KR102313611B1 - Apparatus and method for sensing the state of plasma torch - Google Patents

Abstract

The present invention relates to an apparatus and method for sensing a state of a plasma torch. The apparatus for sensing a state of a plasma torch in accordance with the present invention, which is positioned between a plasma torch for generating plasma and a plasma direct current power supply device for supplying direct current power to the plasma torch to detect a wear or deformation state of a cathode of the plasma torch, comprising: a voltage sensing unit sensing a direct current voltage, which is to be applied to the plasma torch, from the plasma direct current power supply device; a current sensing unit sensing a current flowing through the plasma torch as a direct current voltage is applied from the plasma direct current power supply device to the plasma torch; and a comparison/analysis unit sensing the wear or deformation state of the cathode of the plasma torch by comparing/analyzing a voltage value (V_t) and a current value (I_t), sensed at a specific time point (t) by the voltage sensing unit and the current sensing unit respectively, with a voltage value (V_t-1) and a current value (I_t-1), sensed at a time point (t-1) before the specific time point, to detect a variation of the voltage value and the current value. The present invention can rapidly exchange worn or deformed cathodes and prevent usage of excessively worn or deformed torches to smoothly operate a semiconductor process by sensing the wear or deformation state of the cathode due to erosion or thermal damage occurring on the surface of the cathode in a process of generating the plasma.

Description

Apparatus and method for sensing the state of plasma torch}

The present invention relates to an apparatus and method for detecting a plasma torch state, and more particularly, erosion and A plasma torch state sensing apparatus and method capable of detecting abrasion or deformation of a cathode due to thermal damage.

Plasma torches use electrodes to generate an electric arc within the torch. A gas flows through the torch, and an electric arc ionizes the gas, creating a plasma. In this process, an arc concentration phenomenon due to a large current occurs on the surface of the anode, and erosion occurs on the surface of the cathode due to the concentration phenomenon of the arc and thermal damage proceeds at the same time. The erosion of the cathode, which is the biggest problem of the conventional plasma torch, acts as a serious limitation in the plasma torch. Therefore, from the user's point of view, it is necessary to detect abrasion and deformation of the cathode, and to manage an appropriate replacement time of the torch.

On the other hand, Korean Patent Application Laid-Open No. 10-2011-0019721 (Patent Document 1) discloses a "plasma torch having an electrode wear detection system", and the plasma arc torch according to this is a main torch body; an electrically conductive nozzle defining an aperture for allowing gas to flow toward the workpiece; an electrode holder disposed within the main torch body; an electrode detachably attached to the electrode holder and projecting forward from the electrode holder towards an opposing surface of the electrically conductive nozzle, the electrode defining an end face and an axial length L, wherein the length L is an electrode in which the end face of the electrode decreases as it wears during use of the plasma arc torch; and an electrically non-conductive wear stop fixedly mounted within the main torch body and constituting a first engagement surface axially spaced apart from the opposing surface of the nozzle by a predetermined axial distance D. The electrode or nozzle is movable relative to the main torch body, and the movable component constitutes the protrusion. The wear stop is positioned a predetermined distance from the nozzle of the plasma arc torch so that, before excessive wear, the electrode can contact the nozzle and create a pilot arc for torch operation. When the length of the electrode becomes shorter than the predetermined length due to wear, the protrusion of the electrode engages the wear stop, which stops the electrode from contacting the nozzle. In this process, the excessively worn electrode is characterized in that it is not used in the subsequent torch operation.

In the case of Patent Document 1 as described above, a wear stopper is provided within the main torch body at a predetermined distance from the nozzle, and when the electrode is shortened due to wear, the protrusion of the electrode is engaged with the wear stopper, so that the electrode does not contact the nozzle, There is an effect of preventing the excessively worn electrode from being used in the subsequent torch operation, but this is a mechanism for detecting the wear of the electrode in a mechanical way by the wear stop part, so it only detects the mechanical wear of the electrode and generates plasma. The deformation state of the cathode due to erosion and thermal damage occurring on the surface of the cathode in the process contains a problem that cannot be detected.

