JPH11260803A - Method for controlling wafer temperature - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for controlling the temperature of a wafer processed by a plasma processor to an arbitrary distribution with good reproducibility. SOLUTION: An inner refrigerant flow passage 23 and an outer refrigerant flow passage 24, which are separated, are formed in an electrostatic checking electrode 13, on which a wafer 1 in the middle a processing is installed. Refrigerants whose temperatures are adjusted to be different are respectively circulated by circulators 25 and 26, and by having distribution generated in an electrode temperature, wafer temperature distribution is controlled.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for controlling a wafer temperature suitable for controlling the temperature of a wafer processed by plasma or the like to an arbitrary distribution.

[0002]

2. Description of the Related Art The prior art is disclosed in Japanese Patent Application Laid-Open No. Hei 7-2495.
86, after electrostatically adsorbing the wafer on the electrode,
It has been proposed to control the wafer temperature distribution by introducing cooling gases having different pressures to the back surface of the wafer.

[0003]

Considering the application of the prior art to an electrode on which a wafer to be etched is placed, there are the following problems to be solved. Even if the gas pressure on the back surface of the wafer is controlled to be constant, the distribution of the gas pressure on the back surface of the wafer varies depending on the amount of gas leakage between the wafer and the electrodes, and it has been difficult to control the wafer temperature distribution with good reproducibility.

An object of the present invention is to provide a method capable of controlling a wafer temperature to an arbitrary distribution with high reproducibility.

[0005]

In order to achieve the above-mentioned object, a plurality of coolant channels which are separated from each other are provided in an electrode on which a wafer is mounted, and a coolant whose temperature is controlled to a different temperature in each channel. To generate a distribution by controlling the electrode temperature. This is achieved by supporting the wafer to be processed on this electrode by electrostatic attraction. Further, by performing the process while introducing a cooling gas to the back surface of the wafer, the heat transmittance between the wafer and the electrode can be increased, and the reproducibility can be further improved.

The temperature of the wafer to be etched is determined by the electrode temperature, the heat transfer rate between the wafer and the electrode, and the amount of heat input from the plasma to the wafer. It is relatively easy to control the electrode temperature to a constant temperature, but the heat transfer rate between the wafer and the electrode largely depends on the electrostatic attraction force and the back pressure of the cooling gas, and it is difficult to control with good reproducibility. Therefore, it is considered that the reproducibility of the wafer temperature distribution is better when the electrode temperature is controlled than when the wafer temperature distribution is controlled by the back surface pressure as in the related art.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows a configuration of an embodiment of a so-called magnetic field microwave etching apparatus to which the present invention is applied.
This will be described below. The etching of the wafer 1 is performed by using a process gas 4 introduced at a predetermined flow rate into a discharge tube 3 made of a material such as quartz that transmits the microwave 2.
Further, high frequency power is applied by a high frequency power supply 9 to a lower electrode 8 attached to a chamber 7 forming a vacuum processing chamber, thereby controlling the energy of ions incident on the wafer 1.

On the lower electrode 8, a conductor and a material having a low thermal conductivity, in this case, an electrode 1 made of SUS, is used.
0, Al ₂ O ₃ than consisting insulating film 11, and the electrostatic chucking electrode 13 composed of the brazing material 12 for joining them have been fixed. Further, a DC power supply 15 is connected to the lower electrode 8 via a low-pass filter 14 including a coil and a capacitor. When the wafer 1 is sucked at the start of the etching process, a DC voltage is applied to the electrostatic attraction electrode 13 by connecting the switch 16 to the terminal 17 while the plasma 6 is generated, and the wafer 1 is released after the etching process is completed. At this time, the electrostatic attraction electrode 13 is grounded via the resistor 19 by connecting to the terminal 18 while the plasma 6 is generated.

On the other hand, the wafer 1 to be etched is cooled while the wafer 1 is detected by the pressure gauge 20 while the wafer 1 is supported on the electrostatic attraction electrode 13 by the method described above.
The flow rate of the He gas 22 is controlled by the mass flow controller 21 so that the pressure on the back surface is kept constant. The electrostatic adsorption electrode 13 has an inner refrigerant flow path 23 and an outer refrigerant flow path 24 which are isolated from each other. The refrigerant whose temperature is controlled by circulators 25 and 26 is supplied to the inner refrigerant line 27 and the outer refrigerant flow path 24, respectively. The temperature is controlled by circulating through the refrigerant line 28.

Next, the surface shape of the electrostatic attraction electrode 13 will be described with reference to FIG. A plurality of ring-shaped gas grooves 29 and a plurality of radial gas grooves 30 are provided on the surface of the insulating film 11 to reduce the pressure loss generated when the He gas 22 flows between the wafer 1 and the insulating film 11 to reduce the wafer pressure. The pressure on the back side is made uniform.

Next, FIG. 3 shows the results of a study on the controllability of the wafer temperature distribution in the embodiment of the present invention. The etching conditions were the ordinary etching conditions for an Al wiring film: microwave power 1000 W, solenoid coil current 18/18 A, processing pressure 1 Pa, process gas flow rate 200 ccm, Rf power 100 W, electrostatic adsorption voltage −4.
The temperature of the wafer 1 was measured by attaching a thermo tape to the front surface of the wafer 1.

The temperature of the refrigerant circulating in the inner refrigerant line 27 is kept constant at 20 ° C. and the temperature of the refrigerant circulating in the outer refrigerant line 28 while circulating in the electrostatic adsorption electrode 13 is reduced from 20 ° C. to 0 ° C.
It has been confirmed that the temperature distribution of the wafer 1 having a high periphery can be controlled to a high temperature distribution at the center with good reproducibility by lowering the temperature to ° C.

[0013]

According to the present invention, it is possible to provide a method capable of controlling the wafer temperature to an arbitrary distribution with good reproducibility.

[Brief description of the drawings]

FIG. 1 is a diagram showing an overall configuration of an etching apparatus to which an embodiment of the present invention is applied.

FIG. 2 is a diagram showing a surface shape of an electrostatic attraction electrode to which one embodiment of the present invention is applied.

FIG. 3 is a diagram showing controllability of a wafer temperature distribution according to the present invention.

[Explanation of symbols]

13 --- electrostatic adsorption electrode, 23 --- inner refrigerant flow path, 2
4 ---- outside refrigerant flow path, 25, 26 --- circulator, 27 --- inside refrigerant line, 28 --- outside refrigerant line

Claims (2)

[Claims] 1. A method for controlling a wafer temperature in a plasma processing apparatus for processing a wafer electrostatically adsorbed on an electrode by converting a process gas into plasma, wherein a plurality of refrigerant channels isolated from each other are formed in the electrode. And circulating a coolant having a different temperature in each of the flow paths. 2. The method according to claim 1, wherein a cooling gas is introduced into the back surface of the wafer.