JPH07106330A - Formation of insulating layer in semiconductor device - Google Patents

Abstract

PURPOSE:To facilitate the control in the manufacturing step of an insulating layer furthermore enabling the capacity and reliability as the insulating layer such as heat resistance, insulation breakdown strength, film stress, etc., to be enhanced. CONSTITUTION:Within the title forming method of insulating layer composed of the three steps as follows i.e., the first step of forming metallic layer 13 on the main surface of a semiconductor substrate 11, the second step of forming the first insulating layer 14 covering the metallic layer 13 and the third step of forming the second insulating layer 15 covering the first insulating layer 14, the film stress of the first insulating layer is lower than that of the second insulating film 15 but the insulation breakdown strength is higher than that of the second insulating layer 15.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for forming an insulating layer in a semiconductor device.

[0002]

2. Description of the Related Art SOG (Spin) is a technique for planarizing an interlayer insulating layer in a semiconductor device having a multilayer wiring structure.
On Glass) is often used. In the planarization technique using SOG, conventionally, an SiO film (hereinafter referred to as a plasma oxide film) formed by a plasma CVD apparatus is formed immediately above a wiring layer containing Al as a main material, and then an SOG layer is applied. It was common to form.

FIG. 3 is a cross-sectional view schematically showing an example of the above-mentioned prior art. 31 is a silicon substrate, 32 is a field insulating layer, 33 is a metal layer containing Al as a main material, 34 is a plasma oxide film, Reference numeral 35 is an SOG layer.

[0004]

SUMMARY OF THE INVENTION In the prior art,
As the interlayer insulating layer, the plasma oxide film 34 must have high withstand voltage, low film stress, and good step coverage. Further, heat resistance against heat load during SOG curing is also required. Therefore, conventionally, 1 × 10 9 dyn / cm
A plasma oxide film, which has a compressive stress of about 2 and whose film forming conditions are set so that other film characteristics are good, was mainly used. However, forming a plasma oxide film having all of these film characteristics has a problem that it is difficult to control in the manufacturing process.

An object of the present invention is to provide an insulating layer in a semiconductor device, which facilitates control in the manufacturing process of the insulating layer and can improve performance and reliability as an insulating layer such as heat resistance, dielectric strength, and film stress. It is to provide a method of forming.

[0006]

According to a first aspect of the present invention, there is provided a method of forming an insulating layer of a semiconductor device, comprising a step of forming a metal layer on a main surface side of a semiconductor substrate and a step of forming a first insulating layer covering the metal layer. And a step of forming a second insulating layer that covers the first insulating layer, wherein the first insulating layer has a lower film stress than the second insulating layer and a high withstand voltage. To be A method of forming an insulating layer of a semiconductor device according to a second aspect of the invention is the method of forming the first insulating layer and the second insulating layer continuously by the same plasma CVD apparatus, The discharge power of plasma is changed with the second insulating layer.

[0007]

EXAMPLE FIG. 2 is a diagram showing the plasma discharge power dependence of the characteristics of the plasma oxide film formed in the plasma CVD apparatus using SiH4 and N2O. Figure 2
In, the discharge power indicated by a is lower than the discharge power indicated by b, but the film forming conditions other than the discharge power are set to be the same. When a film is formed with the discharge power shown in b,
The same plasma oxide film as the conventional example has a compressive stress of about 1.times.10@9 dyn / cm @ 2. On the other hand, when the film is formed with the discharge power indicated by a, 5 × 10 9 dyn / cm
It becomes a plasma oxide film with a compressive stress of about 2. Therefore, the withstand voltage is higher (not shown) as compared with the case where the film is formed with the discharge power shown in b, and BOE (Buffered) is used.
The etching rate and film stress due to the oxide etch are reduced, and the film thickness uniformity is improved.

FIG. 1 is a sectional view schematically showing an embodiment of the present invention. 11 is a semiconductor substrate, 12 is a field insulating layer, 13 is a metal layer containing Al as a main material, and 14 is a first layer. A plasma oxide film, 15 is a second plasma oxide film, and 16 is an SOG layer.

Next, a method of forming a plasma oxide film (insulating layer) of the embodiment will be described with reference to FIG.

A field insulating layer 12 is formed on the main surface side of a semiconductor substrate 11, and a metal layer 13 containing Al as a main material is formed by a normal film forming process, a photolithography process and an etching process. Here, the film thickness of the metal layer 13 is
It is 700 to 900 nm. Next, in the plasma CVD apparatus, the first plasma oxide film 14 is formed with a discharge power of 50 to 150 nm in FIG. 2A, and then the second plasma oxide film 15 is formed in the same plasma CVD apparatus as in FIG.
With a discharge power of 200 to 500 nm. afterwards,
After applying the SOG layer 16 by a usual method, it is cured.

In the above embodiment, the insulating layer has a two-layer structure,
The purpose of each insulating layer is different, such as the first insulating layer is a low stress / high withstand voltage layer and the second insulating layer is a high heat resistant layer. Optimal conditions can be set. Therefore, the control in the manufacturing process is simplified, and the performance and reliability of the insulating layer such as heat resistance, dielectric strength, and film stress are improved as the entire insulating layer.

In the above embodiment, the same plasma CV is used.
Since the device D is formed by successive steps in which only the discharge power condition is changed, a new film forming device and a gas system supply / exhaust pipe are not required.

Although the above-mentioned embodiment is applied to the plasma oxide film formed under the SOG layer used for the planarization technique in the semiconductor device having the multilayer wiring structure, it is applied under the plasma nitride film used as the final protective layer. It may be applied to the formed plasma oxide film.

[0014]

According to the method for forming an insulating layer in a semiconductor device of the present invention, the insulating layer has a two-layer structure, the first insulating layer is a low stress / high withstand voltage layer, and the second insulating layer is a high heat resistant layer. As described above, since the purpose of each insulating layer is different, it is possible to set the optimum conditions in the manufacturing process according to each purpose. Therefore, control in the manufacturing process of the insulating layer becomes easy, and the performance and reliability of the insulating layer such as heat resistance, dielectric strength, and film stress can be improved.

[Brief description of drawings]

FIG. 1 is a sectional view schematically showing an embodiment of the present invention.

FIG. 2 is a diagram showing plasma discharge power dependence of plasma oxide film characteristics in the example of the present invention.

FIG. 3 is a sectional view schematically showing a conventional example.

[Explanation of symbols]

 11 ... Semiconductor substrate 13 Metal layer 14 First plasma oxide film (first insulating layer) 15 Second plasma oxide film (second insulating layer)

Claims (4)

[Claims] 1. A step of forming a metal layer on the main surface side of a semiconductor substrate, a step of forming a first insulating layer covering the metal layer, and a second insulating layer covering the first insulating layer. And a step of forming the insulating layer, wherein the first insulating layer has a lower film stress and a higher dielectric strength than the second insulating layer. 2. A step of forming a metal layer on the main surface side of a semiconductor substrate, a step of forming a first insulating layer covering the metal layer with a plasma CVD apparatus, and a second step of covering the first insulating layer. The insulating layer of the plasma C
And a step of continuously forming with a VD device, wherein the discharge power of plasma is changed between the first insulating layer and the second insulating layer. 3. The method for forming an insulating layer in a semiconductor device according to claim 1, wherein the metal layer has Al as a main material. 4. The insulating layer in a semiconductor device according to claim 1, wherein the first insulating layer and the second insulating layer are layers containing silicon oxide as a main component. Forming method.