JPH0414217A - Dry thin film processing device - Google Patents

Abstract

PURPOSE:To contrive to make even the density of gas particles on a plasma transport road by a method wherein the route of a plasma flow is surrounded with a coaxial double cylinder- shaped cylindrical body, four pieces or more of gas introducing ports are provided in the inner wall surface of the cylindrical body in a rotationally symmetrical state and four pieces or more and even pieces of vacuum exhaust vents are provided in the inner wall surface of another coaxial double cylinder-shaped cylindrical body arranged coaxially with the above cylindrical body on the side closer to a substrate of this cylindrical body in a rotationally symmetrical state. CONSTITUTION:A coaxial double cylinder-shaped cylindrical body 24 is arranged between a plasma producing chamber 3 and a substrate 11 in such a way that the axial line of the cylindrical body 24 is made to coincide with the axial line of the chamber 3. The body 24 is connected to a gas line 12 penetrating a treating chamber 9 and four pieces or more of gas introducing ports 24a are formed in the inner wall surface of the body 24 in a rotationally symmetrical state so that reaction gas is turned into a viscous flow in the interior of the body 24 and can be uniformly introduced in the chamber 9 at a low speed in the peripheral direction of the chamber 9. A coaxial double cylinder-shaped cylindrical body 25 is arranged in such a way that the axial line of the cylindrical body 25 is made to coincide with the axial line of the chamber 3. The flow of evacuation of air from a vacuum exhaust vent 25d is prevented from concentrating on a vacuum exhaust vent on the side closer to a vacuum pump 23, bypasses along a rack surface and exhaust gas is made to evenly flow around the substrate.

Description

[Detailed Description of the Invention] [Industrial Field of Application] This invention is an ECR method dry thin film used in the ultra-LSI film formation process that requires low-temperature film formation in semiconductor manufacturing equipment represented by LSI manufacturing equipment. Regarding processing equipment.

[Conventional technology]

Microwave A for the purpose of improving film quality in low-temperature film formation
CVD and etching equipment using ECR (electron cyclotron resonance) plasma using the itta resonance effect are being studied. FIGS. 8 and 9 show examples of conventional configurations of this type of thin film processing apparatus.

Plasma generation chamber 3 and processing chamber 9 that also serve as microwave resonators
is evacuated, and a carrier gas (plasma generation gas) such as N2.0□ or Ar is flowed into the plasma generation chamber 3 through the gas supply means 4 according to the purpose, and microwaves are passed through the waveguide. 1. An excitation solenoid 6 is installed outside the microwave resonator 3 into which the microwave is fed through the microwave introduction window 2.
is placed and a magnetic field that satisfies the ECR conditions is generated inside the resonator), and ECR plasma is generated. This plasma is pushed into the processing chamber 9 and the semiconductor wafer l! ! When silane gas is sent through the gas introducing means 12 into the space facing the IT table 10 to be processed and activated by the plasma, silicon is deposited on the surface of the semiconductor wafer (hereinafter simply referred to as substrate) 11 due to the action of the generated active species. A thin film is formed.

In such a conventional device, the silane gas inlet is of the port type illustrated as the silane gas introducing means 12 in FIG. 8, or the gas is supplied through a pipe line extending further into the device from the boat. Conventionally, either a gloss whirling ring 15 as shown in FIG. 9 has been provided.

The shower ring 15 is an annular ring made of a hollow pipe, and small holes 15a for introducing gas are formed at intervals in the circumferential direction.

Further, in order to change the distance between the open lower part of the plasma generation chamber 3 and the substrate 11 to obtain optimum thin film forming conditions, the substrate stand 10 is supported in the processing chamber 9 via an expansion joint 13.

