JPS61281883A - Dry type thin film processing device - Google Patents

Abstract

PURPOSE:To process a substrate having a large area at a uniform rate over the entire surface to be processed by introducing microwaves diagonally with the magnetic lines of force generated in a metallic vessel into said vessel and making uniform the density of the plasma generated by the resonance effect thereof. CONSTITUTION:About 2.45GHz microwaves are introduced through a waveguide 1 and a vacuum window 2 into the metallic vessel 3 and the magnetic lines of force are generated by a solenoid 6 disposed to the outside. Gas such as N2 supplied from a gas inlet 4 is electrolytically dissociated by the resonance effect of the microwaves and magnetic field by which the plasma is obtd. The plasma is forced through an aperture 3a into a reaction vessel 9 provided on the outside of the vessel 3 to activate the gaseous raw material such as SiH4 introduced therein through a gas inlet 12 to form the thin film on the substrate 11. A square waveguide 51 and a square tapered waveguide 52 are connected to the waveguide 1 of the dry type thin film processing device made into the above-mentioned constitution and the microwaves are injected therein diagonally with the central axis of the above-mentioned magnetic lines of force so as to be multiple-reflected in the vessel 3, by which the power density of the microwaves is uniformly distributed.

Description

[Detailed description of the invention] [Technical field to which the invention pertains]

The present invention is an 8@ processing apparatus for growing a semiconductor thin film or etching a thin film on a substrate using plasma, which comprises means for generating microwaves, means for transmitting the microwaves, and Active atoms that are combined with a means and turn gas into plasma due to the resonance effect with microwaves. The method comprises: means for generating magnetic lines of force that generate molecules or ions; and a metal container having an opening whose axis substantially coincides with the central axis of the magnetic flux generated by the magnetic force generating means, and the active atoms are pushed out from the opening of the metal container. The present invention relates to a dry thin film processing apparatus that uses one molecule or ion to form or etch a thin film on the surface of a substrate placed outside the metal container.

[Prior art and its problems]

In the technical field to which this invention pertains, process technology using ECR plasma has recently attracted attention. What is ECR?Electron Cyclotron Re5ona
nce (electron 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 where centrifugal force and Lorentz force are balanced is called the ECR condition. When the centrifugal force is represented by -rω and the Lorentz force by -qr6JR, the condition for their balance is ω/B=q/intestinal. Here, ω is the angular velocity of the microwave, B is the magnetic flux density, and q/− is the specific charge of the electron. The microwave frequency generally used is 45 GH, which is approved for industrial use, and in that case 0
．． Q8?5T is the resonance magnetic flux density. For example, a method shown in FIG. 4 is known as a thin film processing apparatus applying BCR plasma. In this device, a metal container 31 and a reaction tank 9 are evacuated, and microwaves are passed through a waveguide 1 to a place where N heavy gas flows from a gas port 4 to a metal container 3. A metal plate 7 with a large-diameter hole 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 combine to form a semi-open micro It constitutes a wave resonator. 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 into the reaction tank 9, and when silane gas (SiHe) is sent from the gas population 12 into the space toward the sample stage 10 and activated by the plasma, the generated active species react with the substrate 11. A thin film is then formed on the surface of the substrate 11. This apparatus can also be used for etching substrates by flowing an etching gas from gas number 4 instead of N heavy gas. A rectangular waveguide is usually used as a microwave waveguide, and the transmission mode at this time is TEl. This mode has the electromagnetic field distribution shown in FIG. The same figure (al
1 is a diagram showing the respective directions of the electric field E (solid line) and the magnetic field H (broken line) when the cross section of the waveguide is viewed from the front. Figure 1b) is a longitudinal cross-section at the AA position of (al) viewed in the direction of the arrow.The black circles represent the electric field perpendicular to the paper and towards the spine of the paper, and the white circles represent the electric field towards the front of the paper. The dashed line indicates the magnetic field that intersects this electric field.The direction of the microwave incidence has been adopted as shown in Figure 4 (a direction in which both the electric and magnetic fields of the microwave are orthogonal to the lines of magnetic force generated by the solenoid 6). However, this microwave injection method had the following drawbacks: In FIG.
The typical size of the waveguide for cuz is a rectangle of 9.5cs x 2.7CM, which is quite small compared to the inner diameter of the metal container. The incident microwave is just about to be emitted from the waveguide into free space, and most of its energy goes straight through the resonator, encounters the hole in the large-diameter metal plate 7, and enters the reaction tank. Therefore, the power density of the microwave inside the metal container 3 is not controlled only by the resonance mode but also by the shape of the cross section of the waveguide 1 and the power density inside the metal container 3. The plasma generated thereby also has a complicated distribution within the metal container, and as a result, it is inevitable that the processing speed of the substrate will be uneven depending on the location on the substrate surface. There is also a sixth etching device using ECR plasma.
The method shown in the figure is known. In this method, microwaves generated by a magnetron 41 are transferred to waveguides 42 and 43.
Gas is injected into the quartz tube 44 through the solenoid 45, and when a magnetic flux density that satisfies the ECR condition is obtained inside the quartz tube 44, the gas is turned into plasma. This plasma is sent out from the inside of the quartz tube 44 to the inside of the reaction tank 47, and reaches the substrate 49 placed on the sample stage 4th.
Here, active species in the plasma react with the surface of the substrate 49,
Etching progresses. If necessary, a permanent magnet is placed under the sample stage 48 to facilitate transport of the plasma to the substrate. In this method, the waveguide 42 is formed to have a rectangular cross-sectional shape, and the waveguide 43 is formed to have a circular cross-sectional shape, and the waveguide path is converted from a rectangular shape to a cylindrical shape. In the conversion method, the transmission mode TB+a (5th
Figure) is the transmission mode TM in a circular waveguide as shown in Figure 7. 1, thus creating a region of zero electric field strength on the central axis of the cylinder, and therefore this method also results in significant non-uniformity of the plasma distribution, resulting in an increase in the processing speed of the substrate depending on the surface of the substrate. This had the disadvantage of causing unevenness depending on location.

