JP2008066319A - Plasma treatment apparatus and plasma treatment method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To perform stable plasma treatment to a substrate by stabilizing plasma in a treatment vessel, when treating the substrate by applying high-frequency power and a DC voltage to identical or separate electrodes. <P>SOLUTION: A plasma treatment apparatus 1 comprises: a high-frequency power supply 16 for applying high-frequency power to at least one of electrodes 5, 6; a DC power supply 22 for applying a DC voltage to at least one of the electrodes 5, 6; a matching circuit 15 provided between the electrode 5 to which high-frequency power is applied, and the high-frequency power supply 16; and a control unit 25 for controlling the high-frequency power supply 16 so that the high-frequency power applied to the electrode is adjusted in advance at timing when the application of a DC voltage to the electrode 5 by the DC power supply 22 is started or completed while high-frequency power is applied to the electrode 5 by the high-frequency power supply 16. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a plasma processing apparatus that has one or more electrodes in a processing container, supplies high frequency power to at least one of the high frequency electrodes to generate plasma in the processing container, and processes a substrate. The present invention relates to a plasma processing method.

  For example, plasma processing is widely used in substrate processing such as etching and film formation in manufacturing processes of semiconductor devices and liquid crystal display devices.

  The plasma processing is usually performed by a plasma processing apparatus. In this plasma processing apparatus, for example, electrodes that are vertically opposed to each other are provided in a processing container. By supplying high-frequency power to one or both of these electrodes, plasma is generated and plasma processing of a substrate is performed. Is to be done.

  In recent years, in addition to applying high-frequency power from a high-frequency power source to the electrodes in the processing vessel via a matching unit, plasma processing technology has been developed for applying a DC voltage from a DC power source to the electrodes in the processing vessel for various purposes. I came. Patent Document 1 discloses a plasma processing technique for facilitating plasma ignition by applying a DC voltage to an upper electrode before applying high-frequency power to each of an upper electrode and a lower electrode provided facing each other in the processing container. Is disclosed.

  Further, in Patent Document 2, plasma is generated by applying a high frequency power to each of an upper electrode and a lower electrode provided facing each other in a processing container and applying a DC voltage to the upper electrode to raise a self-bias voltage. A plasma processing technique for making plasma uniform by increasing the thickness of the sheath is disclosed.

JP 2003-124198 A JP 2000-323460 A

  However, the plasma processing techniques described in Patent Documents 1 and 2 do not consider the influence of the start or end of application of a DC voltage to the electrodes on the high-frequency power applied to the same or separate electrodes. In practice, when a DC voltage is applied to the same or separate electrodes while high-frequency power is applied to the electrodes by the high-frequency power supply, the impedance of the plasma generated by the high-frequency power changes suddenly, and a large reflected energy returns to the high-frequency power supply. Will be. Under such circumstances, the reflection protection circuit of the high frequency power supply is activated and the output of the high frequency power is lowered, so that it is very difficult to control the application operation of the high frequency power by the high frequency power supply and the matching operation of the matching unit. End up. As a result, the plasma in the processing container hunts or disappears in the worst case, and the substrate cannot be stably plasma processed. Furthermore, the plasma becomes non-uniform, and there is a risk of causing charge-up damage to the substrate.

  The present invention has been made in view of the above problems, and when processing a substrate by applying high-frequency power and DC voltage to the same or separate electrodes, the plasma in the processing vessel is stabilized, and the substrate is stabilized. It is an object of the present invention to provide a plasma processing apparatus and a plasma processing method capable of performing plasma processing.

  In order to solve the above-described problems, according to the present invention, the processing container has one or more electrodes, and high-frequency power is supplied to at least one of the electrodes to generate plasma in the processing container, A plasma processing apparatus for processing, a high-frequency power source that applies high-frequency power to at least one of the one or more electrodes, a DC power source that applies a DC voltage to at least one of the one or more electrodes, and the high-frequency power In a state where high frequency power is applied to the electrode by the high frequency power supply and the matching device provided between the electrode to which the high frequency power supply is applied, application of a DC voltage to the electrode by the DC power supply is started or And a control device that controls the high-frequency power source so as to preliminarily adjust the high-frequency power applied to the electrode at the timing of termination. Zuma processing apparatus is provided.

  In the plasma processing apparatus, when the high-frequency power applied to the electrode by the high-frequency power source is adjusted in advance, the high-frequency power applied to the electrode may be adjusted to be lowered.

  In the plasma processing apparatus, the control device performs a matching operation at a timing at which application of a DC voltage to the electrode by the DC power supply is started or ended in a state in which high-frequency power is applied to the electrode by the high-frequency power supply. The matching unit may be controlled so as to adjust in advance.

