JP2009054778A - Plasma processing apparatus and plasm processing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To equalize the slice speed of a workpiece in each slice electrode with a simple configuration. <P>SOLUTION: The plasma processing apparatus comprises: a plurality of slice electrodes 4 that are arranged with an interval in a prescribed direction and cut a silicon ingot 100 as a workpiece; a voltage application section 8 for generating a potential difference between each slice electrode 4 and the silicon ingot 100 so that plasma is generated between each slice electrode 4 and the silicon ingot 100 when the plurality of slice electrodes 4 are arranged so that they oppose the silicon ingot 100 in a direction orthogonally crossing the prescribed direction; and a plurality of variable resistors 10 that are interposed between the voltage application section 8 and each slice electrode 4 and can adjust voltage applied to each slice electrode 4 and current flowing to each slice electrode 4 so that the slice speed of the silicon ingot 100 is equalized at a place corresponding to each slice electrode 4. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a plasma processing apparatus and a plasma processing method.

  2. Description of the Related Art Conventionally, there has been known a plasma processing apparatus for manufacturing a silicon wafer by cutting a workpiece such as a silicon ingot by plasma etching (see, for example, Patent Document 1).

In the plasma processing apparatus disclosed in Patent Document 1, a slice electrode is disposed so as to face a workpiece, and a power source is electrically connected to the slice electrode. Then, a voltage is applied from the power source to the slice electrode to generate a potential difference between the slice electrode and the workpiece, thereby generating plasma between the slice electrode and the workpiece, and etching the plasma. The workpiece is cut by the action. In this plasma processing apparatus, the workpiece is cut by plasma etching while the workpiece is gradually moved toward the slice electrode by the lifting mechanism.
JP 2006-196845 A

  Incidentally, in the plasma processing apparatus as described above, it is required to improve the slicing efficiency of the workpiece. As a technique for improving the slicing efficiency of a workpiece, a plurality of slice electrodes are arranged in a predetermined direction and each slice electrode is arranged to face the workpiece in a direction orthogonal to the predetermined direction. It can be considered that plasma is generated between the slice electrode and the workpiece to slice the workpiece into a plurality of steps in one step.

  However, in this case, the slice speed of the workpiece may vary at locations corresponding to the slice electrodes. When the slicing speed of the workpiece at each slice electrode varies, the distance between each slice electrode and the workpiece is shifted as the workpiece slice progresses. There is a possibility that the portion where the plasma stops being generated and the slice stops appears in the portion.

  Therefore, a moving mechanism is provided for each slice electrode, and the position of each slice electrode is adjusted so that the distance between each slice electrode and the workpiece is equalized by the moving mechanism. It is also conceivable to equalize the slicing speed of the workpiece.

  However, in this case, there is a problem that the configuration of the processing apparatus becomes complicated and the processing apparatus becomes large.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a plasma processing apparatus and a plasma processing capable of equalizing the slice speed of a workpiece in each slice electrode with a simple configuration. Is to provide a method.

  As a result of intensive studies to achieve the above object, the inventors of the present application pay attention to the fact that the slice speed of the workpiece in the slice electrode changes by changing the voltage applied to the slice electrode and the current flowing through the slice electrode. By utilizing this fact, the voltage applied to each slice electrode and the current flowing through each slice electrode are adjusted by each control element interposed between the voltage application unit and the plurality of slice electrodes, respectively. It has been found that the slicing speed of the workpiece can be equalized.

  That is, a plasma processing apparatus according to the present invention is a plasma processing apparatus for cutting a workpiece by plasma etching, and is arranged at intervals in a predetermined direction, and a plurality of slice electrodes for cutting the workpiece. The plasma is generated between each slice electrode and the workpiece when the plurality of slice electrodes are arranged so as to face the workpiece in a direction orthogonal to the predetermined direction. A voltage application unit that generates a potential difference between each slice electrode and the workpiece, and a voltage application unit that is interposed between the voltage application unit and each slice electrode, respectively, at a position corresponding to each slice electrode. A plurality of control elements capable of adjusting the voltage applied to each slice electrode and the current flowing through each slice electrode so that the slice speed of the workpiece is equalized; .

