Etching apparatus, method for measuring self-bias voltage, and method for monitoring etching apparatus

Abstract

The invention provides a means for estimating a self-bias voltage under arbitrary etching conditions via a simple procedure. The present invention provides a method for measuring self-bias voltage of an etching apparatus comprising an electrostatic chuck mechanism 1 and 10 for chucking a sample 2, a mechanism 13 and 14 for supplying cooling gas 12 to a rear surface of the sample 2 and controlling the pressure thereof, and a means for measuring the relative force of electrostatic chuck of the sample based on the rear surface pressure control status of the sample 2 being processed, wherein the relative force of electrostatic chuck of the sample and the electrostatic chuck voltage corresponding to the force of electrostatic chuck are acquired based on the rear surface pressure control of the sample 2 when high-frequency bias power is applied to the sample 2 being processed, and the relative force of electrostatic chuck of the sample and the electrostatic chuck voltage corresponding to the force of electrostatic chuck are acquired based on the rear surface pressure control status of the sample when high-frequency bias power is not applied to the sample being processed, and the self-bias voltage is estimated using the acquired forces of electrostatic chuck and the electrostatic chuck voltages corresponding to the two statuses.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a view illustrating the outline of the arrangement of an etching apparatus to which the present invention is applied;

FIG. 2A is a view illustrating how the pressure of the wafer cooling gas is controlled, showing the time variation of pressure;

FIG. 2B is a view illustrating how the pressure of the wafer cooling gas is controlled, showing the time variation of cooling gas flow rate during control;

FIG. 3 is a view showing the measurements of the integrated value of cooling gas flow rate during a certain period of time excluding the initial dead time as according to FIG. 2B, which is measured while changing the electrostatic chuck voltage;

FIG. 4 is a view illustrating the properties of electrostatic chuck when reaction products are attached to the inner side of the processing chamber by the increase in the number of substrates being etched and the etching atmosphere is changed thereby;

FIG. 5 is an explanatory view showing how the property of electrostatic chuck can be acquired from cooling gas control cycles;

FIG. 6 is an explanatory view showing the case in which the property of the force of electrostatic chuck is controlled via the pressure control valve of the cooling gas;

FIG. 7 is a view illustrating the outline of a dipole-type electrostatic chuck mechanism; and

FIG. 8 is an explanatory view showing how the dipole-type mechanism becomes equivalent to the arrangement of FIG. 1.

Claims

1. A method for measuring self-bias voltage in an etching apparatus comprising an electrostatic chuck mechanism for chucking a sample, a mechanism for filling a cooling gas to a rear surface of the sample subjected to electrostatic chuck and controlling the pressure of the cooling gas, and a means for measuring a relative force of electrostatic chuck of the sample based on a status of control of the rear surface pressure of the sample during processing, the method comprising: acquiring the relative force of electrostatic chuck of the sample and the electrostatic chuck voltage corresponding to the force of electrostatic chuck based on the status of control of the rear surface pressure of the sample when high-frequency bias power is applied to the sample during processing;acquiring the relative force of electrostatic chuck of the sample and the electrostatic chuck voltage corresponding to the force of electrostatic chuck based on the status of control of the rear surface pressure of the sample when high-frequency bias power is not applied to the sample during processing; andestimating the self-bias voltage applied to the sample via the high-frequency bias power using the acquired forces of electrostatic chuck and the electrostatic chuck voltages corresponding to the forces of electrostatic chuck of both statuses.

2. The method for measuring self-bias voltage according to claim 1, comprising estimating the self-bias voltage when high-frequency bias power is applied by computing the difference between electrostatic chuck voltages at a point where the acquired forces of electrostatic chuck are equal for both statuses.

3. The method for measuring self-bias voltage according to claim 1, comprising acquiring the force of electrostatic chuck for chucking the sample by the electrostatic chuck mechanism based on the flow rate of the cooling gas supplied to the rear surface of the sample.

4. The method for measuring self-bias voltage according to claim 1, comprising acquiring the force of electrostatic chuck of the sample by the electrostatic chuck mechanism based on the flow rate of the cooling gas supplied to the rear surface of the sample; andestimating the self-bias voltage when high-frequency bias power is applied by computing the difference between electrostatic chuck voltages at a point where the acquired forces of electrostatic chuck are equal for both statuses.