  In the plasma processing apparatus, when the matching operation of the matching unit is adjusted in advance, the matching may be adjusted based on the prediction of the plasma change in the processing container.

  In the plasma processing apparatus, the control device previously stores information on a timing at which application of a DC voltage to the electrode by the DC power supply is started or ended, or information on a DC voltage applied to the electrode by the DC power supply. It may be held.

  The said plasma processing apparatus WHEREIN: The said control apparatus may control the said DC power supply so that the application of the DC voltage to the said electrode may be started or complete | finished.

  In the plasma processing apparatus, the controller is configured to start or end the application of high-frequency power to the electrode by the high-frequency power supply in a state where a direct-current voltage is applied to the electrode by the direct-current power supply. The matching unit may be controlled so as to perform a matching operation in consideration of the influence on the plasma by the DC voltage applied to the.

  In addition, according to the present invention, there is provided a plasma processing method for processing a substrate by generating a plasma in a processing container by supplying high frequency power to at least one of one or more electrodes provided in the processing container. Applying high-frequency power to at least one of the one or more electrodes, applying a direct-current voltage to at least one of the one or more electrodes, and applying the direct-current voltage in a state where the high-frequency power is applied to the electrodes. A plasma processing method is provided in which the high-frequency power applied to the electrode is adjusted in advance at a timing at which is started or ended.

  In the said plasma processing method, when adjusting the high frequency electric power applied to the said electrode previously, you may adjust so that the high frequency electric power applied to the said electrode may be reduced.

  In the plasma processing method, the high-frequency power is applied to the electrode while matching impedance between the plasma in the processing container and a high-frequency power source that supplies the high-frequency power, and the high-frequency power is applied to the electrode. In this state, the impedance matching may be adjusted in advance at the timing when the application of the DC voltage to the electrode starts or ends.

  In the plasma processing method, when the impedance matching is adjusted in advance, the impedance may be adjusted based on prediction of a change in plasma in the processing container.

  In the plasma processing method, in the state where a DC voltage is applied to the electrode, when the application of the high frequency power to the electrode is started or terminated, the influence of the DC voltage applied to the electrode on the plasma is considered. Then, the impedance matching may be performed.

  According to the present invention, in the state where high-frequency power is applied to the electrode, when the application of the DC voltage to the electrode that is the same as or different from this electrode is started or terminated, the electrode is considered in consideration of the influence of the DC voltage application operation. By preliminarily adjusting the high frequency power applied to, it is possible to prevent the application operation of the high frequency power supply and the matching operation of the matching unit from becoming unstable. Thereby, the plasma in the processing container can be stabilized, and the substrate can be stably plasma-processed.

  Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings. In the present specification and drawings, elements having substantially the same functional configuration are denoted by the same reference numerals, and redundant description is omitted.

  FIG. 1 is a configuration diagram of a plasma etching apparatus 1 as a plasma processing apparatus according to an embodiment of the present invention. As shown in FIG. 1, the plasma etching apparatus 1 includes a processing container 2 having a substantially cylindrical shape, for example. A processing space K is formed inside the processing container 2. The wall C2 of the processing container 2 is grounded for safety. In the processing container 2, an upper electrode 5 and a lower electrode 6 are arranged to face each other. The upper electrode 5 and the lower electrode 6 have a substantially disk shape and are made of a conductive material. An insulator C1 is interposed between the upper electrode 5 and the wall C2. The lower electrode 6 also serves as a mounting table for the substrate W. Processing gas is supplied to the processing space K through the gas supply path 10 and the upper electrode 5 that also functions as a shower head. Further, the processing gas in the processing space K is exhausted through the gas exhaust path 11.

  A high frequency power source 16 is electrically connected to the upper electrode 5 via a matching unit 15. The high frequency power supply 16 can apply high frequency power having a frequency of, for example, 60 MHz to the upper electrode 5 so that the processing gas in the processing space K is turned into plasma. The matching unit 15 can match impedance between the plasma generated in the processing space K and the high-frequency power source 16.

  A DC power source 22 is electrically connected to a connection point 20 between the matching unit 15 and the upper electrode 5 via a low-pass filter 21, and a DC voltage can be applied to the upper electrode 5. Note that a capacitor (not shown) is provided in series in the matching unit 15.

  The high frequency power supply 16, the matching unit 15, and the DC power supply 22 are connected to the stabilization control device 25. The stabilization control device 25 is configured to apply high-frequency power to the upper electrode 5 by the high-frequency power source 16, to perform impedance matching operation between the high-frequency power source 16 and the plasma in the processing space K by the matching unit 15, and the upper portion by the DC power source 22. It is possible to stabilize the plasma treatment of the substrate W by controlling the operation of applying a DC voltage to the electrode 5 as described later.