  In this plasma processing apparatus, the voltage applied to each slice electrode and the current flowing through each slice electrode are adjusted by control elements interposed between the voltage application unit and each slice electrode, respectively, so that the portions corresponding to the slice electrodes are adjusted. The slicing speed of the workpiece can be equalized. Furthermore, the control element used in this plasma processing apparatus can have a simple configuration as compared with a moving mechanism for adjusting the distance of the slice electrode relative to the workpiece. For this reason, when a control element is provided for each slice electrode as in this plasma processing apparatus, the configuration of the plasma processing apparatus can be simplified as compared with the case where the moving mechanism is provided for each slice electrode. Therefore, in this plasma processing apparatus, the slice speed of the workpiece in each slice electrode can be equalized with a simple configuration.

  In the plasma processing apparatus, a voltage detection unit that detects a potential difference between each slice electrode and the workpiece, and between each slice electrode and the workpiece detected by the voltage detection unit. Based on the potential difference, the voltage applied to each slice electrode and the current flowing to each slice electrode are adjusted by each control element so that the slice speed of the workpiece at the location corresponding to each slice electrode is equalized. It is preferable to provide a control unit for controlling.

  If comprised in this way, based on the electric potential difference between each slice electrode detected by the voltage detection part by a control part and a to-be-processed object, the voltage applied to each slice electrode by each control element, and each slice electrode automatically Since the adjustment of the flowing current is controlled and the slice speed of the workpiece in each slice electrode is equalized, for example, compared with the case where the slice speed in each slice electrode is equalized by controlling each control element manually, for example. The work burden on the user can be reduced.

  A plasma processing method according to the present invention is a plasma processing method for cutting a workpiece by plasma etching using the plasma processing apparatus, wherein the plurality of slice electrodes are arranged at intervals in the predetermined direction, and Arranging a plurality of slice electrodes so as to face the workpiece in a direction orthogonal to the predetermined direction, and applying a voltage to the slice electrodes from the voltage application unit via the control elements; A step of generating a potential difference between each slice electrode and the workpiece so that a plasma is generated between each slice electrode and the workpiece; and A voltage applied to each slice electrode and a voltage applied to each slice electrode so that a slice speed of the workpiece at a position corresponding to the electrode is equalized And a step of adjusting the current.

  In this plasma processing method, by adjusting the voltage applied to each slice electrode and the current flowing through each slice electrode by each control element, the slice speed of the workpiece at the location corresponding to each slice electrode is equalized. Can do. Furthermore, the control element used in this plasma processing method can have a simpler configuration than a moving mechanism for adjusting the distance of the slice electrode relative to the workpiece. Therefore, in this plasma processing method, similarly to the plasma processing apparatus, it is possible to equalize the slice speed of the workpiece in each slice electrode with a simple configuration.

  As described above, according to the present invention, the slice speed of the workpiece in each slice electrode can be equalized with a simple configuration.

  Embodiments of the present invention will be described below with reference to the drawings.

  FIG. 1 is a schematic view of a plasma processing apparatus according to an embodiment of the present invention. First, the configuration of a plasma processing apparatus according to an embodiment of the present invention will be described with reference to FIG.

  The plasma processing apparatus according to the present embodiment is for manufacturing a silicon wafer by slicing a silicon ingot 100 as a workpiece by plasma etching. This plasma processing apparatus includes an unillustrated chamber, a lifting mechanism 2, a plurality of slice electrodes 4, a workpiece-side electrode 6, a voltage application unit 8, a variable resistor 10, a voltmeter 12, and a control. Part 14.

The chamber not shown forms a reaction chamber in which plasma etching is performed. An exhaust pipe (not shown) and a gas introduction pipe are connected to the chamber. After the inside of the chamber is evacuated through the exhaust pipe, nitrogen trifluoride (NF ₃ ) as an etching gas is passed through the gas introduction pipe. The inside can be filled.