Korean Patent Publication No. 10-2011-0019721 (2011.02.28.)

The present invention was created to improve the problems of the prior art as described above, and erosion and Plasma that detects the wear or deformation state of the cathode due to thermal damage, so that the worn or deformed cathode can be quickly replaced, and the semiconductor process can run smoothly by preventing the use of an excessively worn or deformed torch An object of the present invention is to provide an apparatus and method for detecting a torch state.

In order to achieve the above object, a plasma torch state sensing device according to the present invention,

A device positioned between a plasma torch generating plasma and a plasma DC power supply supplying DC power to the plasma torch to detect abrasion or deformation of the cathode of the plasma torch,

a voltage sensing unit sensing a DC voltage applied to the plasma torch from the plasma DC power supply;

a current sensing unit sensing a current flowing through the plasma torch as a DC voltage is applied from the plasma DC power supply to the plasma torch; and

_{A voltage value (V t} ) and a current value (I _t ) respectively sensed at a specific time point (t) by the voltage sensing unit and the current sensing unit at a time point (t-1) before the specific time point ( V _t-1 ) and current value (I _t-1 ) are compared/analyzed to detect a change in voltage value or current value, and are continuously detected with the maximum voltage and current values detected before and after a specific time point (t) Calculate the re-strike period (T _t ) from the time difference between the maximum voltage and current values, By calculating the retry period (T _{t-1 ) from the lag of} It is characterized in that it includes a comparison/analysis unit that detects wear or deformation of the cathode of the plasma torch.

Here, the voltage sensing unit,

a voltage sensor sensing a voltage applied to both ends of the plasma torch;

a first band-pass filter for passing signals of a preset frequency band to the voltage signal sensed by the voltage sensor and attenuating signals of other frequency bands; and

and a voltage signal output buffer serving as a voltage amplifier for stabilizing the output signal of the first bandpass filter.

In addition, the current sensing unit,

a current sensor for sensing a current flowing into or flowing out of the plasma torch;

a second band-pass filter for passing signals of a preset frequency band to the current signal sensed by the current sensor and attenuating signals of other frequency bands; and

It may be configured to include a current signal output buffer serving as a current amplifier for stabilizing the output signal of the second band-pass filter.

At this time, the current sensor is connected between the plasma DC power supply device and the anode electrode of the plasma torch to sense the current flowing into the plasma torch, or the plasma DC power supply to detect the current flowing out of the plasma torch It may be connected between the device and the cathode electrode of the plasma torch.

In addition, the comparison / analysis unit,

an A/D converter that receives output signals (analog signals) from the voltage signal output buffer and the current signal output buffer, respectively, and converts them into digital data;

The voltage value and current value respectively converted into digital data by the A/D converter are received, respectively, the voltage value (V _t ) and the current value (I _t ) sensed at a specific time point (t) are displayed at a point before the specific time point ( The state of wear or deformation of the cathode of the plasma torch by comparing/analyzing the voltage value (V _t-1 ) and the current value (I _{t-1 ) respectively sensed at t-1) and detecting a change in the voltage value or current value} a microcontroller that detects; and

The information sensed by the microcontroller is transmitted to the central control unit of the gas scrubber that purifies and discharges various gases (eg, toxic gas, acid gas, combustible gas, environmental harmful gas) generated during the semiconductor manufacturing process. It can be configured including /receiver.

