JPH06136542A - Plasma cvd device - Google Patents

Abstract

PURPOSE:To considerably suppress the occurrence of pinholes in a thin semiconductor film and the exfoliation of the film by preventing the deposition of granular silicon on the inner wall of a reactor. CONSTITUTION:Gas for preventing residence is introduced from a sweeping means 15 into parts in which reactive gas is liable to stay in a reactor 1 so as to prevent the retention of the reactive gas and the formation of granular silicon is suppressed. The formation of powdery silicon due to the rapid cooling of the reactive gas is prevented by heating the gas for preventing retention.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a plasma C which is an apparatus for manufacturing an amorphous silicon semiconductor film, a silicon nitride film, a silicon oxide film, etc. used for semiconductor devices, for example.
It relates to a VD device.

[0002]

2. Description of the Related Art FIG. 6 shows a cross-sectional structure of a reaction vessel of a conventional parallel plate type plasma CVD apparatus using glow discharge plasma. The structure of a conventional plasma CVD apparatus will be described with reference to FIG.

As shown in the figure, this plasma CVD apparatus has a reaction vessel 101 in which a film is formed. An upper electrode 102 for generating glow discharge plasma is installed on the inner upper surface of the reaction vessel 101.
The lower electrode 103 is installed in parallel with and facing to. A region sandwiched between the upper electrode 102 and the lower electrode 103 becomes a discharge region 104 for glow discharge. On the surface of the upper electrode 102, a reaction gas, which is a plasma source, is discharged in the discharge region 104
A large number of reaction gas introduction holes 105 so as to be uniformly distributed in
Are provided at equal intervals. A high frequency power supply 106 that supplies high frequency power for generating plasma by glow discharge is connected to the upper electrode 102. Lower electrode 1
03 is supported by the heater 107, and the substrate 10
8 has a function as a holder to be mounted.

The side surface of the reaction container 101 has a reaction container 101.
A pressure sensor 109 for measuring the internal pressure is provided. An exhaust pipe 110 for exhausting the reaction gas in the reaction vessel 101 is provided on the lower surface of the reaction vessel 101, and the exhaust pipe 110 is provided with a reaction gas through a pressure adjusting valve 111 for adjusting the pressure in the reaction vessel 101. It is connected to a vacuum pump 112 for exhaust.

Plasma CVD having the above structure
The operation of the device will be described.

First, a substrate 108 on which a film is to be formed is mounted on the lower electrode 103 outside the reaction vessel 101, and the lower electrode 103 is transported by a transport rail and a transport drive system (not shown) to face the upper electrode 102. It is installed on the heater 107. Substrate 108 on lower electrode 103
Is heated and held at a desired temperature of 100 to 400 ° C. by the heater 107.

Next, the reaction gas is introduced from the reaction gas introduction hole 105 formed on the surface of the upper electrode 102, and becomes plasma by glow discharge in the discharge region 104, and the substrate 10
8 is deposited and a film is formed.

The reaction gas introduced into the discharge region 104 passes through the exhaust pipe 110 and is fed from the vacuum pump 112 to the reaction vessel 1.
01 is exhausted to the outside. The pressure inside the reaction vessel 101 can be controlled to a desired value within 0.1 to several Torr by a pressure sensor 109 and a pressure adjusting valve 111 formed in the middle of the exhaust pipe 110.

When an amorphous silicon semiconductor film is formed on the surface of the substrate 108, monosilane gas and hydrogen gas are used as a reaction gas. The reaction gas introduced into the discharge region 104 becomes plasma by glow discharge under a predetermined condition, and the decomposed silicon radicals cause the substrate 1
An amorphous silicon semiconductor film is formed on the 08 surface.

Similarly, when forming a silicon nitride film, monosilane gas, ammonia gas and nitrogen gas are used as reaction gases, and when forming a silicon oxide film, monosilane gas and laughing gas are used as reaction gases. Plasma is generated by glow discharge under predetermined conditions.

[0011]

In the reaction vessel 101, monosilane gas, which is a reaction gas decomposed by glow discharge and passed through the discharge region 104, stays or is rapidly cooled. The object 113 is generated. The silicon powder 113 is likely to be deposited on the region 114 where the gas is likely to stay in the reaction vessel 101 and the inner wall surface of the reaction vessel 101 having a low temperature. If the silicon powder 113 adheres to the surface of the substrate 108 being transported, pinholes and film peeling will occur in the semiconductor thin film formed on the substrate 108, and the product yield of semiconductor devices will be reduced.