  The lifting mechanism 2 adjusts the vertical position of the silicon ingot 100. Specifically, the elevating mechanism 2 has a mounting table 2a on which the silicon ingot 100 is mounted, and the vertical position of the silicon ingot 100 can be determined by moving the mounting table 2a up and down. Adjust. Further, the elevating mechanism 2 moves the silicon ingot 100 gradually upward during plasma etching, so that the silicon ingot 100 is sliced by plasma etching from the upper surface downward.

  The plurality of slice electrodes 4 are used for cutting the silicon ingot 100. Plasma is generated between each slice electrode 4 and the silicon ingot 100, and the silicon ingot 100 is sliced by the etching action of the plasma.

  Specifically, the plurality of slice electrodes 4 are fixedly installed in the space in the chamber. Each slice electrode 4 is formed in a strip-shaped thin film, and is arranged such that the direction in which the short side extends is the vertical direction. The slice electrodes 4 are arranged in parallel to each other at equal intervals in the horizontal direction, and are arranged so as to face the upper surface of the silicon ingot 100 set on the mounting table 2a in the vertical direction.

  Each slice electrode 4 is formed by sandwiching a metal foil such as a copper foil with an insulating film made of a resin material and performing hot pressing. A voltage is applied to each slice electrode 4 from the voltage application unit 8 on the metal foil. Accordingly, plasma is generated between the lower end of the metal foil and the surface of the silicon ingot 100 facing the metal foil, and plasma is not generated on the side surface side of the slice electrode 4 covered with the insulating film.

Then, when plasma is generated between each slice electrode 4 and the silicon ingot 100, NF ₃ as an etching gas is dissociated, and fluorine atoms (F ⁰ ) and fluorine ions (F ⁻ ) are generated. As the fluorine atoms (F ⁰ ) and fluorine ions (F ⁻ ) react with the silicon atoms (Si) of the silicon ingot 100 to generate SiF ₄ gas, slicing by etching of the silicon ingot 100 proceeds.

  The workpiece-side electrode 6 is electrically connected to the silicon ingot 100 and is attached to the bottom surface of the silicon ingot 100. The workpiece-side electrode 6 is electrically connected to the voltage application unit 8 and grounded. Thereby, the potential of the silicon ingot 100 is the ground potential (0 V).

  The voltage application unit 8 generates a potential difference between each slice electrode 4 and the silicon ingot 100 so that plasma is generated between each slice electrode 4 and the silicon ingot 100.

  Specifically, the voltage application unit 8 is configured to be able to apply a voltage to each slice electrode 4 via the variable resistor 10, and is electrically connected to the workpiece-side electrode 6. . When a voltage is applied from the voltage application unit 8 to each slice electrode 4, a potential difference is generated between the silicon ingot 100 that is at the ground potential and each slice electrode 4.

  Each of the plurality of variable resistors 10 has a function of individually adjusting a voltage applied to each slice electrode 4 and a current flowing through each slice electrode 4. The variable resistor 10 is included in the concept of the control element in the present invention.

  Specifically, each variable resistor 10 is interposed between the voltage application unit 8 and each slice electrode 4, and is configured such that its resistance value can be adjusted. Each variable resistor 10 receives a control signal from the control unit 14 and changes the resistance value of the variable resistor 10 according to the control signal. By changing the resistance value of each variable resistor 10, the voltage applied to each slice electrode 4 is adjusted, and the potential difference between each slice electrode 4 and the silicon ingot 100 is individually adjusted. Further, as the resistance value of each variable resistor 10 changes, the current flowing between the voltage applying unit 8 and each slice electrode 4 through each variable resistor 10 is individually adjusted.

  The plurality of voltmeters 12 detect a potential difference between the slice electrode 4 and the silicon ingot 100. The voltmeter 12 is included in the concept of the voltage detection unit of the present invention. Each voltmeter 12 is provided corresponding to each slice electrode 4. And each voltmeter 12 is provided so that the potential difference between the site | part between each slice electrode 4 and the said variable resistor 10 connected to it directly and the workpiece side electrode 6 may be detected. Yes. The potential of the portion between the slice electrode 4 and the variable resistor 10 is the same as the potential of the slice electrode 4, and the potential of the workpiece side electrode 6 is the same ground potential as the potential of the silicon ingot 100. Therefore, the potential difference detected by each voltmeter 12 corresponds to the potential difference between each slice electrode 4 and the silicon ingot 100. Data on the potential difference between each slice electrode 4 and the silicon ingot 100 detected by each voltmeter 12 is sent to the control unit 14 in real time.