  For example, a high frequency power supply 31 that supplies high frequency power having a frequency of 2 MHz is electrically connected to the lower electrode 6 through a matching unit 30. The high-frequency power source 31 can apply high-frequency power having a frequency of, for example, 2 MHz to the lower electrode 6 so as to draw ions in the plasma generated in the processing space K into the lower electrode 6. The matching unit 30 can match impedance between the plasma generated in the processing space K and the high-frequency power source 31.

  Next, a method of plasma etching the substrate W as an example of the plasma processing method according to the embodiment of the present invention using the plasma etching apparatus 1 configured as described above will be described with reference to FIG.

  First, as shown in FIG. 1, the substrate W is carried into the processing container 2 and placed on the lower electrode 6. Exhaust is performed from the exhaust path 11, the inside of the processing container 2 is depressurized, and a predetermined processing gas is supplied from the gas supply path 10 through the upper electrode 5 into the processing container 2.

A high frequency power having a plasma generation frequency of 60 MHz is applied to the upper electrode 5 by the high frequency power supply 16 via the matching unit 15. Thereby, the processing gas in the processing space K is turned into plasma. Next, high frequency power having a frequency of 2 MHz is supplied to the lower electrode 6 from the high frequency power supply 31 via the matching unit 30, and ions in the generated plasma are drawn into the substrate W, whereby the surface film of the substrate W is etched. Is done. Further, a DC voltage is applied to the upper electrode 5 by the DC power source 22 so as to increase the self-bias voltage V _SB of the upper electrode 5 to make the plasma uniform. After the etching is performed for a predetermined time, the supply of the high frequency power and the direct current voltage is stopped, the substrate W is unloaded from the processing container 2, and a series of plasma etching processes is completed.

During the series of plasma etching processes described above, the stabilization controller 25 controls the application operation of the DC power supply 22, the application operation of the high frequency power supply 16, and the matching operation of the matching unit 15. FIG. 2 is a timing chart showing the application operation of the DC power supply 22, the application operation of the high-frequency power supply 16, and the matching operation of the matching unit 15 controlled by the stabilization control device 25 during plasma etching. In FIG. 2, the horizontal axis direction indicates the passage of time, and the vertical axis directions respectively indicate the DC voltage value V _DC applied to the upper electrode 5 by the DC power source 22 and the high frequency power applied to the upper electrode 5 by the high frequency power source 16. It shows voltage values V _RF, the value Z _p of the prediction impedance of the plasma in the processing space _K, and matching device 15 is the change in the value Z _m of the actual impedance Z and the impedance of the high frequency power source 16 side to match the plasma, respectively. Note that the predicted impedance value Z _p of the plasma is a predicted value that is calculated in advance by the stabilization control device 25 that controls the application operation of the high-frequency power supply 16 and the DC power supply 22 before the application operation is performed. When calculating the predicted impedance value Z _p of the plasma, the self-bias voltage V _SB of the upper electrode 5 may be measured using a measuring device (not shown) and calculated based on the measured value.

In FIG. 2, the DC voltage V _DC and the voltage V _RF indicate a high value on the vertical axis and a low value on the vertical axis. On the other hand, the impedance Z _m of the predicted impedance Z _p and the matching device 15 of the plasma vertical on the axis direction indicates a lower value under the vertical axis direction indicates a high value. Hereinafter, the application operation of the DC power source 22, the application operation of the high-frequency power source 16 and the matching operation of the matching unit 15 controlled by the stabilization controller 25 will be described with reference to FIG. In the following, in order to simplify the description, the high-frequency power applied to the lower electrode 6 by the high-frequency power supply 31 will not be described in detail, but depending on the operation of applying the voltage V _RF to the upper electrode 5 by the high-frequency power supply 16. The application operation to the lower electrode 6 by the high frequency power supply 31 is performed as appropriate.

First, in the initial state (time A1 shown in FIG. 2), the high frequency power from the high frequency power supply 16 and the DC voltage from the DC power supply 22 are not supplied to the upper electrode 5. That is, the value of the voltage V _RF applied to the upper electrode 5 by the high frequency power supply 16 and the value of the DC voltage V _DC applied to the upper electrode 5 by the DC power supply 22 are both zero. Therefore, in this point A1, since in the processing container 2 plasma has not yet occurred, it does not indicate the predicted impedance Z _p of the plasma. The matcher 15 for controlling the impedance Z _m of the high frequency power source 16 side does not operate.

