JPH0353530A - Manufacture of semiconductor device - Google Patents

Abstract

PURPOSE:To enhance the evenness of film thickness while assuring the breakdown strength characteristics of oxide films by a method wherein the first oxide film in almost even thickness is formed on a semiconductor substrate by rapid heating and short time oxidation processes and successively the second oxide film in arbitrary thickness is formed by the same processes in the same reaction chamber. CONSTITUTION:Firstly, the first oxide film in excellent evenness of film thickness is formed by rapid heating and short time oxidizing an oxide film on a silicon substrate at relatively low temperature of 750-850 deg.C. Next, the second oxide film in arbitrary thickness is formed by performing the normal rapid heating and short time oxidizing processes continuously at the high temperature of 1100-1200 deg.C in the same reaction chamber as that wherein the said rapid heating and short time oxidizing processes are performed so that the film thickness may be proportional to the oxidation time raised to 1/2 power in no danger of accelerating the initial oxidation rate in the oxidation process since the first oxide film is previously formed in the oxidation process of the second oxide film. Accordingly, the oxidation process is advanced while assuring the evenness of the oxide film thickness. Furthermore, the break-down strength characteristics in high reliability can be displayed due to the second rapid heating and short time oxidation processes successively performed.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for manufacturing a semiconductor device for forming an oxide film, and particularly to a method for manufacturing a semiconductor device for forming an oxide film, and particularly for rapid thermal oxidation (RTO).
The present invention relates to a method for forming a uniform oxide film through a rmal oxidation process.

[Summary of the invention]

In the method for manufacturing a semiconductor device of the present invention, a substantially uniform first oxide film is formed on a semiconductor substrate by rapid heating and short-time oxidation treatment, and then in the same reaction chamber where the rapid heating and short-time oxidation treatment was performed. By forming a second oxide film having an arbitrary thickness by thermal short-time oxidation treatment, the uniformity of the WA thickness is improved while ensuring the breakdown voltage characteristics of the oxide film.

[Conventional technology]

Oxide film formation technology includes vapor phase chemical reaction (CVD), spatter. There are two methods: a deposition method in which a SiO2 film is deposited on a substrate by spin coating, and an oxidation method using normal pressure oxidation, high pressure oxidation, and oxygen plasma oxidation. Among these, the oxidation method is atmospheric pressure oxidation. 700-11 in oxygen gas or water vapor like high pressure oxidation
Two methods are known: oxidation at a relatively high temperature of 400 to 700"C and a method of oxidizing a silicon substrate at a relatively low temperature of 400 to 700"C using oxygen plasma as the oxidizing species.Atmospheric pressure oxidation is the most common method. This method is particularly important in LOCOSM and gate oxide film formation for isolation between elements.In recent years, as MOS memories have been miniaturized, gate oxide films have become thinner, and oxide films with a thickness of less than 100 When using a conventional electric furnace with a heater such as an incandescent wire as a heat source to form an oxide film with a thickness of 100 mm or less, it is necessary to reduce the oxidation rate and improve the uniformity of the film thickness. At the same time, the film is oxidized at a relatively low temperature of 900° C. or less to prevent diffusion of impurities and thereby prevent deterioration in film quality.

However, as the oxide film becomes a GI film, it is necessary to further lower the processing temperature, and such lowering of the temperature may cause deterioration in film quality, such as a decrease in pressure resistance or the film becoming porous. be.

