JPS6082671A - Vapor growth device - Google Patents

Abstract

PURPOSE:To provide a titled device for growing a film having uniform thickness and quality by providing plural gas spouting holes between a plasma chamber provided with differential pressure and a gas mixing chamber, and fixing the pitch of the holes in the radial direction and the number on the circumference. CONSTITUTION:A substrate 2 such as Si is placed on a hot plate 3 having a heater 5 in a plasma chamber, and a gaseous mixture of SiH4 and N2 is spouted from a reaction gas mixing chamber 6 through reaction gas spouting ports 7, and allowed to react by plasma to form an SiN film on the substrate 2. In said CVD device, the pitch of said gas spouting ports 7 of an electrode in the radial direction and the number per unit length on the circumference are fixed and set so that the gas concn. at the lower part of the electrode can be made uniform. The SiN film having uniform thickness and quality and excellent heat resistance is formed in this way.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] The present invention relates to plasma silicon nitride CVD (che'
11cal vapor deposition)
Concerning the device and forming method. In particular, the present invention relates to a CVD apparatus and method for forming plasma silicon nitride which has good uniformity and good heat resistance.

[Background of the invention]

The reaction systems conventionally known as plasma CVD of silicon nitride include S j H4-NH3N2 system and 5i) (4
There is the N2 series. In general, the S i HJNHs Nz system is often used.

However, in the case of SfH<NHsN2 system, hydrogen is easily incorporated into the film, which lowers the heat resistance. In addition, as shown in Figure 1 of the conventional apparatus Fi, since the reaction gas comes out from the center of the hot plate, SiH,
- In the case of N2 type, uniformity of film thickness and uniformity of film quality were insufficient. In FIG. 1, 1 is an upper electrode, 2 is a substrate, 3 is a hot plate, 4 is a reaction gas, and 5 is a heater.0 [Object of the Invention] The object of the present invention is 5jH4N! The present invention provides an apparatus and method for forming plasma silicon nitride with improved uniformity and heat resistance.

[Summary of the invention]

The production of plasma SiN using the 5jH4Nz system has so far been superior to SjH in terms of film thickness uniformity and film quality uniformity.
The 4NH3f'h series is also inferior. The reason for this is that the clusters in the reaction gas are not uniformly distributed between the electrodes.

Therefore, instead of the conventional method shown in Fig. 1, we adopted a single shower system as shown in Fig. 2, and as a result of examining the plasma conditions, we found that:
Even in the S I H4N2 system, it was possible to produce 5iNi with good film quality uniformity and film thickness uniformity, and poor heat resistance.

In FIG. 2, 6 is a reaction mixture mixing chamber, 7 is a gas outlet, 3 is a hot plate, 5 is a heater, and 2 is a material substrate.

That is, the CVD apparatus has a structure in which a plasma chamber and a gas mixing chamber 6 are provided, a pressure difference is provided between the two, and the pitch of holes 7 for ejecting reaction gas from the gas mixing chamber to the plasma chamber is constant in the radial direction. Nasu.

The following conditions are suitable for forming a silicon nitride film.

In the 5rH4N2 plasma CVD method, the total concentration of 5fH4 is 0.5 to 2.0% (volume ratio) and the substrate temperature is 350.
It is best to set it to ±50'C. A particularly suitable plasma condition is a discharge pressure of 0.3±0.1 Torr. In addition, 4 channels S j H4/N2 flow rate 200-/sin, N2 flow t 200 ml/M, discharge power 200W (frequency 1
3.56MH2) is used for the full length condition. However, the gas flow rate, the frequency of discharge power, etc. are not particularly fixed. Regarding these points, normal plasma C
The method used in the VD method can be used.

[Embodiments of the invention]

Hereinafter, the present invention will be explained in detail with reference to Examples.

Figure 2 shows the CV used for plasma SiN formation according to the present invention.
D device is shown. 6 is a mixing chamber for reaction gas, and 7 is a reaction gas outlet. 2 is a substrate (Si or GaAs et
c), 3 is a hot plate, and 5 is a heater. 7 and 3 are Atg.

