JPH01312853A - Manufacture of semiconductor device - Google Patents

Abstract

PURPOSE:To reduce coverage of a wiring metal to improve the productivity of semiconductor device by depositing a tungsten or a tungsten silicide in a contact hole similar in thickness to a undoped silicon oxide film by a selective vapor growth method. CONSTITUTION:An undoped silicon oxide film 12 to protect an interconnection metal and a gate electrode from short circuit is deposited on a substrate 11. Then, a PSG film (or BPSG film) 13 is deposited on the silicon film 12 and a contact hole 14 is made. Following to a preprocessing with a liquid of diluted fluoric acid (HF) system, a tungsten film (or tungsten silicide film) 15 is deposited on the contact hole 14 at a similar thickness to the silicon oxide film 12 by a selective CVD(chemical vapor deposition) method. Then, an interconnection metal such as an aluminum alloy is deposited. Thus, even with the application of selective CVD growth facility, the coverage by the interconnection metal in highly integrated, fine contact hole can be reduced and the productivity can be improved.

Description

[Detailed Description of the Invention] [Summary of the Invention] This invention relates to a method for manufacturing a semiconductor device in which tungsten or tungsten silicide is embedded in a contact hole (or a peer hole) by a selective vapor deposition (CVD) method. The purpose of the present invention is to provide a method for manufacturing a semiconductor device that can improve the coverage of metal wiring in a microscopic contact hole and improve productivity.
a step of depositing a silicon oxide film doped with phosphorus (P) or phosphorus (P) and boron (B) on the non-doped silicon oxide film; and a step of forming a contact hole in the non-doped and doped silicon oxide film. , a step of pre-treating the contact hole with hydrofluoric acid;
A method for manufacturing a semiconductor device, comprising the step of embedding a tungsten or tungsten silicide film into the contact hole by selective vapor deposition to a thickness equal to or shallower than the non-doped silicon oxide film after the pretreatment. 9 [Industrial Application Field] The present invention relates to selective vapor deposition 5CVD: Selecti
veChemical Vapor Deposit
The present invention relates to a method of manufacturing a semiconductor device in which tungsten (-) or tungsten silicide (WSix) is embedded in a contact hole (or via hole) using the on method.

(Prior Art) In recent years, with the demand for higher integration of semiconductor devices, there has been a demand for miniaturization of contact holes (or peer holes).However, with conventional wiring made of aluminum-silicon (AI-5t) alloy, Excessive silicon epitaxial growth (hereinafter referred to as in-phase epitaxial Si) in the contact hole increases contact resistance, and increases in aspect ratio lead to a decrease in wiring coverage.As a countermeasure for the former increase in contact resistance, barrier Prevention of in-phase epitaxial Si using metal has been proposed, but this is not sufficient to prevent the latter reduction in coverage rate.Therefore, as a method to satisfy both conditions,
In recent years, a technique for filling contact holes with tungsten (W) or tungsten silicide (WSix) using selective CVD has attracted attention.

In this selective CVD method, the goal is to completely fill the contact hole, but because the manufacturing equipment is not yet complete, it takes time to grow the film, making it impossible to improve productivity and making it easy for the selectivity to deteriorate. Additionally, there are problems such as the grown film peeling off from the substrate, and mass production technology for completely filling contact holes is still insufficient.

Therefore, a method of filling about half of the contact hole has been considered.

FIG. 4 is a sectional view of a conventional contact hole portion.

In the figure, a non-doped silicon oxide film 2 is deposited on a substrate 1 to a thickness of about 0.1 to 0.2 μm by CVD, and a phosphorus, silicate glass (PSG) film (or BPSG) is deposited on this silicon oxide film 2. Membrane) 3 from 0.6 to 0.8
It is deposited to a film thickness of about μm. After opening the contact hole 4, pretreatment is performed using a dilute hydrofluoric acid (IIF) solution. At this time, due to the difference in etching rate with respect to HP between the silicon oxide film 2 and the PSG film 3, the PSG film 3 recedes with respect to the underlying silicon oxide film 2, and a step is created in the contact hole 4. Next, a tungsten film 5 is grown by selective CVD. In an actual semiconductor device manufacturing process, when the tungsten film 5 is grown over this step, the growth is isotropic to a thickness equal to or greater than that of the silicon oxide film 2. In this state, a wiring metal 6 such as an aluminum alloy is formed by sputtering, and a protective film 7 is formed on the wiring metal 6. Therefore, in such a manufacturing method, the wiring metal 6 reflects the deposited shape of the tungsten film 5 and is free from sputtering shadowing.
(owing) effect, which deteriorates the coverage range.

