JPH0336271A - Thin film formation - Google Patents

Abstract

PURPOSE:To compensate the nonuniformity of a film and to obtain uniform film thickness by combinedly using a stage of forming a thin film by an ECR plasma CVD method and a stage of forming a thin film by a photo-CVD method. CONSTITUTION:An ECR plasma CVD method is used and a plasma stream 2 is introduced via a window 14 into a treatment chamber 15 to form a thin film on a base material 1, by which the thin film whose thickness is increased in the central part and reduced at the periphery is formed. Further, a photo-CVD method is used and light 4 is introduced through a photoirradiation window 5 to form a thin film on the base material 1, by which the thin film whose thickness is reduced in the central part and increased at the periphery is formed. By combinedly using both stages mentioned above, a thin film of uniform film thickness can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for forming a thin film. The present invention can be applied to various fields in which thin films are formed on substrates by CVD method,
For example, it can be used to form thin films in the manufacturing process of electronic materials (semiconductor devices, etc.).

[Summary of the invention]

The present invention uses the ECR plasma CVD method by forming a thin film on a substrate by ECR plasma CVD method, and by irradiating light approximately parallel to the substrate or from the back side to form a thin film on the substrate by photoCVD method. Even if the thickness of the thin film formed by the method is non-uniform, the non-uniformity is compensated for by the thin film formed by the photo-CVD method, thereby making it possible to obtain a thin film with a uniform thickness.

[Conventional technology]

The ECR plasma CVD method uses electron cyclotron resonance (
Since plasma is obtained by excitation by ECR), it has the advantage of being able to form high-density plasma at low pressure and allowing high-speed growth of thin films at low temperatures.

Furthermore, by applying a bias, day positioning and etching can proceed simultaneously, and a flat film can be formed even when the underlying substrate has a stepped portion. From this point of view, the ECR plasma CVD method is suitable for, for example, next-generation ultra-L
It can be said that this is a very effective technology as an SI manufacturing process. Regarding the conventional ECR plasma CVD method,
Disclosures are made in JP-A-60115235 and JP-A No. 62-224923.

[Problem that the invention seeks to solve]

Generally, in the ECR plasma CVD method, as shown in FIG. 5, microwaves are introduced into a plasma generation chamber 11 through a waveguide or the like as shown by an arrow 12, and a magnetic field is applied by a magnet coil 13 disposed around the chamber. Plasma generation chamber 1
A thin film is formed on the substrate 1 by generating ECR-excited plasma in the substrate 1, guiding the plasma flow through the plasma extraction window 14 to the processing chamber 15, and performing CVD in the processing chamber 15.

However, the plasma flow introduced from the plasma extraction window 14 is in a diverging magnetic field, and the plasma flow also conceptually diverges toward the end as shown in FIG. Arrow 2 schematically indicates such a plasma flow.

For this reason, as schematically shown in FIG. 6(a), the plasma density becomes low around the base 1, and the thickness of the formed film becomes thin. Therefore, there is a problem that the thickness distribution of the thin film formed on the substrate is poor within the substrate. A conceptual diagram of the film thickness distribution within the substrate is shown in FIG. 6(b), and the film thickness in the periphery is thus thinner.

The present invention solves the above problems and enables ECR plasma CVD
It is an object of the present invention to provide a thin film forming method that can form a thin film with a uniform thickness while taking advantage of the advantages of the method.

[Means for solving problems]

The present invention is a thin film forming method for forming a thin film on a substrate, which includes a step of forming a thin film on the substrate by ECR plasma CVD method, and a step of forming the thin film on the substrate by irradiating light substantially parallel to the substrate or from the back side. The method includes a step of forming a thin film thereon by a photo-CVD method. In the present invention, thin film formation by E(, R plasma CVD method and optical C
The process of forming a thin film by the VD method may be performed either first or simultaneously.

This configuration achieves the above object.

[For production]

The operation of the present invention will be explained.

Using the photoCVD method, for example, as shown in Figure 2(a), a light 3 such as an excimer laser (A r F, etc.) capable of photodecomposing a reactive gas is irradiated onto the substrate in parallel to cause a photoreaction. If this happens, the light intensity will decrease in the direction of propagation of the light due to absorption of light by the reactant gas, and the reaction rate will also decrease. In other words, in the case of photo-CVD, the film thickness around the substrate 1 increases as shown in the film thickness distribution shown in FIG. 2(I). It becomes thicker near the light source.

In the present invention, ECR plasma CVD method and optical CVD method are used.
Since the method is used in combination with the ECR plasma CVD method, the non-uniformity of the thickness distribution of the thin film due to the ECR plasma CVD method can be compensated for by the optical CVD method, and its uniformity can be realized.

