JPH0783013B2 - Plasma processing device - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a plasma processing apparatus, and particularly to a plasma processing suitable for cooling a sample such as a semiconductor element substrate to a low temperature of 0 ° C. or lower for plasma processing. It relates to the device.

[Conventional technology]

As a technique of cooling a sample to a low temperature of 0 ° C. or lower and performing plasma treatment, for example, as described in JP-A-61-240635, a sample stage is cooled by vapor such as liquid nitrogen and then cooled. It is known that a sample is cooled to 0 ° C. or lower through a sample table and the cooled sample is plasma-etched.

[Problems to be solved by the invention]

In the above conventional technique, no consideration is given to the heat insulation of the exposed surface of the processing chamber except the sample mounting surface of the sample table. Therefore, in this case, the processing gas on the exposed surface of the sample table in the processing chamber,
Adsorption of reaction products is unavoidable, which causes the following problems.

(1) When the growth of the adsorbed material on the exposed surface of the sample table in the processing chamber progresses, the phenomenon of peeling off in the form of solid matter occurs, and troubles such as clogging of the exhaust device occur.

(2) Sublimation of the adsorbed material on the exposed surface of the processing chamber of the sample table and discharge of the sublimated material to the outside of the processing chamber are required separately.

(3) If the processing chamber is opened in the state where the adsorbate is present, the adsorbate is sublimated and gas is released to the outside, which is dangerous for the operator.

(4) If the processing chamber is opened in the presence of adsorbed substances, if the adsorbed substances are chlorine-based adsorbents, there is a risk that hydrochloric acid will be generated due to the reaction with moisture in the air, creating a corrosive environment and damaging the equipment. is there.

A main object of the present invention is to provide a plasma processing apparatus capable of preventing troubles such as clogging of an exhaust system.

[Means for solving problems]

The above-mentioned object is provided with a processing chamber and a sample table provided in the processing chamber and having a sample installation surface and a refrigerant passage, and cools a sample mounted on the sample table with a refrigerant to a low temperature of 0 ° C. or lower,
In a plasma processing apparatus that processes the cooled sample using plasma, a heat insulating unit is provided between the exposed surface of the sample stage into the processing chamber and the refrigerant passage and at a portion other than the sample installation surface. It is achieved by providing.

[Action]

Even if the sample table is cooled to a low temperature of 0 ° C. or less, the heat insulating means is provided on the exposed surface of the processing chamber excluding the sample installation surface of the sample table on which the sample is installed and cooled to a low temperature of 0 ° C. or less by the refrigerant. Adsorption of the processing gas and reaction products on the exposed surface of the processing chamber other than the sample installation surface of the sample table is suppressed. On the other hand, the sample installed on the sample installation surface of the sample table is cooled to a predetermined temperature of 0 ° C. or less through the sample table and processed by using plasma.

〔Example〕

 An embodiment of the present invention will be described below with reference to FIG.

In FIG. 1, a sample table 20 is provided in the processing chamber 10.
In other words, the sample stage shaft 21 is, in this case, the upper part of the process stage 10
It is provided so as to project inward. At the top of the sample table shaft 21,
A sample setting table 22 is provided with the sample setting surface as the upper surface. Except for the sample installation surface of the sample table 20, on the exposed surface in the processing chamber,
Insulation means are provided. In this case, a heat insulating material should be provided on the surface of the sample mounting table 22 excluding the sample mounting surface and around the sample table shaft 21.
30 are provided. The heat insulating material 30 is held by the cover 31. The cover 31 is airtightly provided on the bottom wall of the processing chamber 10. A coolant channel 23 is formed on the sample installation table 22 so as to correspond to the sample installation surface. A refrigerant supply path 24 and a refrigerant discharge path 25 are formed in the sample table shaft 21 and the sample installation table 22 so as to communicate with the refrigerant channel 23, respectively. The coolant supply path 24 is connected to a coolant supply source (not shown) for cooling the sample 40 to a predetermined temperature. As the heat insulating material 30, the temperature of the exposed surface of the cover 31 in the processing chamber 10 can be kept at a temperature equal to or higher than the dew point temperature of the processing gas and the reaction product under the pressure in the processing chamber 10, corresponding to the temperature of the sample 40. Things are selected. For example, when the temperature of the sample 40 is about −40 ° C., for example, styrofoam is selected as the heat insulating material, and the temperature of the sample 40 is −150.
When the temperature is about ° C, for example, perlite is selected. In this case, an exhaust nozzle 11 is provided on the bottom wall of the processing chamber 10, and the exhaust nozzle 11 has a decompression exhaust device (not shown).
Are connected via an exhaust pipe (not shown). Also,
The processing chamber 10 includes a processing gas receiving means (not shown), a magnetic field microwave plasma generating means for plasmaizing the processing gas introduced by the means, a non-magnetic field microwave plasma generating means, a parallel plate electrode type plasma generating means, Plasma generation means (not shown) such as magnetron discharge plasma generation means
And have.

