JPS6187319A - Chemical vapor phase film forming equipment using plasma - Google Patents

Abstract

PURPOSE:To enable obtaining the uniform distribution of film thickness easily adjusting gas flow distribution in a simple construction by changing the position of a perforated plate for dispersing gas flow provided between a perforated plate type electrode surface and the aperture of a gas supply pipe connected to the back of the electrode. CONSTITUTION:An electrode 2 facing to wafer 10 to be treated is made in a box type, many air holes 16 are provided on the surface facing to the wafer 10, a gas supply pipe is connected on the back of the electrode 2 and a perforated plate 13 for dispersing gas flow is provided near the aperture of the gas supply pipe connected to the box type electrode 2. In such a chemical vapor phase film forming equipment, means which can freely adjust the position of the perforated plate 13 bringing near to or separating from the aperture of the gas supply pipe are provided. For example, the gas flow dispersion plate 13 is connected to a pipe 7 with a rod 14 and can be moved vertically by tightening or loosening a nut 15 at the top of the pipe 7.

Description

[Detailed Description of the Invention] [Field of Application of the Invention] The present invention relates to a chemical vapor deposition apparatus that forms a thin film on the surface of a wafer by a chemical reaction by placing a wafer 1 used for semiconductor products etc. in a low-temperature plasma stream. (abbreviation CVD equipment)
In particular, it relates to a plasma CVD apparatus that has been improved so as to be able to easily control the film thickness to make it uniform.

[Prior art]

In plasma CVD equipment that has parallel planar electrodes facing each other, attempts have been made to optimize the gas flow or plasma intensity in order to make the film thickness distribution uniform, but the It is difficult to make the reaction gas concentration uniform on the surface. Furthermore, a method has been proposed in which the reaction rate is made uniform by providing an electric field intensity distribution that fully compensates for the concentration difference in one reactant gas, but if this method is used, the structure of the electrodes and power supply will be complicated, and the equipment cost will increase. increases.

A convenient method to make the film thickness uniform is to measure the non-uniformity of the film thickness distribution on the substrate through a film deposition experiment, and change the distribution density of the holes in the reactant gas outlet accordingly. It is taken. For example, if the film thickness at the outer periphery of the substrate is thin, more holes are made at the outer periphery of the gas outlet so that more gas can be blown to the outer periphery.

In this method, it is extremely inefficient to process the blow-off holes in accordance with each change in film-forming conditions, and it is difficult to apply it to an actual mass-produced RK.

[Purpose of the invention]

The present invention has been made in view of the above-mentioned circumstances, and its purpose is to easily adjust the gas flow distribution and obtain a uniform film thickness distribution with an inexpensive and simple configuration. The present invention aims to provide a plasma chemical vapor deposition apparatus.

[Summary of the invention]

As mentioned earlier, the conventional film thickness adjustment method of controlling the gas flow distribution by changing the arrangement of holes drilled on the surface of a box-shaped electrode in order to blow out the reactant gas requires Since the perforated plate-like electrode component must be replaced at any time, a great deal of time and effort is required, which is uneconomical.

The basic principle of the present invention is that the perforated plate constituting the entire front surface of the box-shaped electrode is replaced, and the perforated plate-shaped electrode surface is connected to the gas supply connected to the back thereof without being moved. The gas flow distribution is adjusted by changing the position of a perforated plate for gas flow dispersion provided between the pipe opening and the opening.

Based on the above principles and for the aforementioned purposes (by simple configuration,
In order to easily adjust the gas flow distribution, the plasma CVD apparatus of the present invention allows the porous plate for gas flow dispersion to be moved freely toward and away from the opening of the gas supply pipe. It is characterized by providing a means for adjusting.

[Embodiments of the invention]

Next, an embodiment of the present invention will be described with reference to FIGS. 1 to 3. FIG. 1 is a vertical sectional view of an embodiment of the plasma CVD apparatus of the present invention. An upper electrode 2 and a lower electrode 6, which are insulated from each other by nitrogen gas, are arranged vertically in the center of the vacuum chamber 1. The upper electrode is a high frequency power source 4
The lower electrodes 3 are each connected to ground.

The upper electrode 2 is formed from a shaft portion 52 and a disk portion 6, and a vibrator 7 is provided from above the shaft portion 5 as an air supply pipe. - Two openings 9 are provided in the chamber bottom plate 8 below the crab electrode and communicate with a vacuum pump (not shown) through an exhaust pipe. A base wafer 10 made of stainless steel or glass, for example, is placed on the lower electrode 3. To form a thin film, a constant amount of υ reaction gas (for example, monosilane and hydrogen) is supplied to the 5W amount controller 11 from above the vibrator 7, and at the same time it is exhausted through the opening 9.

