JPH05226290A - Etching system - Google Patents

Abstract

PURPOSE:To uniform the plasma distribution on the surface of a wafer and suppress the production of plasma on the inner wall of a reaction chamber by enlarging the diameter of a microwave introduction window than that of the semiconductor wafer and enlarging the diameter of the reaction chamber than that of the microwave introduction window. CONSTITUTION:In case the density distribution of a semiconductor wafer 7 is uniform within the range of the diameter of a microwave introduction window 12, and the diameter of the wafer 7 is smaller than that of the microwave introduction window 12, ECR plasma provides the surface of the wafer 7 with a highly uniform etching result. Microwaves introduced into a reaction chamber 13 through the microwave introduction window 12, is weak out of the range of the diameter of the window. If the diameter of a reaction chamber 13 is larger than that of the microwave introduction window 12, therefore, the production of plasma is suppressed in proximity to the inner wall of the reaction chamber 13. This uniforms the distribution of plasma on the surface of wafers to offer a uniform etching effect. It also suppresses the production of plasma on the inner wall of a reaction chamber to prevent the harmful influence of reaction products.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a dry etching apparatus using plasma in a semiconductor manufacturing process.

[0002]

2. Description of the Related Art FIG. 2 is a diagram showing a schematic structure of a conventional etching apparatus of this kind shown in, for example, "Introduction to Ultrafine Processing" (Ohm Co., 1989). In the figure, 1
Is a magnetron or the like and is a microwave source for generating microwaves of a frequency of 2.45 GHz, 2 is a waveguide for propagating the microwave generated by the microwave source 1, and 3 is formed in a closed container. A reaction chamber 4, a microwave introduction window made of quartz, which is arranged so as to partition the inside of the reaction chamber 3 from the inside of the waveguide 2, and 5 is a reaction chamber in the same closed container as the reaction chamber 3. It is a processing chamber formed with a chamber diameter larger than 3.

Reference numeral 6 denotes a flat plate-shaped electrode which is disposed below the processing chamber 5 and is connected to a high frequency bias source (not shown), 7 denotes a semiconductor wafer as an object to be processed placed on the electrode 6, and 8 denotes An exhaust port provided in the lower part of the processing chamber 5 is connected to a vacuum pump (not shown). A gas supply port 9 is provided in the upper portion of the processing chamber 5, and is connected to an etching gas supply source (not shown). Reference numeral 10 denotes an electromagnet coil arranged so as to surround the reaction chamber 3 from the outside of the closed container, and is configured to generate a magnetic field in a direction perpendicular to the surface of the semiconductor wafer 7 on the electrode 6.

Next, the operation of the conventional etching apparatus configured as described above will be described. First, the vacuum pump is operated to evacuate the inside of the closed container through the exhaust port 8 to make the reaction chamber 3 and the processing chamber 5 in a vacuum state, and then the gas supply port 9
The etching gas is supplied from the etching gas supply source via the via to maintain the inside of the reaction chamber 3 and the processing chamber 5 at a predetermined pressure. Next, the microwave generation source 1 is operated to generate microwaves, propagated by the waveguide 2 and guided into the reaction chamber 3 through the microwave introduction window 4 to generate plasma.
Then, by operating the electromagnet coil 10 to apply a magnetic field to the plasma in the reaction chamber 3, a strong plasma called ECR plasma is generated, and the plasma is used to etch the semiconductor wafer 7 in the processing chamber 5. Is applied.

[0005]

The conventional etching apparatus is configured as described above, and since the inner diameter of the waveguide 2 for propagating the microwave is defined as Φ100 mm according to the JIS standard, the microwave introduction window. The reason is that the window diameter of 4 is structurally formed to be substantially the same as the inner diameter of the waveguide 2, and the chamber diameter of the reaction chamber 3 for generating ECR plasma can also generate stronger plasma as the chamber diameter is smaller. so,
It is formed to have the same diameter as or slightly larger than the window diameter of the microwave introduction window 4.

On the other hand, the plasma generated in the reaction chamber 3 is the semiconductor wafer 7 placed on the electrode 6 in the processing chamber 5.
Since it spreads a little due to the diffusion phenomenon above, a uniform plasma distribution does not occur on a wafer surface larger than Φ100 mm, such as a 6-inch wafer (Φ150 mm).
The density distribution in the peripheral area is smaller than that in the central area. Therefore, the amount of etching on the semiconductor wafer 7 is large in the central portion and small in the peripheral portion, and the etching uniformity is deteriorated.
Further, since the window diameter of the microwave introduction window 4 is substantially equal to the chamber diameter of the reaction chamber 3, a strong EC is obtained even on the wall surface of the reaction chamber 3.
There is a problem in that the R plasma is generated and the reaction product generated by etching the inner wall surface adversely affects the etching process of the semiconductor wafer 7.