[Problem to be solved by the invention]

The size of wafers used for manufacturing VLSI chips tends to be larger, ranging from 6 inches to 8 inches, and the non-uniformity of the distribution of the formed thin film thickness within the wafer surface can be reduced by ±5% even on such large diameter wafers. Generally, it is required to keep it within the following range. Since the TR film formation rate is mainly determined by the plasma density and electron temperature, it is important to make them uniform in the plane direction, but even if these things are made uniform, it is not enough to make the growth rate uniform. It is essential to equalize the gas flow. Conventionally used gas introduction methods and vacuum evacuation methods have the drawback that the uniformity of the gas flow deteriorates as the gas flow rate fluctuates, and for example, the demands for increasing the film formation rate and improving the film thickness distribution are at odds with each other.

Furthermore, as wafers become larger in diameter, there is a strong demand for uniform growth rate and reduction of particle contamination. In the conventional method, a fl film is formed on the inner walls of the plasma generation chamber 3 and the processing chamber 9 other than the substrate 11, and when it reaches a certain thickness, it peels off and becomes particles, which fall and accumulate on the substrate 11, causing particle contamination. This cannot be avoided, and even if a large number of LSI chips can be produced by increasing the diameter, there is a drawback that a large number of defective films and LSI chips are generated due to particles.

SUMMARY OF THE INVENTION An object of the present invention is to provide a dry thin film processing apparatus that can always maintain uniformity of the gas flow even when the gas flow rate fluctuates, and that particles do not accumulate on the substrate.

[Means for Solving the Problems] In order to solve the above problems, the present invention takes the following measures.

(1) The path of the plasma flow from the plasma generation chamber to the film forming substrate is surrounded by an axially symmetrical coaxial double cylindrical body, and the gas flows from outside the processing chamber through the coaxial double cylindrical body to the path of the plasma flow. At least four inlets are provided at rotationally symmetrical positions on the inner wall of the coaxial double cylinder to prevent uneven distribution of the supplied gas.

(2) The path of the plasma flow from the plasma generation chamber to the film forming substrate and the wafer holding mechanism are surrounded by a coaxial double cylindrical body different from the coaxial double cylindrical body, and the path of the plasma flow is A number of integer multiples of 2, at least 4, are provided at rotationally symmetrical positions on the inner wall of the coaxial double cylindrical body to exhaust gas from the coaxial double cylindrical body to the outside of the processing chamber through the coaxial double cylindrical body. Equalize the flow.

(3) The wafer holding mechanism is configured using an electrostatic chuck, and the device is oriented so that the film-forming surface of the wafer, which is attracted and held by the attraction surface of the electrostatic chuck, faces vertically downward or vertically. Configure.

[Effect]

The operating pressure of ECR plasma is usually around 1 to 5 mTorr, and it belongs to a pressure range where properties intermediate between viscous flow and molecular flow appear. Therefore, the force acting on gas molecules is Coulomb attraction due to the magnetic field diffusion effect of electrons on charged particles.

For neutral molecules (atomic groups), the primary force is elastic collision. In order to maintain a uniform film growth rate within a wafer in such a system, it is important to maintain a uniform density distribution of gas particles in the space through which plasma is transported.

According to the above means (1), the amount of gas ejected from the gas inlet formed on the inner wall of the coaxial double cylindrical body is such that the gas space behind the gas inlet that constitutes the gas source of the ejected gas is
A conduit that is formed between the inner tube and the outer tube of the coaxial double cylindrical body and has a sufficiently large volume compared to the cross-sectional area of the gas inlet, so that gas is introduced from the outside into this gas space. Even if the size of the gas inlet or the connection position with the outer cylinder changes, there is no substantial difference between the gas inlets. The exhaust port cannot be made very small because it is necessary to maintain a constant low pressure in the processing chamber by supplying a large amount of gas to accelerate the rate of film formation on the wafer, but the number of vacuum exhaust ports is an integral multiple of 2. .

Since at least four vacuum exhaust ports are formed at rotationally symmetrical positions on the inner wall, these vacuum exhaust ports are arranged on both sides of the diameter of the coaxial double cylindrical body through the vacuum exhaust ports provided in the outer cylinder of the coaxial double cylindrical body. The gas can be arranged symmetrically, and the gas that is uniformly supplied to a relatively far distance in front of the wafer is evenly exhausted near the wafer, reducing the gas flow density throughout the entire path of the plasma flow from the plasma generation chamber to the wafer. distribution becomes uniform.

