JPS6240728A - Dry etching device - Google Patents

Abstract

PURPOSE:To clean the inside of a chamber without regenerating dust by chemically etching adhered products on the inner surface of the chamber by etching gas to discharge them. CONSTITUTION:O2 and F radical are generated by a discharge in a discharge tube 21, and its etching gas is supplied through an inlet tube 20 into a chamber 11. The gas thus supplied into the chamber 11 chemically reacts with a reaction product adhered to the inner surface of the chamber 11 to become gas (CO2, CO, H2O, etc.) to be exhausted through an exhaust tube 17 and cleaned. Accordingly, after an RIE of a wafer is performed, the produced adhered to the inner surface of the chamber 11 is chemically etched with gas supplied from the tube 20. Thus, the inner surface of the chamber 11 can be preferably cleaned without regenerating dusts due to sputtering as the conventional one.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a dry etching apparatus, particularly for dry etching of silicon, 5iOz in the manufacturing process of semiconductors 8'11 such as integrated circuits.
It relates to equipment used for etching films such as Aλ and Aλ.

[Technical background of the invention]

BACKGROUND ART In recent years, drying and automation in the manufacturing process of semiconductor devices have rapidly progressed, and accordingly, processing equipment with high precision and high edge seating has been actively developed.

On the other hand, in semiconductor integrated circuits, the miniaturization of elements continues,
Recently, ultra-LSIs with a minimum dimension of 1 to 2 μm have also been manufactured. It is no exaggeration to say that the ultimate yield of such ultra-thin devices is a battle against fine dust on the micrometer scale during the process. For this reason, the processing equipment adopts a structure that prevents contamination from dust as much as possible. In particular, in dry etching apparatuses, reaction products between the etching gas and the material to be etched or the resist adhere throughout the vacuum chamber. If this amount of adhered material increases, it will separate from the chamber wall surface and cause contamination of the material to be etched. Therefore,
A need arises to periodically clean the vacuum chamber.

By the way, as a conventional dry etching apparatus, one having the structure shown in FIG. 2 is known. That is, numeral 1 in the figure is a vacuum chamber having an open bottom and serving as an anode. A cathode 2 is fixed to the opening of the chamber 1 with an insulating plate 3 interposed therebetween. A high frequency power source 5 is connected to the cathode 2 via a matching circuit 4. Note that the chamber 1 is grounded. A water-cooled vibro is arranged on the back surface of the cathode 2. At the right end of the chamber 1,
An exhaust pipe 7 is formed, and a partition valve 8 is interposed in the exhaust pipe 7. A gas introduction pipe 9 is connected to the upper part of the chamber 1 .

A method of performing reactive ion etching (RIE) on a wafer on which a material to be etched, such as a resist pattern, has been formed using the above-mentioned dry etching apparatus will be described. First, a wafer (not shown) is placed on the cathode 2, the partition valve 8 is opened, and the gas in the chamber 1 is exhausted from the exhaust pipe 7. Next, a reactive gas such as CF4 is introduced from the gas introduction pipe, and after maintaining the chamber 1 at a constant pressure of about 1 to 20 pa, the matching circuit 4 is connected to the high frequency power source 5.
High-frequency power is supplied to the cathode 2 through. This results in
A discharge occurs between the cathode 2 and the chamber 1, which also serves as the anode, and C
F3, F ions and F radicals are generated and attracted to the cathode 2, and CF3, F ions and F radicals are generated on the cathode 2.
The surface of the wafer exposed from the resist pattern is etched.

On the other hand, if reaction products adhere to the inner surface of the chamber 1 due to the RIE, cleaning is performed by the following method. First, without placing the wafer on the cathode 2, the gas in the chamber 1 is exhausted from the exhaust pipe 7, and then the gas inlet pipe 9
A gas such as O2 or CF4 +02 is introduced from the chamber 1 to maintain a constant pressure of about 70 to 100 Pa, and then high frequency power is supplied to the cathode 2 from a high frequency power source 5 through a matching circuit 4. As a result, a discharge occurs between the cathode 2 and the chamber 1, which also serves as the anode, and 04 ions and 04 ions are generated.
4 radicals are generated. These ions and radicals react with reaction products attached to the inner surface of the chamber 1 to form gas (C
O2, Go, H2O, etc.) and are exhausted through the exhaust pipe 7 for cleaning.