In addition, the plasma torch state detection method according to the present invention in order to achieve the above object,

It is located between the plasma torch that generates plasma and the plasma DC power supply that supplies DC power to the plasma torch, and is a device that detects wear or deformation of the cathode of the plasma torch. A plasma torch state sensing method based on a plasma torch state sensing device comprising a part,

a) detecting a DC voltage applied to the plasma torch from the plasma DC power supply device by a voltage sensor of the voltage sensing unit;

b) detecting a current flowing through the plasma torch as a DC voltage is applied from the plasma DC power supply to the plasma torch by the current sensor of the current sensing unit;

c) receiving the voltage signal and the current signal (analog signal) respectively sensed by the voltage sensor and the current sensor by the A/D converter of the comparison/analysis unit and converting each into digital data;

d) receiving the voltage values and current values respectively converted into digital data by the A/D converter by the microcontroller of the comparison/analysis unit;

_{e) the voltage value (V t} ) and the current value (I _t ) respectively sensed at a specific time point (t) by the microcontroller based on the received voltage value and current value at the time point (t-1) before the specific time point Comparing / analyzing the voltage value (V _t-1 ) and the current value (I _{t-1 ) respectively sensed in );}

f) transmitting, by the information transmitting/receiving unit of the comparison/analysis unit, the result of the change in the voltage value or the current value obtained by the comparison/analysis to the central control unit of the gas scrubber.

Here, the step of passing a signal of a frequency band preset to the voltage signal by the first bandpass filter of the voltage sensing unit in step a) and attenuating signals of other frequency bands may be further included.

In this case, the method may further include amplifying and outputting a voltage by a voltage signal output buffer of the voltage sensing unit in order to stabilize the output signal of the first bandpass filter.

In addition, the method may further include a step of passing a signal of a frequency band preset to the current signal by a second bandpass filter of the current sensing unit in step b) and attenuating signals of other frequency bands.

In this case, the method may further include amplifying and outputting a current by a current signal output buffer of the current sensing unit in order to stabilize the output signal of the second bandpass filter.

According to the present invention, by detecting the wear or deformation state of the cathode due to erosion and thermal damage occurring on the cathode surface in the process of generating plasma by ionizing the gas flowing through the torch by the electric arc generated in the plasma torch, There are advantages in that a worn or deformed cathode can be quickly replaced, and a semiconductor process can be smoothly operated by preventing the use of an excessively worn or deformed torch.

1 is a diagram schematically showing the overall configuration of a plasma torch state sensing device according to the present invention.
2 is a diagram schematically showing the internal system configuration of the plasma torch state sensing device according to the present invention.
3 is a flowchart illustrating an execution process of a plasma torch state detection method according to the present invention.
4 is a diagram illustrating voltage and current waveforms in a state 1 without torch wear and deformation after the plasma torch is ignited.
5 is a diagram illustrating a voltage waveform period in a state 1 without torch wear and deformation after the plasma torch is ignited.
6 is a diagram illustrating voltage and current waveforms in state 2 with torch wear and deformation after the plasma torch is ignited.
7 is a view showing the change in the voltage waveform period of the state 2 with torch wear and deformation after completion of ignition of the plasma torch.
8 is a diagram illustrating voltage and current waveforms in state 3 with torch wear and deformation after completion of ignition of the plasma torch.
9 is a view showing the change in the voltage waveform period of the state 3 with torch wear and deformation after completion of ignition of the plasma torch.

The terms or words used in the present specification and claims should not be construed as being limited to their ordinary or dictionary meanings, and the inventor may properly define the concept of the term in order to best describe his invention. Based on the principle, it should be interpreted as meaning and concept consistent with the technical idea of the present invention.

Throughout the specification, when a part "includes" a certain element, it means that other elements may be further included, rather than excluding other elements, unless otherwise stated. In addition, terms such as “…unit”, “…group”, “module”, and “device” described in the specification mean a unit that processes at least one function or operation, which is hardware or software or a combination of hardware and software. can be implemented as

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

1 and 2 show a plasma torch state sensing device according to an embodiment of the present invention. FIG. 1 is a diagram schematically showing the overall configuration, and FIG. 2 is a diagram schematically showing an internal system configuration.

1 and 2 , the plasma torch state sensing device 100 according to the present invention includes a plasma torch 140 for generating plasma, and a plasma DC power supply device for supplying DC power to the plasma torch 140 . A device positioned between 150 and detecting abrasion or deformation state of the cathode (cathode electrode 140c) of the plasma torch 140, the voltage sensing unit 110, the current sensing unit 120, and the comparison/analysis unit 130 is included.

