JPH0576549B2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention is applicable to solar cells, fuel cells, thin film semiconductors,
The present invention relates to an apparatus for forming amorphous thin films used in various electronic devices such as electrophotographic photoreceptors and optical sensors.

[Conventional technology]

FIG. 2 shows a conventional semiconductor thin film manufacturing apparatus, for example,
This is a known technique described in, for example, Japanese Patent No. 47710.

In the figure, electrodes 02 and 03 are provided vertically to form a discharge space in an airtight reaction vessel 01, and these electrodes 02 and 03 are connected to a high frequency power source 04.
electrically connected to. A coil 05 for generating a magnetic field parallel to the direction of the electric field in the discharge space is horizontally arranged around the outer periphery of the reaction vessel 01, and is electrically connected to an AC power source 06. The exhaust hole 07 communicates with a vacuum pump (not shown), and the reaction gas introduction pipe 08 communicates with monosilane (SiH ₄ ) and hydrogen gas (H ₂ ) cylinders, respectively. In addition, 09 is a heater, and the board 010
It is used to heat.

Now, after placing the substrate 010 on the electrode 03 and reducing the pressure inside the reaction vessel 01 to about 1 mmHg, a mixed gas of monosilane and hydrogen gas is introduced into the reaction gas introduction pipe 08.
A high frequency voltage of 13.5 MHz is applied between the electrodes 02 and 03 while supplying the same voltage.

On the other hand, a commercial AC voltage of 50 or 60 Hz is applied to the coil 05, and about 100 Hz is applied between the electrodes 02 and 03.
Generates a Gaussian magnetic field. Note that the board 010
is heated to about 300°C using heater 09.

A gas such as sinosilane introduced from the reaction gas introduction pipe 08 is decomposed in the discharge space between the electrodes 02 and 03, and is attached to the surface of the substrate 010 while being stirred by the fluctuating magnetic field generated by the coil 05.
Forms an amorphous thin film.

[Problem that the invention seeks to solve]

In the conventional device described above, two electrodes 02, 0
Since the variable magnetic field generated by coil 05 is applied parallel to the direction of the electric field generated between electrodes 02 and 3,
Ions such as silicon existing in the discharge space between the electrodes 03 are stirred, and a relatively uniform amorphous thin film is formed on the substrate 010.

However, the substrate 010 is placed above the electrode 03 and is located within the discharge space between the electrodes 02 and 03. As a result, they are basically directly hit by high-energy ions.

That is, Coulomb force F ₁ =qE acts on ions with charge q due to the electric field E between electrodes 02 and 03,
The ion particles will directly hit the substrate 010 and damage the amorphous thin film that is being formed.

Since the direction of the varying magnetic field B generated by the coil 05 is parallel to the electric field E generated in the discharge space, ions and electrons in the discharge space
Larmor motion causes a swirling motion, but the stirring effect of the swirling motion is not very large and requires an extremely large amount of electric power.

Since it is placed on one electrode 03 of the substrate 010, the size of the substrate 010 that can be processed at one time is limited, and it is not possible to form an amorphous thin film on a substrate that has a larger area than the electrode 03. Also, it is not possible to form an amorphous thin film on both sides of the substrate 010 at the same time.

Since the substrate 010 is placed on one of the electrodes 03, it is difficult to form a uniform film on a large-area substrate in direct current discharge or low-frequency discharge, where the supply of secondary electrons necessary for sustaining the discharge is essential. It is. Therefore, an expensive high frequency power source is absolutely necessary.

[Means for solving problems]

The present invention provides an apparatus for forming an amorphous thin film on a substrate using glow discharge plasma. and a first discharge electrode disposed with an edge facing one surface of the substrate, and a plurality of electrode plates arranged in parallel in the reaction vessel with an edge facing the other surface of the substrate. A second discharge electrode arranged, a power source that supplies a discharge voltage between the electrode plates of the first and second discharge electrodes, and a power source that surrounds the reaction vessel and is connected between the pair of discharge electrode plates. It has a coil and an AC power source that generate a magnetic field in a direction perpendicular to the generated electric field, and a gas supply device that reduces the pressure inside the reaction vessel and supplies a reaction gas.

[Effect]

In the present invention, two sets of electrodes for glow discharge plasma generation consisting of a plurality of electrode plates arranged in parallel are prepared, and the substrates are sandwiched and the edges of the electrode plates are placed facing each other. .

Further, a magnetic field was generated by a coil and an AC power source in a direction perpendicular to the electric discharge field generated between each set of electrode plates.

A charged particle drifts in a direction perpendicular to the electric field given the initial velocity of the Coulomb force given by the discharge electric field between the electrode plates and the Lorentz force given by the magnetic field, but when it leaves the electric field, , the Coulomb force weakens from the edge of the electrode plate toward the surface of the substrate, and the cyclotron movement caused by the Lorentz force causes the particles to fly in a Larmor orbit.

On the other hand, electrically neutral radical particles deviate from the trajectory of the charged particle group and try to travel straight, but they collide with charged particles (especially ions) and are forced to correct their course. Moreover, this magnetic field is fluctuating, and the radical particles are scattered uniformly.