[Problems with background technology]

However, ions such as oxygen not only react with the reaction products attached to the inner surface of the chamber 1, but also sputter the chamber material or the cathode material, so there is a problem that these sputtered substances become a cause of dust. Ta.

[Purpose of the invention]

SUMMARY OF THE INVENTION The present invention provides a dry etching apparatus which can clean the inside of a chamber without causing dust to reoccur, and which can also control etching shapes and remove damage caused by RIE.

[Summary of the invention]

The present invention includes a vacuum chamber in which an anode and a cathode are disposed, a gas introduction pipe for introducing gas into the chamber, an exhaust means for maintaining the chamber at a constant pressure, and a space between the anode and the cathode. means for supplying high-frequency power; an introduction pipe connected to the chamber for introducing etching gas generated by plasma excitation of a reactive gas; and a reactive gas interposed in the middle of the introduction pipe and flowing through the introduction pipe. The device is characterized in that it is equipped with a plasma generator for exciting the gas. According to the present invention, as described above, it is possible to obtain a dry etching apparatus that can clean the inside of the chamber without causing the regeneration of dust, and can also control the etching shape and remove damage caused by RIE. .

[Embodiments of the invention]

Hereinafter, embodiments of the present invention will be described in detail with reference to FIG.

Reference numeral 11 in the figure is a vacuum chamber having an open bottom and serving as an anode. A cathode 12 is fixed to the opening of the chamber 1 with an insulating plate 13 interposed therebetween.

A high frequency power source 5 is connected to this cathode 12 via a matching circuit 14. Note that the chamber 11 is grounded. A water cooling pipe 1 is provided on the back surface of the cathode 12.
6 is placed. An exhaust pipe 17 is formed at the right end of the chamber 11, and a first
A partition valve 181 is interposed. One gas introduction pipe is connected to the upper part of the chamber 11 .

Further, an etching gas introduction pipe 20 is connected to the upper part of the chamber 11. A discharge tube 21 made of a quartz tube to which a reactive gas is supplied from the outside is interposed in the middle of the introduction tube 20, and a waveguide 22 is fitted into the discharge tube 21.

Then, the discharge tube 21 in a vacuum state is passed through this waveguide 22.
By applying microwaves 23 of, for example, 2.45 GH2, a discharge is generated in the discharge tube 21, the reactive gas therein is excited, and the etching gas is supplied into one of the chambers through the introduction tube 20. Ru. Note that the introduction tube 20 between the discharge tube 21 and the connection part of the chamber 11
A second partition valve 182 is interposed therein.

Next, a method of performing reactive ion etching (RIE) on a material to be etched, such as a wafer on which a resist pattern has been formed, using the above-described dry etching apparatus of the present invention will be described. First, a wafer (not shown) is placed on the cathode 12, the second partition valve 182 is closed, the first partition valve 181 is opened, and the gas in the chamber 11 is exhausted from the exhaust pipe 17. Next, from the gas introduction pipe 19, CF4
1 to 20P inside the chamber 11.
After maintaining a constant pressure state of about a, high frequency 1! i!
! 15 supplies high frequency power to the cathode 12 through a matching circuit 14. As a result, a discharge occurs between the cathode 12 and the chamber 11 that also serves as an anode, generating CF3, F ions and F radicals, which are attracted to the cathode 12 and CF3, F radicals are generated.
Ions and F radicals collide with the wafer on the cathode 12, etching the surface of the wafer exposed from the resist pattern.