The voltage sensing unit 110 detects a DC voltage applied to the plasma torch 140 from the plasma DC power supply 150 . Here, the voltage sensing unit 110 includes a voltage sensor 111 for sensing a voltage applied to both ends of the plasma torch 140 as shown in FIG. 2 ; a first band-pass filter 112 for passing signals of a preset frequency band to the voltage signal detected by the voltage sensor 111 and attenuating signals of other frequency bands; and a voltage signal output buffer 113 serving as a voltage amplifier for stabilizing the output signal of the first band-pass filter 112 .

The current sensing unit 120 senses a current flowing through the plasma torch 140 as a DC voltage is applied from the plasma DC power supply 150 to the plasma torch 140 . The current sensing unit 120 includes a current sensor 121 for sensing a current flowing into or flowing out of the plasma torch 140 ; a second band-pass filter 122 for passing a signal of a preset frequency band to the current signal sensed by the current sensor 121 and attenuating signals of other frequency bands; and a current signal output buffer 123 serving as a current amplifier for stabilizing the output signal of the second bandpass filter 122 .

At this time, the current sensor 121 is connected between the plasma DC power supply 150 and the anode electrode 140a of the plasma torch 140 to sense the current flowing into the plasma torch 140, It may be connected between the plasma DC power supply 150 and the cathode electrode 140c of the plasma torch 140 to sense the current flowing out of the plasma torch 140 . In this embodiment, a case in which the current sensor 121 is connected between the plasma DC power supply 150 and the cathode electrode 140c of the plasma torch 140 is exemplified.

_{The comparison/analysis unit 130 compares the voltage value (V t} ) and the current value (I _t ) respectively sensed at a specific time point (t) by the voltage sensor unit 110 and the current sensor unit 120 before a specific time point. _{The voltage value (V t-1} ) and the current value (I _t-1 ) respectively sensed at the time point (t-1) are compared/analyzed to detect a change in the voltage value or the current value, and the specific time point (t) _{Calculate the re-strike period (T t} ) from the time difference between the maximum voltage and current values detected before and after and the maximum voltage and current values continuously detected, and the maximum detected before and after the time point (t-1) before a specific time point The wear or deformation state of the cathode (cathode electrode 140c) of the plasma torch 140 is detected by calculating the _{restrike period (T t-1} ) from the time difference between the voltage and current values and the maximum voltage and current values continuously sensed. do. The comparison/analysis unit 130 receives the output signals (analog signals) from the voltage signal output buffer 113 and the current signal output buffer 123, respectively, and converts them into digital data by an A/D converter ( 131) and; A voltage value and a current value respectively converted into digital data by the A/D converter 131 are received, respectively, the voltage value (V _t ) and the current value (I _t ) sensed at a specific time point (t) before the specific time point (I t ) _{By comparing/analyzing the voltage value (V t-1} ) and the current value (I _t-1 ) respectively sensed at the time point (t-1) and detecting a change in the voltage value or current value, the abrasion of the cathode of the plasma torch or a microcontroller 132 that senses the deformation state; and a central control unit 160 of a gas scrubber that purifies and discharges the information sensed by the microcontroller 132 to various gases (eg, toxic gas, acid gas, combustible gas, environmental harmful gas) generated during the semiconductor manufacturing process. ) may be configured to include an information transmitting/receiving unit 133 to transmit.

Then, a plasma torch state sensing method based on the plasma torch state sensing apparatus according to the present invention having the above configuration will be described below.

3 is a flowchart illustrating an execution process of a plasma torch state detection method according to an embodiment of the present invention.

Referring to FIG. 3 , the plasma torch state detection method according to the present invention includes a plasma torch 140 for generating plasma as described above, and a plasma DC power supply device 150 for supplying DC power to the plasma torch 140 . ) is located between the voltage sensing unit 110, the current sensing unit 120 and the comparison/analysis unit 130 as a device for detecting the wear or deformation state of the cathode (cathode electrode 140c) of the plasma torch 140 . A plasma torch state detection method based on the plasma torch state detection apparatus 100 comprising A DC voltage applied to the torch 140 is sensed (step S301).