Therefore, rapid heating and short-time oxidation using halogen lamp irradiation has recently attracted attention as a technique for improving the above-mentioned film quality deterioration (for example, Japanese Patent Application Laid-Open No. 63-211
See Publication No. 759. ). This rapid heating, short-time oxidation treatment is performed using infrared radiation from a halogen lamp (near-infrared light with a wavelength of 0.4 to 4.0 μm). The sample is continuously irradiated for a short period of time (several seconds or minutes). An oxide film dry-oxidized in oxygen gas using halogen lamp irradiation has a pressure resistance equal to or better than an oxide film wet-oxidized in water vapor using an electric furnace. [Problems to be Solved by the Invention] However, with the above-mentioned method of forming an oxide film by rapid heating and short-time oxidation treatment using halogen lamp irradiation, pressure resistance is ensured, but on the other hand, the in-plane film thickness of the semiconductor substrate is The disadvantage is that the uniformity of the Generally, the relationship between the thickness of an oxide film and the degree of variation in film thickness is such that as the film thickness becomes thinner, the variation in thickness tends to increase. In addition, when comparing the oxide film formed by conventional rapid heating short-time oxidation and the oxide film formed using an electric furnace, according to the experimental results,
In the region where the film thickness is less than 200 mm, the uniformity of the oxide film due to rapid heat short-time oxidation is greatly deteriorated, and the value of the uniformity of the oxide film due to rapid heat short-time oxidation treatment is the same as the uniformity of the oxide film produced by electric furnace. It became about 1/2 of that. This is considered to be because the initial oxidation rate when processing the oxide film is faster than when an electric furnace is used. Furthermore, in the extremely thin film thickness region of 50 or less, the degree of variation in the oxide film due to rapid heating and short-time oxidation treatment exceeds approximately 10%, and with this decrease in uniformity, the breakdown voltage distribution also decreases. There is a problem with doing so.

Therefore, the present invention is a method of forming a film by rapid heating and short-time oxidation treatment, which is superior in terms of both film pressure characteristics and film thickness uniformity, especially for a oxidized film with a film thickness of 100 mm or more. The purpose of this paper is to provide a method for manufacturing semiconductor devices that utilize a thin oxide film. [Means for Solving the Problems] The multi-layer interconnection method of the present invention has been proposed to achieve the above-mentioned object, and it is possible to perform a substantially uniform first oxidation process on a semiconductor substrate such as a silicon substrate. A step of shaping the film by a first rapid heat short time oxidation treatment, and a second step of forming a second oxidation layer of an arbitrary thickness in the same reaction chamber in which the first rapid heat short time oxidation treatment was performed. It is characterized by the following steps: 1. Step 2: Forming by rapid heating and short-time oxidation treatment. Here, the second oxide film is obtained by further oxidizing the first oxide film, and is formed integrally.

Here, the first rapid heating short time oxidation treatment reduced the processing degree to 750.
It can be carried out at a temperature of 850°C to 850°C, more preferably 780 to 820°C. The second rapid heating short time oxidation treatment can be carried out at a temperature of about 1100 to 1200°C. In addition, the temperature increase rate to the treatment temperature of the first rapid heating short-time oxidation treatment was 50°C/s e
c or less, and the temperature increase rate to the processing temperature of the second rapid heating short-time oxidation treatment is 5 to 100 degrees (/sec, 10
A temperature of 0° C./sec or more is not preferable from the viewpoint of uniformity.

Further, the thickness of the first oxide film is, for example, 20 or less,
For example, the sum of the film thicknesses of the second oxide film and the first oxide film is 100
The method for manufacturing a semiconductor device of the present invention can be applied to forming an oxide film that is thinner than that of a human.

[Effect]

First, by rapidly oxidizing an oxide film on a silicon substrate at a relatively low temperature of 750 to 850° C. for a short period of time, a first oxide film having excellent film thickness uniformity is formed. Next, in the same reaction chamber where the above rapid heating short time oxidation treatment was performed, a normal rapid heating short time oxidation treatment is continuously performed at a high temperature of 1100 to 1200°C to form a second oxide film of an arbitrary thickness. Since the first oxide film has already formed during the oxidation process of the second oxide film, the film thickness is proportional to the 1/2 power of the oxidation time, and the initial oxidation rate in the oxidation process is There is no risk of it becoming faster. Therefore, the rapid heat short time oxidation is performed at a lower oxidation rate than the conventional rapid heat short time oxidation, so the oxidation progresses while maintaining the uniformity of the oxide film thickness. In addition, since the second rapid heating and short-time oxidation is performed, highly reliable voltage resistance characteristics can be obtained. [Embodiment] A preferred embodiment of the present invention will be described with reference to the drawings.

