JPS6010617A - Substrate heating method in plasma cvd apparatus - Google Patents

Abstract

PURPOSE:To eliminate a heating mechanism and form an a-Si film steadily by maintaining a temperature of a substrate using an energy of a plasma discharge during the formation of the a-Si film. CONSTITUTION:A cylindrical wall 1, a circular top wall 4a and a bottom wall 4b are insulated by insulators 3a, 3b and a reaction chamber wall is composed of these walls 1, 4a, 4b. A cylindrical substrate 2 is put on a rotary mechanism 9 and fixed to it. A material gas is introduced through pipes 6. A high frequency power is applied to a cathode by a high frequency source 5 to generate a plasma discharge between the electrode 1 and the substrate 2. The material gas is decomposed and an a-Si film is formed on the surface of the substrate 2.

Description

DETAILED DESCRIPTION OF THE INVENTION A substrate heating method in Vapor Deposition, in particular, a high-order silane gas higher than disilane (Si2I'-a) gas is completely introduced, a Si plasma discharge is generated by a high frequency power source, and amorphous silicon, for example, is deposited on the substrate. The present invention relates to a method of heating a substrate in a plasma field apparatus for forming films of silicon nitride, silicon carbide, etc.

In recent years, plasma CVD has attracted attention as a method for forming thin films of amorphous silicon (hereinafter referred to as a-Si). In this method, the reaction chamber is depressurized to a high vacuum, and a film-forming gas containing a raw material gas such as a higher-order silane gas such as disilane (Si2f (, ) gas) is supplied to the reaction chamber, and then the raw material gas is removed by plasma discharge. It is decomposed and an a-Si film is formed on a substrate made of aluminum or the like placed in a reaction chamber.

Conventionally, this type of device has been constructed as shown in FIG. After raising the temperature to , a plasma discharge is generated between the cathode electrode 1 (which also serves as the wall of the vacuum chamber) connected to the high frequency power source 5 and the substrate 2 (which becomes the anoto electrode), and the substrate 2
An a-81 layer is formed on the surface of the substrate. In addition, 11
is a thermocouple for monitoring the temperature of the base 2. This heating is necessary to maintain the entire substrate 2 at a high temperature (for example, 250° C.) in order to form a stable a-Si layer on the substrate 2.

As mentioned above, in conventional plasma CVD equipment,
A heating element 2 such as a sheathed heater is brought into contact with the surface of the substrate opposite to the film-forming surface, or placed nearby (inside the cylindrical substrate 2 in FIG. 1) to heat the entire substrate 2. , further maintaining this heated temperature.

On the other hand, when forming a-8i film, when all raw material gases such as Jinrano gas are supplied, the gas temperature is generally introduced into the reaction chamber at a low temperature around room temperature from the viewpoint of preventing gas decomposition and ignition. Therefore, when low temperature source gas is blown onto the surface of the substrate 2 which has been heated and held at a high temperature suitable for forming the a-8i film, the surface of the substrate 2 is cooled down. Unable to maintain set temperature.

However, in order to monitor the drop in temperature on the surface of the substrate using the conventional heating method, it is necessary to wait until the entire substrate reaches the same temperature, and the force n of the heated surface and the film-forming surface of the broken substrate 2 must be Since these are not the same, there is a delay in the response time of the temperature monitor 11, resulting in inaccurate temperature control of the surface (film forming surface) of the substrate 2, which leads to a decrease in the electrical properties of the a-8i film being formed. There is.

The present invention eliminates the complexity of the equipment configuration and the inaccuracy of temperature control associated with heating the substrate using a heating heater as in the conventional example described above, and greatly simplifies the heating method of the substrate in the aS+ continuous film forming apparatus. At the same time, it quickly responds to the temperature drop on the surface of the substrate used for raw material gas supply and maintains the substrate at a temperature suitable for forming the A-81 film.
The purpose is to make it possible to form an aS+ film with stable electrical properties.

The present invention achieves the dual purpose of heating the entire substrate using plasma discharge energy generated during A-8I film formation, and maintaining the temperature of the substrate or preventing temperature drop due to the introduction of source gas.

An embodiment of the present invention will be described below with reference to all the drawings. Second
The figure is a side sectional view of a plasma CVD apparatus according to the present invention, in which the same members as in the apparatus of FIG. 1 are given the same reference numerals. Cylindrical wall 1, circular upper wall 4
a and the cylindrical lower wall 4b are connected to annular insulating insulators 3a and 3b, respectively, in a gaseously insulated manner, and these walls 1, 4a, and 4b constitute the reaction chamber wall of the apparatus. do. The cylindrical wall 1 is connected to a power source 5 for supplying high frequency power and acts as a cathode electrode.

At the center of the bottom of the lower wall 4b, there is provided a rotation mechanism 9 on which a cylindrical base 2 made of aluminum or the like is entirely mounted, fixed and rotated. During the reaction, it rotates together with the substrate 2 to make the thin film (a-8i film) formed on the surface of the substrate 2 uniform. The base body 2 is electrically grounded 10 via a rotating mechanism 9 and acts as an anode electrode. Further, the upper wall 4a and lower wall 4b of the reaction chamber wall are similarly electrically grounded 10. Reference numeral 6 denotes a quartz vibrator for supplying raw material gas (disilane gas), and is arranged to surround the base body 2 so that the raw material gas is evenly supplied to the surface of the base body 2. 7 is an exhaust system disposed below the lower wall 4b of the reaction chamber to maintain the reaction chamber in vacuum.