In Figure 2, the whole 't4~5X 10-4Tc)r
Evacuate at r ton and use N2 gas tO, 3 to 0.4 Torr.
After installation, IJ was discharged with a discharge power of 200W.
-I did Jung. After cleaning, N2 containing 4% SiH4 was flowed at a flow rate of 300 ml/M% N2 stream 100 ml/win, and discharged for a predetermined time with a discharge power of 200 W to obtain a Six film of a predetermined thickness. By setting the gas ejection ports of the electrode 7 at a constant pitch in the radial direction, and by making the number of holes per unit length constant on the circumference, the porosity on each circumference is equal, and even at the center of the electrode. It was designed so that the amount of gas ejected at the periphery was equal and the gas concentration at the bottom of the electrode was equal.

Figure 3 shows the plasma Si under the conventional method and various conditions.
The etching depth in the film thickness direction of the N film is shown.

Here, the plasma CVD conditions of 8, 9, and 11 in the 5IH4N2 system are substrate grooves vao, respectively.

3 is a characteristic curve of a plasma SiN film at 350C, 250C, an SiH4 concentration of 1%, and a total flow rate of 400 ml/min. 10 is 5jH4-
This is a plasma SiN film in the NH3N2 system.

That is, all of the samples other than 8 indicate that the etching rate changes in the film thickness direction. 9 and 11 are for the film thickness direction,
Etching speed is increasing.

On the other hand, the etching speed of No. 10 is slow. In any case, this shows that the film quality is non-uniform in the film thickness direction.

On the other hand, in the case of No. 8 according to the present invention, the etching depth and time are not linear, the etching rate in the film thickness direction is constant, and the film quality is uniform.

Note that a film with good uniformity in film thickness and film quality was obtained at a substrate temperature of 300±2 Orr.

Furthermore, the Six film obtained at a substrate temperature of 300±2oc was 80
It has been confirmed that the film does not peel off even at high temperatures of 0C, and is a heat-resistant film.

Figure 4 shows each SiH of the 81)14 N2 system in the present invention.
4 shows the relationship between concentration and film thickness distribution. Here S iH4m
WIl”L8 jH4/S iH4+N2X100(%
).

From the figure, it can be seen that the film thickness uniformity is good when the 5IH4 concentration is 1%. When the SiH4 concentration is less than 0.5%, the formation rate becomes slow and it becomes impractical.

〔Effect of the invention〕

According to the present invention, there is a great effect on 11@thickness and film uniformity.

Since the plasma SiN film of the present invention has good uniformity in film thickness and film quality, it is most suitable as a film to be processed by dry etching. In addition, it has excellent heat resistance up to i grade 800c,
It is suitable as an annealing film after ion implantation and as a diffusion mask.

[Brief explanation of drawings]

1 is a schematic diagram of a conventional plasma silicon nitride forming apparatus. FIG. 2 is a schematic diagram of a 5IH4-N2 plasma silicon nitride forming apparatus according to the present invention. FIG. 3 is a schematic diagram of a conventional plasma silicon nitride forming apparatus. and substrate temperature further S I H4N H
FIG. 3 is a diagram showing the relationship between etching depth and etching time of a 3N2-based plasma SiN film. Figure 4 shows the entire film thickness distribution, with each SiH4 concentration (
FIG. 3 is a diagram showing the relationship between SiH4/St 14+N2X100) (φ) and the position in the substrate. ■... Upper electrode, 2... Substrate, 3... Hot plate, 4... Reaction gas flow, 5... Heater, 6...
Reactant gas mixer 1 Figure 2 Continuation of Figure 1 page [Inventor] Kobashi Demoted 1-28 Higashi Koigakubo, Kokubunji City Hitachi, Ltd. Central Research Laboratory

Claims (1)

[Claims] 1. It has at least a plasma chamber and a gas mixing chamber, a pressure difference is provided between the two, and a plurality of gas ejection holes are provided between the two, and the pitch of the gas ejection holes is constant in the radial direction. A vapor phase growth apparatus characterized in that the number of gas ejection holes on the circumference is constant.