  The controller 14 is configured to equalize the slice speed of the silicon ingot 100 at the position corresponding to each slice electrode 4 based on the potential difference data between each slice electrode 4 and the silicon ingot 100 sent from each voltmeter 12. The voltage applied to each slice electrode 4 and the current flowing through each slice electrode 4 are controlled by changing the resistance value of each variable resistor 10 so as to be

  Specifically, the control unit 14 has a not-shown calculation unit, and in this calculation unit, data on the potential difference between each slice electrode 4 and the silicon ingot 100 sent from each voltmeter 12, Based on the resistance value data of each variable resistor 10 at that time, the slice speed at a position corresponding to each slice electrode 4 is calculated, and the average value of the slice speeds in each slice electrode 4 is further calculated. The

  Then, the control unit 14 compares the average value of the slice speeds with the data of the slice speeds at the locations corresponding to the respective slice electrodes 4, and the slice speed at the predetermined slice electrode 4 is the slice speed. If the average value is deviated from the average value, a control signal for adjusting the resistance value is sent to the variable resistor 10 connected to the slice electrode 4. The variable resistor 10 that has received this control signal changes its own resistance value according to the control signal. As a result, the potential difference between the slice electrode 4 connected to the variable resistor 10 and the silicon ingot 100 is adjusted, and the current flowing between the voltage application unit 8 and the slice electrode 4 through the variable resistor 10. Is adjusted, and the intensity of the plasma at the portion corresponding to the slice electrode 4 is adjusted. In this way, the control of the slice speed equalization in each slice electrode 4 by the control unit 14 is performed.

  Next, a plasma processing method for the silicon ingot 100 using the plasma processing apparatus of the present embodiment will be described.

  First, the silicon ingot 100 is set on the mounting table 2a of the elevating mechanism 2 in the chamber (not shown), and the workpiece side electrode 6 is attached to the bottom surface of the silicon ingot 100 to connect the workpiece side electrode 6 and the workpiece. The silicon ingot 100 is electrically connected. Then, the plurality of slice electrodes 4 are installed at intervals on the upper side in the vertical direction of the silicon ingot 100 so as to face the upper surface of the silicon ingot 100.

Next, the inside of the chamber is evacuated, and then the chamber is filled with NF ₃ as an etching gas.

  Next, a voltage difference is generated between each slice electrode 4 and the silicon ingot 100 by applying a voltage from the voltage application unit 8 to each slice electrode 4 via each variable resistor 10.

  Thereafter, the silicon ingot 100 is gradually raised by the lifting mechanism 2, and the upper surface of the silicon ingot 100 is gradually approached to the lower end of each slice electrode 4. When the lower end of each slice electrode 4 and the upper surface of the silicon ingot 100 come close to a certain distance, plasma is generated between the lower end of each slice electrode 4 and the upper surface of the silicon ingot 100, and the silicon ingot 100 is etched. Slice progresses.

  In the process of slicing the silicon ingot 100, the resistance value of each variable resistor 10 is adjusted by the control signal from the control unit 14, so that the voltage applied to each slice electrode 4 and the current flowing through each slice electrode 4 are adjusted. Is adjusted, and the slice speed of the silicon ingot 100 in each slice electrode 4 is equalized.

  Specifically, a potential difference between each slice electrode 4 and the silicon ingot 100 is detected by each voltmeter 12, and data on this potential difference is input to the calculation unit of the control unit 14. The calculation unit calculates the slice speed of the silicon ingot 100 at a location corresponding to each slice electrode 4 based on the input potential difference data and the resistance value data of each variable resistor 10 at that time. .

