JP2978991B2 - Chemical dry etching equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a chemical dry etching apparatus for processing a substance in a processing chamber using plasma.

[0002]

2. Description of the Related Art In the field of manufacturing semiconductor devices, particularly in the field of dry etching of semiconductor wafers, a plasma is generated by irradiating microwaves to a reduced-pressure etching material gas, and the length of the plasma generated by the generation of the plasma is increased. 2. Description of the Related Art A chemical dry etching apparatus is known in which a radical (free atom) having a long life is introduced into an etching chamber in which semiconductor wafers are placed and the wafers are etched.

A chemical dry etching apparatus of this type generally includes a quartz tube made of SiO _{2 at} one end connected to a supply source of an etching material gas, and one end connected to a microwave generator for generating microwaves. A hollow waveguide in which a quartz tube is inserted crosswise on the opposite side, an etching chamber connected to the other end of the quartz tube, and in which a semiconductor wafer as a material to be etched is placed, and an etching chamber. A vacuum pump for reducing the pressure in the room.

An etching material gas generated from an etching material gas source is irradiated with microwaves generated from a microwave generator in a quartz tube kept in a vacuum state together with an etching chamber by the operation of a vacuum pump, and plasma is generated. Radicals (free atoms) generated and generated by plasma generation are introduced into an etching chamber, and the semiconductor wafer mounted thereon is etched by the action of radicals.

[0005]

In the above-described conventional chemical dry etching apparatus, CF ₄ gas is generally used as an etching material gas for a semiconductor wafer made of Si from the viewpoint of etching properties such as SiO _2. Have been. However, the plasma and its radicals generated in the quartz tube are transported to the etching chamber where the semiconductor wafer is placed, and the plasma and radicals are generated on and near the peripheral wall of the quartz tube where microwaves are introduced. Is particularly actively performed, unnecessary etching occurs due to generated radicals and the like in the portion of the quartz tube, and the quartz tube is partially damaged when left unattended for a long time.

Therefore, conventionally, in order to avoid such inconvenience, the service life of the quartz tube is extended by periodically rotating the quartz tube. On the other hand, since the quartz tube is made of transparent SiO ₂ as described above, the discharge color when plasma is generated from the etching material gas, that is, the state of plasma generation, can be easily confirmed from the outside. It is practically difficult to replace the quartz tube with another material from the viewpoint that the material is relatively small and microwaves are favorably introduced into the quartz tube.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a chemical dry etching apparatus which has a relatively simple structure and prevents damage to a quartz tube.

[0008]

According to the present invention, there is provided, in accordance with the present invention, a processing chamber and quartz having one end communicating with the processing chamber and the other end communicating with a material gas supply source for supplying a material gas. A waveguide connected to the quartz tube and defining a microwave introduction unit for introducing microwaves into the quartz tube; a protection member made of ceramic is mounted on the microwave introduction unit of the quartz tube; A chemical dry etching apparatus is provided.

In the above apparatus, the quartz tube is provided with an annular convex portion having a constant inner diameter and an inner diameter smaller than the inner diameter, the protective member has a cylindrical shape, and the protective member is formed on the quartz tube by the annular convex portion. It can be configured to be mounted in contact with the.

[0010]

[Operation and Effect] By forming the inner peripheral surface of the microwave introduction portion 2a of the quartz tube 2 into which the microwave is introduced by using the ceramic inner tube 9, the portion of the quartz tube which is most susceptible to etching can be resistant to etching. Since the inner surface is covered with a protective member made of a ceramic material having a significantly high etching property, the portion of the quartz tube 2 into which the microwave is introduced can be effectively protected from local etching. The location where the protection member is provided can be limited to the portion of the quartz tube where microwaves are introduced and in the vicinity thereof, so that the opaque protection member can be attached, as with the conventional device, via the peripheral wall of the quartz tube. The state of generation of plasma inside from the outside can be easily confirmed by the discharge color.

Further, the protective member itself mounted on the quartz tube does not require direct strength to withstand the vacuum pressure in the etching chamber or the quartz tube, so that it is sufficient to prevent local etching of the quartz tube. Since it only has to be formed in a thin thickness,
Even when microwaves are introduced, a decrease in the efficiency of introduction of microwaves due to so-called dielectric loss hardly causes a problem.

Further, the protective member can be easily provided by being inserted into the quartz tube in a state where one end thereof is in contact with the annular convex portion formed on the quartz tube. In addition, the fitting and insertion can be securely performed, and maintenance and inspection of the quartz tube portion that is easily damaged can be facilitated. Also, since the ceramic inner tube only needs to be inserted into the inner surface of the quartz tube, the tube itself does not require vacuum pressure resistance, and has the dimensions necessary to prevent the quartz tube from being etched or the convenience in forming the ceramic tube. In consideration of the above, it can be simply and easily formed into an appropriate size.

[0013]

Next, a chemical dry etching apparatus according to the present invention will be described in detail with reference to the drawings according to an embodiment. FIG. 1 shows a cross section of a main part of a chemical dry etching apparatus according to an embodiment of the present invention.