Application of the voltage V _RF from the high frequency power supply 16 to the upper electrode 5 is started by the control of the stabilization control device 25 (time point A2 shown in FIG. 2), and the value of the voltage V _RF is increased at a predetermined increase rate. When the voltage V _RF reaches a predetermined value (time point A3 shown in FIG. 2), the voltage V _RF is held at the predetermined value. By the application of a voltage V _RF, since the processing chamber 2 increases in plasma is generated from the process gas, the predicted impedance Z _p of the calculated plasma has decreased. Further, when the voltage V _RF becomes constant, the predicted impedance Z _p also becomes constant. Matching device 15, based on the actual plasma impedance Z, for matching the impedance Z _m of the high-frequency power supply 16 side, the impedance Z _m represents a generally similar behavior with the predicted impedance Z _p.

After the plasma in the processing container 2 becomes stable, application of the DC voltage _VDC to the upper electrode 5 by the DC power source 22 is started under the control of the stabilization controller 25 (time point A6 shown in FIG. 2). The value of the DC voltage V _DC is increased at a predetermined increase rate. When the DC voltage _VDC reaches a predetermined value (time point A8 shown in FIG. 2), the DC voltage _VDC is held at the predetermined value. This predetermined value may be a value at which the self-bias voltage V _SB of the upper electrode 5 generated by the DC voltage V _DC optimizes the thickness of the plasma sheath, for example.

The stabilization control device 25 preliminarily (before the time point A5 shown in FIG. 2) (time point A5 shown in FIG. 2) starts the application of the DC voltage _VDC by the DC power source 22 described above. The application operation of the high-frequency power supply 16 is controlled so that the voltage V _RF applied to is reduced at a predetermined reduction rate. The voltage V _RF is decreased until the application of the DC voltage V _DC is started (time A6 shown in FIG. 2). Retention after application of the DC voltage V _DC is started, increases the value of the voltage V _RF at a predetermined increase rate, the voltage V _RF reaches a predetermined value (time point shown in FIG. 2 A8) to the predetermined value Control is performed.

Further, the stabilization control device 25 calculates the calculated predicted impedance Z _p before the timing (time A4 shown in FIG. 2) before the application of the DC voltage _VDC described above (time A6 shown in FIG. 2). controlling the matching device 15 to advance executing the application at the start of the matching operation of the predicted DC voltage V _DC (matching operation between time points A6 and A8 of the impedance Z _m shown by a dotted line in FIG. 2) from. More specifically, the thickness of the plasma sheath of the upper electrode 5 is determined from the matcher position of the matching unit 15 before applying the DC voltage _VDC , the output of the high frequency power supply 22 and the peak-to-peak voltage V _PP of the upper electrode 5. Further, the change of the thickness of the plasma sheath according to the application of the DC voltage _VDC (that is, the capacity of the plasma sheath) is calculated, and the matching unit 15 is controlled so that the matching operation based on the calculated result is performed in advance. is doing. After the application of the DC voltage _VDC is started, the matching unit 15 returns to the matching operation based on the actual plasma impedance Z.

As described above, the voltage V _RF applied from the high frequency power supply 16 to the upper electrode 5 and the DC voltage V _DC applied from the DC power supply 22 to the upper electrode 5 are kept constant (FIG. 2). Time point A8). Further, a state in which the predicted impedance Z _p and the matching device 15 of the plasma is held constant the impedance Z _m of the high frequency power source 16 side to match. In this state, the substrate W is etched for a predetermined time.

After the etching of the substrate W is finished, the control of the stabilization control device 25 starts the reduction of the DC voltage V _DC applied to the upper electrode 5 by the DC power source 22 (that is, the operation for finishing the application of the DC voltage V _DC ). (Time A11 shown in FIG. 2). The DC voltage _VDC is reduced at a predetermined reduction rate, and finally, the application of the DC voltage _VDC to the upper electrode 5 by the DC power supply 22 is stopped (time A13 shown in FIG. 2).

The stabilization control device 25 preliminarily (at time A10 shown in FIG. 2) before the timing (time A11 shown in FIG. 2) at which the application of the DC voltage _VDC by the DC power supply 22 is started. The application operation of the high frequency power supply 16 is controlled so as to lower the voltage V _RF applied to the upper electrode 5 at a predetermined reduction rate. The voltage V _RF is lowered until the end of the application of the DC voltage V _DC is started (time A11 shown in FIG. 2). After end operation of the application of the DC voltage V _DC is started, increases the value of the voltage V _RF at a predetermined increase rate, and the predetermined voltage V _RF reaches a predetermined value (time point shown in FIG. 2 A13) Control to keep the value.

Further, the stabilization control device 25 calculates the prediction before the timing (time point A11 shown in FIG. 2) (time point A9 shown in FIG. 2) before the end operation of applying the DC voltage _VDC described above is started. controlling the matching device 15 to execute application at the end of the matching operation of the DC voltage is predicted from the impedance Z _p (the alignment operation between the time points A11 and A13 of the impedance Z _m shown by a dotted line in FIG. 2) in advance. After the application of the DC voltage V _DC is finished, the matching unit 15 returns to the matching operation based on the actual plasma impedance Z.

