JP2884056B2 - High frequency power supply for generating discharge plasma and semiconductor manufacturing apparatus - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a high-frequency power supply apparatus for generating discharge plasma and a semiconductor manufacturing apparatus, and more particularly, to applying high-frequency power output from a high-frequency power generation source including an oscillation circuit to a discharge plasma generator serving as a load. The present invention relates to a semiconductor manufacturing apparatus including a high-frequency power supply device for generating discharge plasma, which is configured to generate discharge plasma by causing the discharge plasma to be used for etching, thin film formation, and the like. is there.

[0002]

2. Description of the Related Art FIG. 3 is a block diagram of a conventionally known high-frequency power supply for generating discharge plasma. In FIG. 3, reference numeral 1 denotes an oscillating circuit, the oscillating frequency of which is a frequency assigned to industrial use or the like. fixed to fo. Reference numeral 2 denotes a power amplifier. The power amplifier 2 detects a deviation between the set power set by the power setting unit 3 and the high-frequency power fed back from the power directional coupler 4, and calculates a power amplification factor corresponding to the deviation. And amplifies the oscillation frequency based on a control signal from the power control circuit 5 to output high-frequency power.
The power amplifier 2 and the oscillating circuit 1 constitute a high-frequency power generation source.

Reference numeral 6 denotes a discharge plasma generator serving as a load, and 7 denotes a frequency of the high-frequency power output from the high-frequency power generation source and applied to the discharge plasma generator 6 through the transmission line 8. An automatic matching device that matches the resonance frequency of the load impedance, a phase difference / impedance detection circuit 9 for detecting a phase difference の and an impedance Z between a voltage and a current of high-frequency power, and an impedance configured by a capacitance C and an inductance L The matching circuit 10 and the impedance matching circuit 10 are adjusted so that the phase difference ψ detected by the detection circuit 9 becomes zero (resonance condition is satisfied) and their ratio becomes the characteristic impedance Zo of the transmission line 8. Component C or inductance L
Is automatically provided. The means for adjusting the capacitance C or the inductance L, which is a component of the impedance matching circuit 10, is not limited to the means for automatically adjusting via the servo motor control circuit 11 described above, but may include a dial mechanism (not shown). In some cases, the adjustment is manually performed through the control unit.

In the conventional high frequency power supply device for generating discharge plasma having the above-described configuration, the oscillation circuit 1 outputs the fixed frequency fo.
The high frequency power oscillated by the power amplifier 2 and amplified by the power amplifier 2 is transmitted to the automatic matching device 7 via the transmission line 8, and the automatic matching device 7 matches the load impedance of the discharge plasma generator 6. After that, it is transmitted to and applied to the discharge plasma generator 6 to generate discharge plasma. Specifically, the phase difference ψ and the impedance Z between the voltage and current of the high-frequency power applied to the discharge plasma generator 6 are equal to the phase difference / impedance detection circuit 9 in the automatic matching unit 7.
, And the detected phase difference ψ becomes zero (resonance condition is satisfied) and the ratio thereof becomes the characteristic impedance Zo of the transmission line 8 via the servo motor control circuit 11. The capacitance C or the inductance L, which is the ten components, is automatically adjusted or manually adjusted via a dial mechanism (not shown).

[0005]

Generally, an electrical equivalent circuit of the discharge plasma generator 6 as a load is represented by a capacitance Co and a resistance R, and the capacitance Co fluctuates greatly before and after the discharge plasma is generated. Specifically, the capacitance Co before discharge plasma generation is about 2
The capacitance Cs after the generation of the discharge plasma is about 250 pF. Therefore, the voltage and current of the high-frequency power are adjusted so that the capacitance C or the inductance L, which is a component of the impedance matching circuit 10 in the automatic matching unit 7, satisfies the resonance condition shown in the following equation 1 under a fixed frequency fo. In order to make the phase difference ψ always zero, quickly and before and after the generation of discharge plasma, and
We need to make a big change.