The present invention is a method for manufacturing a semiconductor device in which a silicon oxide film is formed by rapid heating and short special oxidation using halogen lamp heating.

First, the surface of the silicon substrate, which is a semiconductor substrate, is cleaned.
Perform surface treatment with dilute hydronic acid. A thin native oxide film is formed on the semiconductor substrate after this surface treatment. Next, as shown in Fig. 1, the temperature was raised to 800°C using halogen lamp heating at a rate of 50° (:/sec or less), and a first rapid short-time oxidation was performed at 800°C. II
A first oxide film with a thickness of about 20 mm is formed. In addition, the treatment temperature of the first rapid heating short time oxidation treatment is 750 to B5.
The range is preferably 0″C, more preferably,
The temperature is 780-820°C. Then, it is continuously heated to 150°C in the same reaction chamber where the first rapid short-time oxidation was performed. After the temperature reaches 1150 DEG C., a second oxide film of the desired thickness is formed by normal short-time oxidation at this temperature. The appropriate rate of temperature increase up to 1150'C is 5 to 100'C/sec, and a rate of 100°C/sec or more is not preferred from the viewpoint of uniformity.

In addition, in the second rapid heating short-time oxidation, the treatment temperature was set to 1 10
It can be carried out within the range of 0 to 1200°C. Here, FIG. 2 shows the film thickness (horizontal axis) of the oxide film obtained by the oxide film shape method of this example and the degree of variation in film thickness (
It also shows a comparison between oxide films produced by electric furnaces and oxide films produced by conventional rapid heating short-time oxidation. As shown in FIG. 2, the oxide film obtained in this example has a highly uniform thickness that is almost the same as that obtained using an electric furnace. The variation in film thickness is only 5%
That's about it. On the other hand, when compared with the conventional oxide film produced by rapid heating and short-time oxidation, more than twice the uniformity is obtained in the region of film thickness of 100 or less. By performing the two-step rapid heat short-time oxidation as described above to form an oxide film, the first oxide film has been formed in advance, so the actual oxidation rate is reduced in the oxidation process of the second oxide film. Since the oxide film becomes low, there are no factors that cause variations in film thickness, and a uniform oxide film is formed. Additionally, since it is oxidized at high temperatures, its pressure resistance properties are improved. [Effects of the Invention] In the method for manufacturing a semiconductor device of the present invention, as shown in step 5, rapid heating short-time oxidation is performed in two stages at different temperatures. That is, a uniform oxide film is formed at a relatively low temperature, and the quality characteristics of the oxide film are improved at a high temperature and rapid heating for a short time. In the second thermal short-time oxidation, since the first oxide film has already been formed, the oxidation rate does not increase, and the oxidation proceeds while the uniformity of the oxide film is maintained. Therefore, even in the case of a thin oxide film having a thickness of about 100 layers or less, an oxide film having excellent voltage resistance characteristics and uniformity can be realized.

[Brief explanation of drawings]

FIG. 1 is a diagram showing a temperature schedule for an example of the method for manufacturing a semiconductor device according to the present invention. FIG. 2 is a diagram showing the relationship between film thickness and uniformity in an example of the method for manufacturing a semiconductor device according to the present invention.

Claims (1)

[Claims] A step of forming a substantially uniform first oxide film on a semiconductor substrate by a first rapid heat short time oxidation treatment, and a step of forming a substantially uniform first oxide film to an arbitrary thickness in the same reaction chamber in which the first rapid heat short time oxidation treatment was performed. A method for manufacturing a semiconductor device, comprising the step of forming a second oxide film by a second rapid heating short-time oxidation treatment.