JPS61213377A - Method and apparatus for plasma deposition - Google Patents

Abstract

PURPOSE:To form a deposited film having a uniform compsn. on a substrate having a large area by constituting the magnetic field distribution in a plasma deposition device of a combined magnetic field consisting of plural magnetic fields. CONSTITUTION:Plural substrates 9 are placed on a rotary table 13 in a vacuum chamber 1 and a gaseous mixture composed of SiF4 and N2 is introduced through a supply pipe 10 into the chamber. Microwave power of 0.1-10GHz is introduced from a microwave generating part 6 into the chamber through a waveguide 2 to generate microwave discharge by the synergistic effect of the microwave electric field and the magnetic fields generated by magnetic field generators 4, 5, 12. The SiF4 is decomposed by the generated plasma and the amorphous SiN film consisting of the resulted product of decomposition is deposited and formed on the plural substrates 9 under rotation. A magnetic field generator 12 which generates the magnetic field in the direction intersecting with the above-mentioned magnetic field axis is provided in combination in addition to the magnetic field generators 4, 5 consisting of permanent magnets, electromagnets, etc. disposed to form the coaxial magnetic fields. The deposited film having the uniform compsn. and thickness is formed on the substrates having the wide area by adjusting the magnetic field intensity of these generators 4, 5, 12.

Description

[Detailed Description of the Invention] [Field of Application of the Invention] The present invention relates to a method and apparatus for forming a deposited film, and in particular to a method and apparatus for forming a deposited film on a predetermined substrate by decomposing a source gas for forming a deposited film by high frequency exposure. This invention relates to a plasma deposition method and an apparatus thereof.

[Background of the invention]

CVD method is a thin film production method using a gas phase.

There are sputtering methods and plasma CVD methods, but the plasma CVD method in particular has advantages such as low processing temperature and high film formation rate, so it is suitable for amorphous SL (α-8= ) for semiconductor device manufacturing processes and solar cells. It is being actively used in the production of membranes.

In the conventional plasma CVD apparatus, the mainstream is a parallel plate type RF type plasma deposition blind apparatus in which high frequency power in the radio frequency (RF) range is applied to opposing parallel plate electrodes to generate plasma. This method has the advantage of being able to form a thin film with uniform thickness and composition over a large area by placing the sample on the electrode, making it possible to realize a highly productive device, but it also has the following drawbacks: There is.

(1) The gas pressure that can be discharged is generally 10-2 to 10-'
Ton; and the electron temperature of discharge is low (~4 gV)
For this reason, halogenated silicon gas, which has a chemical structure with high binding energy, cannot be decomposed sufficiently, so there is a limit to the physical properties of the film that can be coated with cedar. (2) An ion sheath is formed in front of the sample, which automatically Since a self-bias is applied to the sample, the ions entering the sample have a kinetic energy equivalent to the self-bias, but this energy is more than several hundred #V, which affects the characteristics of the film produced. (3) The electrode material (metal) is in contact with the plasma, and the electrode material is sputtered. It mixes into the produced film as an impurity.

For this reason, as a plasma CVD apparatus with high electron temperature and low incident ion energy, for example,
A microwave discharge type plasma deposition apparatus as presented in No. 18 has been developed. FIG. 1 is an explanatory diagram of the configuration of a microwave discharge type plasma deposition apparatus. In the figure, 1 is a vacuum chamber, 2 is a waveguide for introducing microphone A-waves, 3 is a discharge tube, 4 is a magnetic field generator for electron cyclone resonance using an electromagnet or a permanent magnet, and 5 is a desired magnetic field in the vacuum chamber. A magnetic field generator using an electromagnet or a permanent magnet for forming a distribution, 6 a microwave generator, 7 a sample chamber, 8 a sample stage, 9 a sample, 10 a source gas inlet, and 11 an exhaust boat. Note that the vacuum chamber 1 consists of the inside of the discharge tube 3 and the sample chamber 7.