In addition, as a DC voltage is applied from the plasma DC power supply 150 to the plasma torch 140 by the current sensor 121 of the current sensing unit 120, the current flowing through the plasma torch 140 is measured. is detected (step S302).

Here, in detecting the DC voltage applied to the plasma torch 140 by the voltage sensor 111 and the current flowing in the plasma torch 140 by the current sensor 121 as described above, this sequence must be It is not limited to be performed in the same order as in the flowchart of FIG. 3 , and in some cases, the current is first sensed by the current sensor 121 and then the voltage may be sensed by the voltage sensor 111 , , the voltage and current may be simultaneously sensed by the voltage sensor 111 and the current sensor 121 .

On the other hand, when the voltage and current are respectively sensed by the voltage sensor 111 and the current sensor 121 as described above, the voltage signal and the current signal (analog) detected by the voltage sensor 111 and the current sensor 112, respectively. signal) is received by the A/D converter 131 of the comparison/analysis unit 130 and converted into digital data, respectively (step S303).

Then, the voltage value and the current value converted into digital data by the A/D converter 131 by the microcontroller 132 of the comparison/analysis unit 130 are received (step S304).

Then, based on the received voltage value and current value, the voltage value (V _t ) and the current value (I _t ) respectively sensed at a specific time point (t) by the microcontroller 132 at a time point before the specific time point The voltage value (V _t-1 ) and the current value (I _t-1 ) sensed at (t-1) are compared/analyzed, respectively (step S305).

Then, by the information transmitting/receiving unit 133 of the comparison/analysis unit 130, the result of the change of the voltage value or the current value obtained by the comparison/analysis is displayed in various gases (for example, , toxic gas, acid gas, combustible gas, environmental harmful gas) is purified and transmitted to the central control unit 160 (see FIG. 1) of the exhaust gas scrubber (step S306).

In a series of processes as described above, in step S301, a signal of a frequency band preset to the voltage signal is passed by the first bandpass filter 112 of the voltage sensing unit 110, and a signal of a frequency band other than that is passed. The signal may further comprise attenuating.

In this case, the method may further include amplifying and outputting a voltage by the voltage signal output buffer 113 of the voltage sensing unit 110 in order to stabilize the output signal of the first bandpass filter 112 .

In addition, in the step S302, a signal of a frequency band preset to the current signal is passed by the second bandpass filter 122 of the current sensing unit 120, and signals of other frequency bands are attenuated. may include

In this case, the method may further include amplifying and outputting the current by the current signal output buffer 123 of the current sensing unit 120 to stabilize the output signal of the second bandpass filter 122 .

Meanwhile, in the above series of processes, the voltage value and current value comparison/analysis by the microcontroller 132 in step S305 will be described in detail.

4 is a diagram illustrating voltage and current waveforms in a state 1 without torch wear and deformation after the plasma torch is ignited.

Referring to FIG. 4 , the plasma torch 140 is in an ignition completion state at time t, and the voltage signal of the torch received by the A/D converter 131 at an arbitrary time point t+n is V1, and the current signal is I1. And, if the voltage signal of the torch received by the A/D converter 131 after n period elapses is V2 and the current signal is I2, the abrasion and deformation of the cathode (cathode electrode 140c) of the plasma torch 140 is Otherwise, V1 = V2 and I1 = I2. In this way, it can be seen that the voltage and current waveforms are constant because the plasma torch 140 does not change the state of wear or deformation of the torch after ignition is completed.

5 is a diagram illustrating a voltage waveform period in a state 1 without torch wear and deformation after the plasma torch is ignited.

