JPH08130210A - Vertical type plasma reactor - Google Patents

Abstract

PURPOSE: To provide a vertical type plasma reactor wherein plasma is uniformly generated by keeping the gap between an outer electrode and a metal cylinder, generation of abnormal discharge is prevented, and the structure of the metal cylinder is improved so as to realize an unifrom flow of plasma gas. CONSTITUTION: The title reactor consists of the following; a cylindrical reaction vessel 1 provided with a gas feeding pipe 13, a gas discharging pipe 15, and temperature control mechanism 3, an outer electrode 2 arranged on the outer periphery of the reaction vessel 1, and a metal cylinder 4 which is coaxially arranged inside the reaction vessel 1 and has many holes on the side wall. The upper end part and the lower end part of the metal cylinder 4 have movability in the axial direction by the effect of apertures having specific patterns.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vertical plasma reactor, and more specifically, by improving the structure of a metal cylindrical body which constitutes the vertical plasma reactor, more stable plasma processing is enabled. The present invention relates to a vertical plasma reactor.

[0002]

2. Description of the Related Art A plasma reactor used for plasma low temperature etching processing, plasma low temperature ashing processing, plasma CVD processing, etc. is a cylindrical reaction equipped with a gas introduction pipe, a gas discharge pipe connected to a vacuum system, and a temperature control mechanism. Mainly composed of containers. The vertical plasma reactor in which the reaction vessels are arranged in the vertical direction is of a type in which a wafer boat is loaded with a plurality of samples and is loaded from the bottom of the reaction vessel.

In the above vertical plasma reactor, a metal cylinder having a large number of holes in its peripheral wall is coaxially arranged inside the reaction vessel, and this metal cylinder is coaxially fed (cylindrical coaxial type). Is used as an internal electrode, and as an etching tunnel in a counter electrode type, and is configured to generate plasma with an external electrode arranged on the outer periphery of the reaction container.

By the way, in the conventional vertical plasma reactor, due to the plasma treatment, a difference occurs in the thermal strain between the reaction container that comes into contact with the outside air and the metal cylinder inside the reaction container, and the metal cylinder distorts. As a result, the gap between the metal cylinder and the external electrode becomes non-uniform, resulting in a change in the impedance of the generating circuit, resulting in a variation in the plasma distribution state, and a uniform plasma for one sample or for multiple samples. The problem that processing cannot be performed arises.

Therefore, the present inventors have previously proposed an improved structure of a vertical plasma reactor for addressing the above problems. In such a plasma reactor, at least one end of a metal cylindrical body is provided with a top plate and / or an upper end side of a reaction container via a donut plate-shaped diaphragm.
Alternatively, it has a structure in which it is locked to the bottom plate on the lower end side (see JP-A-6-168910).

[0006]

However, while the diaphragm in the vertical plasma reactor described above can buffer the axial expansion and contraction of the metal cylindrical body due to temperature change, it itself becomes equivalent to the internal electrode or etch tunnel. It has been found that there is a problem that it functions and causes abnormal discharge. Further, when such a diaphragm is installed, a gap for interposing the diaphragm must be provided between the end of the metal cylinder and the top plate (and / or the bottom plate). As a result, plasma gas flows into the inside from the upper end (and / or the lower end) of the metal cylinder other than the holes on the surface of the metal cylinder, so that radicals are generated in the plurality of samples loaded in the wafer boat. There is a problem that it does not work uniformly.

The present invention has been made in view of the above circumstances, and an object thereof is to buffer the expansion and contraction of the metal cylindrical body in the axial direction due to the temperature change so that the gap between the external electrode and the metal cylindrical body is made uniform. Like this, the vertical structure enables more stable plasma processing due to the improved structure of the metal cylindrical body that prevents the occurrence of abnormal discharge and realizes a uniform flow of plasma gas while holding the same It is to provide a plasma reactor.

[0008]

That is, the gist of the present invention is to provide a cylindrical reaction container equipped with a gas introduction pipe, a gas discharge pipe connected to a vacuum system, and a temperature control mechanism, and A vertical plasma reactor of the opposed electrode type using a coaxial feed type or an etch tunnel, which is mainly composed of an external electrode arranged and a metal cylindrical body coaxially arranged inside the reaction vessel and having a large number of holes in its peripheral wall. The upper end and the lower end of the metal cylinder are respectively formed by a predetermined pattern of openings provided along the circumferential direction of the metal cylinder along the axial direction of the metal cylinder. The frame structure is such that the peripheral walls are not continuous, and
The present invention resides in a vertical plasma reactor characterized by being locked to a top plate on the upper end side and a bottom plate on the lower end side of the reaction vessel.

