JPH0136245B2 - - Google Patents

Description

Detailed Description of the Invention [Industrial Field of Application] The present invention is a method for heating a substrate by continuously introducing one or several kinds of raw material gas into a reduced pressure container, and plasma decomposing the gas using high frequency waves or the like. lead to the surface,
The present invention relates to a plasma CVD apparatus that generates an amorphous thin film on the surface of this substrate.

[Prior Art] Conventionally, this type of plasma CVD apparatus has, for example,
As shown in FIG. 1, a pair of high-frequency electrodes d and e are placed in a reduced pressure vessel c having a raw material gas inlet a at one end and an exhaust gas inlet b at the other end.
etc. to form a plasma discharge field f between these two electrodes d and e, a substrate g is placed closer to the exhaust gas outlet b than this plasma discharge field f, and a substrate is placed on the back side of this substrate g. It is common to have a heater h for heating.

[Problems to be Solved by the Invention] However, with just this, the reaction gas plasma decomposed in the plasma discharge field f will not reach the substrate g.
It also goes around the back side of the substrate and adheres to the heater h, which has a higher temperature than the substrate g. Therefore, there is a disadvantage that the thermal efficiency of the heater h gradually decreases, which adversely affects the formation of a thin film on the substrate surface. Also,
In such a device, most of the plasma-decomposed reaction gas is discharged outside the vacuum container c without reaching the surface of the substrate g, which unduly increases the amount of raw material gas consumed and discharges the gas. This has the disadvantage that a large amount of toxic gas must be processed.

The present invention aims to solve the above problems.

[Means for Solving the Problems] In order to achieve such objects, the present invention has the following features:
The following measures were taken.

That is, the plasma CVD apparatus according to the present invention has the following features:
The device having the basic configuration as described above includes a front wall having a through hole in the center facing the plasma discharge field, and a back wall having the center close to the opening of the front wall. A hollow body-shaped exhaust duct is provided, and the inside of the exhaust duct is communicated with the exhaust gas outlet, and a substrate holder is provided in the center of the rear wall so as to face the opening. A gas inlet of an exhaust duct formed in an annular shape between the opening edge and the back wall is located near the periphery of the substrate held by the substrate holder.

[Function] In this device, an annular gas suction port is formed between the opening edge of the opening provided in the wall and the rear wall adjacent to the opening edge. Since the substrate holder is provided on the back wall facing the opening thereof, the gas inlet of the exhaust duct is located near the periphery of the substrate held by the substrate holder. Moreover, since the inside of this exhaust duct is communicated with the exhaust gas outlet, all the gas in the reduced pressure container is introduced into the exhaust duct from the gas suction port and is exhausted to the outside of the reduced pressure container through the exhaust gas outlet. .

With such a device, all the gas that has passed through the plasma discharge field is collected on the surface of the substrate, guided around the surface of the substrate, and led to the gas inlet of the exhaust duct. It will be destroyed. Therefore, the reaction gas may get around to the back side of the substrate,
It is possible to effectively prevent the exhaust gas from being guided to the exhaust gas outlet without reaching the surface of the substrate.

[Example] Hereinafter, an example of the present invention will be described with reference to FIGS. 2 to 4.

A pair of high-frequency electrodes 4 are connected to a high-frequency power supply (not shown) in the center of a reduced pressure container 3 that has a raw material gas inlet 1 at one end and exhaust gas outlets 2, 2 at the other end. , 5 are arranged facing each other, and a plasma discharge field 6 is formed between these two electrodes 4, 5. Further, substrates 7, 7 are arranged at positions facing the raw material gas inlet 1 through the plasma discharge field 6 in the reduced pressure vessel 3, and a heater 8 is provided on the back side of the substrates 7, 7. . A gas introduction pipe 9 is connected to the raw material gas introduction port 1, and one type or several types of raw material gas are continuously introduced into the decompression vessel 3 through the gas introduction pipe 9. Further, a gas exhaust pipe 12 communicating with a vacuum pump 11 or the like is connected to the exhaust gas outlet ports 2, 2, and unnecessary gas in the decompression container 3 is successively discharged to the outside through the gas exhaust pipe 12.

Further, an exhaust duct 13 communicating with the exhaust gas outlet 2 is provided in the decompression vessel 3. The exhaust duct 13 is a hollow body formed by connecting a flat front wall 13a and a rear wall 13b whose center portion is close to the front wall 13a by a peripheral wall 13c. The parts are provided with caps 13d, 13d for communicating the exhaust duct 13 with the exhaust gas outlet ports 2, 2. Base 1
3d and 13d are cylindrical pieces with flanges, and are attached to the back wall 1.
It is slidably fitted into the outer periphery of cylindrical openings 13e, 13e provided in 3b. Note that 14 brings the caps 13d, 13d into close contact with the opening end surfaces of the exhaust gas outlet ports 2, 2, and the front wall 13a.
The vacuum vessel 3 supports the exhaust duct 13 at the edge of the vacuum vessel 3.
This is a spring for tightly contacting the locking collar 15. Further, a substrate holder 16 is attached to the center of the back wall 13b of the exhaust duct 13, and the substrates 7, 7 are removably fitted into stepped holding holes 16a, 16a of this substrate holder 16. At the same time, a cover plate 17 for fixing the substrates 7, 7 is attached to the back surface of the substrate holder 16. Further, the substrate holder 1 on the front wall 13a of this exhaust duct 13
A through hole 13f is bored at a portion corresponding to 6, and an annular gas suction port 13g is formed between the opening edge of the through hole 13f and the rear wall 13b. Therefore, this gas suction port 13g is connected to the substrates 7, 7.
The opening will be in the vicinity of the periphery.