[Problem to be solved by the invention]

Therefore, due to the instability of selective CVD growth equipment, complete burying of contact holes has not been established as a mass production technology, and half-filling, as in the past, causes problems such as poor wiring metal formation. was.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a method for manufacturing a semiconductor device, which can reduce the coverage of metal wiring in fine contact holes with high integration, even with a conventional selective CVD growth apparatus, and improve productivity.

[Means to solve problems]

The above problem involves the process of depositing a non-doped silicon oxide film on a substrate, and the step of depositing phosphorus on the non-doped silicon oxide film.
P) or a step of depositing a silicon oxide film doped with phosphorus (P) and boron (B), a step of forming a contact hole in the non-doped and doped silicon oxide film, and a step of pre-processing the contact hole with hydrofluoric acid. and a step of embedding a tungsten or tungsten silicide film into the contact hole by selective vapor deposition to a thickness equal to or shallower than the non-doped silicon oxide film after the pre-treatment. The problem is solved by a method of manufacturing a semiconductor device.

FIG. 2 is a diagram illustrating the principle of the manufacturing method of the present invention. Referring to FIGS. 1(a) and 1(b), first, as shown in FIG. 1(a), a non-doped silicon oxide film 12 is deposited on a substrate 11 to prevent a short circuit between the wiring metal and the gate electrode. A PSG film (or BPSG film) 13 is deposited on this silicon film 12, and a contact hole 14 is opened. After pretreatment with a dilute hydrofluoric acid (IP) solution, a tungsten film (or tungsten silicide film) is formed by selective CVD.
15 is buried in the contact hole 14 to a thickness approximately equal to that of the silicon oxide film 12. Next, as shown in FIG. 3B, a wiring metal 16 such as aluminum alloy is deposited.

[Effect]

In the present invention, in-phase epitaxial Si is prevented by embedding the tungsten film 15 using the selective CVD method.

In addition, by embedding the tungsten film 15 in the contact hole 14 to a thickness similar to that of the silicon oxide film 12, the effect on the coverage of the interconnect metal 16 is better than when embedding it halfway, and the shadow of sputtering is reduced. It is possible to prevent coverage from worsening due to the coverage effect.

〔Example〕

Hereinafter, the present invention will be specifically explained with reference to an illustrated embodiment.

FIGS. 2(a) to 2(f) are sectional views showing the manufacturing process of a semiconductor device according to an embodiment of the present invention. Note that parts corresponding to those in FIG. 1 are denoted by the same reference numerals.

First, as shown in FIG. 2(a), a non-doped silicon oxide film 12 of 0.1 to 0.2 μm is deposited on a substrate 11 by CVD.
Deposits to a film thickness of about Here, the reason why the non-doped silicon oxide film 12 is deposited is that the etching rate of a single PSG layer with respect to hydronic acid is fast, so it may be regressed during pre-treatment for later metal deposition, and there is a possibility of a short circuit between the metal and the gate electrode. This is because there is.

Next, as shown in FIG. 3B, a PSG film 13 is deposited on the silicon oxide film 12 to a thickness of about 0.6 to 0.8 μm by CVD.

Next, as shown in FIG. 2C, a contact hole 14 is opened by reactive ion etching (RIE).

Next, as shown in the same figure (d), the selection CV in the later process
Before growing the tungsten film using the D method, dilute hydrofluoric acid (IIF
) Pretreatment is performed with a system solution to clean the substrate surface in the contact hole area and ensure good contact. As a result, the non-doped silicon oxide film 12 and the PS
Due to the difference in etching rate for HF between the G film 13 and the PSG film 13, the PSG film 13 recedes and a step is created in the contact hole 14.

Next, as shown in FIG. 2E, a tungsten film 15 is grown on the substrate 11 in the contact hole 14 by selective CVD to a thickness comparable to that of the silicon oxide film 12.

Next, as shown in FIG. 3(f), a wiring metal 16 is deposited by, for example, sputtering.

According to the method of forming such a contact part, selective CVD
A silicon oxide film 12 is formed in the contact hole 14 by a method.
By burying the wiring metal 16 to a film thickness of about 100 ml, it is possible to prevent in-phase epitaxial Si, and the coverage of the wiring metal 16 can be relaxed compared to when burying the wiring metal 16 halfway, and it is possible to prevent poor coverage due to the shadowing effect of sputtering. In addition, since the contact holes are not completely filled, mass production becomes easy in a short time and productivity can be improved.