[0009]

In the present invention, the skeleton structure of the upper and lower ends of the metal cylindrical body buffers the expansion and contraction of the metal cylindrical body in the longitudinal direction due to temperature changes, so that the gap between the metal cylindrical body and the external electrode is reduced. Always keep uniform. Further, the frame structure forming a part of the peripheral wall of the metal cylindrical body, since the distance from the external electrode is the same as other parts of the peripheral wall, there is no abnormal discharge between the external electrode, and, The structure in which the upper end and the lower end of the metal cylinder are directly locked to the top plate and the bottom plate prevents peculiar drift of plasma gas at the upper and lower ends of the metal cylinder, and It enables a uniform inflow of plasma gas.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the accompanying drawings. 1 is a partially cutaway side view showing an embodiment of the vertical plasma reactor of the present invention, FIG. 2 is a cutaway side view showing the internal structure of the cylindrical reaction vessel of the vertical plasma reactor in FIG. 1, and FIG. It is a perspective view showing an example of a metallic cylinder. Hereinafter, in this embodiment, the vertical plasma reactor will be simply referred to as “reactor”.

The reactor of the present invention, as shown in FIG.
A cylindrical reaction vessel (1) equipped with a gas introduction tube (13), a gas discharge tube (15) connected to a vacuum system, and a temperature control mechanism (3), and an external electrode arranged around the outer periphery of the reaction vessel. (2) and the reaction container (1) are mainly composed of a metal cylindrical body (4) coaxially arranged at a predetermined interval with the reaction container (1) and having a large number of holes in its peripheral wall.

The reactor of the present invention may be either a coaxial feed type or a counter electrode type using an etch tunnel. The coaxial feed type reactor is a reactor in which the metal cylindrical body (4) is grounded and used as an internal electrode, while the counter electrode type reactor does not ground the metal cylindrical body (4). This is a reactor used as an etch tunnel.

The cylindrical reaction vessel (1) is usually made of quartz glass and is placed on a pedestal with its axis oriented vertically. Such a gantry is constructed, for example, by supporting the upper base (10) by the columns (9) and (9) provided upright on the lower base (12). As shown in FIG. 2, the reaction vessel (1)
In order to introduce the plasma gas into the reaction container, a gas introduction pipe (13) provided with a large number of gas ejection holes (not shown) along the longitudinal direction is inserted from above. Further, from above the reaction vessel (1), a gas discharge pipe (15) having a large number of gas suction holes (not shown) provided along the longitudinal direction is inserted, and by driving a vacuum system,
The reaction exhaust gas is exhausted to the outside of the system through the suction holes.

The temperature control mechanism (3) comprises, for example, a heat source (30) such as a far infrared heater and a reflector (32) for utilizing radiant heat in the reaction vessel (1). Such a temperature control mechanism (3) is usually arranged at 4 to 6 positions surrounding the reaction vessel (1). As a temperature control mechanism, a heat source such as a ceramic heater that is not affected by plasma is arranged on the inner peripheral side of the metal cylindrical body (4) to heat the sample inside from a closer distance. You can also do it. Further, each of the above heaters may have a structure in which it is divided into upper and lower parts.

The external electrode (2) is usually the reaction vessel (1).
Is closely attached to the outer peripheral surface of the device and is connected to a high frequency power source (not shown) via a matching device for impedance adjustment. Further, the metal cylindrical body (4) is usually made of a surface-treated aluminum alloy or the like, and has a diameter such that a wafer boat (16) for loading a sample can be inserted therethrough. The holes provided in the peripheral wall of the metal cylindrical body (4) are, for example, circular small holes having a diameter of 0.5 to 10 mm, and are evenly distributed at intervals of 0.5 to 20 mm. The detailed structure of the metal cylinder (4) will be described later.

By the way, the reaction vessel (1) is mounted on the upper base (10) through the bottom plate (7) at the lower end, as shown in FIG. 2, but at the center of the bottom plate (7). A circular opening having a diameter slightly smaller than that of the metal cylindrical body (4) and having a diameter such that a wafer boat can be inserted therein is provided coaxially with the reaction container (1), while the upper base (10) is provided with the circular opening. Is provided with a circular opening coaxial with the opening and having a slightly larger diameter.

The above-mentioned circular opening of the bottom plate (7) has a reaction vessel lower lid (10) having a convex vertical cross section.
It is hermetically sealed by 2). That is, the upper step of the reaction vessel lower lid (102) is formed so as to fit into the circular opening of the upper base (10), and the upper end surface of the sealing member abuts the lower surface of the bottom plate (7). (Not shown) is attached.