[Formula 1]

However, as in the above-described conventional high-frequency power supply apparatus for generating discharge plasma, the capacitance C or the inductance L, which is a component of the impedance matching circuit 10, is manually adjusted via a dial mechanism (not shown). However, even if the adjustment is performed automatically through the servo control circuit 11, there is a limit in the reduction of the adjustment time due to the influence of, for example, the inertia of the servomotor, and as a result, immediately after the application of the high-frequency power, There has been a problem that discharge plasma cannot be generated, and in some cases, even if discharge plasma is generated, the plasma is stopped halfway.

In view of the above, the present invention has been made in view of the above-described circumstances, and instantaneously satisfies the impedance matching condition with the application of high-frequency power to quickly generate discharge plasma. It is an object of the present invention to provide a high-frequency power supply device for generating discharge plasma that can generate the plasma and that can stably maintain the discharge plasma after the generation.

[0008] The invention described in claim 2 is the above-described claim 1.
In addition to the object of the invention described above, it is another object of the present invention to be able to quickly and stably follow a change in load impedance.

The invention according to claim 3 is the same as the above-described claim 1.
Another object of the present invention is to make it possible to achieve the object of the invention described in 2 above at the lowest cost.

Further, the invention according to claim 4 makes efficient use of the high-frequency power supply device for generating discharge plasma according to the invention according to claim 1, 2, or 3 to make semiconductor manufacturing such as etching and thin film formation very efficient. Another object of the present invention is to provide a semiconductor manufacturing apparatus which can be executed efficiently and efficiently.

[0011]

In order to achieve the above object, a high-frequency power supply for generating discharge plasma according to the present invention comprises a discharge plasma generator serving as a load and an oscillating circuit. A high-frequency power generation source including an automatic matching device that matches the frequency of the high-frequency power output from the high-frequency power generation source and applied to the discharge plasma generator with the resonance frequency of the load impedance of the discharge plasma generator. In the high frequency power supply device for generating discharge plasma, the oscillation circuit is configured to be variable in frequency, and a plasma generation detector for detecting the generation of plasma by the discharge plasma generator is provided. Changes the oscillation frequency of the oscillation circuit to match the resonance frequency of the load impedance before discharging, After the plasma generation detector performs a detection operation, a frequency control circuit for switching and controlling the oscillation frequency of the oscillation circuit to a fixed frequency preset to match the optimum resonance frequency of the load impedance after discharge is provided. It is characterized by having
Until high frequency power is applied to the discharge plasma generator and the plasma generation detector detects plasma generation, the oscillation frequency of the oscillation circuit is changed via the frequency control circuit so as to match the resonance frequency of the load impedance before discharge. Thus, the impedance matching condition is instantaneously satisfied, and the discharge plasma can be generated quickly. Then, if discharge plasma is generated and the plasma generation detector performs detection operation accordingly, the oscillation frequency of the oscillation circuit is set via the frequency control circuit so as to match the resonance frequency of the load impedance after discharge. By switching to a fixed frequency that is
Through the automatic matching device, it is possible to exhibit the impedance matching action following the fluctuation of the load impedance and to always stably maintain the generation of the discharge plasma.

According to a second aspect of the present invention, in the high frequency power supply for generating discharge plasma according to the first aspect of the present invention, the automatic matching device reduces the phase difference between the voltage and current of the high frequency power to zero. A servo motor control circuit for adjusting the servo motor control circuit satisfies the resonance condition under the fixed frequency with respect to the load impedance fluctuation based on the detection operation signal of the plasma generation detector. Thus, it is possible to perform a high-speed and stable high-speed matching operation with respect to a change in load impedance after the discharge plasma is generated by using the servo characteristics of the servomotor.