  Here, the slicing speed in each slice electrode 4 has a correlation between the potential difference between each slice electrode 4 and the silicon ingot 100 and the resistance value of each variable resistor 10, and the calculation unit determines each slice speed based on these correlations. The slice speed at the slice electrode 4 is calculated.

  Specifically, the time average value of the potential difference between each slice electrode 4 and the silicon ingot 100 changes according to the resistance value of the variable resistor 10 connected to each slice electrode 4. Due to the change of the time average value of the potential difference between each slice electrode 4 and the silicon ingot 100, the slice speed in each slice electrode 4 changes.

  FIG. 2 shows changes in the slice speed when the time average value of the potential difference between the slice electrode 4 and the silicon ingot 100 is changed. From FIG. 2, the time average value of the potential difference between the slice electrode 4 and the silicon ingot 100 and the slice speed at the location corresponding to the slice electrode 4 are in direct proportion, and the slice electrode 4 and the silicon ingot 100 It can be seen that as the time average value of the potential difference increases, the slice speed at the location corresponding to the slice electrode 4 also increases. This is because as the time average value of the potential difference between the slice electrode 4 and the silicon ingot 100 increases, the ratio of the plasma lighting time to the total time increases, and the slice speed increases accordingly.

  Further, the current flowing through each slice electrode 4 also changes according to the resistance value of the variable resistor 10 connected to each slice electrode 4. The slice speed is also changed by a change in the current flowing through each slice electrode 4.

  FIG. 3 shows changes in the slice speed when the resistance value of the variable resistor 10 is changed with the time average value of the potential difference between the slice electrode 4 and the silicon ingot 100 being constant. 3 that the slice speed increases as the resistance value of the variable resistor 10 decreases. This is because, as the resistance value of the variable resistor 10 decreases, the current flowing through the slice electrode 4 connected to the variable resistor 10 increases, and the amount of radicals that contribute to the etching reaction increases accordingly. This is because the speed increases.

  As shown in FIG. 2, when the resistance value of the variable resistor 10 increases, the slope of the proportional line between the time average value of the potential difference between the slice electrode 4 and the silicon ingot 100 and the slice speed decreases. As the resistance value of the variable resistor 10 decreases, the slope of the proportional line between the time average value of the potential difference between the slice electrode 4 and the silicon ingot 100 and the slice speed increases. The calculation unit calculates the slice speed in each slice electrode 4 based on the potential difference between the slice electrode 4 and the silicon ingot 100 and the resistance value of the variable resistor 10 using the relationship shown in FIG. An average value of slice speeds in each slice electrode 4 is calculated.

  And the control part 14 compares the average value of the said slice speed calculated by the calculating part, and the calculated slice speed in each slice electrode 4, and the slice speed has shifted | deviated from the average value of the said slice speed. If the slice electrode 4 is present, the arithmetic unit calculates the resistance value of the variable resistor 10 necessary for matching the slice speed of the slice electrode 4 to the average value of the slice speed based on the relationship shown in FIG. Thereafter, the control unit 14 outputs a control signal including the calculated resistance value data to the variable resistor 10 connected to the slice electrode 4 whose slice speed is shifted from the average value of the slice speed. The variable resistor 10 that has received this control signal changes its own resistance value in accordance with the control signal. Thereby, the slice speed in the slice electrode 4 connected to the variable resistor 10 is adjusted, and the slice speed in each slice electrode 4 is equalized. As a result, the slicing of the silicon ingot 100 in each slice electrode 4 proceeds at an equal speed, and the silicon ingot 100 is sliced into a plurality of silicon wafers.

  As described above, in this embodiment, the resistance value of each variable resistor 10 interposed between the voltage application unit 8 and each slice electrode 4 is adjusted, and the voltage applied to each slice electrode 4 and each slice electrode are adjusted. It is possible to equalize the slice speed of the silicon ingot 100 at the locations corresponding to the slice electrodes 4 by adjusting the current flowing through the slice electrodes 4. Furthermore, the variable resistor 10 in the present embodiment can have a simple configuration as compared with a moving mechanism for adjusting the distance of the slice electrode 4 to the silicon ingot 100. For this reason, when the variable resistor 10 is provided for each slice electrode 4 as in this embodiment, the configuration of the plasma processing apparatus is simplified compared to the case where the moving mechanism is provided for each slice electrode 4. Can do. Therefore, in this embodiment, the slice speed of the silicon ingot 100 in each slice electrode 4 can be equalized with a simple configuration.