Referring to FIG. 5, the period t1 = (t+2n-k) - (t+2n-2k) in the voltage signal waveform before the period k with the time point t+2n as the center, and in the voltage signal waveform after the period k Period t2 = (t+2n+2k) - (t+2n+k). The period t1 = t2 of the voltage signal waveform and the frequency F1 = F2. Therefore, before and after time t+2n, the plasma torch 140 can be viewed as a state without wear or deformation. As such, it can be seen that the restrike reaction cycle, which is a characteristic of the plasma torch, appears uniformly because there is no change in the state of wear and deformation of the torch after the plasma torch 140 is ignited.

4 and 5, it is preferable to sense the state of the plasma torch 140 in real time under the condition that t > 0, n > 0, and 0 < k < n.

6 is a view showing the voltage and current waveforms of state 2 with torch wear and deformation after ignition of the plasma torch is completed, and FIG. 7 is a voltage waveform period of state 2 with torch wear and deformation after completion of ignition of the plasma torch A diagram showing the changes.

Referring to FIG. 6 , the plasma torch is in the ignition completion state at time t, the voltage signal of the torch received by the A/D converter 131 at an arbitrary time point t+n is V1, the current signal is I1, and n If the voltage signal of the torch received from the A/D converter 131 after the lapse of time is V3 and the current signal is I3, if there is wear or deformation of the cathode (cathode electrode 140c) of the plasma torch 140, V1 ≠ V3 and I1 ≠ I3. As such, it can be seen that the plasma torch 140 exhibits a characteristic that a voltage is increased and a current is decreased due to a change in the state of torch wear and deformation after ignition is completed.

Further, in Fig. 7, with the time point t+2n as the center, the period t1 = (t+2n-k) - (t+2n-2k) in the voltage signal waveform before the period k, and the period in the voltage signal waveform after the period m t2 = (t+2n+2m) - (t+2n+m) . The period t1 ≠ t3 of the voltage signal waveform, and the frequency F1 ≠ F3. Therefore, before and after time t+2n, the plasma torch 140 can be viewed as a state in which the separation distance between the cathode electrode 140c and the anode electrode 140a is increased due to wear and deformation. In this way, it can be seen that the plasma torch 140 has a longer period because the restrike reaction period, which is a characteristic of the plasma torch, is changed due to a change in the state of torch wear and deformation after ignition is completed.

In FIGS. 6 and 7 , it is preferable to sense the state of the plasma torch 140 in real time under the condition that t > 0, n > 0, 0 < k < n, and 0 < m < n.

On the other hand, FIG. 8 is a diagram showing the voltage and current waveforms of the state 3 with torch wear and deformation after the ignition of the plasma torch is completed, and FIG. 9 is the voltage of the state 3 with the torch wear and deformation after the ignition of the plasma torch is completed. It is a diagram showing the change of the waveform period.

Referring to FIG. 8 , the plasma torch 140 is in an ignition completion state at time t, and the voltage signal of the torch received by the A/D converter 131 at an arbitrary time t+n is V1, and the current signal is I1. And, if the voltage signal of the torch received from the A/D converter 131 after n period has elapsed is V4 and the current signal is I4, there is wear and deformation of the cathode (cathode electrode 140c) of the plasma torch 140 . , then V1 ≠ V4, and I1 ≠ I4. As such, it can be seen that the voltage is decreased and the current is increased by the change in the state of torch wear and deformation after the plasma torch 140 is ignited.

Further, in Fig. 9, with the time point t+2n as the center, the period t1 = (t+2n-k) - (t+2n-2k) in the voltage signal waveform before the period k, and the period in the voltage signal waveform after the period p t4 = (t+2n+2p) - (t+2n+p). The period t1 ≠ t4 of the voltage signal waveform, and the frequency F1 ≠ F4. Therefore, before and after time t+2n, the plasma torch 140 can be viewed as a state in which the separation distance between the cathode electrode 140c and the anode electrode 140a is reduced due to wear and deformation. In this way, it can be seen that the plasma torch 140 has a shorter period because the restrike reaction period, which is a characteristic of the plasma torch, is changed due to a change in the state of torch wear and deformation after ignition is completed.

