JPS6159840A - Vapor growth method - Google Patents

Abstract

PURPOSE:To equalize a thin-film forming rate extending over the whole surface of a substrate by forming a film or a part consisting of a metal having conductivity close to the quality of material of the substrate and surface secondary- electron radiation characteristics to a carbon susceptor section in the peripheral section of the substrate and coating a carbon surface. CONSTITUTION:Substrates 5 are held or fastened by each two pin 9 fitted to a carbon susceptor 6. Since the pins are set up where close on the center line of the substrate, the substrate is held under the state in which it is fast stuck approximately to the carbon susceptor, and there is no possibility of slip-off. An escape groove 10 for inserting tweezers is formed to the carbon susceptor in order to easily mounting or dismantling the substrate. A substrate peripheral section 8 in the carbon susceptor 6 is coated with aluminum or an aluminum alloy through flame spray coating, application, etc. Accordingly, the secondary- electron radiation characteristics of the substrate and a susceptor section are brought close, thus equalizing a thin-film forming rate.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a plasma CVD method that does not reduce the formation of a thin film around a substrate.

[Conventional technology]

In the semiconductor process, CVD (Chemica
1Vapor Deposition (Vapor Deposition) technology has become indispensable, and this technology supplies a gas consisting of the substance that constitutes the thin film material to be formed onto a substrate such as a wafer, and then forms the desired thin film on the substrate through a chemical reaction. Among the CVD methods, plasma CVD is a method for forming
This method is widely used because the reaction proceeds at relatively low temperatures.

Figure 2 shows the basic configuration of this device. Cylindrical container 1
is equipped with a gas inlet 2 and an exhaust port 3, and the whole is an electric furnace 4.
is inserted into. A plurality of carbon susceptors 6 on which substrates 5 are mounted are sealed in the container 1 . The carbon susceptor is provided with pins for holding the substrates, and the substrates are held facing each other. Since a high frequency voltage is applied to the carbon susceptor 6, the carbon susceptors 6 are connected alternately so as to constitute opposing electrodes, and are connected to an external high frequency power source 7. A reaction gas is introduced through the gas inlet 2 and the electric furnace 4 is heated to 300 to 400°C.
By heating the support plate and applying a high-frequency voltage to the support plate, the plasma excitation generated in the gap between the support plates accelerates the chemical reaction, and depending on the gas used, silicon oxide, silicon nitride, P
S G (Phosph.

A thin film such as 5ilicate Glass) is formed.

In addition to carbon, aluminum is also used as a material for the susceptor 6, but as the axial dimension of the container 1 increases, there is a risk of deformation in the case of an aluminum susceptor. Therefore, carbon susceptors with high high temperature strength are generally used.

[Problem that the invention seeks to solve]

When a carbon susceptor is used, differences in conductivity, secondary electron emission characteristics, etc. between the surface of the substrate such as a wafer and the carbon surface during the reaction will cause a difference in plasma excitation state, and the rate of H film formation around the substrate will decrease. descend. The results are shown by the solid line a in Figure 3. Approximately 1 On from the outer circumference + approximately 10% on the inside, 5
It can be seen that the formed film thickness is reduced by about 20% on the inner side of the dragon. Therefore, the portion near the outer periphery of the substrate cannot be used, and the productivity of the chip decreases accordingly.

Means for Solving Problem C] In the present invention, in order to solve the above problems, at least the carbon susceptor portion around the substrate is made of aluminum, or aluminum, which has conductivity and surface secondary electron emission characteristics close to that of the substrate material. By covering the carbon surface with an alloy metal film or parts, the thin film formation rate is made uniform over the entire surface of the substrate.

[Effect]

In plasma CVD, it is known that the plasma excitation characteristics during operation do not have a large effect on the film thickness formation rate. Plasma is generated by ionization caused by collisions between electrons and incoming gas molecules, but the generation of electrons is significantly influenced by the generation of secondary electrons due to electrons entering the substrate or carbon susceptor. By making the secondary electron emission characteristics of the substrate and the susceptor part as close as possible, it is possible to make the thin film formation rate uniform. Since carbon has a low surface smoothness and a secondary electron emission ratio inferior to that of the substrate, this problem is improved by disposing a metal such as aluminum.

〔Example〕

FIG. 1 shows an example in which an aluminum film 8 is provided around the substrate of a carbon susceptor 6 according to the present invention. The configuration of the entire device is almost the same as in Fig. 2 except for the susceptor part. Fig. 1(a) is an A-AIgr side view of Fig. 1(b).
FIG. 1(b) shows an oblique view. Although the carbon susceptor has a shape extending in the left-right direction in the figure, only a portion of the wafer is shown in FIG. 1 for convenience of explanation. In this figure, the substrate 5 is held or locked by two pins 9 provided on the carbon susceptor 6, respectively. Since the position of the bottle is close to the center line of the substrate, the substrate is held in close contact with the carbon susceptor, and there is no risk of it falling off. Further, the carbon susceptor is provided with an escape groove 10 for inserting a bottle set in order to facilitate attachment and detachment of the substrate.

The substrate peripheral portion 8 of the carbon susceptor is coated with aluminum or an aluminum alloy by thermal spraying, coating, or the like.

Thermal spraying technology is a method in which the metal material to be adhered passes through a high-temperature flame at high speed and is sprayed onto the surface of an object in a molten state to form a film, making it relatively easy to form a film where necessary. Similar effects can be expected by using aluminum metal parts without using the thermal spraying method.

The results of plasma CVD performed using the method shown in the embodiments of the present invention are shown by the dotted line in FIG. The dotted line is 5 from the surrounding area.
Although the film thickness increased by about 5% on the 1-inner side, it can be seen that this is a significant improvement compared to the solid line a according to the conventional method. In this embodiment, aluminum is used, so the film thickness is slightly increased, but an aluminum alloy or other metals may also be used.

〔Effect of the invention〕

By implementing the present invention, it has become possible to increase the formation rate to the periphery of the substrate, whereas in the conventional plasma CVD method, the thin film formation rate inevitably decreases at the periphery of the substrate.

[Brief explanation of drawings]

FIG. 1 shows the structure of the carbon susceptor used in the implementation of the present invention, where FIG. 1(b) is a perspective view and FIG. 1(a)
shows a sectional view taken along line A-A in FIG. 1(b). FIG. 2 shows an overall configuration diagram of the plasma CVD apparatus. FIG. 3 is a diagram showing the distribution of the formed film thickness in comparison with the conventional method. In the drawing, 1 is a quartz reaction tube, 2 is a reaction gas inlet,
3 is an exhaust port, 4 is an electric heating furnace, 5 is a substrate such as a wafer,
Reference numeral 6 indicates a carbon susceptor, 7 a high frequency power source, 8 a metal covering portion such as aluminum, 9 a substrate holding pin, and 10 a groove for inserting tweezers. Figure 1 (Ku) Figure 1 (b)

Claims (1)

[Claims] A carbon susceptor that holds a substrate is attached to the susceptor part around the substrate with a metal member exposed, and a high frequency is applied between the electrodes facing the carbon susceptor to generate plasma and remove the substrate. A vapor phase growth method characterized by forming a thin film on top.