To explain the entire operation of the apparatus of the above embodiment, first, the cylindrical substrate 2 is heated in a vacuum chamber (not shown) to a temperature necessary for forming the a-8i film. The heating means in this case may be any known one, such as a sheathed heater, a flat panel heater, or an infrared heater using a halogen lamp. The above vacuum chamber for heating the substrate is in contact with another vacuum chamber (not shown) in which the apparatus shown in FIG. 2 is arranged via a gate (not shown).

The vacuum chamber for this CVD apparatus and the reaction chamber of the apparatus are maintained in a vacuum state in advance.

The heated substrate 2 is transported from the heating vacuum chamber to the apparatus vacuum chamber with the gate opened.

Next, for example, the upper wall 4a of the reaction chamber of the apparatus is opened, and the substrate 2 is placed and fixed on the rotation mechanism 9.

Thereafter, the gate and upper wall 4a are closed, and the reaction chamber is maintained in a vacuum state only by the exhaust system 7. After this rotation mechanism 9
is rotated in its axial direction and grounded 10 at the same time, and then a raw material gas at room temperature, i.e., disilane (Si
2 l-l6) Gas is introduced.

When introducing this disilane gas, 10-2~]
, maintained at a vacuum level of 0" Torr. The raw material gas is 2r16+5isHs+・'$ノM
Next Shira 7 i Ska Despicable, Mono 7 Run (S i f
l, ) The gas is not promising. This is because when monosilane gas is used at a high input power density, the decomposition efficiency of the gas decreases, so that high-density plasma cannot be applied as in the case of the high-order silane 7. This is because the plasma discharge lowers the temperature, thereby cooling the base 2 which has been heated up.

When disilane gas is supplied into the reaction chamber, a high frequency power source 5 is applied to the cylindrical wall, that is, the cathode electrode 1.13.
A high frequency power of 56 MHz is applied, and a plasma discharge is generated in the reaction chamber, particularly between the cathode electrode 1 and the substrate 2, which is the anode electrode, and the disilane gas is decomposed, so that an a-8i film is formed on the surface of the substrate 2. Ru.

The input high-frequency power during the above a-8i film formation is set to a value necessary to maintain the surface temperature of the substrate 2, and in this example, the input power density is from 0.12 w/ca to 0.17 wA4. It was possible to maintain the set temperature.

At this time, the deposition rate of the a-8i film is proportional to the input power, and 3
The range was from 0λ/sec to 5 OA/sec.

The substrate is heated by plasma discharge because electrons and negative ions generated in the plasma, as well as neutral radical particles excited with high energy, collide with the substrate, and the kinetic energy of the particles is released. It is thought that this is converted into thermal energy on the surface of the substrate.

As mentioned above, since the surface of the substrate 2 (previously heated) cooled by the disilane gas introduced at room temperature is the same as the surface of the substrate 2 heated by the plasma discharge, the effect of cooling by the disilane gas is This makes it possible to maintain the temperature of the surface of the base 20 constant.

In the above example, a preheating chamber independent of the reaction chamber was provided in order to heat the substrate from room temperature to the temperature required for film formation. Before film formation, the substrate at room temperature 1 is placed in a reaction chamber, an inert gas such as helium (He) gas or argon (Ar) gas is introduced into the reaction chamber in vacuum, and high high-frequency power is applied. It is also possible to generate a plasma discharge, heat it according to the same principle as the embodiment shown in Fig. 2, raise it to the desired temperature by a few steps, and then introduce disilane gas to form an a-8i film. be. In this case, the configuration of the device will be similar to that of the device shown in FIG.

As explained above, by maintaining the temperature of the substrate using the energy of plasma discharge during a-8i film formation, there is no need for a heating mechanism like in the conventional example, and there is an advantage that the structure of the reaction chamber can be simplified. Furthermore, since no heating mechanism is provided, there is an advantage that the configuration of the moving mechanism for conveying the substrate etc. can be freely selected.

Furthermore, since the surface of the substrate exposed to plasma, that is, the surface on which the substrate is heated, and the surface of the substrate on which a-8i is deposited are the same, a This is effective in achieving stable film formation of -8i film.

[Brief explanation of the drawing]

FIG. 1 is a side sectional view of a conventional plasma CVD apparatus, and FIG. 2 is a side sectional view of one embodiment of the present invention. 1. Cylindrical wall (cathode electrode) 2. Base (anode electrode) 6. Raw material gas supply vibrator patent applicant Canon Co., Ltd.

Claims (1)

[Claims] Plasma CVD that forms an amorphous silicon film on a substrate by forming a plasma of a film-forming gas containing at least a higher order silane gas than disilane (5i2H6) gas.
A substrate heating method in a plasma CVD apparatus, characterized in that the substrate is heated by the plasma to maintain the temperature of the substrate or prevent a temperature drop.