KR20100098097A - Apparatus and method for plasma ignition and power control - Google Patents

Abstract

PURPOSE: A method for plasma ignition and power control and a device thereof are provided to execute plasma ignition and power control by actively varying output power according to the variation of a load or the variation of the power consumption of an AC switching power. CONSTITUTION: A controller initializes a variable n for counting the number of times of a trial for ignition to 1(S10). A first high frequency pulse is supplied to a plasma generator by controlling an AC switching power(S20). The ignition state of plasma due to the high frequency pulsing is determined in the inside of a plasma chamber(S30). The variable n is increased to n=n+1. A high frequency pulse for the plasma ignition is generated again(S40). The plasma ignition failure message is transferred to a system controller or an administrator(S50). An ignition process is completed(S60). A power control processor is started(S70).

Description

Method and apparatus for plasma ignition and power control {APPARATUS AND METHOD FOR PLASMA IGNITION AND POWER CONTROL}

The present invention relates to a method and apparatus for plasma ignition and power control. Specifically, a stable initial plasma ignition by high frequency pulsation can be obtained, and the variation of load or power consumption of AC switching power in power supply after plasma ignition can be obtained. A method and apparatus for improved plasma ignition and power control that can actively change output power in response to changes to prevent damage to AC switching power supplies.

Plasma discharges are used for gas excitation to generate active gases containing ions, free radicals, atoms, molecules. There are several plasma sources for generating plasma, such as capacitively coupled plasma sources using radio frequencies and inductively coupled plasma sources. Inductively coupled plasma sources include inductive antennas and transformers. The active gas is widely used in various fields, and typically, variously used in semiconductor manufacturing processes such as etching, deposition, cleaning, and ashing. In recent years, wafers and LCD glass substrates for the manufacture of semiconductor devices are becoming larger. Therefore, there is a need for a plasma source that has a high controllability to plasma ion energy and has a large area processing capability.

Stable initial ignition of plasma is a very important issue directly related to productivity. If the plasma ignition fails for any reason, the productivity will be lowered because the process stops. That is, the steps that have been performed before the plasma ignition step may need to be processed again. In this case, the process fails and must be initialized again to restart the process. As wafers and LCD glass substrates become more and more large, the loss rate for one process failure becomes higher.

On the other hand, the plasma reactor has a power source for providing radio frequency power. In general, the power supply source has a protection circuit for preventing damage caused by abnormal conditions such as short circuit or disconnection occurring on the load side. By the way, in the case of a power supply that provides a constant voltage or constant current output, only constant current control is possible when the load is short or near low impedance. In this state, if the prescribed constant current is outputted, the power supply may exceed the allowable loss of the amplification unit, and the power supply may be damaged. In addition, in the case of a power supply providing a constant power output, the load is controlled in a short circuit or a disconnected state, and the protection function is performed only within the maximum allowable set value or set current limit by the reflected wave. Therefore, except when the limit by the reflected wave is set to be extremely reduced, the power supply source is normally set when the power loss limit of the amplification part of the power supply is exceeded because 10 to 20% of the rated output of the power supply is set as the reflected wave power allowance. Will be damaged.

In particular, in the case of a plasma reactor using an AC switching power supply which does not have an impedance matching device and performs output power control, more active power control is required for more effective initial plasma ignition and stable power supply after plasma ignition.

An object of the present invention is to obtain a stable initial plasma ignition by high-frequency pulsing, and to actively change the output power in accordance with the load change or the power consumption of the AC switching power in the power supply after the plasma ignition by To provide a method and apparatus for improved plasma ignition and power control that can prevent damage.

One aspect of the present invention for achieving the above technical problem relates to a plasma ignition and power control method. The plasma ignition and power control method of the present invention comprises the steps of: providing a plasma chamber comprising a discharge gas; Providing a plasma generator supplying induced electromotive force for plasma discharge into the plasma chamber; Providing an AC switching power supply for supplying high frequency power to the plasma generator; And inducing plasma ignition by providing a high frequency pulse generated from the AC switching power supply to the plasma generator.

The method may further include inducing plasma ignition by providing a high frequency pulse generated again from the AC switching power supply to the plasma generator when the plasma ignition is not performed in the plasma chamber.

In one embodiment, after plasma ignition, the method further includes the step of variably controlling the output power of the AC switching power supply to the impedance of the load.

In an embodiment, the step of variably controlling the output power of the AC switching power source by correlating the impedance of the load may include detecting an impedance value of the load; Determining the impedance state of the load by comparing the detected impedance value with a reference value; When the load state is determined to be a high impedance state, adjusting the output of the AC switching power supply within a power allowance reference value based on the high impedance value of the load; And if the load state is determined to be a low impedance state, adjusting the output of the AC switching power supply within a power tolerance reference value based on the low impedance value of the load.

