JPS58180014A - Thin film forming method - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION (1) Technical Field of the Invention The present invention relates to a method for forming a thin film, and more particularly, to a method for forming a thin film that can be used as a dielectric material such as a capacitor, and which can be made cheap. It is about the method.

(2) Conventional technology and problems Thin film capacitors, dynamic memory capacitors,
To create the optical waveguide, the entire dielectric material is formed by sonic thermal oxidation of the metal.

The 3a, 4a, and 5a elements can be oxidized at temperatures below 50 degrees Celsius to form chemically stable oxides. However, since these are in an amorphous p1 unstable crystalline state or in a low-density state, phase transition and densification may occur during subsequent heat treatment. After forming a new AT shadow, heat treatment is carried out for 1 time, and the above oxide thin film undergoes a phase transition, and a new oxide film enters into the oxide thin film at the pass through which the oxide thin film undergoes a phase transition. There was a drawback that the characteristics of the oxide thin film were completely deteriorated. Therefore, a method of stabilizing the thin oxide B1At by heat treatment before forming a new film can be considered, but this method has drawbacks such as m-crystallization progressing too rapidly.

(3) Purpose of the Invention In view of the above-mentioned problems, the present invention provides a method for stabilizing a thin film on a substrate by suppressing crystallization of the thin film by heat treatment.
The present invention aims to provide a method for forming an R film that does not deteriorate the properties of the thin film.

(4) Structure of the Invention According to the present invention, the above object is achieved by disposing 3a,
A thin g of oxide of a metal selected from group 4a and group 5a elements is formed, and the t! This is achieved by using a thin film forming method that has the special feature of including a step of performing stabilizing heat treatment while the surface is covered with an oxidation-resistant film.

To summarize the present invention, when the thin film formed on the substrate is amorphous or in an unstable state with low density, it is stabilized by heat treatment. It is something that is done. 50 on the board
When a thin film formed by oxidation at temperatures below about 0° C. is stabilized by heat treatment, it becomes a thin film, which undergoes a phase transition. For example, as shown in Figure 1, we have confirmed that when a tantalum oxide film formed on a substrate is heat-treated, crystallization begins at around 700°C, and crystal growth is particularly intense on the (100) plane. The horizontal axis of the diagram is the heat treatment theory, and the vertical axis is the integrated intensity of the Xm spectrum, which indicates the crystal grain size.
It is something. Furthermore, we also found that the crystal grain size was large, and that the film quality deteriorated with aging.

On the other hand, when the crystallization state of Ta5k was investigated by heat-treating the surface with a silicon nitride film, which is an oxidation-resistant film, before post-heat treatment, the crystallization of IP was suppressed as shown in Figure 2. That's what we discovered. Figure 82 shows the results of heat treatment in a house atmosphere, and Figure 3 shows the results of heat treatment in an unloaded atmosphere.

This phenomenon is thought to be because crystallization mainly occurs from the surface, and the nuclei are generated in large amounts during the heat treatment in the printing atmosphere.
I think so. If this oxidizing film is coated, the generation of nuclei will be suppressed and crystallization will not proceed. 4. It was observed that the crystal grain size did not become too large.

In addition, if the oxide film (0 surface atoms move horizontally in the main V direction and the crystal grows around the nucleus) and the entire model is formed, then the silicon nitride film is a silicon nitride film with atoms on the surface.
It is considered that all movement is obstructed. 1J:,
The same phenomenon is common to oxides 3a, 4a, and 5a, and it also applies to titanium other than tantalum oxide films.

It has also been confirmed that a similar effect can be obtained for gold ls oxides such as thorium and halenium by covering them with an oxidation-resistant film.

(5) Embodiments of the Invention Ta! Form an O@ film, a TlO film, and perform sputtering, preferably reactive sputtering using a mixed gas of argon and nitrogen, to form a thin film of about 30 nm or less (if the surface is rough, the thickness should be enough to cover it). k to be attached.

After this, according to the present invention, Ta, 0. A silicon nitride film of 10 to 20 nm is deposited on each of the film, tie, and film, and then heat treatment is performed for stabilization. The quality can be stabilized by 1il regardless of the atmosphere and processing temperature in this case. For example, the atmosphere is acidic and nitrogen, and the temperature f is in the range of about 900°C to 1100'C. After this stabilization, the silicon nitride film is etched away using hot phosphoric acid, reactive ion etching, etc., and a conductive layer is deposited thereon to form devices such as capacitors and transistors. Further, the silicon nitride film can be included in the device as it is without being etched.

In the above example, a silicon nitride film is used as the oxidation-resistant film, but this can be similarly performed with other oxidation-resistant films, and the stabilizing heat treatment can be performed not only in an electric furnace but also in laser, electron beam annealing, infrared annealing, etc. (6) Effects of the Invention According to the present invention, the heat treatment of the thin film leads to nitridation, which suppresses crystallization of the thin film, resulting in deterioration of film quality. Because it can be prevented,
Fatty electrolyte:/) The film thickness is very thin.

This makes it possible to realize capacitors that can withstand high-temperature heat treatment and have a higher capacity than V.

[Brief explanation of the drawing]

Figure 1 is a diagram showing the change in crystal grain size when a tantalum oxide film is heat treated using the oxidation method, and Figures 2 and 3 are diagrams showing the change in crystal grain size when the tantalum oxide film is heat treated after being coated with an oxidation-resistant film according to the present invention. A diagram showing the change in crystal grain size with respect to temperature yv is shown.

Claims (1)

[Claims] A process of forming a thin oxide film of a dielectric metal selected from 3a+4m and 5a group elements on the support substrate, and performing stabilizing heat treatment with the core thin 1[,/) surface covered with an oxidation-resistant film. Included: i- Characteristic thin film forming method.