[Purpose of the invention]

This invention eliminates the unreasonable distribution of microwave power density within the resonator caused by the unnatural coupling between the waveguide and the resonator, which is caused by the unnatural coupling between the waveguide and the resonator, and makes the plasma density distribution uniform. Accordingly, it is an object of the present invention to provide a dry thin film processing apparatus capable of processing a large-area substrate at a uniform speed over the entire processing surface of the substrate.

[Key points of the invention]

Microwaves are radio waves, but it is well known that they have strong directivity due to their short wavelength.The present invention focuses on this directivity, and calculates the direction of incidence of microwaves from a waveguide to a metal container. This is intended to make the microwave power density within the metal container denser by making it oblique to the lines of magnetic force occurring inside the metal container, causing multiple reflections on the wall surface of the container, and thereby making the density distribution of plasma more uniform.

[Embodiments of the invention]

FIG. 1 shows an embodiment of a dry thin film processing apparatus constructed in accordance with the present invention. Microwaves injected from a waveguide 1 through a vacuum window 2 are transmitted through a rectangular waveguide 51. The light passes through the rectangular tapered waveguide 52 and enters the metal container 3 in a direction oblique to the rotation center axis of the metal container. Here, the rectangular waveguide and the rectangular tapered waveguide are arranged so that the shorter side of their cross section is perpendicular to the rotation center axis of the metal container 3. In such a configuration, the incident microwave is multiple-reflected from the wall surface of the metal container 3 and spreads throughout the resonator formed by the metal container, and as a result, the electromagnetic field inside this resonator satisfies Maxwell's electromagnetic equations. This is consistent with the boundary condition that assumes that a conductor exists on the inner wall of the metal container, and the influence of the power density distribution in a waveguide with a rectangular cross section can be removed, making it suitable for processing a circular substrate inside a resonator. It is possible to obtain a power density distribution. The apparatus is configured as described above, and reaction tank 9. Metal container 3. Rectangular tapered waveguide 52. When the inside of each rectangular waveguide 51 is evacuated and gas is introduced from the gas inlet, plasma is generated and the substrate 11 is processed using the same principle as the conventional device. Further, the uniformity within the substrate 3 and the uniformity of the processing speed of the substrate depending on the location on the substrate surface can be brought closer to ideal conditions by optimizing the design of the internal dimensions of the metal container. In addition, since this embodiment employs a rectangular tapered waveguide system, when the plasma that may be generated inside the tube moves toward the opening 3a along the lines of magnetic force, it can be prevented from colliding with the wall of the waveguide. Since the plasma can flow out into the metal container 3, it is possible to prevent the accumulation of plasma in the tube and the contamination of the vacuum chamber due to spatter on the tube wall. Furthermore, in this embodiment, since the rectangular waveguide 51 is arranged to cross the magnetic field lines, the plasma cannot reach the vacuum window, and there is an advantage that the vacuum window material, such as ceramics or quartz, is not damaged by thermal distortion. There is. FIG. 2 shows another embodiment of the present invention, in which the introduction part of the microwave into the metal container 3 does not necessarily have to be a rectangular tapered waveguide, and even a rectangular waveguide alone can cause multiple reflections. Similar effects can be obtained, and even if the waveguide 53 is not necessarily sandwiched between the solenoids, the waveguide can be placed across the lines of magnetic force, and damage to the vacuum window can be prevented. This is to show what is possible. FIG. 3' shows another embodiment of the present invention, in which there are a plurality of systems for introducing microwaves into the metal container 3. By injecting multiple microwaves from various directions, it is possible to make the distribution of microwave power density within the metal container 3 more uniform. In the above embodiments, the cross-sectional shape of the waveguide is rectangular, and the short side of the rectangle, that is, the direction of the oscillating electric field of the microwave, is perpendicular to the central axis direction of the magnetic flux generated in the metal container. Although the waveguide and the metal container are coupled together in this way, if the deviation of the direction of the microwave's oscillating electric field from the direction perpendicular to the central axis of the magnetic flux is not very large, the efficiency of plasma generation will be significantly reduced. It is possible to make the distribution of microwave power density uniform within the metal container without causing any damage. In addition, by using a circular waveguide instead of a waveguide with a rectangular cross section, even if there is a part where the electric field is zero on the central axis, the microwave is injected obliquely to the central axis direction of the magnetic flux. Then, the distribution of microwave power density can be significantly improved due to multiple reflections within the metal container.