In one embodiment, after the plasma ignition, the method further comprises the step of variably controlling the output power of the AC switching power supply correlated with the power consumption of the AC switching power supply.

In an embodiment, the step of variably controlling the output power of the AC switching power supply to the power consumption of the AC switching power supply may include detecting input power and output power of the AC switching power supply, respectively; Measuring the power consumption of the AC switching power supply based on the detected input power and output power; When the measured power consumption exceeds the power consumption reference value of the AC switching power supply, the output of the AC switching power supply is limited.

In one embodiment, the plasma generator consists of a transformer coupled plasma source comprising a primary winding electrically connected to the AC switching power supply and a magnetic core wound around the primary winding.

In one embodiment, the plasma generator consists of an inductively coupled plasma source comprising a radio frequency antenna electrically connected to the AC switching power supply.

In one embodiment, the plasma generator is comprised of a capacitively coupled plasma source comprising a capacitively coupled electrode electrically connected to the AC switching power supply.

In one embodiment, the method further comprises an ignition electrode generating free charge for plasma ignition into the plasma chamber in response to the high frequency pulse.

Another aspect of the invention relates to an apparatus for plasma ignition and power control. According to one aspect of the present invention, a plasma reactor includes: a plasma chamber including a discharge gas; A plasma generator supplying induced electromotive force for inducing plasma discharge into the plasma chamber; An AC switching power supply for supplying high frequency power to the plasma generator; And a control unit controlling the AC switching power supply to generate a high frequency pulse for plasma ignition and to be supplied to the plasma generator.

In one embodiment, further comprising a load impedance detecting means for detecting the load impedance of the AC switching power supply, wherein the control unit outputs the output of the AC switching power supply based on the load impedance value detected from the load impedance detecting means. Restrict.

In one embodiment, the apparatus further includes power consumption measuring means for measuring power consumption of the AC switching power supply, and the controller is configured to perform the power consumption based on the power consumption value of the AC switching power measured through the power consumption measuring means. Limit the output of the AC switching power supply.

According to the method and apparatus for plasma ignition and power control of the present invention, stable initial plasma ignition by high frequency pulsing can be obtained, and active according to the load variation or the power consumption of the AC switching power supply in the power supply after plasma ignition. By varying the output power, it is possible to prevent damage to the AC switching power supply, thereby enabling improved plasma ignition and power control.

In order to fully understand the present invention, preferred embodiments of the present invention will be described with reference to the accompanying drawings. Embodiment of the present invention may be modified in various forms, the scope of the invention should not be construed as limited to the embodiments described in detail below. This embodiment is provided to more completely explain the present invention to those skilled in the art. Therefore, the shape of the elements in the drawings and the like may be exaggerated to emphasize a more clear description. It should be noted that the same members in each drawing are sometimes shown with the same reference numerals. Detailed descriptions of well-known functions and constructions which may be unnecessarily obscured by the gist of the present invention are omitted.

1 is a block diagram showing the main configuration of a plasma reactor according to a preferred embodiment of the present invention.

Referring to FIG. 1, a plasma reactor 10 according to a preferred embodiment of the present invention is for supplying induced electromotive force for plasma discharge into a plasma chamber 30 and a plasma chamber 30 forming a plasma discharge space. And a plasma generator 20. The plasma generator 20 is driven by receiving high frequency power from the AC switching power supply 60. In particular, in the initial plasma ignition step, the AC switching power supply 60 is controlled by the controller 80 to generate a high frequency pulse to generate a plasma generator ( The plasma ignition is performed inside the plasma chamber 30 by supplying the same to the 20. A detailed description will be made later, but after the plasma ignition, the AC switching power supply 60 actively controls output power based on a change in impedance of a load or a change in power consumption thereof.

Plasma ignition is basically achieved by high frequency pulsing supplied to the plasma generator 20, but an ignition electrode 40 for generating free charge for plasma ignition may be provided inside the plasma chamber 30. The ignition electrode 40 generates free charge for plasma ignition into the plasma chamber 30 in response to the high frequency pulse. For example, if the plasma generator 20 consists of a transformer coupled plasma source (see FIG. 4 or FIG. 5), the ignition electrode 40 is connected to another ignition coil (not shown) wound around the magnetic core 22. And generate free charge for plasma ignition into the plasma chamber 30 in response to the high frequency pulse applied to the primary winding 24.

FIG. 2 is a waveform diagram illustrating a plasma ignition step by high frequency pulsing, and FIG. 3 is a flowchart of the plasma ignition process.