Therefore, uniform amorphous thin films are formed on both sides of the substrate supported outside the discharge electric field space.

〔Example〕

The present invention will be explained below based on an embodiment of the apparatus shown in FIG.

Reference numeral 1 denotes a reaction vessel in which first and second electrodes 2 and 3 for generating glow discharge plasma are housed facing each other. These electrodes 2 (or 3) are a plurality of long electrode plates arranged in parallel, and are connected to a low frequency power source 4, which will be described later, with adjacent electrodes having different poles.

A low frequency power source 4 is connected to each electrode plate of the electrodes 2 and 3 using a commercial frequency of 60 Hz, for example. The coil 5 surrounds the reaction vessel 1 and is connected to an AC power source 6. Reference numeral 7 denotes a reaction gas introduction pipe, which communicates with a cylinder (not shown) and supplies a mixed gas of monosilane and argon to the reaction vessel 1. The exhaust hole 8 communicates with a vacuum pump 9 to exhaust the gas inside the reaction vessel 1.

Now, as shown in the figure, the substrate 10 is supported by appropriate means between the electrodes 2 and 3 so that the edges 2A and 3A face each surface of the substrate 10 and the gaps are equal. Drive the vacuum pump 9 to remove the reaction vessel 1.
After evacuating the inside, a mixed gas of monosilane and argon is supplied from the reaction gas introduction pipe 7. Fill the reaction vessel 1 with the above mixed gas and increase the pressure to 0.05 or more.
Glow discharge plasma is maintained at 0.5 Torr and a voltage is applied to the electrodes 2 and 3 from the low frequency power source 4.
occurs between each electrode plate.

On the other hand, an AC voltage of, for example, 100 Hz is applied to the coil 5 to generate a magnetic field B in a direction perpendicular to the electric field E generated between the electrode plates of the electrodes 2 and 3, respectively. Note that the magnetic flux density may be about 10 Gauss.

Among the gases supplied from the reaction gas introduction pipe 7, monosilane gas is decomposed into radical Si by the glow discharge plasma generated between the electrode plates of the electrodes 2 and 3, and adheres to the surface of the substrate 10 to form a thin film.

At this time, charged particles such as argon ions undergo so-called E×B drift due to Coulomb force F ₁ = qE due to electric field E and Lorentz force F ₂ = q (v×B) between each electrode plate of electrode 2 or 3. cause a movement.

Note that V is the speed of charged particles.

That is, it flies out in a direction perpendicular to the electrodes 2 and 3 and flies toward the substrate 10 with an initial velocity given by the ExB drift. However, outside the discharge space where the influence of the electric field generated between the electrode plates of electrodes 2 and 3 is small, the cyclotron movement due to the magnetic field B generated by the coil 6 causes
It flies in a Larmor orbit.

Therefore, charged particles such as argon ions are absorbed into the substrate 1.
It will no longer hit 0 directly.

On the other hand, the electrically neutral radical Si is exposed to the magnetic field B
The particles deviate from the trajectory of the charged particles and reach the substrate 10, forming an amorphous thin film on the surface thereof. At this time, the radical Si collides with the charged particles flying in the Larmor orbit, so that an amorphous thin film is formed not only in front of the electrodes 2 and 3 but also spread to the left or right. Moreover, since the magnetic field B is varied, it is possible to uniformly form an amorphous thin film on both sides of the substrate 10.

Further, in this embodiment, since the substrate 10 is arranged vertically, it is less likely that amorphous debris adhering to the reaction vessel 10 or the inner surfaces of the electrodes 2 and 3 will fall and contaminate the surfaces thereof.

〔Effect of the invention〕

According to the present invention, in the production of various devices such as solar cells, fuel cells, and electrophotographic photoreceptors,
Since a uniform amorphous thin film with a large area can be formed on both sides of the substrate, it is extremely valuable industrially.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view of an apparatus showing one embodiment of the present invention. FIG. 2 is a longitudinal sectional view showing a conventional device. 1... Reaction container, 2, 3... Electrode, 4... Low frequency power supply, 5... Coil, 6... AC power supply, 7...
Reaction gas introduction pipe, 8...exhaust hole, 9...vacuum pump, 10...substrate.

Claims (1)

[Claims] 1. A reaction container that houses a substrate on which an amorphous thin film is to be formed, and a first discharge device in which a plurality of electrode plates are arranged in parallel so that their edges face one surface of the substrate. an electrode, a second discharge electrode in which a plurality of electrode plates are arranged in parallel in the reaction vessel with their edges facing the other surface of the substrate; and these first and second discharge electrodes. a power supply that supplies a discharge voltage between the electrode plates of the reactor, a coil and an AC power supply that surround the reaction vessel and generate a magnetic field orthogonal to the electric field generated between the pair of discharge electrode plates; 1. An amorphous thin film forming apparatus comprising: a gas supply device that reduces pressure inside a container and supplies a reaction gas.