JPS63301517A - Dry type thin film processor - Google Patents

Abstract

PURPOSE:To accelerate the filming speed also accelerating the growing speed of thin film in proportion to the increase in the supplied microwave power by a method wherein the inner diameter of a cylindrical metallic vessel of a microwave resonator forming a plasma producing chamber is specified. CONSTITUTION:Within the title processor, a plasma producing chamber is formed into cylindrical shape with the central axis and the axial line of the flux of magnetic force coincided with each other while the inner diameter and the height of the cylinder are related so that the frequency may be set up to cause the resonance of TE113 made with the microwave of 2.45GHz also setting up the inner diameter of the cylinder within the range of 15.5-19.5cm or 21.5-25.5cm. Through these procedures, the speed of film formation can be increased, and the film formation speed is increased in proportion to the increase in the supplied microwave power.

Description

[Detailed Description of the Invention] [Industrial Application Field] This invention provides Ec by the interaction between microwaves and a magnetic field.
R (resonant cyclotron resonance) plasma is generated, this plasma is transported from the plasma generation chamber to the reaction chamber by the diffusion magnetic field effect, and this plasma interacts with the film forming material gas such as monosilane that is directly sent into the reaction chamber. Using active ions or species generated by semiconductors,
IC (S product circuit), LSI (Large scale integrated circuit)
, silicon nitride, silicon oxide on substrates such as photoreceptors.

Dry method for forming films such as amorphous silicon
This relates to gt film processing equipment.

[Conventional technology]

A silicon-based film using ECR plasma has a dense film quality. A low stress film can be obtained. Because it has features such as the possibility of low-temperature processing, it is seen as a promising film-forming technology in the future, and research into the film-forming process has been actively conducted in Japan. What is ECR?
, tron Cyclotron Resonance
(Tel Cyclotron Resonance), which accelerates electrons using the resonance effect of a magnetic field and microwaves, and uses the kinetic energy of these electrons to ionize gas to obtain plasma. Electrons excited by microwaves move circularly around magnetic lines of force, and the condition in which centrifugal force and Lorentz force are balanced is called the ECR condition. The centrifugal force is mrω2. When the Lorentz force is expressed as -q "ωB, the condition for their balance is ω/B = q/m. Here, ω is the angular velocity of the microwave, B is the magnetic flux density, and q/m is the specific charge of the electron. The microwave frequency generally used is 2.45 GH, which is accepted for industrial use, and in that case, the resonant magnetic flux density is 0.0875 T.

For example, the one shown in FIG. 3 is known as a thin film processing apparatus using ECR plasma. In this apparatus, the cylindrical metal container 3 of the microwave resonator forming the plasma generation chamber and the reaction chamber 9 are evacuated, and the gas supply means 4 is supplied with N2.0□ depending on the type of film formation intended. ,H,,A
A carrier gas (plasma generating gas) such as , etc. is flowed into the metal container 3 and the microwave is transmitted through the waveguide 1 . A metal plate 7 with a large-diameter opening 13 in the center is attached to the lower part of the metal container 3, which is fed into the metal container 3 through the vacuum window 2, and this metal plate and the metal container 3 generate microwave resonance. It makes up the vessel. A solenoid 6 is disposed outside the resonator, and a magnetic field that satisfies the ECR conditions is generated within the resonator, so that ECR plasma is generated within the resonator. This plasma is pushed out to the reaction chamber 9, and when a raw material gas, for example, silane gas 5IHa, is sent from the gas population 12 into the space facing the sample stage 10 and this gas is activated by the plasma, the generated active species react with the substrate 11. Various silicon-based thin films are then formed on the surface of the substrate 11, depending on the carrier gas ft1g used.

[Problem that the invention seeks to solve]

In such an ECR film forming apparatus, the design specifications of the metal container 3 and solenoid 6 that constitute the microwave resonator have a decisive influence on the plasma parameters that determine the initial characteristics, including the reaction rate, that is, the film forming rate. be.

The present invention relates to the design of a microwave resonator, and hereinafter, problems with the prior art will be explained focusing on this point.