2 and 3, in order to control the initial plasma ignition of the plasma reactor 10, the controller 80 sets the variable n for counting the number of ignition attempts to n = 1 when the ignition process is started in step S10. Initialize In operation S20, the AC switching power supply 60 is controlled to supply the first high frequency pulse to the plasma generator 20 (t1). In step S30, it is determined whether the plasma is ignited in the plasma chamber 30 by the high frequency pulsing. Detection of whether the plasma is ignited, for example, may be made using the load impedance detector 70 connected to the output terminal 64 or detected using the plasma sensor 50.

If the plasma ignition is not performed, the control proceeds to step S40 to increase the variable n to n = n + 1 and to repeat step S20 to generate the high frequency pulse for plasma ignition again (t2, t3) to restart the plasma ignition. Try. The plasma ignition retry may be repeated up to m times of the maximum number of repetitions. The maximum number of repetitions m is variable. If the plasma ignition is not performed even after retrying the plasma ignition up to the maximum number of repetitions, the process proceeds to step S50 to notify the system controller (not shown) or the operator of the plasma ignition failure. When plasma ignition is performed (t4), the control proceeds to step S60 to end the ignition process and starts the power control process (t5) in step S70.

The AC switching power supply 60 performs the repeated high frequency pulsing operation under the control of the controller 80 until the plasma ignition is performed. 2 shows a case where high frequency pulsing is performed three times and plasma ignition is performed at the third time. The high frequency pulsing operation of the AC switching power supply 60 is performed in synchronization with the ignition clock Ignition CLK, and the energy level of the high frequency pulse is determined according to the duty ratio of the ignition clock Ignition CLK. If the ignition is not performed, the impedance of the load is very high and the high voltage due to the energy accumulation of the load and the superposition of the traveling wave and the reflected wave is induced to the load side by repeated high frequency pulsing to increase the plasma ignition probability. When plasma ignition is performed (t4), the load is stabilized to a low impedance state through the transients t4 to t5 in the high impedance state.

4 to 7 are diagrams illustrating a plasma reactor having various kinds of plasma generators.

First, as shown in FIG. 4, the plasma generator 20a mounted in the plasma reactor 10 of the present invention includes a magnetic core 22 surrounding a part of the annular plasma chamber 30a and a primary winding wound thereon. 24 may be configured as a transformer coupled plasma source. The plasma P is guided along the annular plasma chamber 30a. Alternatively, as shown in FIG. 5, the plasma generator 20b may include a magnetic core 22 embedded in the hollow plasma chamber 30b and a primary winding 24 wound thereon. The magnetic core 22 and the primary winding 24 are wrapped and protected by the core cover 26. The plasma P is guided inside the plasma chamber 30b to surround the core cover 26. As another example, as shown in FIG. 6, the plasma reactor 10 may be composed of a plasma generator 20c having a radio frequency antenna constituting an inductively coupled plasma source. Alternatively, as shown in FIG. 7, the plasma generator 20d may be configured as a capacitively coupled plasma source including capacitively coupled electrodes 23 and 25 mounted in the hollow plasma chamber 30d. It may be.

8 and 9 are block diagrams of an active control circuit for controlling the output power according to the impedance variation of the load and a flowchart of the control method thereof.

Referring to FIG. 8, the plasma reactor 10 of the present invention is configured to limit the output of the AC switching power supply 60 to correlate with the impedance variation of the load after plasma ignition by the high frequency pulsing as described above. ) And an impedance comparison circuit 90.

The AC switching power supply 60 converts the power input through the input terminal 62 and outputs the converted power through the output terminal 64 to the load (plasma generator 20). The load impedance detector 70 is configured between the AC switching power supply 60 and the output terminal 64 and detects the impedance of the load connected to the output terminal 64. The impedance comparison circuit 90 compares the load impedance value detected by the load impedance detection unit 70 with the reference impedance value and provides the result to the controller 80. The impedance comparison circuit 90 includes a first impedance comparison circuit 94 for detecting a high impedance state of a load and a second impedance comparison circuit 96 for detecting a low impedance state of a load.

The first impedance comparison circuit 94 compares the high impedance reference value set in the first reference value setting unit 95 with the impedance detection value provided from the load impedance detection unit 70 to determine whether the electrical state of the load is a high impedance state. . The second impedance comparison circuit 96 compares the low impedance reference value set in the second reference value setting unit 97 with the impedance detection value provided from the load impedance detection unit 70 to determine whether the electrical state of the load is a low impedance state. .

