JPH03257823A - High-frequency power matching method and device of plasma etching device - Google Patents

Abstract

PURPOSE:To enable plasma instability state to be reduced remarkably and treatment quality of plasma to be improved by adjusting a matching part so that a phase value (theta) and an impedance value (Z) which were entered previously matching etching conditions before plasma is generated. CONSTITUTION:A theta value and a Z value which meet various conditions (pressure, power, and flow) are entered previously into a theta-Z setting equipment 33. The theta value and Z value are selected and the Z value is entered into an amplifier 23 through a switching equipment 34, etc., and the theta value is entered into an amplifier 27 through a switching equipment 35, etc. A detection signal Z is entered into the amplifier 23 from a Z capacity detector 40. If there is any deviation between signal from the theta-Z setting equipment 33 and that from the Z capacity detector 40, a motor unit 13 is driven based on the deviation and the capacity of a variable capacitor 12 is changed to enable the deviation to be 0. A detection signal theta is entered from a theta capacity detector 43 into the amplifier 27 and a motor unit 16 is driven until the deviation between both signals reaches 0, thus enabling the capacity of a variable capacitor 15 to be adjusted.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an alignment device in a plasma etching apparatus that performs dry etching, which is one of the manufacturing processes of semiconductor devices.

[Prior Art] The plasma etching apparatus described above etches ions under reduced pressure.
Alternatively, the surface of the substrate to be processed (wafer) is etched using radical atoms or molecules.

First, the outline of the plasma etching apparatus will be explained with reference to FIG.

Flat plate tf connected to high frequency power supply 1 via matching device 8
i (cathode electrode) 2, and a counter electrode (anode as the pole) 3 which is at ground potential and faces the flat plate electrode 2 are installed. The canned electrode 2 and the anode electrode 3 are connected to a vacuum container 4.
The cathode t li 2 is insulated from the vacuum container 4 by an insulating material 5 .

The vacuum vessel 4 is provided with an introduction system 6 for introducing a reactive gas and an exhaust system 7 for keeping the pressure inside the vacuum vessel 4 constant.

An object to be processed, for example a silicon wafer 9, is normally placed on the cathode electrode 2.

A high frequency power, for example 13.56M, is applied between the picture electrodes 2 and 3.
When plasma is generated between both electrodes by applying Hz, a large cathode drop voltage (self bias) occurs.

The reactive gas ions are accelerated by this cathode drop voltage and are perpendicularly incident on the wafer 9, so that etching progresses in the vertical direction.

The above-described high frequency power source 1 is normally manufactured to supply a pure resistance of 50 ohms, and the matching device 8 is connected to the picture electrode 2.
3 and the combined resistance of the matching device 8 is adjusted to be 50Ω.

By the way, the factors that determine the processing state when performing etching processing using the above-mentioned etching apparatus include the pressure inside the vacuum container 4, the flow rate of reaction scum, the type of reaction gas,
Examples include applied power.

Further, these factors determine the etching process state and the matching conditions of the matching device 8. Therefore, if the above-mentioned factors are changed to achieve the required etching process, the matching device 8 must also adjust the phase and impedance.6 A conventional matching device 8 is illustrated in FIG. .

The matching device 8 includes a phase/impedance detector 10 that detects the phase θ and impedance Z, a variable capacitor 12 that configures an impedance adjuster 11, a motor unit 13, a phase adjuster 14, a variable capacitor 15, and a motor unit. 16, a controller 19 that drives and controls the motor unit 13.16 based on the detection results with a plasma generation detector 17, an HF coil 18, a matching section 20 comprising the phase/impedance detector 10, and the plasma generation detector 17; It consists of

In the matching device 8, the picture electrode 2 is connected to the high frequency power source 1.
, 3 to generate plasma.

When plasma is generated, the motor unit 1316 is not driven and the capacity of the variable capacitor 12.15 is not adjusted.When plasma is generated, the plasma generation detector 1
7 detects plasma generation, and the detection result is input to the controller 19. By inputting the detection signal of plasma generation, the controller 19 adjusts the phase difference signal between the current and voltage and the level difference signal between the voltage and current detected by the phase/impedance detector 10 to zero. Drives motor unit 13.16, variable capacitor 12.
Adjust the capacity of 15.

[Problem to be solved by the invention] In the conventional matching device described above, matching operation is started from the moment plasma is generated, and the capacitance of the capacitor is changed by the motor unit 13, 16. Plasma is generated until alignment is completed, which takes several seconds, specifically 7 to 8 seconds, so the wafer is etched under unstable plasma and the product In addition to having an adverse effect on quality, the time required for alignment also results in lost time in the etching process, causing a decrease in the operating rate and productivity of the apparatus. Particularly in single-wafer type plasma etching apparatuses in which wafers are etched one by one, the length of time required for alignment is a serious problem in terms of product quality and productivity.