On the other hand, if reaction products adhere to the inner surface of the chamber 11 due to the RIE, cleaning is performed by the following method. First, high frequency i! The application of high frequency power from the source 15 to the cathode 12 is stopped, and the second partition valve 182
After opening the exhaust pipe 1 without placing the wafer on the cathode 12.
7, the gas in the chamber 11 and the discharge tube 21 is evacuated to create a vacuum state. Next, add 02 +CF to the introduction pipe 20.
A gas such as No. 4 is supplied to maintain the inside of the discharge tube 21 interposed in the middle of the introduction tube 20 at a constant pressure state. At this time, the second partition valve 182 also serves as a conductance valve for keeping the pressure in the discharge tube 21 constant. Subsequently, a microwave 23 of 2.45 GH2 is supplied to the discharge tube 21 through the waveguide 22. At this time, the discharge tube 21
Electric discharge occurs within the chamber 11, generating O2 and F radicals, and the etching gas is supplied into the chamber 11 through the introduction tube 20.

The etching gas thus supplied into the chamber 11 chemically reacts with reaction products adhering to the inner surface of the chamber 11 to form gases (Co2, Co1H20, etc.), which are exhausted through the exhaust pipe 17 for cleaning.

Therefore, after RIE of the wafer is performed, the adhering products on the inner surface of the chamber 11 are chemically etched by the etching gas supplied from the introduction pipe 20, so that unlike the conventional method, the regeneration of dust due to sputtering is not caused. The inner surface of the chamber 11 can be cleaned well.

In addition to being used for RrE and cleaning, the dry etching apparatus of the present invention can be used in the following ways.

(2) After placing the wafer with the resist pattern formed on the cathode 12, the first and second partition valves 181.1
-82 is opened and the chamber 1 is evacuated through the exhaust pipe 17.
1 and the discharge tube 21 are brought into a vacuum state, and then a reactive gas such as CF4 is introduced into the gas introduction tube 19 and the introduction tube 20, and the inside of the chamber 11 and the discharge tube 21 are filled with C
F4 nautical ions and radicals are generated, and the wafer surface exposed from the resist pattern is simultaneously etched by RIE and etching gas.

(2) After etching the exposed wafer surface by the above-mentioned RIH, the supply of high-frequency power from the high-frequency electric +1i15 is stopped, the second partition valve 182 is opened, and CF4 radicals are generated in the discharge tube 21. Etching gas is introduced into the wafer 11, and the etched portion of the wafer is lightly etched again using the etching gas. With this method, damage formed in the etched portion of the wafer by RIE can be removed by light etching using etching gas.

(2) Before RIE, the second partition valve 182 is opened to generate CF4 radicals in the discharge tube 21, and the etching gas is supplied into the chamber 11 in which the wafer is placed on the cathode 12 to form a resist pattern. Lightly etch the exposed wafer surface. In this case, etching by the etching gas is isodirectional.

Further, the dry etching apparatus of the present invention is not limited to the structure shown in FIG. 1, but may have a structure including two chambers as shown in FIG. 3. That is, 111.112 in the figure
are the first and second vacuum chambers, and these chambers 1
11 and 112 are connected by a connecting pipe 24 in which a third partition valve 183 is interposed. Note that the first chamber 1
The lower part of 11 is open. the first chamber 11
A cathode 12 is fixed to the opening 1 with an insulating plate 13 interposed therebetween. A high frequency power source 5 is connected to this cathode 12 via a matching circuit 14. However, the first chamber 111 is grounded. A water cooling via 16 is arranged on the back surface of the cathode 12. A first exhaust pipe 171 is formed at the right end of the first chamber 11+, and a first partition valve 181 is interposed in the exhaust pipe 171. A gas introduction pipe 19 is connected to the upper part of the chamber 111 . On the other hand, a second exhaust pipe 172 is formed at the left end of the second chamber 112, and a fourth partition valve 184 is interposed in the exhaust pipe 172. Said second chamber 11
An etching gas introduction pipe 20 is connected to the upper part of the etching gas. A discharge tube 21 made of a quartz tube to which a reactive gas is supplied from the outside is interposed in the middle of the introduction tube 20, and a waveguide 22 is fitted into the discharge tube 21.