The present invention has been made in order to solve the above-mentioned problems, and makes the distribution of plasma on the wafer surface uniform so that etching can be made uniform, and at the same time, the inner wall surface of the reaction chamber can be improved. It is an object of the present invention to obtain an etching apparatus capable of suppressing the generation of plasma and preventing the adverse effects of reaction products.

[0008]

According to the etching apparatus of the present invention, the microwave introduction window has a window diameter larger than the diameter of the semiconductor wafer, and the reaction chamber has a chamber diameter larger than the microwave introduction window. It was formed.

[0009]

The microwave introduction window of the etching apparatus according to the present invention has a window diameter larger than the diameter of the semiconductor wafer to make the plasma distribution uniform on the surface of the semiconductor wafer. By forming the chamber diameter larger than the window diameter of the wave introduction window, generation of plasma on the inner wall surface of the reaction chamber is suppressed.

[0010]

【Example】

Example 1. Embodiments of the present invention will be described below with reference to the drawings. 1 is a diagram showing a schematic configuration of an etching apparatus according to a first embodiment of the present invention. In the figure, the same parts as those of the conventional device shown in FIG. Reference numeral 11 denotes a waveguide for propagating the microwave generated by the microwave generation source 1, which has a JIS standard inner diameter (Φ100 mm).
To a window diameter of a microwave introduction window described later.

Numeral 12 is a microwave introduction window which is fixed to seal one end of the waveguide 11 at the most expanded position of the waveguide 11 and which is made of quartz similarly to the conventional apparatus. Is formed to be larger than the diameter of the semiconductor wafer 7 on the electrode 6. Reference numeral 13 denotes a reaction chamber formed inside a closed container defined by the microwave introduction window 12 from the inside of the waveguide 11, and has a chamber diameter larger than that of the microwave introduction window 12. 14
Is a processing chamber formed in the same sealed container as the reaction chamber 13 with a chamber diameter substantially the same as that of the reaction chamber 13.

Next, the operation of the etching apparatus according to the first embodiment of the present invention constructed as above will be described. Similar to the conventional apparatus, first, the vacuum pump is operated to evacuate the inside of the closed container via the exhaust port 8 to evacuate the reaction chamber 13 and the processing chamber 14, and then the etching gas is supplied via the gas supply port 9. Supply the etching gas from the supply source,
The reaction chamber 13 and the processing chamber 14 are maintained at a predetermined pressure. Next, the microwave generation source 1 is operated to generate microwaves, propagated by the waveguide 2 and guided into the reaction chamber 13 through the microwave introduction window 12 to generate plasma.

Then, by operating the electromagnet coil 10 to apply a magnetic field to the plasma in the reaction chamber 13, the EC
A strong plasma called R plasma is generated, and the semiconductor wafer 7 in the processing chamber 14 is etched by this plasma. The EC generated in this state
Since the R plasma has a uniform density distribution within the range of the window diameter of the microwave introduction window 12, the R plasma is naturally on the surface of the semiconductor wafer 7 having a diameter smaller than the window diameter of the microwave introduction window 12. However, the density distribution is uniform, and an etching treatment with good uniformity can be obtained.

Further, from the microwave introduction window 12 to the reaction chamber 13
The microwaves introduced into the inside have a uniform intensity distribution within the window diameter, but have a very weak intensity distribution with a slight spread outside the window diameter. Therefore, even in the vicinity of the inner wall surface of the reaction chamber 13 whose chamber diameter is formed larger than the window diameter of the microwave introduction window 12, similarly, the intensity distribution is very weak, so that the generation of plasma is suppressed. Since the inner wall surface is not etched, reaction products are not generated and are not adversely affected.

[0015]

As described above, according to the present invention, the window diameter of the microwave introduction window is formed larger than the diameter of the semiconductor wafer, and the chamber diameter of the reaction chamber is formed larger than the window diameter of the microwave introduction window. Therefore, the etching can be made uniform by making the distribution of plasma on the wafer surface uniform, and by suppressing the generation of plasma on the inner wall surface of the reaction chamber to prevent the adverse effects of reaction products. The device can be obtained.

[Brief description of drawings]

FIG. 1 is a diagram showing a schematic configuration of an etching apparatus according to a first embodiment of the present invention.

FIG. 2 is a diagram showing a schematic configuration of a conventional etching apparatus.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Microwave source 6 Electrode 7 Semiconductor wafer 8 Exhaust port 9 Gas supply port 10 Electromagnetic coil 11 Waveguide 12 Microwave introduction window 13 Reaction chamber 14 Processing chamber

Claims (1)

[Claims] 1. An etching apparatus in which a microwave from a microwave generation source is introduced into a reaction chamber through a microwave introduction window, plasma is generated in the reaction chamber, and a semiconductor wafer is etched by the plasma. The etching apparatus is characterized in that the microwave introduction window has a window diameter larger than that of the semiconductor wafer, and the reaction chamber has a chamber diameter larger than that of the microwave introduction window.