In view of these circumstances, the present invention aims to shorten the time required for matching as much as possible and improve product quality and productivity.

[Means for Solving the Problems] The present invention determines the phase and impedance of a high frequency power matching section corresponding to etching processing conditions, and adjusts the matching section to the determined phase and impedance before plasma generation. It is also characterized by a matching section having a phase/impedance detector, a plasma generation detector, a phase/impedance adjustment mechanism, and a target phase value and impedance value corresponding to various etching processing conditions can be set and input. a target value output section that drives the phase/impedance adjustment mechanism, a drive section that selects the output value of the target value output section, and outputs a signal from the phase/impedance detector and a signal from the target value output section. and a control section that detects a signal from the plasma generation detector and switches the signal to be input to the drive section.

[Operation] The matching section is adjusted to match the phase and impedance values that were input in advance according to the etching conditions before plasma generation, and after plasma generation, the signals from the phase and impedance detectors are adjusted. Based on this, matching with the load side is performed by the matching section.

[Implementation example] An embodiment of the present invention will be described below with reference to the drawings.

1 and 4 that are the same as those shown in FIG. 4 are given the same reference numerals, and since the alignment section 20 has the same structure as described above, a description thereof will be omitted.

Phase detection signal θ from the phase and impedance detector 10
is amplified by an amplifier 21 and then input to a motor driver 24 of a motor unit 13 via a switching device 22 and an amplifier 23, and the level difference detection signal from the phase/impedance detector 10 is 2 is amplifier 2
After being amplified in step 5, the signal is input to the motor driver 28 of the motor unit 16 via a switching device 26 and an amplifier 27.

Next, 29 is a storage section, which contains condition tables corresponding to various etchings (pressure P, reaction mass flow rate F, electric power V
) 30a, 30b, 30c, ... are inputted, and when a selection signal from a controller 31, which will be described later, is inputted, the condition tables 30a, 30b, 30c are set.
.

P, F belonging to any of the condition tables.

(2) is output to the setting device 32. Furthermore, in addition to the condition tables 30a, 30b, 30c, .
′) can be entered individually.

A θ-2 setting device 33 is connected to the setting device 32, and the θ-2 setting device 33 is connected to the setting device 32.
-Z setting device 33 is connected to switching device 34.35. The switching devices 34 and 35 are also connected to the storage section 29. The switching device 34 is connected to the amplifier 23 via an amplifier 36 and a switching device 37, and the switching device 35 is connected to the amplifier 27 via an amplifier 38 and a switching device 39.

A two-capacity detector 40 that detects the capacity adjusted by the motor unit 13 is connected to the amplifier 23 via an amplifier 41 and a switching device 42, and a θ capacity detector 40 that detects the capacity adjusted by the motor unit 16 is connected to the amplifier 27. Vessel 43
are connected via an amplifier 44 and a switching device 45.

The controller 31 is connected to the switching devices 22, 26, 37.
42.39.45 switching and condition table selection.

The operation will be explained below using the timing diagram shown in FIG.

To explain the cycle operation of the etching equipment, first, mechanical operations such as wafer transfer and etching chamber closing are performed, and then physical etching conditions are satisfied (specifically, pressure setting, reaction residue distribution, etc.). be exposed. In parallel with the satisfaction of this etching condition, the matching area is adjusted to a predetermined value or a value close to it that makes it easy to start a discharge, and as soon as the etching condition is satisfied and the adjustment of the matching area is completed, high frequency power is applied and plasma is generated. or occur.

Next, the matching operation will be explained in detail.

In the controller 31, the operator creates condition tables 30a, 30b, and 30c according to the lot of wafers to be processed.

Select one of... In addition, wafer lot numbers and condition tables 30a, 30b, 30c, . . .
As long as the correspondence between the two is determined in advance, it is sufficient to select the lot number.

At the start of the etching process, the controller 31 turns off the switching device 22.26 and turns off the switching device 37°42.3.
9.45 is set to ON. In this state, a processing table selection signal is output to the storage section 29. The storage unit 29 determines whether or not there is a condition table corresponding to the selection signal, selects the corresponding condition table if there is one, and switches the switch 34
, 35, connect the θ-2 setter 33 and the amplifier 36, connect the θ-2 setter 33 and the amplifier 38, and change the conditions (pressure P,
, force P and flow rate F) are output to the setting device 32. When these conditions are input, the setting device 32 calculates the range of each condition value when performing etching processing, and calculates the result as θ-
Input to Z setting device 33.