The controller 80 controls the AC switching power supply 60 so that the output of the AC switching power supply 60 is adjusted up or down within the power allowance reference value based on the result value compared from the impedance comparing unit 70. Control of the AC switching power supply 60 is, for example, adjusting the output of the internal output amplifier (not shown) up or down within the power tolerance threshold.

Referring to FIG. 9, after the plasma ignition is normally performed, the controller 80 starts the power control process in step S80. In step S81, the load impedance detection unit 70 detects an impedance value of the load connected to the output terminal 64, and the detected impedance value is provided to the impedance comparison circuit 90. The impedance comparison circuit 90 compares the detected impedance value with a reference value to determine an impedance state of the load, and provides the result to the controller 80.

If it is determined in step S82 that the electrical state of the load is a high impedance state, the control unit 40 proceeds to step S83 to output the output of the output amplifier of the AC switching power supply 60 within the power tolerance reference value based on the high impedance value of the load. Adjust upward Alternatively, if it is determined in step S82 that the electrical state of the load is a low impedance state, the process proceeds to step S84 and adjusts the output of the output amplifier of the AC switching power supply 60 within the power tolerance reference value based on the detected low impedance value of the load. do.

10 and 11 are block diagrams of an active control circuit for controlling output power according to power consumption variation of an AC switching power supply and a control method flowchart thereof.

Referring to FIG. 10, as another example, the plasma reactor 10 of the present invention may control the control of the output power of the AC switching power supply 60 in relation to the power consumption of the AC switching power supply 60. To this end, the input power detector 100 and the output power detector 102 are provided.

The AC switching power supply 60 converts input power through the input terminal 62 and outputs the converted power through the output terminal 64 to the load. The input power detector 100 is configured between the input terminal 62 and the AC switching power supply 60 to detect a power value input to the AC switching power supply 60 through the input terminal 62. The output power detector 102 is configured between the output terminal 64 and the AC switching power supply 60 to detect a power value output through the output terminal 16. The input power value and the output power value detected by the input power detector 100 and the output power detector 102 are respectively provided to the controller 80.

The controller 40 receives the input power value and the output power value of the AC switching power supply 60 detected by the input power detector 50 and the output power detector 52 to measure the power consumption of the AC switching power supply 60. do. Then, if necessary, the AC switching power supply 60 is controlled based on the measured power consumption to limit the output power. Control of the AC switching power supply 60 is such that, for example, the output of the output amplifier of the AC switching power supply 60 is adjusted up or down within the power tolerance threshold.

Referring to FIG. 11, after the plasma ignition is normally performed, the controller 80 starts the power control process in step S90. In step S91, the input power value and the output power value of the AC switching power supply 60 detected by the input power detector 100 and the output power detector 102 are provided to the controller 80. In step S92, the controller 80 measures the power consumption of the AC switching power supply 60 based on the input power value and the output power value provided from the input power detector 100 and the output power detector 102. Subsequently, in step S93, the controller 80 determines whether the measured power consumption exceeds a predetermined power consumption reference value of the AC switching power supply 60. If the measured power consumption value exceeds the preset power consumption reference value, the output of the AC switching power supply 60 is limited in step S94.

As described above, the plasma reactor 10 having the active protection circuit actively raises the output of the output amplifier of the AC switching power supply 60 within the power allowance reference value when a mismatch condition of the load occurs due to a change in the impedance of the load. Alternatively, the AC switching power supply 60 can be safely operated by adjusting downward. Alternatively, the AC switching power supply 60 may be safely operated by actively adjusting the output limit reference value of the output amplifier of the AC switching power supply 60 within the power allowance reference value according to the change in the power consumption of the AC switching power supply 60. have.

The method of limiting the output of the AC switching power supply 60 as described above may be implemented in many cases. For example, when the output amplifier of the AC switching power supply 60 is used as a linear amplifier, a method of restricting the input of the linear amplifier and consequently the output, or a power supply to the linear amplifier (for example, , DC voltage, etc.) to limit the output, or to adjust the gain of the linear amplifier. In addition, the method of limiting the output in response to the change in the impedance of the load and the method of limiting the output in response to the change in the power consumption of the AC switching power supply 60 may be mixed. That is, the output of the AC switching power supply 60 can be actively limited based on the variation in the impedance of the load and the change in power consumption of the AC switching power supply 60, respectively.

The plasma reactor 10 of the present invention does not use a separate impedance matcher for impedance matching between the AC switching power supply 60 and the plasma generator 20. Therefore, the output of the AC switching power supply 60 is actively limited in accordance with the change in the impedance of the load. The impedance of the load is lowered after the initial plasma ignition, and the impedance may be changed by various factors such as an increase in gas supply. Therefore, when the impedance of the load is lowered, by limiting the output of the AC switching power supply 60 to lower the load impedance naturally, it is possible to solve the mismatch state. That is, the impedance increase effect of the load can be obtained at low power, and an appropriate match point can be found to effectively supply power. Such an output limit of the AC switching power supply 60 is to be actively interlocked according to the state of the impedance of the load.