According to a third aspect of the present invention, there is provided a high-frequency power supply for generating discharge plasma according to the first or second aspect of the present invention, wherein the plasma generation detector includes a self-bias voltage associated with plasma generation. In this case, the configuration is simpler than that of other detectors that detect light emission from plasma or ion current (electron current) flowing into the electrode probe.
It can be constructed inexpensively.

A semiconductor manufacturing apparatus according to a fourth aspect of the present invention includes the high frequency power supply device for generating discharge plasma according to the first, second or third aspect of the present invention. As described above, mass production and high quality are desired by effectively utilizing the characteristics of the high-frequency power supply for discharge plasma generation, such as high-speed response, stability and reliability to discharge plasma generation, for etching and thin film formation. Semiconductor manufacturing can be performed very efficiently and efficiently.

[0015]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a configuration diagram of a high frequency power supply device for generating discharge plasma according to the present invention. In FIG. 1, reference numerals 2 to 11 are the same as those in the conventional example shown in FIG. In addition, detailed description thereof will be omitted. Note that the capacitance C and the inductance L of the impedance matching circuit 10 in the automatic matching unit 7 are set to the resonance fixed frequency fo which is the optimum condition after the generation of the discharge plasma.

In FIG. 1, reference numeral 12 denotes a frequency-variable oscillation circuit, which is an oscillation frequency that matches the resonance frequency of the load impedance before discharge, more specifically, a variable frequency circuit that makes the phase difference 電 圧 between the voltage and current of the high-frequency power zero. Ranged frequency f
And a fixed frequency fo preset to match the optimum resonance frequency of the load impedance after discharge. Reference numeral 13 denotes a plasma generation detector for detecting plasma generation by the discharge plasma generator 6, and detects a self-bias voltage accompanying the plasma generation. Reference numeral 14 denotes a frequency control circuit. The frequency control circuit 14 receives the discharge plasma detection signal S1 from the plasma generation detector 13 and the phase difference detection signal S2 between the voltage and current of the high-frequency power from the phase difference / impedance detection circuit 9. Until the plasma generation detector 13 performs the detection operation, the oscillation frequency of the oscillation circuit 12 is discharged based on the input of the phase difference detection signal S2 such that the phase difference の between the voltage and the current of the high-frequency power becomes zero. Oscillation is performed at a variable frequency f that matches the resonance frequency of the previous load impedance, and after the plasma generation detector 13 performs a detection operation, the detection signal S
Based on the input of 1, the switching control is performed so that the oscillation frequency of the oscillation circuit 12 is oscillated at a fixed frequency fo matching the optimum resonance frequency of the load impedance after discharge.

The discharge plasma detection signal S1 from the plasma generation detector 13 is also input to a servo motor control circuit 11 in the automatic matching unit 7, and after the discharge plasma is generated, the servo motor control circuit 11 The generator 6 is configured to always follow the fluctuation of the load impedance of the generator 6 so as to satisfy the resonance condition under the fixed frequency fo.

In the high frequency power supply device for generating discharge plasma having the above configuration, the servo motor control circuit 11 in the automatic matching unit 7 does not operate until the discharge plasma is generated after high frequency power is applied, and the phase difference / impedance detection is performed. The phase difference detection signal S2 of the voltage and current of the high-frequency power detected by the circuit 9 is input to the frequency control circuit 14, and based on the control signal output from the frequency control circuit 14 based on the input of the phase difference detection signal S2. The oscillation circuit 12 oscillates at a variable frequency f such that the phase difference 電 圧 between the voltage and the current of the high-frequency power becomes zero. As a result, the oscillation frequency of the oscillation circuit 12 is automatically adjusted to the resonance frequency of the load impedance before discharge, so that the impedance matching condition is instantaneously satisfied, and the discharge plasma is quickly generated from the discharge plasma generator 13. Can be generated.