The θ-2 setter 33 is pre-inputted with θ values and Z values obtained through experimental experience, etc. that meet these various conditions, and the θ-Z setter 33 selects the θ value and Z value. The Z value is input to the amplifier 23 via a switch 34, an amplifier 36, and a switch 37, and the θ value is input to the amplifier 27 via a switch 35, an amplifier 38, and a switch 39. Further, the detection signal 2 from the Z capacitance detector 40 is inputted to the amplifier 23 via an amplifier 41 and a switching device 42, and the signal from the θ-2 setting device 33 and the signal from the Z capacitance detector 40 are input to the amplifier 23. If there is a deviation between them, the deviation is amplified by the amplifier 23 and input to the motor driver 24.

The motor driver 24 drives the motor unit 13 based on the signal from the amplifier 24 and changes the capacitance of the variable capacitor 12. The capacitance of the variable capacitor 12 is determined by the Z capacitance detector 4
Since the deviation is detected and fed back by 0, the motor driver 24 controls the motor unit 1 when the deviation
Drive 3.

Similarly, a detection signal θ from a θ capacitance detector 43 is input to the amplifier 27 via an amplifier 44 and a switching device 45, and the motor driver 2
8 drives the motor unit 16, and the capacitance of the variable capacitor 15 is adjusted.

The capacitance of the variable capacitor 12.15 is preset as described above, but this adjustment operation is performed in parallel with the etching condition satisfaction period, as described above, and before plasma generation. Thus, at the time when plasma is generated, the total resistance value is adjusted to approximately a predetermined value (50Ω) in the plasma generation state.

Next, when high frequency power is applied between the picture electrodes 2 and 3 and plasma is generated, the plasma detector 17 detects the plasma generation, and the detection signal is input to the controller 31. When the controller 31 receives a plasma detection signal, it turns off the switching devices 37, 42, 39° 45, and switches the switches +
:, 'l' Turn H22 and 26 ON. Therefore, the phase/impedance detector 10 detects the actual Z value at the matching section 20,
detecting the θ value and inputting it to the amplifier 23 and the amplifier 27;
The amplifier 23 and the motor driver 2 so that the Z value and θ value become zero.
4 by the motor unit 13 and also by the amplifier 27
, the capacitances of the variable capacitor 72 and the variable capacitor 15 are adjusted by the motor unit 16 via the motor driver 28, respectively.

Note that the alignment operation after plasma generation is the same as the conventional one.

Next, when the operator instructs or selects from the controller 31 a lot number or etching condition other than the condition tables 30a, 30b, 30c, . The operator determines that the conditions are other than the etching conditions, switches the switch 3435, and connects the storage section 29 and the amplifiers 36 and 38 directly.
' values can be set individually, and the capacitances of the variable capacitors 12 and 15 are adjusted with the θ' and Z' values as targets. The operation of this capacity adjustment is the same as described above, so the explanation will be omitted.

For the individual input of the θ' and Z' values, it is possible to input several settings in advance and select them in accordance with the planned etching conditions, or it is possible to input the settings for each job without changing them. Good too.

By adjusting the variable capacitors 12 and 15 before plasma generation, the combined resistance becomes approximately 50Ω, which is the target value, at the time of plasma generation, and the matching operation of the matching unit 20 in the plasma generation state is as follows. This is carried out smoothly and extremely quickly, and the unstable plasma state at the initial stage of arc generation can be significantly shortened.

[Effects of the Invention] As described above, according to the present invention, the unstable plasma state during etching processing can be significantly shortened, so that the processing quality of wafers is improved and the alignment operation is almost completed before plasma generation. , the alignment operation time can be extremely shortened, processing time can be shortened, and productivity can be improved.

[Brief explanation of drawings]

Fig. 1 is a block diagram of an embodiment of the present invention, Fig. 2 is a timing diagram in the embodiment, Fig. 3 is a basic configuration diagram of a plasma etching device, and Fig. 4 is an explanation of a conventional matching device. It is a diagram. 10 is a phase/impedance detector, 17 is a plasma detector, 20 is a matching section, 26 is a switching device, 29 is a memory, 31 is a controller, 33 is a θ2 setting device, 37.39, 42.45 are switching devices shows. Patent applicant Kokusai Electric Co., Ltd.

Claims (1)

[Claims] 1) A plasma characterized in that the phase and impedance of a high-frequency power matching section corresponding to etching processing conditions are determined in advance, and the matching section is adjusted to the phase and impedance determined before plasma generation. High frequency power matching method for etching equipment. 2) a matching section having a phase/impedance detector, a plasma generation detector, and a phase/impedance adjustment mechanism, and a target value output section into which target phase values and impedance values corresponding to various etching processing conditions are set and input; a drive unit that drives a phase/impedance adjustment mechanism; a drive unit that selects an output value of the target value output unit; and a drive unit that selects an output value of the target value output unit, and transmits a signal from the phase/impedance detector and a signal from the target value output unit from the plasma generation detector; 1. A high-frequency power matching device for a plasma etching apparatus, comprising: a control section configured to detect and switch a signal to input the signal to the drive section.