Next, the end of the application of the voltage V _RF from the high frequency power supply 16 to the upper electrode 5 is started under the control of the stabilization control device 25 (time A14 shown in FIG. 2), and the value of the voltage V _RF becomes a predetermined decrease rate. Is reduced. Eventually, the voltage V _RF is stopped (time A16 shown in FIG. 2). Since the plasma in the processing container 2 decreases due to the reduction of the voltage V _RF , the predicted impedance Z _{p of the} plasma also increases. Matching device 15, based on the actual plasma impedance Z, for matching the impedance Z _m of the high-frequency power supply 16 side, the impedance Z _m represents a generally similar behavior with the predicted impedance Z _p.

  Finally, the supply of the high frequency power from the high frequency power source 16 and the DC voltage from the DC power source 22 to the upper electrode 5 is stopped, and the matching unit 15 is not operating (time point A1 shown in FIG. 2). The same final state (time A16 shown in FIG. 2) is obtained. As described above, the control of the application operation of the DC power supply 22, the application operation of the high frequency power supply 16 and the matching operation of the matching unit 15 by the stabilization control device 25 is completed.

According to the first embodiment described above, in the state where the voltage V _RF is applied to the upper electrode 5 by the high frequency power supply 16 using the stabilization control device 25, the direct current to the upper electrode 5 by the direct current power supply 22 is applied. By controlling the voltage V _RF applied to the upper electrode 5 by the high frequency power supply 16 in advance at the timing when the application of the voltage V _DC is started or ended, the application operation of the DC voltage V _DC is performed by the voltage V _RF. Can be minimized. In particular, since the voltage V _RF applied to the upper electrode 5 is controlled to be lowered in advance before the application of the DC voltage V _DC is started or finished, the reflection returns to the high frequency power supply 16 due to a sudden change in the impedance Z of the plasma. The energy can be reduced, the operation of the reflection protection circuit of the high frequency power supply 16 can be prevented, and the output reduction of the high frequency power can be prevented. Thereby, it is possible to prevent the application operation of the high frequency power supply 16 and the matching operation of the matching unit 15 from becoming unstable. Further, the plasma in the processing container 2 can be stabilized, and the substrate W can be stably plasma-processed.

In addition, by using the stabilization control device 25, the matching operation performed by the matching unit 15 is adjusted in advance at the timing when the application of the DC voltage _VDC to the upper electrode 5 by the DC power source 22 is started or ended. As a result of the control, the influence of the application operation of the DC voltage V _{DC on} the voltage V _RF can be dealt with early, and the control of the matching unit 15 can be prevented from becoming unstable. In particular, when the precondition the alignment operation performed by the matching device 15, by which is adapted to adjust, based on the predicted impedance Z _p of the calculated plasma, to the effects exerted by the operation of applying a direct current voltage V _DC A more appropriate response is possible.

Further, since the stabilization control device 25 controls the high frequency power supply 16, the matching unit 15 and the DC power supply 22, the operation of applying the voltage V _RF to the upper electrode 5 by the high frequency power supply 16 at an optimal timing, The application operation of the DC voltage V _DC to the upper electrode 5 by the DC power supply 22 and the matching operation by the matching unit 15 can be performed, and the influence of the application operation of the DC voltage V _{DC on} the voltage V _RF can be minimized.

  As a second embodiment of the present invention, as shown in FIG. 3, in the state where a DC voltage is applied to the upper electrode 5 by the DC power supply 22, the application of the high frequency power to the upper electrode 5 by the high frequency power supply 16 is started. Alternatively, the high frequency power supply 16 may be controlled so as to perform an application operation in consideration of the influence on the plasma by the DC voltage applied to the upper electrode 5 when the process is terminated.

FIG. 3 shows an application operation of the DC power source 22, an application operation of the high frequency power source 16 and a matching operation of the matching unit 15 controlled by the stabilization control device 25 during plasma etching in the second embodiment of the present invention. It is a timing chart which shows. In FIG. 3, as in the timing chart of FIG. 2, the horizontal axis direction indicates the passage of time, and the vertical axis direction is determined by the DC voltage value V _DC applied to the upper electrode 5 by the DC power source 22 and the high frequency power source 16. The voltage value V _{RF of} the high frequency power applied to the upper electrode 5, the predicted impedance value Z _p of the plasma in the processing space K, and the impedance on the high frequency power supply 16 side that the matching unit 15 matches with the actual impedance Z of the plasma. It shows the change in the value _{Z m.}

In the initial state (time B1 shown in FIG. 3), the high-frequency power from the high-frequency power source 16 and the DC voltage from the DC power source 22 are not supplied to the upper electrode 5. That is, the value of the voltage V _RF applied to the upper electrode 5 by the high frequency power supply 16 and the value of the DC voltage V _DC applied to the upper electrode 5 by the DC power supply 22 are both zero. Therefore, in this point B1, since in the processing container 2 plasma has not yet occurred, it does not indicate the predicted impedance Z _p of the plasma. The matcher 15 for controlling the impedance Z _m of the high frequency power source 16 side does not operate.