  In the present embodiment, the controller 14 controls the silicon ingot 100 at a location corresponding to each slice electrode 4 based on the potential difference data between each slice electrode 4 and the silicon ingot 100 detected by the voltmeter 12. The resistance value of each variable resistor 10 is adjusted so that the slicing speed is equalized. For this reason, since the resistance value of each variable resistor 10 is automatically adjusted by the control unit 14 and the slice speed of the silicon ingot 100 in each slice electrode 4 is equalized, for example, the resistance of each variable resistor 10 is manually set. Compared with the case where the slice speed in each slice electrode 4 is equalized by adjusting the value, the work load on the user can be reduced.

  The embodiment disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is shown not by the above description of the embodiments but by the scope of claims for patent, and all modifications within the meaning and scope equivalent to the scope of claims for patent are further included.

  For example, as in the first modification of the embodiment shown in FIG. 4, the plasma processing apparatus configured to apply a voltage that causes a potential difference between adjacent slice electrodes 4 from the voltage application unit 8 to each slice electrode 4. The present invention can also be applied to.

  Specifically, in the plasma processing apparatus according to this modification, each slice electrode 4 is electrically connected to the voltage application unit 8 via the variable resistor 10. The voltage application unit 8 is configured to output two types of pulse voltages having opposite signs and the same magnitude, and alternately applies the two types of pulse voltages to the slice electrodes arranged in the horizontal direction. It is supposed to be. That is, pulse voltages having the same sign and the same magnitude are applied to the adjacent slice electrodes 4.

  When plasma is generated between each slice electrode 4 and the silicon ingot 100, a current flows through the vicinity of the line segment that linearly connects the plasma corresponding to the adjacent slice electrodes 4 and 4 in the silicon ingot 100. That is, a current flows through the silicon ingot 100 at a minute distance between the slice electrodes 4. In the above embodiment, when plasma is generated between each slice electrode 4 and the silicon ingot 100, a current flows through the silicon ingot 100 between each slice electrode 4 and the workpiece-side electrode 6. However, in this first modified example, such a through current hardly flows. Thereby, in this 1st modification, generation | occurrence | production of the Joule heat of the silicon ingot 100 is suppressed, and the raise of the temperature of the silicon ingot 100 by the Joule heat is suppressed.

And unlike the said embodiment, the voltage application part 8 is not connected to the workpiece side electrode 6, but the DC power supply 20 is connected instead. Thereby, a positive DC voltage is applied from the DC power source 20 to the silicon ingot 100 through the workpiece side electrode 6. This DC voltage is smaller than the peak value of the pulse voltage applied to the slice electrode 4, and when the pulse voltage falls, plasma is generated between the slice electrode 4 and the silicon ingot 100 to which this DC voltage is applied. Is set to such a low voltage value that does not occur. Due to this weak positive DC voltage, the etching gas ions (F ⁻ ) are electrostatically collected in the silicon ingot 100 even during a period when the pulse voltage falls and no plasma is generated between the slice electrode 4 and the silicon ingot 100. The slicing of the silicon ingot 100 proceeds.

  In the plasma processing apparatus according to the first modified example, the potential difference between the portion between each variable resistor 10 and the corresponding slice electrode 4 and the workpiece-side electrode 6, that is, each slice electrode 4 and A potential difference from the silicon ingot 100 is detected by each corresponding voltmeter 12. Based on the potential difference between each slice electrode 4 and the silicon ingot 100 detected by the voltmeter 12 and the resistance value of each variable resistor 10 at that time, the control unit 14 is Similarly, the resistance value of each variable resistor 10 is changed to equalize the slice speed of the silicon ingot 100 in each slice electrode 4.

