JPH0376022B2 - - Google Patents

Description

Detailed Description of the Invention <Industrial Application Field> The present invention relates to an improvement in a method for forming, for example, an interlayer insulating film using a photochemical vapor phase reaction, and in particular to an insulating film formation method for forming a thick silicon-based insulating film in a short time. It is about the method.

<Prior Art> In recent years, thin film forming methods using photochemical vapor phase reactions using light energy have been attracting attention because damage-free films can be formed at constant temperatures. An insulating film formed by this photochemical vapor phase reaction is superior in step coverage, electrical properties, etc., compared to an insulating film formed by atmospheric pressure chemical vapor deposition.

<Problems to be Solved by the Invention> However, in thin film formation by direct excitation photochemical reaction, the film formation rate is low, and the film thickness required for an interlayer insulating film (for example, 200 nm) is low.
The disadvantage is that it takes a very long time to form.

The present invention was devised in view of the above points, and an object of the present invention is to provide an insulating film forming method for forming an insulating film with excellent characteristics on a substrate at low temperature in a short time.

<Means for Solving the Problems> In order to achieve the above-mentioned object, the insulating film forming method of the present invention has excellent electrical properties in the step of forming a silicon-based insulating film on a substrate by photochemical vapor phase reaction. A step of forming a first silicon-based insulating film using SiH ₄ /N ₂ O-based gas, and a second step using Si ₂ H ₆ /O _2- based gas, which has a high deposition rate, on the first silicon-based insulating film. The structure is such that a silicon-based insulating film is formed.

<Function> With the above configuration, the required time for forming an insulating film can be significantly shortened, and in the above embodiment, for example, interlayer insulation using only a SiH ₄ /N ₂ O-based silicon oxide film can be achieved. The time required for forming an insulating film can be significantly shortened compared to forming a film.

<Example> Hereinafter, an example of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a schematic diagram showing an example of a thin film forming apparatus used to carry out the insulating film forming method of the present invention. In FIG. 1, 1 is a reaction chamber (sample chamber);
is the wafer susceptor, 3 is the silicon wafer, and 4 is the wafer susceptor.
IR lamp, 5 is synthetic quartz, 6 is a mercury lamp (Hg lamp), 7 is a gas inlet, 8 is a gate valve, 9 is a mechanical booster pump, and 10 is an oil rotary pump.

First, a P-type (100) silicon (Si) substrate (15 to 20 Ω cm) 3 is placed on the wafer susceptor 2 in the sample chamber 1 of the apparatus configured as described above, and then the rotary pump 10 is activated. After roughly evacuation of the pressure inside the sample chamber 1, the inside of the sample chamber 1 was evacuated to 10 ^-3 [Torr] using the mechanical booster pump 9. During this non-air operation, the temperature of the substrate 3 was raised to 300 [° C.] and maintained using the IR lamp 4. By the above mechanical booster pump 9
After evacuation to 10 ^-3 [Torr] or less, silane (SiH ₄ ) gas and N ₂ O gas are introduced from the gas inlet 7 to, for example, 15 [SCCM] and 250 [SCCM], respectively, to the inside of the sample chamber 1. Maintain the pressure at 2.5 [Torr],
A silicon oxide film as a first silicon-based insulating film was formed on the silicon substrate 3 using a mercury lamp (Hg lamp) 6.

Next, the gas inlet 7 is closed and the inside of the sample chamber 1 is evacuated to 10 ^-3 [Torr] or less using the mechanical booster pump 9, and then disilane (Si ₂ H ₆ ) gas and O ₂ gas are introduced. For example, 3 [SCCM] and 250 [SCCM] are introduced from port 7, the pressure inside sample chamber 1 is maintained at 2.5 [Torr], and a mercury lamp (Hg lamp) is introduced.
6 was used to continuously form a silicon oxide film of 160 nm as a second silicon-based insulating film on the substrate 3 on which the SiH ₄ /N ₂ O-based silicon oxide film was formed.

Next, close the gas inlet 7 and use the mechanical booster pump 9 to pump the inside of the sample chamber 1 to 10 ^-3 [Torr].
After exhausting the air to below, introduce _N2 gas into the sample chamber 1 to return it to atmospheric pressure, open the sample chamber 1, and
I took it out.

Furthermore, Figure 2 shows the substrate temperature dependence of the growth rate of SiH ₄ /N ₂ O-based and Si ₂ H ₆ / _{O 2} - _based silicon oxide films. system, Si ₂ H ₆ /
Regarding the sample in which an O ₂ -based silicon oxide film was formed,
MIS capacitors were fabricated and their electrical-voltage characteristics were shown.

According to the embodiment of the present invention described above, for example, the film thickness
A 200nm insulating film can be formed in about 60 minutes.

On the other hand, when an insulating film with a thickness of 200 nm was formed using only SiH ₄ /N ₂ O-based gas, it took about 250 minutes.

Furthermore, when using high-order silane gas, an insulating film of a desired thickness can be formed in a shorter time.
In this case, as is clear from FIG. 3, electrical characteristics such as dielectric strength voltage deteriorate, which is not preferable.

On the other hand, in the above embodiment, the first
SiH ₄ /N ₂ O has excellent electrical properties as an insulating film for
A Si ₂ H ₆ /O ₂ based silicon oxide film, which has a high deposition rate, is used on top of the first insulating film, and as a result, the desired thickness of the insulating film can be shortened. It can be formed in a short time and without deteriorating the electrical characteristics.

It should be noted that the present invention is not limited to the above embodiments, and can be implemented in various modifications without departing from the gist thereof. For example, the film structure may be SiH ₄ /N ₂ O system, Si It goes without saying that the structure is not limited to the two-layer structure of the ₂ H ₆ /O ₂ -based silicon oxide film, and for example, a three-layer structure may be used.

Furthermore, it goes without saying that conditions such as the gas pressure in the sample chamber, the substrate heating temperature, and the film thickness of each oxide film may be determined as appropriate according to specifications and the like.

<Effects of the Invention> As described above, according to the present invention, leakage current can be reduced and an insulating film can be formed at low temperatures in a short time, and as a result, it can be applied to interlayer insulating films. , is extremely effective.

[Brief explanation of drawings]

FIG _{. 1} is a schematic diagram showing a configuration example of a thin film _forming apparatus used to carry out the insulating film forming method of the present _invention . FIG _. A diagram showing the dependence of silicon oxide film deposition rate on substrate temperature,
FIG. 3 is a diagram showing the current-voltage characteristics of each silicon oxide film. 1...Sample chamber, 2...Wafer susceptor, 3...
...Silicon wafer, 4...IR lamp, 6...Mercury lamp (Hg lamp), 7...Gas inlet.

Claims (1)

[Scope of Claims] 1. In the step of forming a silicon-based insulating film on a substrate by photochemical vapor phase reaction, a first step of forming a first silicon-based insulating film using SiH ₄ /N ₂ O-based gas; a second step of forming a second silicon-based insulating film on the first silicon-based insulating film using a Si ₂ H ₆ /O _2- based gas at a deposition rate faster than that in the first step; 1. A method for forming an insulating film, comprising: forming an insulating film with a multilayer structure.