Microwave (usually 0.1 to 1oG) introduced into the vacuum chamber 1
Hg) is generated, for example, by a magnetron and guided through the circular waveguide 2. The discharge tube 3 is made of an insulator (for example, quartz or alumina 44) to pass microwaves. When a discharge gas is introduced into a vacuum chamber at a predetermined pressure and microwave power is introduced, a microwave electric field and magnetic field generator 4 is generated.
Microwave discharge occurs due to the synergistic effect of the magnetic field. The magnetic field strength is set so that the frequency of cyclotron motion around the magnetic field lines of electrons substantially matches the microwave frequency. However, if the image frequencies perfectly match, the microwave will be completely reflected, so the resonance point is set to be slightly shifted. The generated plasma is transferred by the Lorentz force from the discharge tube section where the magnetic field strength is strong to the sample chamber where the magnetic field strength is weak. The magnetic field generator 5 is installed to constrict the lines of magnetic force at the surface position of the sample 9, confine the plasma carried along the lines of magnetic force, and converge the plasma at the position of the sample. The overall magnetic field distribution is called a mirror magnetic field, and as a result, it becomes possible to confine the plasma in the area surrounded by the broken line I in FIG.

The microwave plasma deposition method and apparatus having the above-mentioned configuration are performed at a gas pressure of 5 x 10"-' to 3 x 10-2T.
discharge is possible at a low gas pressure of orr, a high electron temperature can be obtained (~agv), the decomposition efficiency of the source gas is high, and the incident energy of ions is low (about 20 gV), so it can be used as needed. It has the advantage that the kinetic energy of incident ions can be controlled by applying an external voltage to the sample stage 8, and that there is less contamination due to impurities in the produced film since it is an electrodeless discharge.

However, with the above-mentioned method or apparatus, a uniform composition and film formation rate can only be obtained in an area with a diameter of at most 20 mm when a discharge tube with a diameter of 15 mm is used; There is a tendency for the film formation rate to be high in some parts. This is a major drawback as a method for processing semiconductor wafers. In order to expand the uniform film formation area, it is possible to increase the diameter of the discharge tube 3, but in order to satisfy the electron cyclotron resonance condition, for example, when using a 2.45 GHz microwave, the magnetic field generator 4 Since the required magnetic flux density is about 0.2 T, a large-scale electromagnet is required due to the drastic increase in the diameter of the discharge tube, which is impractical.

If you simply want to expand the plasma region, plasma can be formed in the region indicated by the dotted line (■) in Figure 1 by creating a magnetic field distribution known as a so-called cupped magnetic field, in which the direction of the magnetic field produced by the magnetic field generator 4 and the direction of the magnetic field produced by the magnetic field generator 5 are opposed to each other. However, it is difficult to obtain a uniform composition and film formation rate over a large area, and the plasma contacts the vacuum chamber 7 and sputters the vacuum chamber walls, causing impurity contamination. This method is not practical because of problems such as deposition occurring and causing dust generation. Therefore, the conventional microwave plasma deposition apparatus has a major drawback in terms of mass production of uniform film formation over a large area.

[Purpose of the invention]

An object of the present invention is to provide a plasma deposition apparatus and apparatus which enable uniform film formation over a large area by improving the drawbacks of conventional microwave plasma deposition methods and apparatuses, and which have excellent mass productivity.

[Summary of the invention]

The present invention is a plasma deposition method in which gas in a discharge state is guided to the surface of a sample by a composite magnetic field consisting of a plurality of intersecting magnetic fields to form a film made of the gaseous material on the surface of the sample. Furthermore, the present invention provides a plasma that is provided with a magnetic field generator that generates a magnetic field in a direction perpendicular to the magnetic field axis, in addition to the magnetic field generators that are coaxially arranged in parallel to form a coaxial magnetic field. It is a deposition device.

[Embodiments of the invention]

Hereinafter, the present invention will be explained in detail with reference to examples.0 Example 1 An example of the present invention is shown in FIG. The basic configuration of this embodiment is substantially the same as that of the conventional microwave plasma deposition apparatus shown in FIG. As the magnetic field generator 5, an electromagnet was used.

The first feature of this embodiment is that a magnetic field generator 12 is installed that generates a magnetic field in a direction orthogonal to the direction of the magnetic field generated by the electron cyclotron resonance magnetic field generator. When plasma is generated by making the direction of the magnetic field by the magnetic field generator 5 coincide with the direction of the magnetic field by the magnetic field generator 4, the plasma is generated in the region surrounded by +1JjI in Fig. 2, as described above. Here, we considered ti, M of 5=NW= on a silicon wafer using S, F4 and N2 gas. magnetic field generator d
12 generates a magnetic field in the direction in which the lines of magnetic force by the magnetic field generator 4 are continuous, and the magnetic field generator 5 and the magnetic field generator! It has been experimentally confirmed that by adjusting the elasticity of the generated magnetic field 12, it is possible to expand the plasma generation area in the direction of the magnetic field generator 5 and to expand the uniform film formation area.