Furthermore, according to means (3), by using an electrostatic chuck that does not require a mechanically movable part to hold the wafer, and by configuring the device so that the surface of the wafer on which the film is to be deposited faces vertically downward or in the vertical direction, There are no particles generated from the wafer holding part, and even if the thin film formed on the inner wall of the plasma generation chamber or the coaxial double cylindrical body is peeled off, no particles will be deposited on the wafer.

〔Example〕

FIG. 1 is a diagram showing the configuration of a dry thin film processing apparatus according to an embodiment of the present invention at a preparatory stage for thin film processing, and FIG.
Figure 2 shows the device shown in operation;

In the figure, the same members as in FIGS. 8 and 9 are denoted by the same reference numerals, and explanations thereof will be omitted.

In the figure, the substrate 11 supported by the support stand 18 at the tip of the transport mechanism that transports the substrate 11 to be processed to the processing chamber 9 is transported with the processing surface facing downward in the vertical direction, and the substrate 11 is transported using an electrostatic chuck, which will be described in detail below. The substrate 11 is attracted to the electrostatic chuck 16 by lowering the substrate stand 10 to which the substrate 16 is fixed. After suction, the support stand 18 is retracted and the substrate stand 10 is further lowered to start processing at the thin film processing position shown in FIG. 2.

The electrostatic chuck 16 is usually a flat plate made by arranging two semicircular plate electrodes in the same plane with their diameter sides facing each other and embedding them in a solid dielectric material such as aluminum oxide ceramics. There is a DC high voltage iit'a between these two electrodes.
A voltage is applied from 19. Further, in this embodiment, the electrostatic chuck 16. A fine hole 27 passes through the wafer holding mechanism whose main component is the substrate table 10 in the axial direction, and after thin film processing is completed, a pressurized gas source 22 is supplied to the tm valve 21. Pressurized gas is fed into the contact gap between the electrostatic chuck 16 and the substrate 11 through the throttle valve 20, so that the substrate is separated from the electrostatic chuck and dropped onto the support table 18 of the transport mechanism.

Inside the processing chamber 9, between the plasma generation chamber 3 and the substrate 11, a coaxial double cylindrical cylinder (hereinafter abbreviated as cylinder) 24 is arranged so that the axis of the cylinder coincides with the axis of the plasma generation chamber 3. It is arranged as follows. This cylindrical body 24 passes through the processing chamber 9 and is connected to the gas line 12, and has a plurality of gas inlet ports 24a formed at rotationally symmetrical positions on the inner wall surface, and serves as a guide to adjust the flow of gas. Together with this, it functions as an anti-adhesion cylinder that prevents the film from adhering to the wall surface of the processing chamber 9. FIG. 6 shows a cross section along the line C-C in FIG. 2, and shows the gas line 12.
Eight gas introduction ports 24a are formed laterally symmetrically. Whether the gas flow becomes a molecular flow or a viscous flow is determined by the pressure and diameter of the pipe. Therefore, the gas introduction port 24a is narrowed to form an orifice so that the reaction gas introduced from the gas line 12 becomes a viscous flow inside the cylinder 24, flows uniformly in the circumferential direction at a low speed, and is introduced into the processing chamber 9. A contrivance is to increase the diameter of the pipe by constructing the pipe in the internal space of the cylindrical body. According to experimental results, at least four gas inlet ports 24a are required.

