JPH098113A - Cleaning method and apparatus for electrostatic adsorption electrode - Google Patents

Abstract

PURPOSE: To easily detect the finish of plasma cleaning of an electrostatic attraction electrode with which the wafer to be plasma treated is supported, and to improve the reproducibility of electrostatic attraction. CONSTITUTION: An ohmmeter 24, with which the resistance of an insulating film is measured, is provided in an electrostatic attraction circuit through a plasma and electrostatic attraction electrode, the change in resistance of the insulating film, which is in plasma cleaning, in detected and the plasma cleaning is finished at the point of time when resistance is lowered to the preset value. As a result, the state same as the insulating film before adhesion of a reaction product is obtained, and the reproducibility of electrostatic attraction can be improved.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cleaning method and apparatus for an electrostatic adsorption electrode that supports a plasma-processed wafer by electrostatic adsorption force.

[0002]

2. Description of the Related Art Conventionally, in an etching process using plasma, in order to remove a reaction product adhering to the surface of an insulating film of an electrostatic adsorption electrode, a wafer is not placed on the electrode every certain number of processed wafers. Plasma cleaning has been performed using plasma such as oxygen gas.

[0003]

In the above-mentioned prior art, the plasma cleaning is terminated by the change of the emission intensity or the experience of the operator, and the reaction product is completely removed due to the lack of plasma cleaning. There is a problem in that the insulating film is scraped off due to the absence or conversely the end is delayed, and the life of the electrostatic attraction electrode is shortened.

An object of the present invention is to provide a cleaning method and apparatus for an electrostatic adsorption electrode which can easily detect the end of plasma cleaning and improve the reproducibility of electrostatic adsorption. .

[0005]

In order to achieve the above object, a resistance meter for measuring the resistance of an insulating film is provided in an electrostatic attraction circuit composed of plasma and an insulating film via a switch, and a plasma clear is provided. The change in the resistance of the insulating film during monitoring is monitored. Then, when the resistance drops to a preset value, plasma cleaning is terminated.

As another method for measuring the resistance of the insulating film, there is a method in which an ammeter is provided in an electrostatic attraction circuit composed of plasma, an insulating film and a DC power source.

[0007]

The resistance of the insulating film increases when the amount of the reaction product generated during the etching process attached to the surface of the insulating film of the electrostatic adsorption electrode increases, and decreases when the amount decreases. Therefore, the degree of adhesion of the reaction product on the surface of the insulating film can be detected by monitoring the change in the resistance of the insulating film with a resistance meter or an ammeter. Therefore, by removing the reaction product by plasma cleaning and ending the plasma cleaning at the time when the resistance of the insulating film matches the preset value, the insulating film before the reaction product is attached The same state can be achieved and the reproducibility of electrostatic adsorption can be improved. As a result, the conventional problem that the plasma cleaning is insufficient or the insulating film is scraped to shorten the life of the electrostatic attraction electrode can be solved.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS. In this case, FIG. 1 shows a magnetic field microwave etching apparatus as a plasma processing apparatus. In the plasma etching process of the wafer 1, the process gas 3 introduced into the discharge tube 2 is turned into plasma by the interaction between the electric field of the microwave 4 and the magnetic field of the solenoid coil 5 to form the plasma 6 in the discharge tube 2 and to insulate the plasma. A switch 10 is turned on and a high frequency power is applied from a high frequency power source 11 to a lower electrode 9 which is insulated and provided in a chamber 7 through an object 8. The ion energy in plasma is controlled while controlling the ion energy of the wafer. 1 is made incident. Further, when the etching of the wafer 1 is completed, the etched wafer 1 is operated by the wafer lifting device 12 so that the lower electrode 9 is removed.
From the carrier to a transfer device (not shown), and then transferred to another place by the transfer device.

On the lower electrode 9, as an insulating film 14 is fixed to the electrode 13, for example, an electrostatic adsorption electrode 16 formed by joining a SiC sintered body with a brazing material 15.
Further, a DC power supply 19 is provided on the lower electrode 9 via a low pass filter 17 and a switch 18. When the wafer 1 is attracted to the electrostatic attraction electrode 16 at the start of the etching process, the switch 18 is connected to the terminal 20 while the plasma 6 is generated, and a negative DC voltage is applied to the electrostatic attraction electrode 16. Be done. When the wafer 1 is released after the etching process is completed, the switch 18 is connected to the terminal 21 while the plasma 6 is generated, and the electrostatic attraction electrode 16 is grounded via the resistor 22.

A resistance meter 24 is provided on the lower electrode 9 via a switch 23. When plasma cleaning the electrostatic attraction electrode 16, the switch 18 is turned to the neutral position and the switch 10 is turned off. With the high frequency power supply 11 cut off, the switch 23 is connected to the terminal 25, and a DC voltage is applied to the electrostatic adsorption electrode 16 by the resistance meter 24 while the insulating film 1 is being applied.
The resistance of 4 is sequentially detected.

