JPS6218030A - Ion beam etching equipment - Google Patents

Abstract

PURPOSE:To improve the commission rate and the productivity of etching equipment by a method wherein an etching section is provided with a cleaning plasma-generating means which will accomplish periodic cleaning between continual etching processes. CONSTITUTION:Plasma generating electrodes 10, 11 are installed in an etching section 5 belonging to a vacuum chamber 1 for the generation of plasma. For cleaning, oxygen gas is introduced into the section 5 through a gas introducing pipe 7. The pressure inside the vacuum chamber 1 is maintained at approximately 10<-3>-10<-1>Torr and electric power is applied from a power source 9 across the electrodes 10, 11 for the generation of oxygen plasma in the etching section 5. Carbon deposited on the inner walls of or on a holder 4, etc., in the etching section 5 is intensively oxidized by the oxygen plasma. The carbon is then converted into CO2 or CO, to be discharged through an exhaust port 8. It is desired that, simultaneously with this cleaning of the etching section 5, plasma be generated by microwave introduced through a waveguide 6 into an ion source 2 for the cleaning of the interior of the ion source 2.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an ion beam etching apparatus that performs dry etching by irradiating the surface of a semiconductor wafer or the like with an accelerated and focused ion beam.

As the density of integrated circuits increases, fine etching on the submicron order is required.

A reactive ion beam etching apparatus using a reactive gas has been developed as an etching apparatus for performing such fine processing. This reactive ion beam etching apparatus performs etching using the physical and chemical effects of the irradiated ion beam, and is capable of fine processing, high aspect ratio, and anisotropic etching. Furthermore, it is possible to control the ion irradiation fJJffi, energy, irradiation direction, etc., making it ideal for etching semiconductor wafers.

[Prior Art] FIG. 4 shows a schematic configuration of an ECR type anti-nonreactive ion beam etching apparatus as a conventional ion beam etching apparatus. The vacuum chamber 1 is comprised of an ion source section 2 equipped with an ion beam generating means (not shown) and an etching section 5 in which a wafer 3 to be etched is placed. The wafer 3 is mounted on the holder 4. A waveguide 6 and a gas introduction pipe 7 are connected to the ion source section 2 . The etching processing section 5 is provided with an exhaust port 8 and is connected to a vacuum pump (not shown). An ion extraction electrode group 12 is provided at the lower part of the ion source section 2 .

After evacuating the inside of the vacuum chamber 1 as shown by arrow A from the gas inlet 8, the gas introduction pipe 7. Etching gas (CF4, C2Fs, etc.) at a predetermined vacuum pressure is introduced from the waveguide 6, and microwaves (>2.45 GHz) are supplied from the waveguide 6 as shown by arrow B to generate plasma. Ions are extracted from the generated plasma. +4 [, group 12 etching ions (C
F3'', CF2, CF, F, etc.) is pulled out and accelerated to a predetermined energy toward the wafer 3 as shown by arrow C, and the wafer 3 is irradiated to etch the surface by physical and chemical action.

[Problems to be Solved by the Invention] As etching becomes finer, contamination of wafers by dust in the vacuum chamber becomes a problem. In particular, in a reactive ion beam etching apparatus, since ion beams with good directionality are irradiated, if dust adheres to the wafer, the ion beam is blocked by the dust, resulting in portions not being etched. The main source of such dust is the inner wall of the etching processing section of the vacuum chamber, and carbon and polymer adhering to the wall surface peel off and float inside the etching processing section. In order to remove such dust, conventionally, the wall surface of the vacuum chamber was manually wiped and cleaned. However, manual cleaning work is troublesome and cannot completely clean every detail.

The present invention has been made in view of the above-mentioned drawbacks of the prior art, and an object of the present invention is to provide an ion beam etching apparatus that is equipped with a cleaning means that allows the interior of a vacuum chamber to be completely cleaned in detail without manual intervention. do.

Means for Solving Problem L] In order to achieve this object, the ion beam etching apparatus according to the present invention provides an etching process in which an ion source section including an ion beam generating means and an object to be processed are placed in a vacuum chamber. The ion beam etching apparatus includes a cleaning plasma generating means in the etching processing section.

[Operation] In this apparatus, a cleaning gas such as oxygen gas is introduced into the vacuum chamber through the gas introduction pipe for etching gas, and in this state, plasma is generated in the etching processing area to remove carbon etc. attached to the inner wall surface. It is chemically bonded with and evacuated from the vacuum exhaust port.