As shown in FIG. 1, the chemical dry etching apparatus includes an etching material gas source 1 for supplying CF ₄ gas as an etching material gas, and a tube-shaped quartz tube connected at one end to the etching material gas source 1. , A microwave generator 3 for generating a high frequency in a microwave band, for example, 2.45 GHz, and one end connected to the microwave generator 3 and the quartz tube 2 inserted therethrough. And an etching chamber 5 having an inlet 5a connected to the other end of the quartz tube 2 and an exhaust port 5b connected to a vacuum pump (not shown) and having a surface coated with Teflon. ing. A microwave introduction portion 2a through which microwaves are introduced into the quartz tube 2 is defined in a connection region of the waveguide 4 through which the quartz tube 2 is inserted. The etching material gas in the quartz tube 2 is turned into plasma.

A mounting table 7 for mounting a plurality of semiconductor wafers 6 made of Si or the like in the etching chamber 5.
Is provided. With the pressure in the etching chamber 5 reduced to about 30 Pa by the vacuum pump 6 connected via the discharge port 5 b, the CF ₄ gas is directed from the one end side of the quartz tube 2 to the etching chamber from the etching material gas source 1. Next, a microwave of about 2.45 GHz generated from the microwave generator 3 under the condition of 700 W is introduced into the waveguide 4.
When it is introduced into the quartz tube 2 through the microwave introduction part 2a of the quartz tube 2 through the inside, plasma is generated by the action of the microwave. Long-lived radicals (free atoms) are generated with the generation of this plasma. By introducing such radicals into the etching chamber 5 reduced to about 30 Pa through the inlet 5a, The surface of the semiconductor wafer 6 mounted on the wafer mounting table 7 is etched.

Here, according to the chemical dry etching apparatus of the present embodiment, as shown in FIG. 2, the microwave introduction portion is a hollow cylindrical quartz tube inserted into a rectangular waveguide 4 having a hollow cross section. Although consist 2, certain of the quartz tube 2 having an inner diameter D ₁ is cross-section waveguide 4 is inserted, i.e. annular projection of smaller inner diameter than the inner diameter D ₁ of the above in the vicinity of the microwave introducing portion 2a A portion 2b is formed. More specifically, although the etching material gas is supplied in the direction indicated by arrow A in FIG. 1, an annular convex portion 2b is provided on the upstream side of the microwave introduction portion 2a with respect to the supply of the etching material gas. .

On the other hand, a hollow cylindrical ceramic (Al) is provided on the microwave introduction portion 2a of the quartz tube 2 and the inner surface in the vicinity thereof.
A protection member 9 made of ₂ O ₃ ) is inserted and fitted with one end in contact with the annular projection 2b. For example, when a quartz tube having an outer diameter of 38 mm and a thickness of the peripheral wall of 3.8 mm is used, the inner diameter of the annular convex portion is formed to be 32.2 mm, and the outer diameter of the protective member is approximately 34.2 mm. About 1m
m and a length of 60 mm.

[0018] In this embodiment, the outer diameter of the ceramic inner pipe 9 is and schematic identical to the inner diameter D ₁ of the quartz tube 2, the inner diameter is formed in substantially the same dimensions in an annular protrusion 2b However, the dimensions such as the inner diameter may be appropriately changed according to the convenience of the formation. According to the study of the present inventor, the etching rate is quartz (Si
O ₂ ) is about 71 μm / h, whereas ceramic (Al ₂ O ₃ ) is about 0.13 μm / h. Therefore, as described above, the inner peripheral surface portion of the microwave introduction part 2a into which the microwave is introduced is partially protected by the protection member 9.
By using the structure described above, damage due to etching of the quartz tube can be significantly suppressed, and local etching of the quartz tube as caused by the conventional apparatus can be effectively prevented or prevented. This eliminates the need for complicated work such as regular rotation of the quartz tube.

Further, since the ceramic inner tube is inserted into the inner surface of the quartz tube, the ceramic inner tube itself does not require vacuum pressure resistance.
Accordingly, the thickness of the ceramic inner tube is set to a dimension required to prevent etching of the quartz tube, for example, 1 mm to 1.5 mm.
mm, it seems to be sufficient, but specifically,
It may be determined in consideration of the convenience in forming the ceramic tube.

[Brief description of the drawings]

FIG. 1 is a diagram showing an overall configuration of a chemical dry etching apparatus according to an embodiment of the present invention.

FIG. 2 is an enlarged sectional view of a main part showing a microwave introduction part and a protection member mounted on the apparatus of FIG. 1;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Etching material gas supply source 2 Quartz tube 3 Microwave generator 4 Waveguide 5 Etching chamber 6 Vacuum pump 7 Wafer 8 Wafer mounting table 9 Protection member

Claims (2)

(57) [Claims] 1. A processing chamber, a quartz tube having one end connected to the processing chamber and the other end connected to a material gas supply source for supplying a material gas, and a microwave connected to the quartz tube and having a microwave in the quartz tube. A waveguide defining a microwave introduction section to be introduced, wherein a protection member made of ceramic is attached to the microwave introduction section of the quartz tube on an inner surface side of the quartz tube. Dry etching equipment. 2. The quartz tube has a vicinity of the microwave introduction part.
2. The chemical according to claim 1, wherein an annular convex portion is provided on the inner surface side of the tube, the protective member has a cylindrical shape, and the protective member is mounted on the quartz tube in contact with the annular convex portion. Dry etching equipment.