On the other hand, when the wafer 1 to be etched is cooled, the mass flow controller 26 is opened and He gas 27 is applied to the back surface of the wafer 1 while the wafer 1 is supported on the electrostatic attraction electrode 16 by the method described above. By introducing. The temperature of the lower electrode 9 is controlled by circulating a coolant 29 by a circulator 28.

Next, in the apparatus constructed as described above, as the plasma etching process is repeated, the reaction products during the process adhere to the inside of the chamber 7 and the insulating film 14 of the electrostatic adsorption electrode 16. Therefore, the electrostatic attraction electrode 16
A gas plasma capable of removing reaction products is formed in the discharge tube 2 without disposing the wafer 1 on the upper side, and plasma cleaning is performed. First, the switch 18 is in the neutral position, the switch 10 is turned off to shut off the high frequency power supply 11, oxygen gas is introduced into the discharge tube 2 as the process gas 3, and then the microwave 4 and the magnetic field generated by the solenoid coil 5 are mutually exchanged. Plasma 6 is generated by the action, and plasma cleaning is started. After that, the switch 23 is connected to the terminal 25, a DC voltage is applied to the electrostatic attraction electrode 16 by the resistance meter 24, and the resistance of the insulating film 14 is sequentially detected.
The resistance of the insulating film 14 at this time becomes lower as the plasma cleaning progresses as shown in FIG. 2, and the detected resistance value and the preset setting value are successively compared by a comparator or the like, and both are in agreement. At that time, the microwave 4 and the solenoid coil 5 are turned off, the plasma 6 is extinguished, and the plasma clear
End the training.

By detecting the end of plasma cleaning in this manner, the conventional problem that the plasma cleaning is insufficient or the insulating film 14 is scraped and the life of the electrostatic adsorption electrode 16 is shortened can be solved. Since it can be in the same state as the insulating film before the product adheres, the reproducibility of electrostatic adsorption can be improved.

Next, a second embodiment of the present invention will be described with reference to FIG. 1 is different from FIG. 1 in that instead of the resistance meter 24, an ammeter 30 is provided in an electrostatic adsorption circuit composed of the plasma 6, the insulating film 14, and the DC power supply 19.
During the plasma cleaning, the switch 18 is turned off and the high frequency power source 11 is shut off.
A direct current voltage is applied to the electrostatic attraction electrode 16 by connecting with, and the resistance of the insulating film 14 is detected by the leak current detected by the ammeter 30. Therefore,
The value of the leak current that is sequentially detected is compared with a preset value by a comparator or the like, and when they match each other, the microwave 4 and the solenoid coil 5 are turned off to extinguish the plasma 6 and the plasma clear. By finishing the training, the same effect as that of the above-mentioned embodiment can be obtained.

During the plasma cleaning of these embodiments, a positive voltage is applied to the electrostatic attraction electrode 16 by the DC power supply 19 so that the surface of the insulating film 14 is positively charged. As a result, the ions in the plasma 6 are repelled, so that the insulating film 14 is cleared only by radicals.
It is possible to prevent the insulating film 14 from being scraped by the ions in the plasma during the plasma cleaning.

[0016]

According to the present invention, the end of plasma cleaning can be easily detected, and the reproducibility of electrostatic adsorption can be improved.

[Brief description of drawings]

FIG. 1 is a vertical cross-sectional view showing an etching apparatus which is an example of an apparatus for carrying out the present invention.

FIG. 2 is a diagram showing a relationship between a resistance of an insulating film for electrostatic attraction and a plasma cleaning time by the apparatus shown in FIG.

FIG. 3 is a vertical sectional view showing an etching apparatus which is a second embodiment of the apparatus for carrying out the present invention.

[Explanation of symbols]

6 ... Plasma, 14 ... Insulating film, 16 ... Electrostatic adsorption electrode, 1
9 ... DC power supply, 18, 23 ... Switch, 24 ... Resistance meter,
30 ... Ammeter.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI Technical indication H01L 21/302 N

Claims (3)

[Claims] 1. An electrostatic adsorption electrode for supporting a wafer processed by plasma by an electrostatic adsorption force generated between the wafer and the insulating film, and detecting a change in resistance of the insulating film during plasma cleaning. A cleaning method for an electrostatic adsorption electrode, characterized in that the cleaning is finished at the time when it matches a predetermined set value. 2. An electrostatic attraction electrode for supporting a wafer processed by plasma by an electrostatic attraction force generated between the wafer and the insulating film, wherein a switch is provided in an electrostatic attraction circuit formed by the plasma and the insulating film. An electrostatic chuck electrode is provided with a resistance meter for detecting the resistance of the insulating film during plasma cleaning and comparing the detected resistance with a preset value. Cleaning device. 3. An electrostatic attraction circuit comprising a plasma, an insulating film and a DC power source in an electrostatic attraction electrode for supporting a wafer processed by plasma by an electrostatic attraction force generated between the wafer and the insulating film. And a means for detecting the resistance of the insulating film by a leak current detected by the ammeter and comparing the detected leak current with a predetermined set value. A cleaning device for an electrostatic attraction electrode.