The atmospheric pressure inside the chamber 1 is maintained at 0.5 to 1 torr, and the reaction gas flow rate is adjusted to 100 to 3005 cCn. The lower electrode 3 is kept at about 100° C., and the other components are kept at about room temperature. The upper electrode 2 is formed in the shape of a box, and its front wall (lower side in the figure) is constituted by a porous plate 12.

A reaction gas is ejected from this perforated plate 12 toward the substrate substrate 10 that is the workpiece.

The components described above with respect to FIG. 1 are similar to conventional plasma CVI devices.

In the conventional device, a perforated plate 13 for gas flow dispersion is provided between the reactant gas supply pipe 7 and the perforated plate 12, which are communicated behind the perforated plate 12 constituting the box-shaped upper electrode. Moreover, the gas flow dispersion plate 13 is fixedly supported at a fixed position relative to the perforated plate 12. In the present invention, for convenience of explanation, the front side of an electrode refers to the side where the electrode faces the other electrode, and the opposite side is referred to as the rear side.

In this embodiment, a gas flow dispersion plate 13 is suspended 9 by a rod 14 that is thinner than the lower end surface of the pipe at a portion above the perforated plate 12 where gas comes out from the vibrator 7. The gas flow dispersion plate 16 is connected to the vibrator 7 through the rods 1 and 14, and can be moved up and down by tightening or loosening the nut 15 at the top of the pipe. The gas flow distribution plate 13 is provided with many holes 16 .

With the above configuration, as shown in Figure 2, when the gas flow dispersion plate 13 is pulled up, the gas flow mainly passes through the holes 16 of the dispersion plate 13 as the gap d becomes smaller. . Therefore, the gas flow distribution blown out from the perforated plate 12 is large at the center and small at the periphery, and the gas concentration on the substrate wafer 10 is also high at the center. If the high frequency power applied to the electrodes is constant, the film formation rate at the center of the substrate will be higher than at the periphery.

On the other hand, when the gas flow dispersion plate 13 is pulled down as shown in FIG. 3, the gap d becomes large and the flow rate of gas flowing to the periphery increases. Therefore, the gas flow distribution is opposite to that shown in FIG. 2, and the film formation rate at the center of the substrate wafer 10 is relatively lower than at the periphery.

By utilizing this effect, after the first film formation,
Measure the film thickness distribution, and if there is any non-uniformity in the distribution, immediately adjust the position of the waste flow dispersion plate 13 in a direction to correct it, so that the film thickness is more uniform in the second and subsequent film formations. distribution is obtained.

In the embodiment shown in FIG. 1, by operating the nut 15, the perforated plate 13 for gas flow dispersion moves forward and backward (up and down in the figure), that is, approaches and moves away from the opening of the reaction gas supply pipe 7. However, when carrying out the present invention, the means for operating the position of the perforated plate 13 for gas flow dispersion can be arbitrarily set, for example, a motor, a pole screw, or a nut may be used. good.

As detailed above, the plasma CVD apparatus of the present invention includes:
The gas flow distribution can be easily adjusted using a simple and inexpensive structure in which means is provided to freely adjust the position of the perforated plate for gas flow dispersion so as to approach or separate it from the opening of the gas supply pipe. This has an excellent practical effect in that a uniform film thickness distribution can be obtained.

[Brief explanation of drawings]

FIG. 1 is a vertical cross-sectional view of one embodiment of the plasma CVD apparatus of the present invention, and FIGS. 2 and 3 are similarly explanatory diagrams. 1... Vacuum chamber 2... Upper electrode configured in a box shape 5... Lower electrode 4... High frequency power source 5...
... Shaft part of upper electrode 6 ... Disc part 7 ... Reaction gas supply pipe 8 - Bottom plate of vacuum chamber 9 ... Opening of exhaust pipe 10 ... Substrate Unino 1
1...Flow rate controller 12...Perforated plate 15 constituting the electrode...Porous plate 14 for gas flow dispersion...Rod 15...Soto Fig. 1

Claims (1)

[Claims] The electrode facing the wafer, which is the workpiece, is configured in a box shape, and a large number of ventilation holes are provided on the surface facing the wafer, and a gas supply pipe is connected and fixed to the back surface of the box-shaped electrode, and In a plasma chemical vapor deposition apparatus in which a perforated plate for gas flow dispersion is installed near the point where the gas supply pipe communicates with the box-shaped electrode, A chemical vapor deposition apparatus using plasma, characterized in that it is provided with means that can freely adjust its position so as to approach or separate from an opening.