With such a configuration, the raw material gas introduced into the reduced pressure container 3 from the raw material gas inlet 1 is subjected to plasma decomposition when passing through the plasma discharge field 6, and the surfaces of the substrates 7, 7 heated by the heater 8. Therefore, a high-quality thin film can be formed on the surface of the substrate 7. Then, the unused gas is discharged from the exhaust gas outlet 2, 2 to the vacuum container 3.
It can be discharged outside sequentially. Moreover, in the apparatus according to the present invention, an exhaust duct 13 communicating with the exhaust gas outlet 2 is provided in the decompression vessel 3, and the gas inlet 13g of the exhaust duct 13 is connected to the vicinity of the substrates 7, 7. Since the opening is made open, all the gas that has passed through the plasma discharge field 6 reaches the substrate 7,
Afterwards, all the gases are discharged to the outside of the vacuum vessel 3 through the exhaust duct 13. Therefore, the reaction gas is transferred to the substrate 7,
It is possible to prevent the inconvenience of the particles getting around to the back side of the heater 8 and adhering to the heater 8. In addition, there is no inconvenience that most of the plasma-decomposed reaction gas is discharged outside the vacuum vessel 3 without reaching the surfaces of the substrates 7, 7, so raw material gas can be saved and the toxic gas discharged can be treated. It has the advantage that the amount can be reduced.

Note that the configuration of the exhaust duct is of course not limited to the one described above, and may be, for example, as shown in FIGS. 5 and 6. That is, the fifth
The exhaust duct 13' shown in the figure has the same basic structure as that of the previous embodiment, with wheels 21 and racks 22 added. With such a device, by engaging the drive pinion with the rack 22, it is possible to automatically move the exhaust duct 13' into and out of the vacuum container. Therefore, it is convenient when the exhaust duct 13' is sequentially moved together with the substrate etc. into a plurality of vacuum vessels to deposit several kinds of thin films on the surface of the substrate. In addition, the exhaust duct 13'' shown in FIG.
It is formed between a back wall 3a'' which also serves as an end wall of the reduced pressure container 3'' and a front wall 23 in the form of a partition wall provided inside the reduced pressure container 3''.In this case, the substrate 7'',
The substrate holder 16'' holding the substrate 7'' is fixed to the center of the rear wall 3a'', and the gas inlet 13g'' of the exhaust duct 13'' is located between the rear wall 3a'' and the front wall 23. It is formed. That is, the exhaust duct 13'' includes a front wall 23 having an opening 13f'' in the center facing the plasma discharge field 6, and a rear wall 3a with the center close to the opening 13f'' of the front wall 23. The inside of the exhaust gas outlet 2 is in communication with the exhaust gas outlet 2. A substrate holder 1 is placed in the center of the rear wall 3a''.
6'' facing the opening 13f'',
The gas inlet 13g'' of the exhaust duct 13'', which is formed in an annular shape between the opening edge of the opening 13f'' and the back wall 3a'', is located near the periphery of the substrate 7'' held by the substrate holder 16''. It is located in However,
If this is the case, the exhaust duct 13'' will be integrally formed with the vacuum vessel 3'', so
Although it is not possible to remove only the exhaust duct 13'', it has the advantage of simplifying the configuration because the number of parts is small.

[Effects of the Invention] Since the present invention has the above-described configuration, all of the gas that has been plasma decomposed in the plasma discharge field can be guided to the substrate placement area, and the gas can be guided into the exhaust duct along the surface of the substrate. can be guided to. Therefore, it is possible to effectively prevent a large amount of reactive gas from getting around to the back side of the substrate and adhering to the heater, and preventing much of the plasma-decomposed reactive gas from being discharged outside the vacuum vessel without reaching the substrate. .
Therefore, it is possible to reasonably reduce the amount of raw material gas consumed and perform an efficient film forming operation, and the amount of toxic gas to be processed can also be effectively reduced.

[Brief explanation of drawings]

FIG. 1 is a schematic sectional view showing a conventional example, FIG. 2 is a schematic sectional view showing an embodiment of the present invention, FIGS. 3 and 4 are perspective views showing an exhaust duct in the same embodiment, and FIG. The figure is a perspective view showing another embodiment of the present invention.
FIG. 6 is a schematic sectional view showing still another embodiment of the present invention. 1... Raw material gas inlet, 2... Exhaust gas outlet,
3, 3''...Reduced pressure vessel, 3a''...Back wall, 6...Plasma discharge field, 7,7''...Substrate, 13, 13', 13''
...Exhaust duct, 13f, 13f''...Opening, 13
g, 13g''...Gas inlet, 16, 16''...Substrate holder, 23...Front wall.

Claims (1)

[Claims] 1. A plasma discharge field is provided in a reduced pressure container having a raw material gas inlet and an exhaust gas outlet, and a substrate on which a thin film is to be produced is exposed to the raw material gas through the plasma discharge field in the reduced pressure container. In a plasma CVD apparatus disposed at a position facing an inlet, a front wall having a through hole in the center facing the plasma discharge field, and a back surface having the center close to the opening of the front wall. A hollow body-shaped exhaust duct comprising a wall is provided, the inside of the exhaust duct is communicated with the exhaust gas outlet, and a substrate holder is provided in the center of the rear wall so as to face the opening. and a gas inlet of an exhaust duct formed in an annular shape between the opening edge of the opening and the rear wall is located near the periphery of the substrate held by the substrate holder. plasma
CVD equipment.