Embodiments of the method and apparatus for plasma ignition and power control of the present invention described above are merely illustrative, and various modifications and equivalent implementations may be made by those skilled in the art to which the present invention pertains. You can see that examples are possible. Accordingly, it is to be understood that the present invention is not limited to the above-described embodiments. Therefore, the true technical protection scope of the present invention will be defined by the technical spirit of the appended claims. It is also to be understood that the present invention includes all modifications, equivalents, and substitutes within the spirit and scope of the invention as defined by the appended claims.

1 is a block diagram showing the main configuration of a plasma reactor according to a preferred embodiment of the present invention.

2 is a waveform diagram illustrating a plasma ignition step by high frequency pulsing.

3 is a flow chart of a plasma ignition process.

4 to 7 are diagrams illustrating a plasma reactor having various kinds of plasma generators.

8 and 9 are a block diagram of an active control circuit for controlling the output power in accordance with the impedance variation of the load and a flowchart of the control method thereof.

10 and 11 are block diagrams of an active control circuit for controlling output power according to power consumption conversion of an AC switching power supply and a control method flowchart thereof.

* Description of the symbols for the main parts of the drawings *

10: plasma reactor 20: plasma generator

21: ignition electrode 22: magnetic core

24: primary winding 30: plasma chamber

32: gas inlet 34: gas outlet

40: ignition electrode 50: plasma sensor

60: AC switching power supply 62: input stage

64: output stage 70: load impedance detection unit

80: control unit 90: impedance comparison circuit

Claims (13)

Providing a plasma chamber comprising a discharge gas; Providing a plasma generator supplying induced electromotive force for plasma discharge into the plasma chamber; Providing an AC switching power supply for supplying high frequency power to the plasma generator; And Providing a high frequency pulse generated from the AC switching power supply to the plasma generator to induce plasma ignition. According to claim 1, When plasma ignition is not performed inside the plasma chamber, And re-inducing plasma ignition by providing a high frequency pulse generated again from the AC switching power supply to the plasma generator. According to claim 1, And after plasma ignition, variably controlling the output power of the AC switching power supply to the impedance of the load. The method of claim 3, Variably controlling the output power of the AC switching power source by correlating the impedance of the load Detecting an impedance value of the load; Determining the impedance state of the load by comparing the detected impedance value with a reference value; When the load state is determined to be a high impedance state, adjusting the output of the AC switching power supply within a power allowance reference value based on the high impedance value of the load; And And down-adjusting the output of the AC switching power supply within a power allowance reference value based on the low impedance value of the load when the load state is determined to be a low impedance state. According to claim 1, And after plasma ignition, variably controlling the output power of the AC switching power supply with the power consumption of the AC switching power supply. 6. The method of claim 5, Variably controlling the output power of the AC switching power supply to the power consumption of the AC switching power supply Detecting an input power and an output power of the AC switching power supply, respectively; Measuring the power consumption of the AC switching power supply based on the detected input power and output power; And limiting the output of the AC switching power supply when the measured power consumption exceeds the power consumption reference value of the AC switching power supply. According to claim 1, The plasma generator And a transformer coupled plasma source comprising a primary winding electrically connected to the AC switching power supply and a magnetic core wound around the primary winding. According to claim 1, The plasma generator And an inductively coupled plasma source comprising a radio frequency antenna electrically connected to the AC switching power supply. According to claim 1, The plasma generator And a capacitively coupled plasma source comprising a capacitively coupled electrode electrically connected to the AC switching power supply. According to claim 1, And an ignition electrode for generating free charge for plasma ignition into the plasma chamber in response to the high frequency pulse. A plasma chamber containing a discharge gas; A plasma generator supplying induced electromotive force for inducing plasma discharge into the plasma chamber; An AC switching power supply for supplying high frequency power to the plasma generator; And And a control unit controlling the AC switching power supply to generate a high frequency pulse for ignition of plasma and to be supplied to the plasma generator. 12. The method of claim 11, Load impedance detecting means for detecting a load impedance of the AC switching power supply, And the control unit limits the output of the AC switching power supply based on the load impedance value detected from the load impedance detecting means. 12. The method of claim 11, Power consumption measuring means for measuring power consumption of the AC switching power source, And the control unit limits the output of the AC switching power supply based on the power consumption value of the AC switching power measured by the power consumption measuring means.

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