On the other hand, a top plate (5) is arranged at the upper end of the reaction vessel (1), and a central portion of the top plate (5) radiates heat after processing, so that a stepped circular shape is formed. The opening has been opened. A reaction container upper lid (52) having a vertical vertical section is fitted into the circular opening,
A circular opening is hermetically sealed by a seal member (not shown) attached to the stepped portion of the upper lid.

The upper lid (52) of the reaction vessel is an air cylinder (14) supported on the top plate (5) side.
It is configured so that it can be moved up and down by and is pressed against the top plate (5) during operation. As shown in FIG. 1, the top plate (5) has a seal flange (6) between the top plate and the bottom plate (7).
A support rod (8) which is laid across both ends of (6),
Supported by (8).

Sample (wafer) to be plasma-processed (1
7), (17) ... Are mounted on a wafer boat (16) partially shown in FIG. 2 and loaded into the metal cylindrical body (4) through the circular opening of the bottom plate (7). It
The wafer boat (16) is usually constructed by vertically arranging quartz columns provided with a plurality of notches so as to surround the outer periphery of the sample, and a large number of samples to be loaded are vertically moved by the notches. Hold a predetermined gap.

As shown in FIG. 1, the wafer boat (16) is mounted on a stage (110) of a moving mechanism (11) arranged between a lower base (12) and an upper base (10) which form a pedestal. Is mounted via the above-mentioned reaction container lower lid (102). The moving mechanism (11) includes a linear guide (not shown) and a driving means (not shown) such as a servo motor or a cylinder device, and as shown by a virtual line in FIG. The horizontally mounted stage (110) can be intermittently moved upward or downward with the loading and unloading of the sample.

The greatest feature of the present invention is that the metal cylinder (4) has a specific structure. In the reactor of the present invention, as shown in FIGS. 1 and 2, the metal cylinder (4) is used. )
The upper end portion and the lower end portion of each have a frame structure such that the peripheral wall is not continuous along the axial direction of the metal cylindrical body by the openings of the predetermined pattern provided along the circumferential direction of the metal cylindrical body. Then, the reaction container (1) is locked to the top plate (5) on the upper end side and the bottom plate (7) on the lower end side.

As shown in FIG. 3, the metal cylindrical body (4) has a cylindrical body (41) having the above-mentioned small holes in its peripheral wall, and buffer members (42) arranged at both ends of the cylindrical body. ), (4
2) and mainly. Cushioning member (42),
(42) is formed in a short-axis cylindrical shape with the same diameter and the same material as the cylindrical body (41), and its peripheral wall has a large number of axial lines arranged along the circumferential direction, for example. Slits are provided so as to form a predetermined pattern.

Specifically, the above-mentioned slits are usually about 3 to 10 on the peripheral walls of the cushioning members (42) and (42).
The slits are formed to have a width of mm and a length of about 50 to 100 mm along the circumferential direction, and the interval between the slits adjacent to each other in the circumferential direction is about 15 to 40 mm. The rows of slits continuous in the circumferential direction of the cushioning members (42) and (42) are about 2 to 5 rows (three rows in the drawing) at an array pitch of about 8 to 20 mm in the axial direction of the cushioning members. Further, the slits of the respective columns that are adjacent to each other in the axial direction are arranged at positions where they do not overlap each other, that is, at positions where the phases differ by 180 degrees, for example.

In other words, at the upper end and the lower end of the metallic cylindrical body (4), in the cushioning members (42) and (42), the peripheral wall portion excluding the slit is shaped like a substantially parallelogram due to the opening of the slit. The metal cylinder body (4) is made to have axial flexibility.

Further, a flange (43) extending outward from the cylindrical body is attached to the open end of the one cushioning member (42) which is the upper end of the metallic cylinder (4). As shown in FIG. 2, the upper end of the metal cylindrical body (4) is fixed to the lower surface of the top plate (5) by bolts through a plurality of holes formed in the flange (43). Further, FIG.
As shown in FIG. 5, a flange (44) extending inward of the cylinder is attached to the open end of the other cushioning member (42) which is the lower end of the metal cylinder (4). The lower end of the metal cylindrical body (4) is bolted around the circular opening on the upper surface of the bottom plate (7) as shown in FIG. 2 through a plurality of holes opened in the flange (44). Fixed by.