5. The method for measuring self-bias voltage according to claim 1, comprising acquiring the force of electrostatic chuck for chucking the sample by the electrostatic chuck mechanism based on the pressure of the cooling gas supplied to the rear surface of the sample.

6. The method for measuring self-bias voltage according to claim 1, comprising acquiring the force of electrostatic chuck for chucking the sample by the electrostatic chuck mechanism based on the pressure of the cooling gas supplied to the rear surface of the sample; andestimating the self-bias voltage when high-frequency bias power is applied by computing the difference between electrostatic chuck voltages at a point where the acquired forces of electrostatic chuck are equal for both statuses.

7. A method for monitoring an etching apparatus comprising an electrostatic chuck mechanism for chucking a sample, a mechanism for filling a cooling gas to a rear surface of the sample subjected to electrostatic chuck and controlling the pressure of the cooling gas, and a means for measuring a relative force of electrostatic chuck of the sample based on a status of control of the rear surface pressure of the sample during processing, the method comprising: acquiring the relative force of electrostatic chuck of the sample and the electrostatic chuck voltage corresponding to the force of electrostatic chuck based on the status of control of the rear surface pressure of the sample when high-frequency bias power is applied to the sample during processing;acquiring the relative force of electrostatic chuck of the sample and the electrostatic chuck voltage corresponding to the force of electrostatic chuck based on the status of control of the rear surface pressure of the sample when high-frequency bias power is not applied to the sample during processing;estimating the self-bias voltage applied to the sample via the high-frequency bias power using the acquired forces of electrostatic chuck and the electrostatic chuck voltages corresponding to the forces of electrostatic chuck of both statuses; andacquiring a plurality of estimated self-bias voltages of the sample, and monitoring the status of the etching apparatus based on the transition thereof.

8. The method for monitoring the etching apparatus according to claim 7, comprising estimating the self-bias voltage when high-frequency bias power is applied by computing the difference between electrostatic chuck voltages at a point where the acquired forces of electrostatic chuck are equal for both statuses; andacquiring a plurality of estimated self-bias voltages of the sample, and monitoring the status of the etching apparatus based on the transition thereof.

9. The method for monitoring the etching apparatus according to claim 7, comprising acquiring the force of electrostatic chuck of the sample by the electrostatic chuck mechanism based on the flow rate of the cooling gas supplied to the rear surface of the sample;estimating the self-bias voltage when high-frequency bias power is applied by computing the difference between electrostatic chuck voltages at a point where the acquired forces of electrostatic chuck are equal for both statuses; andacquiring a plurality of estimated self-bias voltages of the sample, and monitoring the status of the etching apparatus based on the transition thereof.

10. The method for monitoring the etching apparatus according to claim 7, comprising acquiring the force of electrostatic chuck for chucking the sample by the electrostatic chuck mechanism based on the pressure of the cooling gas supplied to the rear surface of the sample;estimating the self-bias voltage when high-frequency bias power is applied by computing the difference between electrostatic chuck voltages at a point where the acquired forces of electrostatic chuck are equal for both statuses; andacquiring a plurality of estimated self-bias voltages of the sample, and monitoring the status of the etching apparatus based on the transition thereof.

11. An etching apparatus comprising: an electrostatic chuck mechanism for chucking a sample;a mechanism for filling a cooling gas to a rear surface of the sample subjected to electrostatic chuck and controlling the pressure thereof;a means for acquiring a relative force of electrostatic chuck of the sample and the electrostatic chuck voltage corresponding to the force of electrostatic chuck based on a status of control of the rear surface pressure of the sample during processing; anda means for estimating the self bias voltage applied to the sample via the high-frequency bias power, using the electrostatic chuck voltages corresponding to the same force of electrostatic chuck respectively acquired by applying high-frequency bias power to the sample and acquired by not applying high-frequency bias power thereto.

12. The etching apparatus according to claim 11, comprising: a means for monitoring the status of the etching apparatus based on the transition of self-bias voltages respectively estimated for a plurality of samples.