In FIG. 1, a sample 40 is loaded into the processing chamber 10 by a known transfer means (not shown), and in this case, one sample 40 is loaded to the sample table.
The sample is installed on 20 sample installation surfaces with the surface to be processed facing upward. On the other hand, the refrigerant is supplied from the refrigerant supply source to the refrigerant flow passage 23 via the refrigerant supply passage 24, and is discharged from the refrigerant discharge passage 25 to the outside of the system after flowing through the refrigerant flow passage 23. As a result, the sample table 20 is cooled. However, the temperature of the exposed surface of the cover 31 in the processing chamber 10 is maintained at the dew point temperature of the processing gas and the reaction product under the pressure in the processing chamber 10 by the heat insulating material 30. Sample 40
Is cooled and held at a predetermined temperature of 0 ° C. or lower via the sample table 20. On the other hand, the processing gas introduced into the processing chamber 10 is turned into plasma by the plasma generating means, and the surface of the sample 40 to be processed is subjected to predetermined processing by the plasma. The processing gas and reaction products during the processing are exhausted from the exhaust nozzle 11 without being adsorbed by the cover 31.

In this embodiment, the adsorption of the processing gas and the reaction product on the cover can be suppressed, so that the following effects can be obtained.

(1) Since the solid-state peeling-off phenomenon from the cover is eliminated, it is possible to prevent the occurrence of troubles such as clogging of the reduced pressure exhaust device.

(2) Special work such as sublimation of the adsorbed substance from the cover and discharge of the sublimated substance to the outside of the processing chamber can be eliminated.

(3) Since the gas is not released to the outside even if the processing chamber is opened, the safety of the operator can be secured.

(4) Even if the processing chamber is opened, a corrosive environment is not created and the risk of equipment damage can be eliminated.

FIG. 2 illustrates another embodiment of the present invention.
The difference from the figure is that the heat insulating means is a vacuum heat insulating means.

In FIG. 2, a space 32 is formed around the surface of the sample table 22 excluding the sample table surface and around the sample table shaft 21 to form a cover.
31 'is provided. The space 32 is a space that is isolated from the inside of the processing chamber 10 by not communicating with it. A decompression exhaust device (not shown) is connected to the cover 31 'so as to communicate with the space 32. An apparatus (not shown) for evacuating the inside of the processing chamber 10 may be shared as the decompressing apparatus.
The cover 31 'may be provided on the sample table 20 via a heat insulating material, or the cover 31' may be directly formed on the sample table 20 by forming the cover 31 'with a material having heat insulation and airtightness. It is necessary to prevent the temperature of the cover 31 'from decreasing due to heat conduction with the sample table 20. In FIG. 2, the same parts and the like as those in FIG. 1 are designated by the same reference numerals and the description thereof will be omitted.

In FIG. 2, the space 32 is decompressed and exhausted by the decompression exhaust device, and the space 32 becomes a vacuum heat insulating layer. Therefore, even if the sample table 20 is cooled, the cooling of the cover 31 'is prevented and the cover 31' is cooled.
Adsorption of process gas and reaction products to the is suppressed.

In this embodiment, the same effect as that of the above-described embodiment can be obtained. In addition, the heat insulating effect can be further improved and the heat insulating work can be further facilitated as compared with the one embodiment.

〔The invention's effect〕

According to the present invention, it is possible to suppress the adsorption of the processing gas and the reaction product on the sample stage cooled to 0 ° C. or less, so that it is possible to prevent the occurrence of troubles such as clogging of the reduced pressure exhaust device.

[Brief description of drawings]

FIG. 1 is a longitudinal sectional view of a main part of a plasma processing apparatus according to an embodiment of the present invention, and FIG. 2 is a longitudinal sectional view of the same portion as FIG. 1 of another embodiment of the present invention. 10 …… Processing room, 20 …… Sample stand, 30 …… Insulation material, 31,31 ′
...... Cover, 32 ...... space

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Tsunehiko Tsubone 794 Azuma Higashitoyo, Shimomatsu City, Yamaguchi Prefecture Inside the Kasado Plant, Hitachi Ltd. (56) Reference JP-A-61-240635 (JP, A) JP 61-40024 (JP, A) JP-A-63-301522 (JP, A) JP-A-63-60529 (JP, A) Actually opened 61-106028 (JP, U)

Claims (3)

[Claims] 1. A processing chamber and a sample stage provided in the processing chamber and having a sample mounting surface and a coolant passage, wherein the sample placed on the sample stage is cooled by a coolant to a low temperature of 0 ° C. or lower,
In a plasma processing apparatus that processes the cooled sample using plasma, a heat insulating unit is provided between the exposed surface of the sample stage into the processing chamber and the refrigerant passage and at a portion other than the sample installation surface. A plasma processing apparatus characterized by being provided. 2. The heat insulating means is composed of a heat insulating material selected from materials capable of holding the temperature of the exposed surface at a temperature equal to or higher than the dew point temperature of the processing gas and the reaction product under the pressure in the processing chamber. The plasma processing apparatus according to claim 1, wherein the plasma processing apparatus is a plasma processing apparatus. 3. The plasma processing apparatus according to claim 1, wherein the heat insulating means is a vacuum heat insulating means.