In order to sufficiently increase the electric field strength in the plasma generation chamber,
The metal container of the plasma generation chamber is configured to function as a resonator, and due to various conditions, the container is formed into a cylindrical shape and the resonant mode of microwaves within the container is set to T.
The E++i mode is often used, and in this case, the inner diameter of the cylinder has traditionally been 20] without exception.
9th Annual Conference of the Four Electrical Engineers of Japan; 9-3 Application of ECR plasma to thin film formation; see Gen Matsu and Kiuchi).

As will be discussed in more detail later, this design dimension is problematic for an ECR plasma generation resonator, as the injected microwave power is not fully utilized for plasma generation, resulting in low deposition rates and It had the disadvantage that even if the power was increased, the film formation rate did not increase much. Moreover, this shortcoming itself was not generally considered a problem.

In view of the above-mentioned conventional problems, an object of the present invention is to appropriately set the design dimensions of a cylindrical metal container constituting a resonator to increase the film formation rate, and to increase the film formation rate as the microwave injection power increases. An object of the present invention is to provide an ECR plasma film forming apparatus that can increase the growth rate.

[Means for solving problems]

According to the macrowave resonator theory, the following equation holds true.

The microwave resonance mode is TM, 1. In the case of mode, the resonance mode of the microwave is TE, 1. For mode, press X here. , ,'l l The inner diameter of the vessel, C is the speed of light, and L is the length of the cylindrical cavity. Further, S is the half-wave number between the two end faces of a standing wave whose nodes are the positions of both end faces of the cylindrical cavity resonator. Therefore, if the resonance mode of the microwave is TEII mode,
From equation (2), it becomes. That is, in order to generate TE113 mode resonance, the relationship shown in equation (3) must be satisfied between the inner diameter and length of the cavity resonator.

As can be seen from this equation, the inner diameter of the resonator for generating resonance varies depending on the D/L that gives the shape of the resonator, and an elongated resonator with a small D/L has a small inner diameter, and the D/L is small. A resonator with a large L has a large inner diameter. Therefore, like the conventional resonator, D/L -1, f-2,
If the inner diameter is determined as 45×10qH, D-19,71 is obtained. Conventionally, this fraction was rounded up to D-L-20.
It was set to cm.

However, a competition mode exists for this dimension (D=20ci). That is, T M z l as a resonance mode.

Considering the mode, the right side of equation (1) is 2.672
c2 = 2.4 XIO'' On the other hand, when D = 20 cm, the left side of equation (1) becomes 2.4 XIO'', and the TM21° mode is excited simultaneously with the T E + 13 mode. Moreover, TM□. mode, as in the case of T E + + s mode,
The inner diameter of the resonator is 19.7 (not caused by the approximate inner diameter where J is rounded up, but D = 20
Since formula (1) is strictly satisfied in al, the sharpness of the resonance, that is, the Q value is high, and the input microwave power is affected by the resonance of this mode, and the 7M mode does not contribute to the generation of ECR plasma. Therefore, the distribution of power to plasma generation in the TE mode becomes smaller.

Furthermore, the TE++* mode is T M + + at D=15cn. mode and D=21
In cm, T M t x I mode and D = 26 cm
This conflicts with the T M t + t mode. Note that the above T M t +. , TM+Io, s=Q, which means that the electromagnetic field distribution within the resonator is uniform in the length direction.

Experience has shown that for cylindrical resonators with openings at the end faces, ±
The above conflict cannot be avoided unless D is adjusted within a range of 0.5 cm. Furthermore, in order to avoid competition, if D is made smaller, the diameter of the substrate on which the thin film is formed must also be made smaller, and in practical terms, D=15 cm is the lower limit.

Furthermore, considering the practical size of the solenoid, the practical upper limit is D=26ca+ from the viewpoint of magnetic field distribution. Therefore, the inner diameter of the cylindrical resonator that produces resonance in the TE++x mode while avoiding excitation in the 7M mode is D = 15.5 to 19.5 cin and D = 21.
Desirable finished dimensions are 5 cm to 25.5 cm.