Particularly, in a plasma CVD apparatus for a large area glass substrate such as a thin film transistor using an amorphous silicon semiconductor for a liquid crystal display panel or an amorphous solar cell, not only the adhesion to the substrate 108 but also the pressure inside the reaction vessel 101. It also adheres to the sensor 109, the drive unit, etc., and causes device trouble.

As a measure for preventing the adhesion of the silicon powder 113, there is a method of heating the entire reaction vessel 101 to 150 ° C. to 200 ° C. or higher. However, the above-mentioned large-sized device has a large heat capacity and causes a trouble due to a heat load in the drive unit, which is not a sufficient countermeasure.

The present invention has been made to solve the above-mentioned problems of the prior art. By preventing the deposition of silicon particles on the inner wall of the reaction vessel, the yield of semiconductor devices manufactured is reduced. It is an object of the present invention to provide a plasma CVD apparatus capable of significantly reducing the pinholes and film peeling of a semiconductor thin film, which are the factors that cause this.

[0015]

Means for Solving the Problems Plasma CVD of the present invention
The apparatus comprises a reaction container in which a thin film forming substrate is set, a means for introducing a reaction gas for plasma generation into the reaction container, and a means for converting the introduced reaction gas into plasma and adhering it to the substrate. And a sweep means for introducing a retention preventing gas into a portion of the reaction vessel where the reaction gas is accumulated, and thereby the above-mentioned object is achieved.

The sweep means may be provided with means for heating the retention gas.

[0017]

By introducing the staying-preventing gas from the sweeping means into the portion where the reaction gas is likely to stay inside the reaction vessel, the reaction gas can be prevented from staying and the generation of silicon particulate matter can be reduced.

By heating the retention preventing gas, generation of silicon powdery substances due to rapid cooling of the reaction gas is also prevented.

[0019]

EXAMPLE 1 The present invention will be described below with reference to examples.

<First Embodiment> FIG. 1 shows a sectional structure of a reaction container of a parallel plate type plasma CVD apparatus according to the present embodiment. The structure of the plasma CVD apparatus of this embodiment will be described with reference to FIG.

As shown in the figure, this plasma CVD apparatus has a reaction container 1 in which a film is formed. An upper electrode 2 for generating glow discharge plasma is installed on the inner upper surface of the reaction vessel 1, and a lower electrode 3 is installed in parallel with the upper electrode 2 so as to face the upper electrode 2. Upper electrode 2 and lower electrode 3
The region sandwiched between and becomes the discharge region 4 for glow discharge. On the surface of the upper electrode 2, a large number of reaction gas introduction holes 5 are provided at equal intervals so that the reaction gas as a plasma source is uniformly distributed in the discharge region 4. A high-frequency power source 6 that supplies high-frequency power for generating plasma by glow discharge is connected to the upper electrode 2. Lower electrode 3
Is supported by the heater 7 and has a function as a holder on which the substrate 8 is mounted.

A pressure sensor 9 for measuring the pressure inside the reaction container 1 is provided on the side surface of the reaction container 1. Reaction vessel 1
An exhaust pipe 10 for exhausting the reaction gas in the reaction container 1 is provided on the lower surface of the exhaust pipe 10. The exhaust pipe 10 is for exhausting the reaction gas through a pressure adjusting valve 11 for adjusting the pressure in the reaction container 1. It is connected to the vacuum pump 12. A sweep gas introducing pipe 15 is installed on the upper surface or the side surface of the reaction vessel 1 where the reaction gas is likely to be rapidly cooled or accumulated.

FIG. 2 shows a perspective view of the sweep gas introducing pipe 15. As shown in the figure, the sweep gas introduction pipe 15 is
It is a tube with many small holes at equal intervals on its side surface. From the small hole of the sweep gas introducing pipe 15, for example, an inert gas such as argon or helium or a diluent gas such as hydrogen or nitrogen is ejected. The flow rate of the ejected gas is controlled to a constant flow rate by a mass flow controller (not shown).

Plasma CVD having the above structure
The film forming operation in the apparatus is the same as the conventional one. During film formation, an inert gas or a diluent gas is introduced into the reaction container 1 from the sweep gas introduction pipe 15. Due to the introduced gas, the reaction gas does not stay and a smooth gas flow occurs. As a result, it is possible to prevent deposition of silicon particles.

<Second Embodiment> FIG. 3 shows a sectional structure of a reaction vessel of a parallel plate type plasma CVD apparatus according to this embodiment. The parts having the same functions as those of the device of the first embodiment shown in FIG.