Further, in the present invention, the upper end and the lower end of the metal cylindrical body (4) are extended in advance in the axial direction and locked to the top plate (5) and the bottom plate (7). Is preferred. Specifically, when the metal cylinder (4) is fixed to the top plate (5) and the bottom plate (7) based on the linear expansion coefficient at the temperature when the metal cylinder is used, The respective cushioning members (42) and (42) are vertically stretched and fixed by a length corresponding to the expansion amount. This makes it possible to minimize the stress in the metal cylinder (4) when the metal cylinder (4) is heated.

The metal cylinder (4) shown in FIG.
Usually, a cylindrical body (41) and cushioning members (42), (42)
Is manufactured by stamping a base material, and these and the annular flanges (43) and (44) are welded and assembled to each other. When the flange (44) is formed so as to project inward of the metal cylindrical body (4) as described above, the metal cylindrical body is attached to the bottom plate (7) in the assembly of the reactor. Easy to fix to.

The treatment conditions by the reactor of the present invention are the same as those of the conventional one, and as the plasma gas, oxygen, hydrogen, argon, water, etc. are used in accordance with the treatment purpose, for example, in the case of ashing treatment. In the case of etching treatment, fluorine, oxygen, chlorine or the like is used. And
Depending on the type of these plasma gases and the set electric field strength, the inside of the cylindrical reaction vessel (1) has an appropriate degree of vacuum.

When such a plasma treatment is carried out, the inside of the cylindrical reaction vessel (1) is heated by the attached temperature control mechanism (3) and the generation of plasma, so that inside the reaction vessel. The arranged metal cylinder (4) is heated and expanded. At that time, a temperature difference usually occurs between the cylindrical reaction vessel (1) and the metal cylindrical body (4) that are in contact with the atmosphere, and a difference in linear expansion coefficient also occurs.

However, in the reactor of the present invention,
The upper end and the lower end of the metal cylinder (4) have a specific skeleton structure, and the skeleton structure buffers the expansion and contraction of the metal cylinder (4) in the longitudinal direction (axial direction). Specifically, when the temperature of the metal cylinder (4) becomes higher than that of the reaction vessel (1), the expansion of the metal cylinder (4) in the longitudinal direction due to the heat causes the buffer members (42), ( Since it is buffered by the bending (contraction) in 42), the outer surface of the metal cylindrical body (4) is not distorted even during the progress of the plasma treatment. Moreover, the upper and lower ends of the metal cylindrical body (4) are
Since it is securely fixed to the top plate (5) and the bottom plate (7) via 2) and (43), the axial center of the metal cylindrical body (4) and the reaction vessel (1) may be displaced. There is no. Therefore, the gap between the metal cylinder (4) and the reaction vessel (1), that is, the external electrode (2) is uniformly maintained.

Particularly, in the reactor of the present invention, when the upper end and the lower end of the metal cylindrical body (4) are extended in advance in the axial direction and locked to the top plate (5) and the bottom plate (7), The stress in the metal cylinder (4) when heated can be minimized, and the distortion of the metal cylinder in the diametrical direction can be further prevented.

As a result, in the reactor of the present invention, the impedance in the plasma generating circuit does not change, so that the distribution of plasma generated between the external electrode (2) and the metal cylindrical body (4). The state can always be kept stable, and the loaded samples (17), (1
7) It is possible to perform uniform plasma treatment on each of the samples or between the samples.

Further, the above frame structure has a cylindrical body (41).
Since it is constituted by the respective buffer members (42), (42) continuous with each other, that is, it is constituted by the peripheral wall of the upper and lower ends of the metal cylindrical body (4), and the distance from the external electrode is different from that of the peripheral wall. Since it is the same as the part of No. 3, there is no abnormal discharge between the external electrode (2). Moreover, the above-described structure in which the upper end and the lower end of the metal cylinder (4) are directly locked to the top plate (5) and the bottom plate (7) without providing a gap has the above-mentioned structure. In this case, it is possible to prevent a peculiar non-uniform flow of the plasma gas in the above, and to allow the plasma gas to uniformly flow into the metal cylinder.

In other words, in the reactor of the present invention, since the upper and lower ends of the metal cylindrical body (4) are not opened, the generated plasma gas causes the cylindrical body (4) constituting the metal cylindrical body (4) 41) small hole and cushioning member (42),
It passes through the slit of (42). Therefore, in the reactor of the present invention, radicals can be made to uniformly act on the plurality of samples (17), (17), ... Loaded in the wafer boat (16), and more stable plasma processing can be performed. Is.