In FIGS. 8 and 9 , it is preferable to sense the state of the plasma torch 140 in real time under the condition that t > 0, n > 0, 0 < k < n, and 0 < p < n.

In addition, it can be seen from FIGS. 7 and 9 that the cycle of increasing and decreasing the voltage is varied due to a restrike phenomenon among the inherent characteristics of the plasma torch. Here, the restrike phenomenon is a representative characteristic appearing in arc plasma using DC power. In the restrike phenomenon, the arc generated at the shortest distance from the electrode moves along the electrode surface by the plasma gas, and the arc length increases, and as a result, the plasma voltage rises. However, the longer arc is extinguished by high resistance, and an arc is generated again at the shortest distance between the electrodes, and this phenomenon is called a restrike phenomenon. In the present invention, the voltage of the plasma torch 140 increases from a low voltage to a high voltage due to this restrike phenomenon in the present invention, and at the same time as the plasma disappears, the voltage is rapidly lowered to the minimum value again by measuring, comparing/analyzing, and measuring, comparing/analyzing the period of the plasma torch 140 . It is possible to detect wear and deformation of the cathode.

As described above, the plasma torch state sensing apparatus and method according to the present invention ionize the gas flowing through the torch by the electric arc generated in the plasma torch to generate plasma by erosion and thermal damage occurring on the surface of the cathode. By detecting the wear or deformation state of the cathode, it is possible to quickly replace the worn or deformed cathode, and to prevent the use of an excessively worn or deformed torch, there is an advantage in that the semiconductor process can be smoothly operated.

As described above, the present invention has been described in detail through preferred embodiments, but the present invention is not limited thereto, and it is common in the art that various changes and applications can be made without departing from the technical spirit of the present invention. self-explanatory to the technician. Therefore, the true protection scope of the present invention should be construed by the following claims, and all technical ideas within the scope equivalent thereto should be construed as being included in the scope of the present invention.

100: (the present invention) plasma torch state detection device
110: voltage sensing unit 111: voltage sensor
112: first band-pass filter 113: voltage signal output buffer
120: current sensing unit 121: current sensor
122: second band pass filter 123: current signal output buffer
130: comparison / analysis unit 131: A/D converter
132: microcontroller 133: information transmitting/receiving unit

Claims (10)