As shown, the plasma CV of this embodiment
The apparatus D has the same structure as that of the first embodiment except that a sweep gas introducing tube 16 with a heater is installed in place of the sweep gas introducing tube 15 in the plasma CVD apparatus shown in FIG.

FIG. 4 shows a sweep gas introduction pipe 1 with a built-in heater.
6 shows a perspective view of FIG. As shown in the figure, the heater built-in sweep gas introduction pipe 16 has a pipe 16a having a large number of small holes provided at equal intervals on the side surface, and a sheathed heater wire 16b is wound inside the pipe 16a. It is provided. Tube 16
The inside of “a” is 200 ° C.
It is kept at 350 ° C. An inert gas such as argon or helium or a diluent gas such as hydrogen or nitrogen is heated from a small hole of the heater-embedded sweep gas introduction pipe 16 and jetted in a sheet shape. The flow rate of the ejected gas is controlled to a constant flow rate by a mass flow controller (not shown).

Plasma CVD having the above structure
The film forming operation in the apparatus is the same as the conventional one. During film formation, a heated inert gas or dilution gas is introduced into the reaction vessel 1 from the heater-embedded sweep gas introduction pipe 16. The introduced gas prevents quenching of the reaction gas, the reaction gas does not stay, and a smooth gas flow occurs. As a result, it is possible to prevent deposition of silicon particles.

In the above first and second embodiments, the parallel plate type plasma CVD apparatus is mentioned, but a plasma CVD apparatus other than the parallel plate type plasma CVD apparatus such as a vertical badge method or a single wafer method is also applicable. The present invention can be applied.

FIG. 6 shows an example in which the present invention is applied to a vertical batch type plasma CVD apparatus. The parts having the same functions as those of the plasma CVD apparatus of the above embodiment are designated by the same reference numerals. In the present embodiment, the same heater built-in sweep gas introduction pipe 16 as in the second embodiment is arranged in the reaction vessel 1 at a place where retention is likely to occur, but instead of the heater built-in sweep gas introduction pipe 16. The sweep gas introducing pipe shown in the first embodiment may be used. In any case, the same effects as those of the first and second embodiments can be obtained.

[0031]

As is apparent from the above description, according to the plasma CVD apparatus of the present invention, an inert gas, a diluting gas, or the like is placed in a region in the reaction vessel where the reaction gas is likely to be rapidly cooled and / or accumulated. By flowing in the form of a sheet, it is possible to prevent the generation of silicon powder and the deposition on the inner wall surface of the reaction vessel. As a result, since the semiconductor thin film manufactured by the plasma CVD apparatus of the present invention has few pinholes and film peeling, the yield of semiconductor devices can be significantly improved.

The above effect can be further enhanced by heating the inert gas or the diluent gas flowing into the reaction vessel.

[Brief description of drawings]

FIG. 1 is a sectional structural view of a reaction container in a plasma CVD apparatus of a first embodiment.

FIG. 2 is a perspective view of a sweep gas introducing pipe of the plasma CVD apparatus shown in FIG.

FIG. 3 is a sectional structural view of a reaction container in the plasma CVD apparatus of the second embodiment.

FIG. 4 is a perspective view of a heater-embedded sweep gas introduction tube of the plasma CVD apparatus shown in FIG.

FIG. 5 is a vertical batch type plasma CV to which the present invention is applied.
It is a cross-sectional block diagram of a D device.

FIG. 6 is a sectional structural view of a reaction container in a conventional plasma CVD apparatus.

[Explanation of symbols]

 1 Reaction Vessel 2 Upper Electrode 3 Lower Electrode 4 Discharge Area 5 Reactive Gas Inlet Hole 6 High Frequency Power Supply 7 Heater 8 Substrate 9 Pressure Sensor 10 Exhaust Pipe 11 Pressure Control Valve 12 Vacuum Pump 13 Silicon Dust 14 Reaction Gas Retention Area 15 Sweep Gas Introducing pipe 16 Heater built-in sweep gas Introducing pipe 16a Pipe 16b Sheath heater wire

Claims (2)

[Claims] 1. A reaction container in which a thin film forming substrate is set, a means for introducing a reaction gas for plasma generation into the reaction container, and the introduced reaction gas is turned into plasma and attached to the substrate. A plasma CVD apparatus comprising: a means for allowing the reaction gas to flow and a sweeping means for introducing a retention preventing gas into a portion of the reaction container where the reaction gas is accumulated. 2. The plasma C according to claim 1, wherein the sweep means includes means for heating the retention gas.
VD device.