Further, inside the processing chamber 9, a plasma generation chamber 3 and a substrate 1 are provided.
A coaxial double cylindrical cylinder (hereinafter abbreviated as cylinder) 25 is arranged between the cylinder 1 and the cylinder 24 closer to the substrate with the axis of the cylinder coincident with the axis of the plasma generation chamber 3. . The internal space of this cylindrical body 25 is a space 2) formed by a ring-shaped shelf 25e.
A plurality of vacuum exhaust ports 25d are formed on the inner wall surface of the space 25c near the substrate 11, and a shelf 25e is partitioned into two spaces, a space 25c and a space 25c.
A plurality of holes are formed in the rain spaces 25a and 25c to communicate with each other, and this cylinder body 25 also functions as a guide to adjust the gas flow and as an anti-adhesion cylinder to prevent the film from adhering to the wall surface of the processing chamber 9. do. 4 shows a cross section taken along line A-A in FIG. 2, and in FIG. 2 and FIG. A vacuum pump 23 is attached to the discharge end of the vacuum exhaust path 9a.

Furthermore, the space 25a inside the cylinder 25 communicates with the space 25c inside the cylinder and the vacuum exhaust port 25d via the vacuum exhaust port 25b, and the inside of the processing chamber 9 can be evacuated by the vacuum pump 23. For vacuum pumps 23 having the same performance, two vacuum exhaust ports 25b are provided symmetrically on the left and right.
A vacuum exhaust port 25 is arranged for each vacuum exhaust port 25b.
By arranging one each d symmetrically, eight vacuum exhaust ports can be equally spaced circumferentially. In order to accelerate the film formation rate, it is necessary to maintain a constant low pressure by flowing a large amount of gas.
, the vacuum exhaust port 25b, the space 25c, and the vacuum exhaust port 25d are made as large as possible, and two vacuum pumps are used.

The reason why the internal space of the cylindrical body 25 is partitioned into two spaces by the shelf 25e is that without the shelf 25e, the vacuum exhaust ports 25d would be formed at symmetrical positions across the straight line connecting the center of the pump 23. If the exhaust flow is
This is because the fIWj4 processing speed on the substrate differs in the circumferential direction of the substrate surface because the flow is concentrated at the vacuum exhaust port closer to No. 3 and stagnation occurs in the direction perpendicular to the straight line. but,
When the shelf 25e is provided, the gas exhausted from the vacuum exhaust port 25d cannot go directly to the vacuum pump 23, but must take a detour along the shelf surface, so the exhausted gas flows uniformly around the substrate. , the uniformity of thin film processing speed on the substrate surface is greatly improved. The formation of such a shelf or the provision of a shelf effect can be easily achieved especially by using a coaxial double inner m structure.

FIG. 3 shows the structure of a dry thin film processing apparatus according to a modified example of the above embodiment, and FIG. 5 shows a cross section taken along the line B-B in FIG. 3, and FIG. shows. The difference from the one in Fig. 2 is that one vacuum pump 23 is used, and two vacuum exhaust ports 25b are arranged symmetrically across the diameter of the cylinder passing through the center of the vacuum pump 23. Mouth 25b
By arranging two vacuum exhaust ports 25d left and right symmetrically across the straight line connecting the
The four gas inlet ports 24a are formed symmetrically across the extension line of the gas inlet 24a. The experimental results show that although the total gas flow rate is small, good gas flow uniformity similar to that in Fig. 2 is obtained, and in order to obtain gas flow uniformity, at least four vacuum exhaust ports 25d are required. It turned out to be necessary.

In the above embodiment, the direction of the apparatus is shown when performing Fli film processing with the surface to be processed of the substrate 11 facing downward in the vertical direction. The plasma flow and the flow of gas introduced into the path of the plasma flow are not bent vertically downward, and uniform thin film processing is possible as in the above embodiment. This means that the plasma flow is caused by the excitation solenoid 6 (No. 1.2.
The gas that is introduced into the path of the plasma flow is ionized or activated in the state of neutral molecules or atoms by the plasma, and is forced to flow in the direction of the plasma flow. It is from.

Note that the reference numeral 14 in FIGS. 1, 2, 3, and 8 is an auxiliary member that cooperates with the excitation solenoid 6 to form a magnetic field to uniformize the density distribution of plasma reaching the substrate on the substrate. It is a solenoid.