As shown in FIG. 3, the direct current voltage V _DC is applied from the direct current power source 22 to the upper electrode 5 under the control of the stabilization control device 25 (time point B2 shown in FIG. 3). The direct voltage _VDC is held at a predetermined value.

Application of the voltage V _RF from the high frequency power supply 16 to the upper electrode 5 is started by the control of the stabilization control device 25 (time B3 shown in FIG. 3), and the value of the voltage V _RF is increased at a predetermined increase rate. When the voltage V _RF reaches a predetermined value (time B4 shown in FIG. 3), the voltage V _RF is held at the predetermined value. By applying the voltage V _RF , plasma is generated from the processing gas in the processing container 2 and increases, so that the predicted impedance Z _{p of the} plasma decreases, and the predicted impedance Z _p also becomes constant when the voltage V _RF becomes constant. . In the second embodiment, since the application of the voltage V _RF is started in a state where the DC voltage V _DC is first applied to the upper electrode 5 and the self-bias voltage V _SB is increased, the voltage V _RF is applied. The plasma has grown rapidly since the start, and the plasma sheath has also become thicker since ignition. Therefore, the predicted impedance Z _p of the calculated plasma, as shown in FIG. 3, than in the first embodiment (between A6 and A8 shown in FIG. 2) rapidly decreases, the voltage V _RF No. The predetermined value is reached earlier than in the first embodiment (time point B4 shown in FIG. 3).

Based on the predicted impedance Z _p calculated as described above, the stabilization control device 25 is configured such that the plasma growth is accelerated by applying the DC voltage V _DC first, and in a stable plasma state, The matching unit 15 is controlled so as to perform the matching operation in consideration of the fact that the plasma sheath is thicker than when the DC voltage _VDC is not applied.

As described above, the voltage V _RF applied from the high frequency power supply 16 to the upper electrode 5 and the DC voltage V _DC applied from the DC power supply 22 to the upper electrode 5 are kept constant (FIG. 3). Time B4) shown in FIG. Further, a state in which the predicted impedance Z _p and the matching device 15 of the plasma is held constant the impedance Z _m of the high frequency power source 16 side to match. In this state, the substrate W is etched for a predetermined time. After the etching is finished, under the control of the stabilization control device 25, the application of the DC voltage V _DC to the upper electrode 5 by the DC power source 22 is stopped, as in the first embodiment shown in FIG. The application of the voltage V _RF to the upper electrode 5 by the power source 16 is sequentially stopped (time points B5 to B10 shown in FIG. 3). Finally, the supply of the high frequency power from the high frequency power supply 16 and the DC voltage from the DC power supply 22 to the upper electrode 5 is stopped, and the matching unit 15 is not operating (time B1 shown in FIG. 3). The same final state (time B11 shown in FIG. 3) is obtained.

According to the second embodiment described above, in the state where the DC voltage V _DC is applied to the upper electrode 5 by the DC power source 22 using the stabilization control device 25, the high frequency power source 16 applies the voltage to the upper electrode 5. When the application of the voltage V _RF is started or ended, the matching unit 15 is controlled so as to perform the matching operation in consideration of the influence on the plasma by the DC voltage V _DC applied to the upper electrode 5. The application operation of the high frequency power supply 16 and the matching operation of the matching unit 15 can be performed more appropriately than in the past. Thereby, it is possible to prevent the application operation of the high frequency power supply 16 and the matching operation of the matching unit 15 from becoming unstable. In the second embodiment, the same effect as that of the first embodiment can be obtained.

  As a third embodiment of the present invention, as shown in FIG. 4, only the DC power source 42 is connected to the upper electrode 5 via a low-pass filter 41, and high frequency power of two different frequencies is supplied to the lower electrode 6. High frequency power supplies 51 and 52 may be connected. The high frequency power source 51 is connected to the lower electrode 6 via the matching unit 50, and the high frequency power source 52 is connected to the lower electrode 6 via the matching unit 53. The frequency of the high frequency power supplied from the high frequency power sources 51 and 52 may be, for example, 100 MHz and 3.2 MHz, respectively. FIG. 4 is a configuration diagram of a plasma etching apparatus 1 as a plasma processing apparatus according to the third embodiment of the present invention.

