JPH08191059A - Plasma treating device - Google Patents

Abstract

PURPOSE: To obtain the better plasma treatment characteristics of a matter to be treated as well as to reduce dusts to fall on the matter to be treated by a method wherein a plasma treating device is formed into a stage structure capable of controlling freely the temperature distribution of the matter to be treated. CONSTITUTION: A stage 7 is divided into a plurality of blocks 8a, 8b... and the blocks are respectively partitioned by partitions 13 consisting of a material of a heat conductivity lower than that of the blocks. All the blocks are cooled by one cooling block 9. It is desirable that the block 9 is also made of a high- heat conductivity metal material, such as an aluminium material. Moreover, the respective blocks are provided with built-in heaters 10a, 10b..., which are separately controlled, and temperatures are separately set in every block by controlling the outputs of these heaters. Electrostatic chucks 11a, 11b... are respectively formed on the surfaces of the blocks and a wafer 6 is made to attract on the surface of the stage 7 by the chucks.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a plasma processing apparatus capable of freely controlling the temperature distribution of an object to be processed.

[0002]

2. Description of the Related Art In recent years, semiconductor devices have been further miniaturized and integrated. In order to realize more precise semiconductor devices, it is necessary to set various conditions that affect the process. Currently, in the semiconductor process, most of the film formation and etching processes use processing gas
This is a plasma process in which a semiconductor wafer is deposited and etched by being introduced into a vacuum chamber and ionized with energy such as DC voltage, μ wave, and high frequency.

The temperature of a semiconductor wafer (hereinafter referred to as a wafer) during the plasma process is one of important parameters for realizing a more precise process, and the wafer temperature distribution during the process can be made uniform. Is required.

In a plasma processing apparatus such as an etching apparatus, a wafer is heated by plasma during processing. Therefore, in order to keep the temperature of the wafer at a desired temperature,
The wafer needs to be cooled. The first conventional technique for cooling a wafer is Japanese Patent Publication No. 56-53853 and Japanese Patent Publication No. 57-4474.
As described in Japanese Patent Publication No. 7, there is a method of electrostatically attracting a wafer to a cooled stage to perform processing. The second prior art is, as described in Japanese Patent Publication No. 27778/1990 and Japanese Patent Laid-Open No. 30128/1990, between the wafer and the stage while the wafer is mechanically held on the stage by a clamp or the like. There is a method of cooling the wafer by introducing a gas for promoting cooling. Furthermore, as a third conventional technique, Japanese Patent Laid-Open No.
As disclosed in JP-A-58-32410 and JP-A-60-115226, there is a method of cooling a wafer by electrostatically adsorbing the wafer and introducing a gas between the wafer and the stage.

In these methods, the temperature of the wafer is
It depends on the heat input from the plasma and the heat transfer rate between the stage and the wafer. The first conventional technique has a problem in that the wafer cannot be cooled sufficiently because the heat transfer rate is not sufficient. In the second and third conventional techniques, the gas pressure between the stage and the wafer is low near the outer circumference of the wafer, so even if the heat input from the plasma is uniform in the plane of the wafer, There is a problem in that a temperature distribution that causes a high temperature is generated. Further, in any case, when the heat input from the plasma is not uniform, a temperature distribution corresponding to that occurs.

Further, as one of the important problems in the semiconductor manufacturing process represented by the plasma processing process, there is a problem of foreign matter (dust) falling on the wafer.
In a plasma process such as CVD or etching, dust grown in plasma, dust generated by peeling from the surface of a processing chamber, or the like falls on a wafer, resulting in deterioration of film quality and reduction of process yield.

Reference (Jpn. J Apl. Phys. 30 (1991) 1887.
It is known that in plasma, dust is negatively charged and floats on the wafer or electrode in the electric field formed by the plasma, as described in Shiratani et al. The behavior of these dusts is affected by gravity, gas flow, electric field, magnetic field, etc., but is also related to the temperature of the wafer that causes thermophoresis.

For details, see the literature (J Apl. Phys. 67 (1990) 64.
90. GM Jellum et al.), For example, a parallel plate type argon RF discharge (0.5 Tor) with an electrode interval of 25 mm.
In r), it is reported that dust having a diameter of 0.5 μm moves from the high temperature side to the low temperature side along the equipotential surface due to the thermophoretic effect due to the temperature gradient of several degrees Celsius / mm.

Here, in a plasma etching apparatus, for example, a wafer exposed to plasma is heated by incident ions, so that the wafer is usually actively cooled in order to obtain desired etching characteristics. And
The temperature around the wafer or electrode is the lowest in the processing chamber. From the viewpoint of the thermophoresis effect, this is a condition under which dust in the chamber is easily collected. Therefore, it is expected that dust will be attracted to the vicinity of the wafer by thermophoresis from the members around the object to be processed exposed to the plasma, the wall surface of the chamber, and the like.

[0010]

SUMMARY OF THE INVENTION It is an object of the present invention to make the temperature distribution of an object to be processed uniform, to obtain better plasma processing characteristics, and to reduce dust falling on the object to be processed.

[0011]

The above object can be achieved by providing a stage structure capable of freely controlling the temperature distribution of an object to be processed.

[0012]

According to the present invention, the stage for heating and cooling the object to be processed has a structure in which the temperature distribution of the object to be processed can be freely controlled.
It is possible to make the temperature of the object to be processed uniform and obtain uniform plasma processing characteristics.