A device positioned between a plasma torch generating plasma and a plasma DC power supply supplying DC power to the plasma torch to detect abrasion or deformation of the cathode of the plasma torch,
a voltage sensing unit sensing a DC voltage applied to the plasma torch from the plasma DC power supply;
a current sensing unit sensing a current flowing through the plasma torch as a DC voltage is applied from the plasma DC power supply to the plasma torch; and
_{A voltage value (V t} ) and a current value (I _t ) respectively sensed at a specific time point (t) by the voltage sensing unit and the current sensing unit at a time point (t-1) before the specific time point ( V _t-1 ) and current value (I _t-1 ) by comparing / analyzing respectively to detect a change in voltage value or current value,
_{The re-strike period (T t} ) is calculated from the time difference between the maximum voltage and current values detected before and after a specific time point (t) and the maximum voltage and current values continuously detected, and the A comparison/analysis unit that detects abrasion or deformation of the cathode of the plasma torch by calculating the re _{-strike period (T t-1} ) from the difference between the maximum voltage and current values detected before and after and the maximum voltage and current values detected continuously includes,
The comparison/analysis unit calculates the voltage value (V _t ), the current value (I _t ), and the re-strike period (T _t ) respectively sensed at a specific time point (t) at a time point (t-1) before the specific time point (t-1). By comparing / analyzing the voltage value (V _t-1 ), the current value (I _t-1 ), and the re _{-strike period (T t-1} ), respectively, the change of the voltage value, the current value, and the re-strike period is detected. In detecting the wear or deformation state of the cathode,
The voltage value (V _t ), the current value (I _t ), and the re-strike period (T _t ) sensed at the specific time point (t) are the voltage values (V _{t− 1} ), when the current value (I _t-1 ) and the retry period (T _t-1 ) are the same as each (V _t = V _t-1 , I _t = I _t-1, T _t = T _t-1 ) , it is determined that there is no wear or deformation of the cathode (cathode electrode) of the plasma torch,
The voltage value (V _t ), the current value (I _t ), and the re-strike period (T _t ) sensed at the specific time point (t) are the voltage values (V _{t− 1} ), when the current value (I _t-1 ) and the retry period (T _t-1 ) are different from each other (V _t ≠ V _t-1 , I _t ≠ I _t-1, T _t ≠ T _t-1 ) , It is determined that there is wear or deformation of the cathode (cathode electrode) of the plasma torch,
The voltage value (V _{t ) sensed at a specific time point (t) is greater than the voltage value (V t-1} ) sensed at a time point (t-1) before the specific time point (t), and the current value detected at a specific time point (t) ( I _{t ) is less than the current value (I t-1} ) sensed at the time point t-1 before the specific time point, and the re-strike period (T _t ) detected at the specific time point t is the time point before the specific time point ( When the restrike period (T _t-1 ) detected at t-1) is greater (V _t > V _t-1 , I _t < I _{t-1 ,} T _t > T _t-1 ), the cathode of the plasma torch It is determined that the separation distance between the electrode and the anode electrode is increased,
The voltage value (V _{t ) sensed at a specific time point (t) is smaller than the voltage value (V t-1} ) sensed at a time point (t-1) before the specific time point (t), and the current value detected at a specific time point (t) ( I _{t ) is greater than the current value (I t-1} ) sensed at the time point (t-1) before the specific time point _{, and the re-strike period (T t} ) detected at the specific time point (t) is the time point before the specific time point ( When it is smaller than the detected restrike period (T _{t-1 ) at t-1) (V t} <V _t-1 , I _t >I _{t-1 ,} T _t < T _t-1 ), the plasma torch A plasma torch state sensing device for determining that the separation distance between the cathode electrode and the anode electrode is reduced.
According to claim 1,
The voltage sensing unit,
a voltage sensor sensing a voltage applied to both ends of the plasma torch;
a first band-pass filter for passing signals of a preset frequency band to the voltage signal sensed by the voltage sensor and attenuating signals of other frequency bands; and
and a voltage signal output buffer serving as a voltage amplifier for stabilizing an output signal of the first bandpass filter.
3. The method of claim 2,
The current sensing unit,
a current sensor for sensing a current flowing into or flowing out of the plasma torch;
a second band-pass filter for passing signals of a preset frequency band to the current signal sensed by the current sensor and attenuating signals of other frequency bands; and
and a current signal output buffer serving as a current amplifier for stabilizing an output signal of the second bandpass filter.
4. The method of claim 3,
The current sensor is connected between the plasma DC power supply device and the anode electrode of the plasma torch to sense the current flowing into the plasma torch, or the plasma DC power supply device and the plasma DC power supply device to detect the current flowing out of the plasma torch A plasma torch state sensing device connected between the cathode electrode of the plasma torch.
4. The method of claim 3,
The comparison / analysis unit,
an A/D converter that receives output signals (analog signals) from the voltage signal output buffer and the current signal output buffer, respectively, and converts them into digital data;
The voltage value and current value respectively converted into digital data by the A/D converter are received, respectively, the voltage value (V _t ) and the current value (I _t ) sensed at a specific time point (t) are displayed at a point before the specific time point ( The state of wear or deformation of the cathode of the plasma torch by comparing/analyzing the voltage value (V _t-1 ) and the current value (I _{t-1 ) respectively sensed at t-1) and detecting a change in the voltage value or current value} a microcontroller that detects; and
Plasma torch state sensing device configured to include an information transmitting/receiving unit for transmitting the information sensed by the microcontroller to a central control unit of a gas scrubber that purifies and discharges various gases generated during the semiconductor manufacturing process. delete delete delete delete delete

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