In this embodiment, a rotary table 13 is used as a sample stage. When examining the ability to form a uniform film over a large area under the above-mentioned conditions, it was confirmed that the uniform film formation area could be expanded approximately twice in terms of area compared to the case where the magnetic field generator 12 was not used.

Next, turn off the current in the magnetic field generating bag [5, and turn off the current in the magnetic field generating device 12
When a magnetic field was generated to generate plasma, it was confirmed that it was possible to form a film with a peak near the magnetic field generator 12. Therefore, we set the sample on the rotary table 13, adjusted the magnetic field generation time by the magnetic field generator 5 and the magnetic field generation time by the magnetic field generator 12, and examined the uniform film formation over a large area.We found that when the magnetic field generator 12 is not used, It was confirmed that the uniform film formation area could be expanded approximately 3.5 times in terms of area compared to the previous method.

Embodiment 2 FIG. 3 is a block diagram in which the present invention is applied to an RF plasma deposition apparatus. The discharge tube 3 was made of an insulator (quartz glass or alumina) and had a gas introduction tube 10. In the figure, 15 is a high frequency generator and a matching box, in which 13.5 MH2 radio waves were used.

Although the high frequency power is here introduced into the discharge tube by the induction filter 14, it can also be introduced in a capacitive type. When 5L02 formation using 5LH4 and N20 gas and pancreas were investigated using this device configuration, it was possible to confirm an expansion of the uniform film formation area as in Example 1.

〔Effect of the invention〕

As explained above, according to the present invention, it is possible to significantly expand the uniform film formation area in plasma deposition methods and apparatuses that have conventionally been considered difficult to uniformly form a film over a large area. The mass productivity of forming a thin film thereon can be significantly improved. In particular, the mass productivity of the microwave plasma deposition apparatus can be improved.

[Brief explanation of drawings]

Figure 1 is a schematic diagram of the configuration of a conventional microwave plasma device.
FIG. 2 is an explanatory diagram of the configuration of a microwave plasma apparatus according to the present invention, and No. 3N is an explanatory diagram of the configuration of an induced RF discharge type plasma apparatus according to the present invention. DESCRIPTION OF SYMBOLS 1... Vacuum chamber, 2... Waveguide, 3... Discharge tube, 4... Magnetic field generator, 5... Magnetic field generator, 6... Microwave generator, 7... - Sample chamber, 8... Sample stage, 9... Sample, 10... Source gas inlet, 11... Exhaust boat, 12... Magnetic field generator, 13... Rotary table, 14. ...Solenoid coil, 15...RF oscillator. Representative Patent Attorney Masaru Ogawa 1 Figure

Claims (1)

[Claims] 1. High-frequency power is applied to a gaseous material to cause the gas to be in a discharge state, and the discharged body is placed within the magnetic field by a composite magnetic field consisting of a plurality of intersecting magnetic fields. A plasma deposition method characterized by introducing the gaseous material into a sample and forming a film made of the gaseous material on the surface of the sample. 2. The high frequency power is a microwave, and the installation is such that at least one magnetic field is formed along the propagation path of the microwave, and the magnetic field strength gradually decreases along the propagation path of the microwave and partially The plasma deposition method according to claim 1, characterized in that it satisfies electron cyclotron resonance conditions. 3. A plasma deposition apparatus comprising a vacuum chamber, means for supplying high-frequency power to the vacuum chamber, means for introducing discharge gas into the vacuum chamber, and means for holding a sample within the vacuum chamber. , comprising at least three magnetic field forming means for forming a magnetic field in the vacuum chamber, and the magnetic field forming means are arranged so that at least one of the directions of the magnetic field formed by the magnetic field forming means intersects the direction of the other formed magnetic field. A plasma deposition device characterized by: 4. A plasma deposition apparatus 5 according to claim 3, wherein at least one of the magnetic field forming means is constituted by an electromagnet, and at least one of the magnetic field forming means is an electromagnetic force and an electric current. 4. The plasma deposition apparatus according to claim 3, wherein the magnetic field strength can be modulated by intermittent or modulation. 6. The plasma deposition apparatus according to claims 2 to 3, characterized in that a rotary table for placing a sample is installed in the vacuum chamber.