FIGS. 3(a) to 3(C) are cross-sectional views of a semiconductor device according to another embodiment of the present invention. Note that parts corresponding to those in FIG. 1 are denoted by the same reference numerals.

In this example, the size of the contact hole 14 is 1.0 μm square when the thickness ratio of the non-doped silicon oxide film 12 and the PSG film 13 formed on the substrate 11 is changed.
This is a comparison of the aspect ratios after embedding when the PSG film retreats by HF treatment by 0.2 μm.

The figure (a) shows that at the time of initial deposition, the thickness of the non-doped silicon oxide (SiOz) film 12 is 0.2 μm, the thickness of the PSG film 13 is 0.8 μm, and the finished film thickness is the same as the thickness of the non-doped SiO2 film 12. is Q, 2 μm, PSG film 1
The film thickness of the tungsten film 15 is 0.2 μm, and the aspect ratio after embedding is 0.4.
29, and the coverage is not sufficient as in the past.

In the figure (b), during the initial deposition, the thickness of the non-doped SiO□ film 12 is 0.3 μm, and the thickness of the PSG film 13 is 0.3 μm.
7μm, and the finished film thickness is non-doped SiO□ film 1.
The thickness of the PSG film 13 is 0.3 μm.
5 μm, and the thickness of the tungsten film 15 is 0°3 μm.
The aspect ratio after embedding was 0.357, and the coverage was relaxed.

In the same figure (C), at the time of initial deposition, the thickness of the non-doped 5i02 film 12 is 0.4 μm, and the thickness of the PSG film 13 is 0.4 μm.
6 pm, and the finished film thickness was non-doped Sin.
The film thickness of the film 12 is 0.4 μm, and the film thickness of the PSG film 13 is 0.4 μm.
The thickness of the tungsten film 15 is 0.4 μm.
The aspect ratio after embedding was 0.286, and the coverage range was further relaxed.

That is, in the above embodiment, the finished film thickness ratio of the PSG film 13 to the silicon oxide film 12 (silicon oxide film 12/PSG film 13) is as shown in FIG.
The coverage was relaxed by increasing the coverage from 1/3 to about 1/2 to 171 of those shown in FIGS.

In the present invention, the tungsten film 15 may be buried to a depth that is at least the same as or shallower than the silicon oxide film 12, and may also be a tungsten silicide film.

PSG l1913 also contains phosphorus (P) in the silicon oxide film.
It is doped with phosphorus (P) and boron (B).
) doped BPSG film may be used.

(Effects of the Invention) As explained above, according to the present invention, a technology has been established for completely filling a contact hole by depositing tungsten or tungsten silicide in a contact hole to a thickness comparable to that of a non-doped silicon oxide film using a selective vapor deposition method. It is possible to prevent in-phase epitaxial Si before the process is completed, and it is also possible to reduce the coverage of interconnect metals, which facilitates mass production and contributes to improved productivity, higher integration of semiconductor devices, and improved reliability. However, it is large.

[Brief explanation of the drawing]

Figures 1 (a) and (b) are diagrams explaining the principle of the manufacturing method of the present invention, Figures 2 (a) to (f) are sectional views of the manufacturing process of the embodiments of the present invention, and Figures 3 (a) to (C ) is a sectional view of the manufacturing process of the embodiment of the present invention, and FIG. 4 is a sectional view of a conventional contact hole portion. In the figure, 11 is a substrate, 12 is a silicon oxide film, 13 is a PSG film, 14 is a contact hole, 15 is a tungsten film, and 16 is a wiring metal. Patent Applicant: Fujitsu Limited Representative Patent Attorney Shodo Kukimoto Yoshiyuki Osuga (j'?-Ikkokuichi)

Claims (2)

[Claims] (1) Non-doped silicon oxide film (1) on the substrate (11)
2) and depositing phosphorus (P) on the non-doped silicon oxide film (12).
, or a step of depositing a silicon oxide film (13) doped with phosphorus (P) and boron (B);
13) forming a contact hole (14) in the contact hole (14), pre-treating the contact hole (14) with hydrofluoric acid, and after the pre-treatment, depositing tungsten or tungsten into the contact hole (14) by selective vapor deposition. A method for manufacturing a semiconductor device, comprising the step of embedding a silicide film (15) to a thickness equal to or shallower than the non-doped silicon oxide film (12). (2) The method of manufacturing a semiconductor device according to claim 1, wherein the thickness ratio of the doped silicon oxide film (13) to the non-doped silicon oxide film (12) is set to 1/2 to 1/1 in terms of finished dimensions.