To perform RIE on a wafer using the dry etching apparatus having the structure shown in FIG.
is closed, the first partition valve 181 is opened, and the gas in the first chamber 111 is exhausted from the first exhaust pipe 17e. Next, a reactive gas such as CF4 is introduced from the gas introduction pipe 19 and the inside of the chamber 111 is maintained at a constant pressure of about 1 to 20 Pa. Then, high frequency power is supplied from the high frequency power source 15 to the cathode 12 through the matching circuit 14. supply

As a result, a discharge occurs between the cathode 12 and the chamber 111 which also serves as an anode, generating CF3, F ions and F radicals, which are attracted to the cathode 12 and are directed to the wafer on the cathode 12. The surface of the wafer exposed from the resist pattern upon impact is etched.

On the other hand, if reaction products adhere to the inner surface of the chamber 111 due to the RTE, cleaning is performed by the following method. First, after stopping the application of high frequency power from the high frequency power source 15 to the cathode 12 and opening the second and third partition valves 182 and 183, the first exhaust pipe 171 is opened without placing the wafer on the cathode 12. The first and second chambers 1
11. Evacuate the gas inside 112 and the discharge tube 21 to create a vacuum state. Next, a gas such as 02+CF4 is supplied to the introduction tube 20, and a discharge tube 21 is inserted between the introduction tube 20.
Maintain a constant pressure inside. Continued, 2.45
A GHz microwave 23 is passed through a waveguide 22 to a discharge tube 2.
Supply to 1. At this time, a discharge occurs within the discharge tube 21 and the
2 and F radicals are generated, and the etching gas is supplied into the first chamber 111 through the introduction pipe 20, the second chamber 112, and the connecting pipe 24. The etching gas thus supplied into the first chamber 111 chemically reacts with the reaction products adhering to the inner surface of the chamber 111 to become a gas (Co2, Co, H20, etc.), and passes through the first exhaust pipe 17. It is evacuated and cleaned.

Furthermore, the third partition valve is closed to open the second chamber 11.
2 is isolated from the first chamber 111, the fourth partition valve 184 is opened to exhaust the inside of the second chamber 112 through the second exhaust pipe 172, and the etching gas is introduced into the second chamber 112 as described above. If supplied, the same chamber 112
can be used as pre-etching or post-etching for the first chamber 111 in which wafer RIE is performed.

In the apparatus shown in FIG. 3, when only RIE and cleaning are performed, it is not necessary to provide an exhaust pipe to the second vacuum chamber.

In the above embodiment, a dry etching apparatus that performs RIE etc. by applying high frequency power between an anode and a cathode has been described, but it can be similarly applied to other dry etching apparatuses such as a magnetron etching apparatus and a high pressure etching apparatus. .

〔Effect of the invention〕

As described in detail above, the present invention provides a dry etching apparatus that can clean the inside of a chamber without regenerating dust, and can also control the etching shape and remove damage caused by RIE. Can be provided.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of a dry etching apparatus according to an embodiment of the present invention, FIG. 2 is a sectional view of a conventional dry etching apparatus, and FIG. 3 is a sectional view of a dry etching apparatus according to another embodiment of the present invention. FIG. 11.111.112...Vacuum chamber, 12...
Cathode, 15... High frequency power supply, 17.171.172.
...Exhaust pipe, 181-184...Partition valve, 19
... Gas introduction tube, 20 ... Introduction tube, 21 ... Discharge tube, 22 ... Waveguide, 23 ... Microwave, 24.
...Connecting pipe.

Claims (2)

[Claims] (1) A vacuum chamber in which an anode and a cathode are arranged, a gas introduction pipe for introducing gas into the chamber, an exhaust means for maintaining the chamber at a constant pressure, and a space between the anode and the cathode. means for supplying high-frequency power; an introduction pipe connected to the chamber for introducing an etching gas generated by plasma excitation of a reactive gas; and a reactive gas disposed in the middle of the introduction pipe and flowing through the introduction pipe. A dry etching apparatus characterized by comprising a plasma generator for exciting gas. (2) The vacuum chamber consists of two chambers communicating through a partition valve, an anode and a cathode are arranged in one chamber, and a first introduction pipe for introducing gas into the chamber is connected, and an exhaust means is provided. and a means for supplying high frequency power between the anode and cathode, and a second gas introduction pipe having a plasma generator interposed therebetween is connected to the other chamber. A dry etching apparatus according to scope 1.