[Effect]

As described above, if the inner diameter of the cylindrical resonator is set within the above-mentioned range and the length of the cylinder is set according to equation (2), the excitation of the 7M mode can be avoided, so that the 7M mode cannot be injected into the resonator. The injected microwave power is effectively consumed in forming the TE++ff mode, which results in an increase in the deposition rate, and as the injected microwave power increases, the growth rate of the thin film also increases proportionally.

〔Example〕

FIG. 1 shows an embodiment of the design of a metal container constituting a cylindrical resonator of a dry thin film processing apparatus constructed based on the present invention. In this embodiment, the inner diameter of the cylinder is set to 191 within one range, and the length of this cylindrical portion is set to 191 (based on formula 31).
．． It is set to 8C1m.

Figure 2 shows a comparison of the relationship between the deposition rate and the injected microwave power when depositing a film using an apparatus designed in this way with the conventional method. ), and N is used as the carrier gas, and curve (a) is the one obtained by the apparatus of this example
Curve (b) is the result of the conventional device. In both devices, the supply ratio of silane gas and N2 is the same,
20"/-r,, 30"/-t, respectively.
.

As seen in the figure, in the conventional apparatus, even if the microwave power is increased, the film formation rate does not increase proportionally and tends to saturate, whereas in the apparatus of this example, the metal container design Since the dimensions strictly satisfy the resonance conditions of the TEI11 mode, the rise of the deposition rate curve is fast, and the inner diameter of the metal container is set within a range that does not allow excitation of the TM mode, so it is possible to inject. Microwave power is effective
It is consumed to form the E + + s mode, and the deposition rate increases proportionally as the injection power increases.

〔Effect of the invention〕

As described above, according to the present invention, the inner diameter of the cylindrical metal container of the microwave resonator forming the plasma generation chamber can be adjusted even if the injected microwave power increases without contributing to plasma generation. Since the setting is made within a range in which TM mode resonance that prevents a proportional increase in the film formation rate does not occur, the injected microwave power has an electric field orthogonal to the magnetic field lines generated by the excitation solenoid 6, and this causes the plasma It is effectively consumed in the formation of the TE mode that contributes to generation, and the film formation rate is higher than that of conventional equipment, and the film formation rate increases proportionally as the injected microwave power increases. There is.

[Brief explanation of drawings]

Fig. 1 is a cross-sectional explanatory diagram of a dry thin film processing apparatus showing an embodiment of the present invention for setting dimensions of a cylindrical metal container constituting a plasma generation chamber, and Fig. 2 shows the film formation rate and injection by the apparatus shown in Fig. 1. FIG. 3 is a diagram illustrating the relationship between the microwave power and the microwave power obtained in comparison with that of a conventional device. FIG. 1: Waveguide (microwave transmission means), 3: Metal container, 4
: Gas supply means, 6: Solenoid, 9: Reaction chamber, 11:
Substrate, 13: opening. Vacuum base Figure 1 Figure 2

Claims (1)

[Claims] 1) A means for generating microwaves, a means for transmitting the microwaves, and a means coupled to the microwave transmitting means to introduce the microwaves and to supply the gas supplied via the gas supply means to the microwaves. The microwave transmitting means includes an excitation solenoid that generates magnetic lines of force that turn into plasma and generate active atoms, molecules, or ions by a resonance effect with the waves, and an opening whose axis substantially coincides with the central axis of the flux of magnetic lines of force generated by the solenoid. A thin film is formed on the surface using a plasma generation chamber having opposite sides and the active atoms, molecules or ions coupled to the plasma generation chamber through the opening and flowing out from the opening along the magnetic flux. A dry thin film processing apparatus is provided with a reaction chamber in which a substrate is disposed, the plasma generation chamber being formed in a cylindrical shape whose axis coincides with the central axis of the magnetic flux, and having an inner diameter and a height of the cylinder. In the case where the relationship is set to produce TE_1_1_3 mode resonance for microwaves with a frequency of 2.45 GHz, the inner diameter of the cylinder is set to 15.5 to 1.
A dry thin film processing device characterized in that the thickness is set within a range of 9.5 cm or 21.5 to 25.5 cm.