〔Effect of the invention〕

As described above, in the present invention, the path of the plasma flow from the plasma generation chamber to the substrate to be film-formed is surrounded by an axially symmetrical coaxial double cylindrical body, and the inner wall surface of this coaxial double cylindrical body is Four or more gas inlet ports are provided at rotationally symmetrical positions to avoid uneven distribution of the gas flow, and another coaxial double cylindrical tube is arranged coaxially with the substrate of this coaxial double cylindrical tube. An even number of 4 or more vacuum exhaust ports are provided at rotationally symmetrical positions to exhaust gas through the inner wall surface of the body, thereby making the gas flow uniform, resulting in a more uniform gas particle density in the plasma transport path. As a result, it is possible to supply a large amount of gas to the plasma transport path and increase the amount of vacuum evacuation, thereby increasing the thin film processing speed while ensuring uniformity of the processing speed distribution on the substrate. Furthermore, by using an electrostatic chuck without a mechanical sliding surface to hold the wafer and configuring the device so that the surface to be processed of the substrate faces vertically downward or vertically during thin film processing, This enables high-quality thin film processing that prevents particle contamination.

[Brief explanation of the drawing]

FIG. 1 is a vertical cross-sectional view showing the configuration of a dry thin film processing apparatus according to an embodiment of the present invention at the preparation stage for thin film processing, and FIG.
3 is a vertical sectional view showing a modification of the embodiment shown in FIG. 1, and FIG. 4 is a cross-sectional view taken along line A-A in FIG. 2. 5 is a cross-sectional view taken along the line B-B in FIG. 3, and FIG. 6 is a cross-sectional view taken along the line C--
FIG. 7 is a cross-sectional view taken along the line D-D in FIG. 3, and FIGS. 8 and 9 are vertical cross-sectional views showing the configuration of a conventional dry thin film processing apparatus. be.

Claims (1)

[Scope of Claims] 1) A three-dimensional microwave circuit including a microwave oscillator, a microwave waveguide, and a pass-through resonator, in which a magnetic field and an alternating electric field of the microwave mutually interact within the pass-through resonator. The action converts the gas introduced into the pass-through resonator into plasma, and uses this plasma to activate the gas introduced into the processing chamber disposed on the side opposite to the microwave waveguide of the pass-through resonator. A wafer holder that holds the semiconductor wafer in the processing chamber and is movable in the axial direction of the pass-through resonator in dry thin film processing equipment that forms a thin film on the semiconductor wafer in the processing chamber or performs thin film processing such as etching the formed film. Mechanism: A gas inlet is arranged between the pass-through resonator and the semiconductor wafer in the processing chamber so as to be coaxial with the pass-through resonator, and for introducing gas activated by the plasma into the processing chamber. at least four coaxial double cylindrical tubes provided at rotationally symmetrical positions on the inner wall; disposed coaxially with the through-type resonator on the anti-encounter type resonator side of the coaxial double cylindrical tubes in the processing chamber; A vacuum pump is installed between the pass-through resonator and the semiconductor wafer and surrounding the wafer holding mechanism, and is used to introduce gas into the processing chamber and to exhaust the gas from the processing chamber so as to maintain a constant pressure inside the processing chamber. A dry thin film processing apparatus comprising: a coaxial double cylindrical body having an integer multiple of 2 openings, at least 4 of which are provided at rotationally symmetrical positions on an inner wall. 2) The dry thin film processing apparatus according to claim 1,
The wafer holding mechanism applies an electrostatic force between an electrode embedded in the solid dielectric and a conductive or semiconductive thin plate-shaped workpiece in contact with the surface of the solid dielectric to attract the workpiece, It is constructed using an electrostatic chuck for holding, and is characterized by having a pass-through resonator oriented such that the surface to be processed of the thin plate-shaped workpiece that is attracted and held is facing downward in the vertical direction or in the vertical direction. Dry thin film processing equipment.