When the discharge plasma is generated, a discharge plasma detection signal S by the plasma generation detector 13 is generated.
1 is input to the frequency control circuit 14, and the oscillation circuit 12 is controlled by a control signal output from the frequency control circuit 14 based on the input of the discharge plasma detection signal S1.
The fixed frequency fo is set so that the oscillation frequency of the load impedance matches the resonance frequency of the load impedance after discharge.
At the same time, the servo motor control circuit 11 of the automatic matching unit 7 starts operating, the impedance matching operation is performed by the automatic matching unit 7, and resonance occurs under the above-mentioned fixed frequency fo with respect to the load impedance fluctuation. High-frequency power can be applied to the discharge plasma generator 13 efficiently by always following the operation so as to satisfy the conditions, and the generation of discharge plasma can always be maintained stably.

FIG. 2 is a conceptual diagram of the control structure of the high-frequency power supply for generating discharge plasma described above.
Reference numeral 1 denotes a high-frequency power generation source, which is composed of the above-mentioned variable frequency oscillation circuit 12, power amplifier 2, power setting device 3, power directional coupler 4, and power control circuit 5 in FIG. It has a frequency f having a variable range necessary to resonate with the electrode Ed of the generator 6 and the above-mentioned fixed frequency fo. The above discharge plasma generator 6
Electrode Ed has an equivalent capacitance Co before plasma generation.
After the plasma is generated, the operation shifts to the equivalent capacitance Cs. The relative ratio between the two equivalent capacitances Co and Cs is generally Co <Cs. When plasma is generated, a DC voltage VDC is generated at the electrode Ed, and the plasma generation detector 13 in FIG. Is configured to be detected.

D1 is a resonance state detection circuit, which is shown in FIG.
Corresponds to the phase difference / impedance detection circuit 9 of the automatic matching unit 7 in FIG. M1 is an impedance matching circuit with the discharge plasma generator 6, which is a load, and corresponds to the impedance matching circuit 10 of the automatic matching unit 7 in FIG. CMP1 is a voltage level comparator for giving an instruction to shift (switch) the oscillation frequency of the high frequency power generation source V1 from f to fo. VR1 is the ON state of the voltage level comparator CMP1 for the DC voltage VDC.
An adjustment voltage for setting the -OFF level, which sets a condition for shifting the oscillation frequency f of the high frequency power generation source V1 from the oscillation frequency f0 to fo, and a voltage level comparator CMP1 including the adjustment voltage VR1 corresponds to FIG. It corresponds to the frequency control circuit 14.

In the control configuration of FIG. 2 described above, in order to create a resonance state that matches the impedance matching circuit M1 and the equivalent capacitance Co of the electrode Ed in the discharge plasma generator 6 before the plasma is generated, before the generation of the discharge plasma. The high frequency power generation source V via the feedback control system while referring to the detection value of the resonance state detection circuit D1.
1 is automatically adjusted to a frequency f necessary for generating discharge plasma. As such automatic frequency f adjusting means, the resonance state detection circuit D1 is used as a phase detection circuit, and a voltage variable frequency circuit (VCO) is used as a phase synchronization circuit (PLL) interposed in a feedback control system together with a compensation element. In this case, the phenomenon that the phase difference between the applied voltage and the load current at the time of resonance shows a value of zero is effectively used. Further, the resonance state is detected by applying the phenomenon that the load current and the load voltage become the maximum value and the minimum value at the time of resonance, and the high-frequency power generation source V1 is automatically adjusted to the frequency f necessary for generating the discharge plasma. Means may be adopted.

After the discharge plasma is generated as described above, a direct current self-bias voltage VDC is generated at the electrode Ed of the discharge plasma generator 6, and this self-bias voltage VDC is applied to the setting adjustment voltage VR1 of the voltage level comparator CMP1. Reaches the voltage level comparator CMP
1 is turned on, the oscillation frequency of the high-frequency power generation source V1 is shifted from f to fo, and is driven at a fixed frequency fo by the impedance matching circuit M1 previously matched to the value of the equivalent capacitance Cs.