  However, in this first modification, a negative voltage may be applied to the slice electrode 4, and the potential difference detected by the voltmeter 12 may be negative due to this. In this case, the processing unit of the control unit 14 performs a process of converting the negative potential difference value detected by the voltmeter 12 to a positive value, and calculates the slice speed using the converted potential difference.

  When a pulse voltage that switches between a positive voltage and a negative voltage is applied to the slice electrode 4, the slice speed is set using only the positive portion of the potential difference detected by the voltmeter 12 in the calculation unit of the control unit 14. What is necessary is just to calculate. Alternatively, the calculation unit performs processing for converting the negative potential difference value to positive using only the negative portion of the potential difference detected by the voltmeter 12, and calculates the slice speed using the converted potential difference. May be. Alternatively, a process of converting the negative part of the potential difference detected by the voltmeter 12 to positive may be performed, and the slice speed may be calculated using the positive potential difference after the conversion and the part of the original positive potential difference. .

  In the first modification, the slice electrodes 4 to which pulse voltages having opposite signs are applied are alternately arranged. However, the slice electrodes to which pulse voltages having the same sign are applied are arranged adjacent to each other, and the slice electrodes And slice electrodes to which pulse voltages of opposite signs are applied may be arranged next to each other. Further, the same number of slice electrodes to which pulse voltages having opposite signs are applied are not necessarily provided, and any number of slice electrodes may be provided.

  Further, in the first modification, the voltage applied to each slice electrode 4 can generate plasma between each slice electrode 4 and the silicon ingot 100, and generates a predetermined potential difference between each slice electrode 4. It may be a voltage of a form other than the pulse voltage that can be generated.

  Moreover, in the said embodiment and 1st modification, although the variable resistor 10 was used as a control element which adjusts the voltage applied to each slice electrode 4, and the electric current which flows through each slice electrode 4, this invention is not restricted to this, A device other than the variable resistor 10 can be used as the control element.

  For example, when an AC power supply is used for the voltage application unit 8, a variable reactor capable of changing reactance is used as the control element instead of the variable resistor 10, and each slice is controlled by controlling the reactance of the variable reactor. You may make it adjust the voltage applied to the electrode 4, and the electric current which flows into each slice electrode.

  Further, as in the second modification of the embodiment shown in FIG. 5, each slice electrode 4 is formed by using an FET 22 (field effect transistor) which is a semiconductor device instead of the variable resistor 10 as the control element. The applied voltage and the current flowing through each slice electrode 4 may be adjusted.

  Specifically, in the second modification, FETs 22 are interposed between the voltage application unit 8 and each slice electrode 4. Then, one of the source and drain of each FET 22 is electrically connected to the voltage application unit 8, the other is electrically connected to each slice electrode 4, and the gate electrode of each FET 22 is electrically connected to the control unit 14. Connecting. Then, the control unit 14 controls the voltage applied to the gate electrode of each FET 22 based on the potential difference between each slice electrode 4 and the silicon ingot 100 detected by the voltmeter 12, thereby controlling the voltage through each FET 22. By adjusting the current flowing through each slice electrode 4 and the voltage applied to each slice electrode 4 via each FET 22, the slice speed of the silicon ingot 100 at the location corresponding to each slice electrode 4 is equalized.

  In the second modified example, the slice speed of the silicon ingot 100 at a position corresponding to each slice electrode 4 can be equalized, and the FET 22 used in the second modified example is a silicon ingot of the slice electrode 4. Compared to a moving mechanism for adjusting the distance to 100, a simple configuration can be achieved. Accordingly, also in the second modified example, it is possible to obtain the effect that the slice speed of the silicon ingot 100 in each slice electrode 4 can be equalized with a simple configuration as in the above embodiment.