Further, according to the present invention, the object to be processed and its surroundings are made to have a predetermined temperature distribution (for example, a temperature distribution which becomes lower from the object to the periphery) before the plasma is shut off. The dust in the plasma can be guided away from the object to be treated, and the dust falling on the object to be treated can be reduced when the plasma is shut off.

[0014]

The present invention is not limited to the field of semiconductor manufacturing, but it is believed that the most useful ones are semiconductor manufacturing equipment and semiconductor manufacturing processes. As a device
An embodiment will be described by taking a microwave plasma etching apparatus as an example.

FIG. 1 is a sectional view showing an embodiment of the present invention. The microwave plasma etching apparatus includes a processing chamber 1, a process gas introduction system 2, a microwave generator 3, a waveguide 4, a coil 5, a stage 7 for holding a wafer 6, and the like. The stage 7 also serves as an electrode that applies a high frequency to the wafer 6. The details of the stage 7 are as shown in FIG. 2, and the stage 7 is divided into a plurality of blocks 8a, 8b .... Since the wafer 6 has a substantially circular shape, it is desirable to divide these blocks as shown in FIG. The number of blocks depends on how accurately the temperature distribution of the wafer is controlled. These blocks are preferably made of a metal material having a high thermal conductivity such as aluminum. Further, each block is partitioned by a partition 13 made of a material having a lower thermal conductivity than the block, such as a ceramic material. All blocks are cooled by one cooling block 9. The cooling block is also preferably made of a metal material having a high thermal conductivity such as aluminum. Further, each block incorporates heaters 10a, 10b ... Which are controlled separately, and the temperature can be set individually for each block by controlling the output of this heater. Electrostatic chucks 11a, 11b, ... Are formed on the surface of each block to electrostatically attract the wafer. Further, a gas of several Torr for promoting heat conduction is introduced between the wafer and the stage. By using the stage having such a configuration, the temperature distribution of the wafer can be set freely. That is, if it is desired to raise the temperature of the center of the wafer, the output of the heater 10a in FIG. 2 may be increased and the temperature of the block 10a may be raised. Conversely, if the temperature of each block is equal but the temperature of the wafer is not uniform (the heat input to the wafer by the plasma is not uniform), you want to make the temperature of the wafer uniform. The set temperature of the block in contact with the high temperature part should be lowered.

Further, in addition to the temperature detecting means 14 of the block itself shown in FIG. 2, or more preferably, a wafer temperature detecting means 15 is added as shown in FIG. 4, and the detected temperature is used to detect each block. By controlling the amount of heat transfer between the wafers, even if the heat input to the wafers changes, the wafers can always be controlled to have a desired temperature distribution.

Being able to change the temperature distribution of the wafer is effective in reducing the dust that falls on the wafer. FIG. 5 shows a flowchart of an etching process which is an embodiment of the present invention. As mentioned above, during etching,
Dust generated by etching or generated from the wall surface of the chamber is electrically charged and floats near the wafer. The temperature of the wafer is desired to be as uniform as possible in order to make the etching uniform. However, when the etching process is almost completed, the temperature of the wafer is high in the central part and the peripheral part is high without shutting off the plasma. When the temperature distribution is changed to be low, the dust moves to the peripheral portion due to the thermophoretic effect due to the temperature gradient on the wafer. At this time, if the lowest temperature part is provided on the outer side of the wafer (block 8d in the embodiment of FIG. 2), dust is attracted to this part. By removing the dust from the wafer in this manner and then interrupting the plasma, it is possible to reduce the amount of dust falling on the wafer when the plasma is interrupted. When increasing the temperature distribution of the wafer before the plasma is interrupted adversely affects the etching process, a clean plasma that does not easily affect the wafer, such as argon plasma, is used as shown in the flowchart of FIG. By changing the temperature distribution of the wafer after switching to, it is possible to reduce the influence on the etching process.

[0018]

With the plasma processing apparatus according to the present invention, it is possible to freely control the temperature distribution of the object to be processed. In the semiconductor manufacturing process, by making the wafer temperature distribution during the plasma processing uniform Will enable us to manufacture high-performance semiconductors. In addition, the plasma processing method according to the present invention can reduce dust falling on the object to be processed and improve the yield of semiconductor elements.

[Brief description of drawings]

FIG. 1 is a sectional view showing an embodiment of the present invention.

FIG. 2 is a sectional view showing an embodiment of the present invention.

FIG. 3 is a perspective view showing block division on a stage.

FIG. 4 is a sectional view showing a second embodiment of the present invention.

FIG. 5 is a flowchart showing an embodiment according to the present invention.

FIG. 6 is a flowchart showing a second embodiment according to the present invention.

[Explanation of symbols]

1 ... Processing chamber, 2 ... Process gas introduction system, 3 ... Microwave generator, 4 ... Waveguide, 5 ... Coil, 6 ... Wafer,
7 ... Stage, 8 ... Block, 9 ... Cooling block, 10
... Heater, 11 ... Electrostatic chuck, 12 ... Heat transfer promotion gas introduction port, 13 ... Partition, 14 ... Stage temperature detecting means, 15 ... Wafer temperature detecting means, 16 ... Exhaust system, 17
… High frequency power supply.

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Claims (1)

[Claims] 1. A plasma source and a stage for holding or heating an object to be processed in a processing chamber for heating or cooling, dividing the stage into a plurality of blocks, and setting the temperature of each block separately for each block. By doing so, the temperature distribution of the object to be processed can be set.