[Embodiment] FIG. 1 is a schematic diagram of an embodiment of an ECR type anti-nonreactive ion beam etching apparatus 1 according to the present invention. In this example, plasma generating electrodes 10 and 11 are provided in the erasing processing section 5 of the vacuum chamber 1 as plasma generating means. Both electrodes 10.11 are connected to a direct current, alternating current, or high frequency power source 9 for plasma generation. The other configurations, functions, and effects regarding ion beam generation and irradiation are the same as those of the reactive ion beam etching apparatus shown in FIG. 4 described above. Note that the same members as in FIG. 4 are given the same numbers.

When performing cleaning work, oxygen gas is introduced from the gas introduction pipe 7 as a cleaning gas. Vacuum chamber 1
Oxygen plasma is generated in the etching processing section 5 by maintaining a vacuum pressure of about 10 -3 to 1 O-ITorr inside and supplying power from the power supply 9 between the electrodes 10 and 11. Carbon (C) adhering to the inner wall surface of the etching processing section 5 or the holder 4 etc. is strongly oxidized by the oxygen plasma and becomes CO2 or CO and is discharged through the exhaust port 8.

At the same time as this cleaning operation, it is desirable to introduce microwaves into the ion source section 2 through the waveguide 6 to generate plasma and clean the inside of the ion source section 2.

One of the plasma generating electrodes 10.11 may be the wall of the etching processing section 5 or the holder 4.

FIG. 2 is a schematic diagram of a second embodiment of the present invention. In this example, a waveguide 13 is connected to the etching processing section 5 as a plasma generating means in place of the plasma generating electrode of the first embodiment. The other configurations are similar to the first embodiment. Microwaves (usually 2.45 GH2) are supplied from the waveguide 13 as shown by the arrow to clean the inside of the etching processing section 5 while avoiding generation of plasma.

FIG. 3 is a schematic diagram of a third embodiment of the present invention. In this example, an etching processing section 5 is used as the plasma generating means.
A thermionic emission filament 14 is provided inside. A DC power source 15 is provided between the filament 14 and the wall of the etching processing section 5 via a switch (not shown) or the like. A DC voltage is applied between the filament 14 and the wall to cause the filament 14 to emit thermoelectrons. These thermoelectrons collide with oxygen gas molecules to generate oxygen plasma and clean the inside. Other configurations and operations are similar to those of the first embodiment.

Although an ECR type reactive ion beam etching apparatus is illustrated in the embodiment, the present invention can also be applied to a Kauffman type or RF type ion beam etching apparatus.

[Effects of the Invention] As explained above, in the present invention, a plasma generating means is provided in the etching processing section where dust adhesion is a problem,
Dust sources such as carbon attached to the inner wall surface etc. can be completely removed by the chemical action of plasma while the interior is kept in a vacuum. Therefore, the cleaning work can be easily and reliably performed, and since there is no need to open the vacuum chamber for cleaning, the cleaning process can be automatically performed periodically between successive etching processes, and the equipment can be operated easily. This will improve productivity by automating the semiconductor device manufacturing process.

[Brief explanation of the drawing]

1 to 3 are schematic diagrams of different embodiments of an ion beam etching apparatus according to the present invention, and FIG. 4 is a schematic diagram of a conventional ion beam etching apparatus. DESCRIPTION OF SYMBOLS 1... Vacuum chamber, 2... Ion source part, 3... Wafer, 4... Holder, 5... Etching processing part, 8...
・Exhaust port, 9...power supply, io, 1i...electrode, 13
... Waveguide, 14... Filament.

Claims (1)

[Scope of Claims] 1. In an ion beam etching apparatus, an ion source section including an ion beam generating means and an etching processing section in which the object to be processed is placed are placed in a vacuum chamber, and a cleaning plasma generating means is provided in the etching processing section. An ion beam etching device characterized by being provided with. 2. Claim 1, wherein the plasma generating means comprises at least one pair of electrodes provided in the etching processing section, and a plasma generating power source that applies a voltage between each pair of electrodes. The ion beam etching apparatus described in Section 1. 3. The ion beam etching apparatus according to claim 1, wherein the plasma generating means includes a waveguide connected to introduce microwaves into the etching processing section. 4. Claim 1, wherein the plasma generating means comprises a thermionic emission filament provided in the etching processing section, and a DC power supply connected between the filament and a wall of the vacuum chamber of the etching processing section. The ion beam etching apparatus described.