  Moreover, the above-mentioned silicon ingot 100 and each slice electrode 4 do not need to be relatively arranged in the vertical direction, and may be arranged in an arbitrary direction. The arrangement direction of the slice electrodes 4 may be an arbitrary direction other than the horizontal direction, and the cutting direction of the silicon ingot 100 may be a direction according to the arrangement direction of the silicon ingot 100 and the slice electrodes 4. Good. For example, the silicon ingot 100 is disposed on the upper side and the slice electrodes 4 are disposed on the lower side of the silicon ingot 100, and the silicon ingot 100 is cut from the lower side to the upper side. Each slice electrode 4 may be arranged on the side of the silicon ingot 100 to cut the silicon ingot 100 in the lateral direction. In these configurations, it is preferable to use a moving mechanism capable of moving the silicon ingot 100 in the cutting direction instead of the lifting mechanism 2 and fix the silicon ingot 100 on the mounting table of the moving mechanism so as not to fall. .

  Moreover, in the said embodiment and each modification, although demonstrated taking the example of the structure which cut | disconnects the silicon ingot 100 as a to-be-processed object, not only a silicon ingot but a thing of various materials is applicable as a to-be-processed object. . For example, a workpiece such as silicon carbide (SiC) or germanium (Ge) may be cut using the plasma processing apparatus and the plasma processing method according to the present invention.

In the above embodiment and the modifications, it was used NF ₃ as the etching gas may be used etchable suitable type of etching gas according to the type of workpiece. For example, SF ₆ or Cl ₂ may be used as an etching gas for the silicon ingot 100. Further, when cutting a workpiece made of SiC, in addition to NF ₃ gas, SF ₆ gas, a mixed gas of NF ₃ and O ₂ , or a mixed gas of SF ₆ and O ₂ is used as an etching gas. Can be used. Further, when cutting a workpiece made of Ge, NF ₃ , SF _6, or the like can be used as an etching gas.

It is the schematic of the plasma processing apparatus by one Embodiment of this invention. It is the correlation figure which showed the relationship between the electrical potential difference between a slice electrode and a silicon ingot, and slice speed. It is the correlation figure which showed the relationship between the resistance value of a variable resistor, and the slice speed in the slice electrode connected with the variable resistor. It is the schematic of the plasma processing apparatus by the 1st modification of one Embodiment of this invention. It is the schematic of the plasma processing apparatus by the 2nd modification of one Embodiment of this invention.

Explanation of symbols

4 Slice electrode 8 Voltage application unit 10 Variable resistor (control element)
12 Voltmeter (Voltage detector)
14 Control unit 100 Silicon ingot (workpiece)
22 FET (control element)

Claims (3)

A plasma processing apparatus for cutting a workpiece by plasma etching,
A plurality of slice electrodes arranged at intervals in a predetermined direction for cutting the workpiece;
The plasma is generated between each slice electrode and the workpiece when the plurality of slice electrodes are arranged to face the workpiece in a direction orthogonal to the predetermined direction. A voltage application unit that generates a potential difference between each slice electrode and the workpiece;
The voltage applied to each slice electrode so as to equalize the slice speed of the workpiece at a location corresponding to each slice electrode, respectively interposed between the voltage application unit and each slice electrode, and the respective slice electrodes A plasma processing apparatus comprising a plurality of control elements capable of adjusting a current flowing through a slice electrode. A voltage detector for detecting a potential difference between each slice electrode and the workpiece;
Based on the potential difference between each slice electrode and the workpiece detected by the voltage detection unit, the slice speeds of the workpiece at locations corresponding to the slice electrodes are equalized. The plasma processing apparatus according to claim 1, further comprising: a control unit that controls adjustment of a voltage applied to each slice electrode and a current flowing through each slice electrode by a control element. A plasma processing method for cutting a workpiece by plasma etching using the plasma processing apparatus according to claim 1,
Disposing the plurality of slice electrodes at intervals in the predetermined direction, and disposing the plurality of slice electrodes so as to face the workpiece in a direction orthogonal to the predetermined direction;
By applying a voltage from the voltage application unit to the slice electrodes via the control elements, plasma is generated between the slice electrodes and the workpiece so that the slice electrodes and the workpiece are processed. Creating a potential difference with the object,
Adjusting the voltage applied to each slice electrode and the current flowing to each slice electrode so that the slice speed of the workpiece at the location corresponding to each slice electrode is equalized by each control element; A plasma processing method provided.

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