By the way, the support rod (8) provided between the top plate (5) and the bottom plate (7) and the seal flanges (6), (6) fixed at both ends thereof are It is provided as a preferred embodiment of the reactor of the present invention. That is, as shown in FIG. 2, in the reactor of the present invention, a support rod (8) is installed outside the reaction vessel (1) and between the bottom plate (7) and the top plate (5). The end faces of the bottom plate (7) and the top plate (5) on the side of the reaction vessel (1) at both ends of the support rod (8) have seal flanges (6) surrounding the ends of the reaction vessel. ) Is disposed, and a seal member is interposed between the reaction container (1) and the seal flange (6).

The support rods (8) are erected at four locations on the outer peripheral side of the reaction vessel (1), for example. These support rods (8) are provided to bear the load of the top plate (5) including the reaction vessel upper lid (52),
As a result, the reaction container (1) can be formed thinner to reduce the equipment cost.

Moreover, when the support rod (8) is installed between the top plate (5) and the bottom plate (7), the inside of the reaction vessel (1) is evacuated, and the top plate (5) and the bottom plate (5) are bottomed. It is possible to support the axial load of the reaction vessel (1) generated when the plate (7) is sucked. That is, the distance between the top plate (5) and the bottom plate (7) can always be kept constant,
It is possible to prevent rupture of the reaction container (1) in an unexpected situation such as excessive or sudden depressurization of the reaction container (1), abnormality of the reaction container (1) itself, etc., and to improve safety.

Further, the seal flange (6) seals both ends of the reaction vessel (1), and therefore the bottom plate (7) is used.
And on the end surface of the top plate (5) on the side of the reaction container (1), and are arranged coaxially with the reaction container. The inner peripheral surface of each seal flange (6) is formed as a tapered surface whose diameter is increased toward the flanges facing each other. A seal member is interposed in each space formed by the tapered surface and the outer peripheral surface of the reaction vessel (1), and the seal member has the tapered surface and the reaction vessel (1). )
Can be closely attached to the outer peripheral surface of.

According to the above sealing mechanism, since the sealing member is located on the outer peripheral side of the reaction vessel (1), generation of particles from the sealing member due to exposure to plasma gas is prevented. . In addition, the sealing member is prevented from being deformed, fused and deteriorated due to the high temperature treatment, and the airtightness in the reaction vessel (1) can be maintained for a long period of time.

In the present invention, the frame structure provided at the upper end and the lower end of the metal cylindrical body (4) is
As long as flexibility can be exhibited in the axial direction, the slits can be formed by appropriately arranging openings of various shapes such as a rhombic shape and an elliptic shape, instead of the slits.
Further, the hole provided in the peripheral wall (cylindrical body (41)) of the metal cylindrical body (4) may be a slit formed parallel to the axis of the metal cylindrical body.

[0042]

As described above, according to the vertical plasma reactor of the present invention, the expansion and contraction of the metal cylinder in the axial direction due to the temperature change is buffered so that the gap between the external electrode and the metal cylinder is reduced. Plasma can be generated uniformly by holding it uniformly, abnormal discharge can be prevented, and a uniform flow of plasma gas can be realized. Is possible.

[Brief description of drawings]

FIG. 1 is a partially cutaway side view showing an embodiment of a vertical plasma reactor of the present invention.

FIG. 2 is a cutaway side view showing an internal structure of a cylindrical reaction container of the vertical plasma reactor shown in FIG.

FIG. 3 is a perspective view showing an example of a metal cylindrical body.

[Explanation of symbols]

 1: Cylindrical reaction vessel 2: External electrode 3: Temperature control mechanism 4: Metal cylinder 41: Cylindrical body 42: Buffer member 43: Flange 44: Flange 5: Top plate 7: Bottom plate 8: Support rod 13: Gas Introducing pipe 15: Gas exhaust pipe 16: Wafer boat 17: Sample (wafer)

Claims (2)

[Claims] 1. A cylindrical reaction container provided with a gas introduction pipe, a gas discharge pipe connected to a vacuum system, and a temperature control mechanism, an external electrode arranged around the outer periphery of the reaction container, and the inside of the reaction container. What is claimed is: 1. A vertical plasma reactor of coaxial feed type or counter electrode type using an etch tunnel, which is mainly composed of a metal cylindrical body arranged coaxially and having a large number of holes in its peripheral wall, wherein the upper end portion of the metal cylindrical body. And the lower end portion has a frame structure in which the peripheral wall is not continuous along the axial direction of the metal cylinder by the opening of the predetermined pattern provided along the circumferential direction of the metal cylinder, and A vertical plasma reactor characterized by being locked to a top plate on the upper end side and a bottom plate on the lower end side of the reaction vessel. 2. The vertical plasma reactor according to claim 1, wherein an upper end portion and a lower end portion of the metal cylindrical body are extended in the axial direction in advance and locked to the top plate and the bottom plate.