That is, by utilizing the above-mentioned characteristics of the photoCVD method, this
When applied to the plasma CVD method, it is possible to improve the deterioration of the thickness distribution around the substrate. The film thickness and deposition (growth) rate can be easily controlled by changing the intensity of the light and the distance between the substrate and the light source (laser light, etc.).

For example, by growing the substrate while rotating it, it is possible to compensate for the film thickness all around the substrate.

In the present invention, photoCVD is performed by irradiating light substantially parallel to the substrate or from the back side. This is because if light is irradiated from the front surface of the substrate, a thick film will grow by photo-CVD even in the central part of the substrate where the film thickness increases by ECR plasma CVD, and the non-uniformity of the film thickness will not be improved. Tokukai Showa 6
Publication No. 2-224923 discloses a technology that combines the ECR plasma CVD method and the optical CVD method (see especially FIG. 7 of the publication), but this conventional technology aims to improve film quality and step coverage. Therefore, the light is irradiated directly onto the substrate. In this case, it is impossible to improve the film thickness distribution. This is because, in the case of direct irradiation, the film thickness increases only in that part, and the film thickness distribution further deteriorates.

In the present invention, the light is not irradiated directly onto the substrate, but is irradiated approximately parallel to the substrate or from the back side, so that the film thickness decreases in the direction in which the light travels as the light passes over the substrate. , a film thickness distribution opposite to that obtained by the ECR plasma CVD method is obtained.

The angle of the light does not need to be direct to the substrate; it may be parallel to the substrate 1 such as a wafer, as shown by ■ in Figure 3, or approximately parallel from the front, as shown by ■. The angle may be freely changed as long as it does not directly hit the substrate, such as from the back side as shown by ■.

〔Example〕

An embodiment of the present invention will be described below with reference to FIG. This embodiment applies to various electronic devices, such as SRA,
It can be used as a manufacturing process for semiconductor devices such as M. Note that, as a matter of course, the present invention is not limited to the examples.

FIG. 1 shows the configuration of the ECRC lasma CVD apparatus used in this example. This device has a light irradiation window 5 that irradiates light 3 (here, laser light such as an ArF laser) toward a substrate 1 (here, a semiconductor wafer) in a processing chamber 15 in which CVD is performed.
have. In this example, the light 3 was irradiated parallel to the surface (thin film formation surface) of the wafer, which is the base 1.

Reference numeral 2 denotes a plasma flow, which is introduced into the processing chamber 15 from the plasma extraction window 14, as explained using FIG. This plasma flow 2 has a diverging shape, so that a thin film is formed that is thick at the center and thin at the periphery. Figure 4 shows the film thickness distribution, with the horizontal axis representing the position of the surface of the substrate 1 and the vertical axis representing the film thickness. Edge) makes me tingle. On the other hand, in the photoCVD method using light 4, as shown by the symbol B in FIG.
It becomes thicker at the periphery. This is because the light intensity gradually weakens due to light absorption by the reactive gas present on the optical path. As a result, the overall film thickness is shown in FIG.
It becomes uniform as shown in . In this example, the table 6 supporting the substrate 1 was rotated to make the entire film thickness uniform. According to this example, a thin film having a uniform thickness and being homogeneous and having little damage, which is an advantage of the ECR plasma CVD method, could be formed.

In Figure 1, 11 is a plasma generation chamber, 12 is a microwave (
13 is a magnet coil for forming a magnetic field.

〔Effect of the invention〕

As described above, according to the thin film forming method of the present invention, it is possible to form a thin film having a uniform thickness while taking advantage of the advantages of the ECR plasma CVD method.

[Brief explanation of drawings]

FIG. 1 is for explaining one embodiment of the present invention, and is a block diagram of an ECRC plasma CVD apparatus used in the embodiment. FIG. 2 is a diagram for explaining the present invention in detail and shows the action of photo-CVD in the present invention. FIG. 3 is a diagram illustrating an example of light irradiation in the present invention. FIG. 4 is a diagram showing the thickness of the thin film formed in the above example. FIGS. 5 and 6 are explanatory diagrams of the problems. 1... Substrate, 2... Plasma flow, 3... Light.

Claims (1)

[Claims] 1. A thin film forming method for forming a thin film on a substrate, the method comprising: forming a thin film on the substrate by ECR plasma CVD; and photo-CVD on the substrate by irradiating light approximately parallel to the substrate or from the back side. 1. A method for forming a thin film, comprising: forming a thin film by a method.