As shown in FIG. 4, a measuring device 55 capable of measuring the value of the voltage V _RF is connected to the upper electrode 5. The high frequency power sources 51 and 52, the matching units 50 and 53, the DC power source 42, and the measuring device 55 are connected to the stabilization control device 25. The stabilization control device 25 is configured to apply high-frequency power to the lower electrode 6 by the high-frequency power sources 51 and 52, and to match impedances between the high-frequency power sources 51 and 52 and the plasma in the processing space K by the matching units 50 and 53. It is possible to stabilize the plasma processing of the substrate W by controlling the operation and the application of the DC voltage to the upper electrode 5 by the DC power source 42, respectively.

A measuring device 55 for measuring the self-bias voltage V _SB of the upper electrode 5 is connected to the stabilization control device 25. Here, based on the self-bias voltage V _SB measured by the measuring device 55 when the DC voltage is applied to the upper electrode 5 after the high-frequency power is applied to the lower electrode 6 as in the first embodiment. Then, a predicted impedance value Z _p of the plasma is calculated. Further, the stabilization control device 25 controls the high-frequency power sources 51 and 52, the matching units 50 and 53, and the DC power source 42 as in the first embodiment.

According to the third embodiment described above, the DC voltage V _DC and the voltage V _RF are applied to different electrodes (that is, the DC voltage V _DC is applied to the upper electrode 5 and the voltages V _RF1 and V _RF2 are applied to the lower electrode. Also when applied to the electrode 6), the voltage V _RF1 and V _RF2 applied to the lower electrode 6 at the timing when the application of the DC voltage V _DC is started or ended using the stabilization control device 25. By controlling so as to adjust each in advance, it is possible to prevent the application operations of the high-frequency power sources 51 and 52 and the matching operations of the matching units 50 and 53 from becoming unstable. In the third embodiment, the effects of the first embodiment can be obtained similarly.

Further, in the state where the DC voltage V _DC is applied to the upper electrode 5 by the DC power source 42 using the stabilization control device 25, the voltages V _RF1 and V _RF2 to the lower electrode 6 by the high frequency power sources 51 and 52 are controlled. When the matching units 50 and 53 are controlled so as to perform the matching operation in consideration of the influence on the plasma by the DC voltage _VDC applied to the upper electrode 5 when the application is started or finished, the second embodiment is performed. The same effect can be obtained.

  As mentioned above, although preferred embodiment of this invention was described referring an accompanying drawing, this invention is not limited to the example which concerns. It is obvious for those skilled in the art that various changes or modifications can be conceived within the scope of the technical idea described in the claims, and of course, the technical scope of the present invention is also possible. It is understood that it belongs to.

  In the above-described embodiment, the case where the upper electrode 5 and the lower electrode 6 are disposed to face each other in the processing container 2 has been described. However, the number of electrodes disposed in the processing container 2 may be one. It may be 3 or more. Moreover, the one or more electrodes arrange | positioned in the processing container 2 may be arbitrary arrangement | positioning structures.

In the embodiment described above, the stabilization control device 25 that controls the high-frequency power supply 16 (51, 52) and the matching unit 15 (50, 53) also controls the application operation of the DC power supply 22 (42). The voltage V _RF (V _RF1 , V _RF2 ) applied to the upper electrode 5 (lower electrode 6) or the matching unit 15 (50, 53) at the timing when the application of the DC voltage V _DC by (42) is started or ended. However, the stabilization control device 25 may not control the DC power supply 22 (42). In that case, the stabilization control device 25 applies information to the electrodes by the DC power supply 22 (42), information on timing at which application of the DC voltage V _DC to the upper electrode 5 is started or ended, or the DC power supply. By previously holding information on the DC voltage to be applied, the voltage V _RF (V _RF1 , V _RF2 ) applied to the upper electrode 5 (lower electrode 6) or the matching operation of the matching unit 15 (50, 53) is adjusted in advance. You may make it do.

  In the embodiment described above, high frequency power and DC voltage are applied to the upper electrode 5 as shown in FIG. 1, and high frequency power is applied to the lower electrode 6, and the upper electrode 5 is applied to the upper electrode 5 as shown in FIG. Although the case where only a DC voltage is applied and two different high frequency powers are applied to the lower electrode 6 has been described, one or more high frequency powers may be applied to any electrode. Further, one or more DC voltages may be applied to any electrode.

  In the embodiment described above, the pre-matching operation of the matching unit 15 (time A4 shown in FIG. 2) under the control of the stabilization control device 25 is applied by the pre-high frequency power supply 16 under the control of the stabilization control device 25. Although the case where the operation is started before the operation (time point A5 shown in FIG. 2) has been described, the start order of these operations may be reversed or may be started simultaneously.

  In the above-described embodiment, the case where the frequencies of the high-frequency power supplied from the high-frequency power supplies 16, 31, 51, and 52 are 60 MHz, 2 MHz, 100 MHz, and 3.2 MHz, respectively. The frequency of may be any frequency.

