, which greatly contributes to improving the quality of semiconductor devices.

[Brief explanation of the drawing]

FIGS. 1(a) to 1(d) are sectional views in the order of steps of a forming method according to the present invention, and FIGS. 2(a) and 2(b) are sectional views in order of steps of a conventional forming method. In the figure, 1 is the semiconductor substrate, 2 is the wiring, 3. 12 is the BPSG film, 11 is the PSG film, the heathered sun and moon, □, ka) Goginjo ゛ Way 3 Blood 2 1 Kyou L'J Saranagi frfxy
Figure 1

Claims (1)

[Claims] The step includes depositing multiple layers of an insulating film including at least one layer of a boron phosphorus silicate glass film in multiple steps, and repeating melting each time the insulating film is deposited to form an insulating film. A method for manufacturing a semiconductor device, characterized in that: