JPH07161646A - Formation of polycrystalline film - Google Patents

Abstract

PURPOSE:To provide identical particle diameters of fine particles and boundary conditions between the fine particles in a polycrystalline film and to improve the uniformity of the polycrystalline film by a method wherein the fine particles formed by decomposing reaction gas with plasma are entrained in a carrier gas flow and are sprayed on a substrate. CONSTITUTION:Reaction gas and carrier gas are respectively introduced in a gas reaction chamber 10 through a reaction gas introducing tube 3 and a carrier gas introducing tube 2. Then, a high frequency is applied to a high-frequency induction coil 9 for plasma generation and a plasma state is induced within the chamber 10. The reaction gas is decomposed by plasma in this chamber 10 and various sizes of fine particles are generated by a natural crystallization. These fine particles are entrained in large-flow rate argon gas and are sprayed on a substrate 5 by a nozzle 8. The substrate 5 and a susceptor 4 are heated by a high-frequency induction coil 6 for heating. A pressure in the chamber 1 is exhausted by an exhaust system 7 and the flow rate of the carrier gas is set at 10 to 100 SLM in the case where the pressure in the chamber 1 is about 1.0Torr.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a polycrystalline film, and more particularly to a method for producing a polycrystalline film with good accuracy.

[0002]

2. Description of the Related Art A conventional vapor-phase reaction polycrystalline film is used in a manufacturing apparatus as shown in FIG. This apparatus is equipped with a reaction chamber 1 that shuts off the reaction system from the external space, and a carrier gas introduction that introduces a carrier gas (hydrogen, argon, etc.) to the reaction chamber 1 to bring the concentration of the reaction gas in the reaction chamber to an appropriate value. Tube 2, reaction gas introduction tube 3 for introducing a reaction gas (silane, disilane or the like in the case of polysilicon) into the reaction chamber 1, a substrate 5 for depositing a polycrystalline film, and this substrate 5, the susceptor 4 supporting the temperature distribution uniformly, the high-frequency induction coil 6 for heating the susceptor 4 and the substrate 5 by high-frequency induction, and keeping the pressure in the reaction chamber 1 constant, the reacted gas and the like outside the reaction chamber 1. It has an exhaust system 7 for exhausting to.

Next, a method for creating the image will be specifically described. First, the carrier gas (eg, argon) in the reaction chamber
And a reaction gas (for example, silane) are introduced through the carrier gas introduction pipe 2 and the reaction gas introduction pipe 3, respectively. This time,
The concentration of silane relative to the carrier gas, argon, is about 0.5 to 5.0%. The pressure in the reaction chamber 1 is atmospheric pressure (about 760 Torr: 100 k for easy handling).
Pa). Here, a high frequency (1
Electric power is applied to heat the susceptor 4 and the substrate 5 to about 300 ° C. to 600 ° C. Reaction gas (silane) is thermally decomposed by the heated substrate 5, and a polycrystalline silicon film is deposited on the substrate 5.

[0004]

In this conventional method for producing a vapor-phase reaction polycrystalline film, by placing a heated substrate in an atmosphere in which a reaction gas having a certain constant concentration is present,
Since the thermal decomposition of the reaction gas and the natural crystallinity of the substance are used, the size of the crystal grains in the polycrystalline film varies and is not uniform. In addition, the boundary condition between the crystal grains is not controlled in the twin state or the amorphous state, so the state of the polycrystalline film is largely influenced by the process conditions, and even if the process conditions are the same, an unstable element may occur. I had many. Further, there is a problem that only a film having a low uniformity in the in-plane characteristics of the same substrate can be formed.

[0005]

The method for producing a vapor-phase reaction polycrystalline film of the present invention is a gas for decomposing a reaction gas by plasma by microwave resonance or high frequency induction method to produce fine particles to be a material of the polycrystalline film. A nozzle that deposits almost constant particles on the substrate by means of inertial collision of particles, reflection, gravity action by mass, diffusion action by carrier gas, etc. And a section.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, the present invention will be described with reference to the drawings.

FIG. 1 is a schematic view of a film forming apparatus used for forming a vapor phase reaction polycrystalline film according to an embodiment of the present invention. The device mainly comprises a gas reaction chamber 10 and a reaction chamber 1 which are connected to each other. A reaction gas introduction pipe 3 into which a reaction gas is introduced, a carrier gas introduction pipe 2 into which a carrier gas is introduced, and a dope gas introduction pipe 11 into which a dope gas is introduced are connected to the gas reaction chamber 10 above. A high frequency induction coil 9 is wound for the purpose of turning the reaction gas introduced into the chamber into a plasma state. The nozzle 8 is located below the gas reaction chamber 10.
And the reaction chamber 1 provided further below
Connected to. A susceptor 4 is provided in the reaction chamber 1, and a substrate 5 having a polycrystalline film formed on its surface is mounted thereon. An exhaust system 7 is connected below the reaction chamber 1. Further, a high frequency induction coil 6 for heating is wound around the reaction chamber 1 at a height that surrounds the susceptor 4 and the substrate 5.

Next, a method for forming a polycrystalline silicon film as a polycrystalline film on the surface of the substrate 5 using this apparatus will be described.

First, in the gas reaction chamber 10, silane (SiH
A reaction gas such as 4) and a carrier gas such as argon (Ar) are introduced through the reaction gas introduction pipe 3 and the carrier gas introduction pipe 2, respectively. At this time, the concentration of the reaction gas with respect to the carrier gas is set to about 0.01 to 0.1%. Next, a high frequency of about 10 to 20 MHz is applied to the high frequency induction coil 9 for plasma generation to induce a plasma state in the gas reaction chamber 10. By the plasma in the gas reaction chamber 10,
The reaction gas such as silane is decomposed and spontaneous crystallization produces silicon fine particles of various sizes. The silicon fine particles are placed on a large flow rate of argon gas and sprayed onto the substrate 5 by the nozzle 8. The shape of the nozzle is set to be wide so that the carrier gas is uniformly sprayed on the substrate 5, or rotated so that the relationship with the substrate 5 can be periodically moved. The substrate 5 and the susceptor 4 are heated by the high frequency induction coil 6 for heating. The temperature of the substrate may be room temperature, but heating to about 150 to 250 ° C. improves the adhesion and quality of the film. The high frequency power applied to the high frequency induction coil 9 for plasma generation is about 10 to 200 times the high frequency power applied to the high frequency induction coil 6 for heating. The pressure in the reaction chamber 1 is set to 0.
It is set to about 1 to 10.0 Torr. The flow rate of the carrier gas is 1 when the pressure in the reaction chamber 1 is about 1.0 Torr.
0 to 100 SLM. The silicon particles generated in the gas reaction chamber 10 are sprayed onto the substrate 5 by this carrier gas flow. Of these silicon particles, those with a large particle size do not adhere to the substrate due to reflection and scattering due to inertial collision, and those with a small particle size do not adhere to the substrate due to diffusion by the gas flow. Only particles of are deposited. The reason why this phenomenon occurs is that particles of this size tend to adhere to the substrate due to the balance between the substance adhesion and surface reactivity due to the surface energy of the particles and the mass.

In FIG. 1, the carrier gas is blown onto the substrate 5 from above, but the carrier gas is attracted to the substrate 5 from another direction, for example, from the side and from below (upside down in FIG. 1). Then, the particle selectivity due to gravity is further improved.

As a result, the particles deposited on the substrate 5 are mainly particles having a particle diameter of 5 to 50 nm, and the particle diameters are more uniform than those in the conventional vapor phase reaction polycrystal production method. Since they are the same, the boundary conditions in the polycrystalline film are also well aligned. Thus, the obtained polycrystalline silicon film has a uniformity improved by about 10 to 100 times as compared with the film formed by the conventional method. Further, a doped polysilicon film can be formed by introducing a doping gas such as phosphine through the dope gas introducing pipe 11.

When a polycrystalline silicon resistor is formed by this method, the resistance processing accuracy is improved by a factor of 2 to 3, and the resistance accuracy is 1
It can be improved about 0 to 20 times.

The present invention can be variously modified. For example, the same device as that of FIG. 1 is used, and by spraying it on a substrate having a large surface step, the surface step can be reduced. When depositing a silicon oxide film in order to reduce the level difference on the substrate surface, it is preferable to use silane and oxygen as reaction gases and argon as a carrier gas. In this case, the particles sprayed on the substrate cause a phenomenon such as a so-called "blown pool" at the surface step portion on the substrate to be easily deposited, so that the surface step on the substrate can be reduced.

[0014]

As described above, according to the present invention, by spraying fine particles generated by a reaction in plasma onto a substrate with a carrier gas, the grain size of the polycrystalline film and the boundary conditions can be made uniform. It is possible to improve the uniformity of the crystal film by about 10 to 100 times as compared with the conventional method.

[Brief description of drawings]

FIG. 1 is a schematic view of an apparatus used for producing a vapor phase reaction polycrystal according to an embodiment of the present invention.

FIG. 2 is a schematic view of an apparatus used in a conventional vapor phase reaction polycrystal production method.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Reaction chamber 2 Carrier gas introduction pipe 3 Reaction gas introduction pipe 4 Susceptor 5 Substrate 6 High frequency induction coil (for heating) 7 Exhaust system 8 Nozzle 9 High frequency induction coil (for plasma) 10 Gas reaction chamber 11 Dope gas introduction pipe

Claims (3)

[Claims] 1. A method for decomposing a reaction gas by microwave resonance or plasma by a high frequency induction method to prepare fine particles to be a material of a polycrystalline film, and depositing the fine particles on a carrier gas flow and spraying them on a substrate. Method for producing polycrystalline film. 2. The method for producing a polycrystalline film according to claim 1, wherein the substrate is heated when the fine particles are sprayed onto the surface of the substrate. 3. The method for producing a polycrystalline film according to claim 1, wherein the fine particles are sprayed from below the substrate.