  The present invention is useful, for example, for a plasma processing apparatus for a substrate, and particularly useful for a plasma etching apparatus for plasma etching a substrate.

1 is a configuration diagram of a plasma etching apparatus 1 as a plasma processing apparatus according to a first embodiment of the present invention. 6 is a timing chart showing the application operation of the DC power supply 22, the application operation of the high-frequency power supply 16, and the matching operation of the matching unit 15 controlled by the stabilization control device 25 at the time of plasma etching. In the second embodiment of the present invention, a timing chart showing the application operation of the DC power source 22, the application operation of the high frequency power source 16 and the matching operation of the matching unit 15 controlled by the stabilization controller 25 during plasma etching. It is. It is a block diagram of the plasma etching apparatus 1 as a plasma processing apparatus which concerns on the 3rd Embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Plasma processing apparatus 2 Processing container 5 Upper electrode 6 Lower electrode 10 Gas supply path 11 Gas exhaust path 15, 30, 50, 53 Matching device 16, 31, 51, 52 High frequency power supply 20 Connection point 21, 41 Low pass filter 22, 42 DC power supply 25 Control device 55 Measuring device C1 Insulator C2 Wall K Processing space V _DC DC voltage V _RF , V _RF1 , V _RF2 voltage V _SB self-bias voltage W Substrate Z _m Impedance on the high frequency power source side by Z _m matcher Z _p plasma Predicted impedance

Claims (12)

A plasma processing apparatus having one or more electrodes in a processing container, supplying high frequency power to at least one of the electrodes to generate plasma in the processing container, and processing a substrate,
A high frequency power source for applying high frequency power to at least one of the one or more electrodes;
A DC power supply for applying a DC voltage to at least one of the one or more electrodes;
A matching device provided between the electrode to which the high-frequency power is applied and the high-frequency power source;
In a state where high-frequency power is applied to the electrode by the high-frequency power supply, the high-frequency power applied to the electrode is adjusted in advance at the timing when application of a DC voltage to the electrode by the DC power supply is started or ended. And a control device that controls the high-frequency power source. 2. The plasma processing apparatus according to claim 1, wherein when the high frequency power applied to the electrode by the high frequency power source is adjusted in advance, the high frequency power applied to the electrode is adjusted to be lowered. The control device adjusts the matching operation in advance at a timing at which application of a DC voltage to the electrode by the DC power supply is started or ended in a state in which high-frequency power is applied to the electrode by the high-frequency power supply. The plasma processing apparatus according to claim 1, wherein the matching unit is controlled. The plasma processing apparatus according to claim 3, wherein when the matching operation of the matching unit is adjusted in advance, adjustment is performed based on prediction of a change in plasma in the processing container. The control device holds in advance information on a timing at which application of a DC voltage to the electrode by the DC power supply is started or ended, or information on a DC voltage applied to the electrode by the DC power supply. The plasma processing apparatus according to any one of claims 1 to 4. The plasma processing apparatus according to claim 1, wherein the control device controls the DC power supply so as to start or end the application of a DC voltage to the electrode. In the state where a DC voltage is applied to the electrode by the DC power source, the control device applies a DC voltage applied to the electrode when the application of the high frequency power to the electrode by the high frequency power source is started or terminated. The plasma processing apparatus according to claim 1, wherein the matching unit is controlled so as to perform a matching operation in consideration of an influence on the plasma due to the plasma. A plasma processing method for processing a substrate by generating a plasma in a processing container by supplying high-frequency power to at least one of one or more electrodes provided in the processing container,
Applying high frequency power to at least one of the one or more electrodes,
Applying a DC voltage to at least one of the one or more electrodes;
A plasma processing method, wherein, in a state where high-frequency power is applied to the electrode, the high-frequency power applied to the electrode is adjusted in advance at a timing when application of the DC voltage is started or ended. The plasma processing method according to claim 8, wherein when the high frequency power applied to the electrode is adjusted in advance, the high frequency power applied to the electrode is adjusted to be lowered. The application of the high frequency power to the electrode is performed while matching the impedance between the plasma in the processing container and a high frequency power source that supplies the high frequency power,
The impedance matching is adjusted in advance at a timing when application of a DC voltage to the electrode starts or ends in a state where high-frequency power is applied to the electrode. Plasma processing method. 11. The plasma processing method according to claim 10, wherein when the impedance matching is adjusted in advance, the impedance is adjusted based on prediction of a change in plasma in the processing container. In the state where a DC voltage is applied to the electrode, when the application of the high frequency power to the electrode is started or terminated, the impedance matching is performed in consideration of the influence on the plasma by the DC voltage applied to the electrode. The plasma processing method according to claim 10, wherein the plasma processing method is performed.

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