JPH0828638B2 - Matching box - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a matching box, and more particularly to a matching box that performs impedance matching between a plasma load and a high frequency power supply.

[Conventional technology]

For example, in a plasma etching apparatus, an electrode provided in a processing chamber and subjected to etching processing is connected to a high frequency power source via a matching box, and impedance matching between a plasma load and the high frequency power source is performed in the matching box. (JP-A-57-98678, JP-A-58-7829,
JP-A-59-134832).

[Problems to be solved by the invention]

In such impedance matching, if matching is achieved near the 100% or 0% limit of the meshing ratio of the inductor and the variable capacitor (hereinafter abbreviated as a variable) that constitutes the matching circuit, matching is performed due to changes in process conditions during discharge. It becomes impossible and it is necessary to change the inductance (number of turns) of the inductor (coil) and adjust. However, the lid of the current matching box must be removed, and the copper strip fixed to the tap of the coil with bolts and nuts must be removed and replaced. Therefore, the adjustment work is difficult and takes a long time. ing.

An object of the present invention is to provide a matching box capable of easily adjusting the impedance matching over a wide range in a short time by making it possible to automatically change the inductance of the inductor depending on the meshing state when matching the variable capacitors. To do.

[Means for solving problems]

The above object is to configure a matching circuit with a pair of variable capacitors and an inductor, detect a matching state signal when high frequency power is applied by a detector provided at the end of the matching circuit, and to detect a pair of matching signals according to the detection signal. A potentiometer that detects the meshing ratio of a pair of variable capacitors in a matching box that drives the variable capacitors with respective motors to change the capacity of the pair of variable capacitors and performs impedance matching between the plasma load and the high frequency power supply, The engagement rate detected by the potentiometer is 20
If the ratio is less than 80% or exceeds 80%, the inductance of the inductor is changed via the motor, and the meshing ratio is 20% to 80%.
% Control is provided, and even if the inductance of the inductor becomes the minimum or maximum, if the meshing ratio of the pair of variable capacitors does not fall within 20% to 80%, high frequency will be output via the control device. This is achieved by the configuration that the power supply is stopped.

[Action]

The engagement ratio of the variable capacitor is detected, and the inductance of the inductor is reduced when the detected engagement ratio of the variable capacitor is near 0%, and the inductance of the inductor is detected when the detected engagement ratio of the variable capacitor is near 100%. Change to increase. As a result, the inductance of the inductor can be automatically changed according to the meshing state at the time of matching the variable capacitors without replacing the copper strip of the inductor.

〔Example〕

An embodiment of the present invention will be described below with reference to the drawings. In the drawing, a high frequency power supply device for a semiconductor manufacturing apparatus such as a plasma etching apparatus is shown as a high frequency power supply 14 and a control unit 1.
3, the matching box 4 and the electrode 2 provided inside the processing chamber 1 are used, and the impedance matching between the plasma load and the high frequency power source 14 is performed by the matching box 4. The matching box 4 has a matching circuit composed of a variable capacitor 6, a variable capacitor 7, and an inductor 5. The matching box 4 detects a matching state signal when high frequency power is applied by the detector 3 and outputs a detector signal 15 as a controller 13
The motors 9 and 10 are rotated by the motor rotation signals 18 and 19 sent from the controller 13, and the variable capacitors 6 and 7 are driven to change the capacitance of the variable capacitors to achieve matching.

The ideal meshing ratio of the two varicaps 6 and 7 during impedance matching is 20 to 80%. Outside this range, if the discharge process conditions change, the varicons will become 0% or 100% in the extreme state, making matching impossible. .

It is necessary to change the inductance of the inductor 5 especially when the variable capacitor 6 is near 0% and near 100%. Therefore, the engagement ratio of the variable capacitor 6 is detected by the potentiometer 11, and when the engagement ratio of the variable capacitor 6 becomes less than 20% or exceeds 80% at the time of completion of matching, the inductor 8 is driven by the motor 8 via the control device 12. The inductance of is changed by a certain amount, and in that state, the variable capacitors 6 and 7 are rotated to achieve matching. Further, in that state, when the meshing ratio of the variable capacitor 6 is not within 20% to 80%, the inductance of the inductor 5 is further changed by a certain amount. Hereafter, this operation is performed when the mesh ratio of the variable condenser 6 is 20% to 80%.
Repeat until entering. Repeat this operation for inductor 5
If the meshing ratio of the variable capacitor 6 does not fall within the range of 20% to 80% even if the inductance of the controller becomes minimum or maximum, the controller 12 issues a matching error signal 20 and the error indicator lamp 21 in the controller 13 lights up. Then, the high frequency power from the high frequency power supply 14 is stopped. Intermeshing state of variable condenser 6 and inductor 5
The relationship of the inductance change of is as follows. The control device 12 outputs the motor rotation signal 16 so that the motor 8 rotates in a direction in which the inductance of the inductor 5 decreases when the meshing ratio of the variable capacitor 6 is near 0%, and increases in the vicinity of 100%.

According to this embodiment, a wide range of impedance matching adjustment work can be performed easily and in a short time.

〔The invention's effect〕

According to the present invention, the inductance of the inductor can be automatically adjusted by the meshing state of the variable capacitors at the time of impedance matching, so that there is an effect that a wide range of impedance matching adjustment work can be performed easily and in a short time.

[Brief description of drawings]

The drawing is a block diagram of a matching box showing an embodiment of the present invention. 1 ... Processing room, 2 ... Electrode, 4 ... Matching box, 5 ... Inductor, 6,7 ... Varicon, 8,9,10 ...
Motor, 11 ... Potentiometer, 12 ... Control device, 13
...... Control unit, 14 ...... High frequency power supply

Claims (1)

[Claims] 1. A matching circuit comprising a pair of variable capacitors and an inductor connected to one of the variable capacitors, and a detector provided at an end of the matching circuit detects a matching state signal when high frequency power is applied. A pair of variable capacitors are respectively driven by motors according to the detection signal to change the capacitances of the pair of variable capacitors, and a matching box for impedance matching between the plasma load and the high frequency power source is connected to the inductor. A potentiometer that detects the meshing ratio of a variable capacitor, and the inductance of the inductor is changed via a motor when the meshing ratio detected by the potentiometer is less than 20% or more than 80%. Control unit to control the inductor ratio from 20% to 80%. When the mesh ratio of the pair of variable capacitors does not fall within the range of 20% to 80% even when the impedance becomes minimum or maximum, the supply of the high frequency power is stopped via the control device. Matching box to do.