The above-described high-frequency power supply for generating discharge plasma can be very effectively applied to a semiconductor manufacturing apparatus which requires mass productivity and high quality, such as an etching apparatus and a thin film forming apparatus. In addition, welding fields such as plastic high frequency welders and ICP
And the like.

[0025]

As described above, according to the first aspect of the present invention, a variable frequency oscillating circuit is used to adjust the oscillation frequency to match the resonance frequency of the load impedance before the plasma discharge and the oscillation frequency after the plasma discharge. Can be switched to a fixed frequency that matches the optimum resonance frequency of the load impedance of the load, so that immediately after the application of high-frequency power, the impedance matching condition can be satisfied instantaneously and discharge plasma can be generated quickly. After the generation, it is possible to maintain the discharge plasma stably while ensuring the responsiveness.

The invention according to claim 2 is the same as the above-described claim 1.
In addition to the effects described above, the generation of the discharge plasma can be stabilized by following the fluctuation of the load impedance after the plasma discharge at a high speed, and the reliability can be improved.

The third aspect of the present invention is directed to the first aspect.
Alternatively, in addition to the effects of the invention described in 2, the plasma generation detector which is indispensable for exhibiting the above-mentioned child function can be configured at the lowest cost.

Further, the invention according to claim 4 is directed to the characteristics of high-speed response, stability and reliability of the high-frequency power supply device for generating discharge plasma according to the invention according to claim 1, 2 or 3 by etching or thin film formation. For example, it is possible to effectively utilize semiconductor manufacturing in which mass productivity and high quality are desired, and to carry out very efficient and efficient semiconductor manufacturing.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a high-frequency power supply device for generating discharge plasma according to the present invention.

FIG. 2 is a conceptual diagram of a control configuration of a high frequency power supply device for generating discharge plasma according to the first embodiment;

FIG. 3 is a configuration diagram of a conventional general high-frequency power supply device for generating discharge plasma.

[Explanation of symbols]

 Reference Signs List 6 discharge plasma generator 7 automatic matching unit 9 phase difference / impedance detection circuit 10 impedance matching circuit 11 servo motor control circuit 12 variable frequency oscillation circuit 13 plasma generation detector 14 frequency control circuit

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int.Cl. ⁶ , DB name) H05H 1/46 H01L 21/3065

Claims (4)

(57) [Claims] A discharge plasma generator serving as a load; a high-frequency power generation source including an oscillation circuit; and a frequency of the high-frequency power output from the high-frequency power generation source and applied to the discharge plasma generator is set to the discharge plasma. In a high frequency power supply device for generating discharge plasma, comprising: an automatic matching device for matching a resonance frequency of a load impedance of a generator, wherein the oscillation circuit is configured to have a variable frequency and a plasma generation by the discharge plasma generator is detected. A plasma generation detector is provided, and until the plasma generation detector performs a detection operation, the oscillation frequency of the oscillation circuit is changed so as to match the resonance frequency of the load impedance before discharge, and the plasma generation detector performs the detection. After operation, the oscillation frequency of the above oscillation circuit is adjusted to the optimum resonance of the load impedance after discharging. Discharge plasma generating high frequency power supply device, characterized in that it provided a frequency control circuit for controlling switching to a fixed frequency which is preset to match the wave number. 2. The automatic matching device includes a servo motor control circuit for adjusting a phase difference between a voltage and a current of a high frequency power to zero, and the servo motor control circuit performs a detection operation of the plasma generation detector. 2. The high-frequency power supply device for generating discharge plasma according to claim 1, wherein the high-frequency power supply device for generating discharge plasma is configured to follow a change in load impedance based on a signal so as to satisfy a resonance condition under the fixed frequency. 3. The high-frequency power supply for discharge plasma generation according to claim 1, wherein the plasma generation detector detects a self-bias voltage accompanying plasma generation. 4. A semiconductor manufacturing apparatus comprising the high-frequency power supply for generating discharge plasma according to claim 1.