【Effect of the invention】

As described above, according to the present invention, the microwave transmission means coupled to the metal container is configured such that microwaves are injected obliquely to the central axis of the magnetic flux generated within the metal container. Since the injected microwave is multiple-reflected within the metal container, the microwave power density within the metal container becomes uniform, and as in the conventional case, the direction of the central axis of the magnetic flux and the injection direction of the microwave It is possible to obtain a thin film processing apparatus that has a much more uniform processing speed on the substrate surface than a thin film processing apparatus that has a uniform processing speed.

[Brief explanation of the drawing]

FIG. 1 is an explanatory cross-sectional view showing an embodiment of the main part of a dry thin film processing apparatus constructed based on the present invention, FIG. 2 is an explanatory cross-sectional view showing a modification of the embodiment of FIG. 1, and FIG. 2 is an explanatory cross-sectional view showing an embodiment that is a further modification of the modification shown in FIG. 2, FIG. 4 is an explanatory cross-sectional view showing an example of the configuration of the main parts of a conventional dry thin film processing apparatus, and FIG. 5 is a rectangular waveguide. Microwave oscillating electric field and magnetic field distribution diagram showing the transmission mode of microwaves, Part 6
The figure is an explanatory cross-sectional view showing an example of the configuration of the main parts of a conventional dry thin film processing apparatus, and FIG. 7 is an oscillating electric field of microwaves showing the transmission mode of microwaves in a circular waveguide. It is a distribution map of a magnetic field. 1: Waveguide, 3: Metal container, 3a: Opening, 6: Solenoid, 11: Substrate, 41: Magnetron, 42.43: Waveguide, 44a: Opening, 45: Solenoid, 49: Substrate,
51.53,55,56,58: Rectangular waveguide, 52:
Rectangular taper waveguide, 61: Waveguide. 2.55, ゛, ,' Nbi 1 person no 4-. Nie Yamaguchi μpapa'
↓ Vacuum base ↓ Vacuum base Figure 3

Claims (1)

[Scope of Claims] 1) A means for generating microwaves, a means for transmitting the microwaves, and a means for generating active atoms by combining with the microwave transmitting means and turning gas into plasma by the resonance effect with the microwaves. , comprising means for generating magnetic lines of force that generate molecules or ions, and a metal container having an opening whose axis substantially coincides with the central axis of the flux of magnetic lines of force generated by the line of magnetic force generating means; In a dry thin film processing apparatus that uses atoms, molecules, or ions to generate or etch a thin film on the surface of a substrate placed outside the metal container, a microwave transmission means coupled to the metal container is configured to transmit the magnetic field lines. A dry thin film processing apparatus characterized in that the apparatus is coupled so as to inject microwaves obliquely to the central axis of the magnetic flux generated in the metal container by the generating means. 2) In the device according to claim 1, the microwave transmission means coupled to the metal container is composed of one or more rectangular waveguides, and the rectangular short side of each rectangular waveguide is Each waveguide is coupled to the metal container in a direction perpendicular to the central axis of the magnetic flux in the metal container, and the axis of the waveguide is oblique to the central axis of the magnetic flux. Dry thin film processing equipment. 3) In the device according to claim 1, the microwave transmission means coupled to the metal container is formed as a rectangular tapered waveguide whose cross section is rectangular and whose long sides increase in length in the axial direction. The rectangular shape is coupled to the metal container such that the short side thereof is perpendicular to the central axis of the magnetic flux within the metal container, and the axis of the waveguide is oblique to the central axis. A dry thin film processing apparatus characterized in that the length of the microwave inlet formed at the coupling position in the direction perpendicular to the short side of the rectangle is equal to the inner diameter of the metal container.