JP2020088203A - Plasma etching apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a plasma etching apparatus capable of easily grasping an adsorption state of a workpiece. A plasma etching apparatus includes an electrostatic adsorption table 10 that electrostatically adsorbs a work piece on a holding surface 11, a gas supply unit that supplies plasma-ized processing gas to the work piece, and carrying out the work piece. A chamber provided with an opening, a decompression unit that depressurizes the inside of the chamber, a transfer unit 60 that holds the workpiece by the transfer pad 61 and carries it in and out of the electrostatic suction table 10 of the chamber, and a charged state of the holding surface 11. It is provided with a charge inspection unit 70 for inspecting. The charge inspection unit 70 compares a surface electrometer 71, which is mounted on a transport pad and measures the charge amount of the facing holding surface 11, with a measured value of the surface electrometer 71 and a preset allowable range of the charge amount. A comparison unit and a notification unit for notifying that the measured value exceeds the permissible range are provided. [Selection diagram] Fig. 2

Description

The present invention relates to a plasma etching device.

In a semiconductor device manufacturing process, a semiconductor wafer thinned by a grinding process is cut along a dividing line to divide an area where a device is formed to manufacture individual semiconductor chips. When a semiconductor wafer is ground, grinding distortion remains on the surface to be ground of the semiconductor wafer, and there is a problem that the bending strength of each device after division is reduced. In order to solve this problem, a technique has been proposed in which the surface to be ground of the semiconductor wafer is subjected to plasma etching to remove grinding strain on the surface to be ground of the semiconductor wafer to improve the bending strength of the device ( For example, see Patent Document 1).

Japanese Patent Laid-Open No. 10-008269

Since the inside of the chamber is depressurized, the plasma etching apparatus disclosed in Patent Document 1 uses an electrostatic attraction table that attracts and fixes the workpiece by static electricity instead of vacuum fixing. The electrostatic attraction is adjusted by applying a voltage to the electrodes of the chuck table.However, even if there is a circuit failure or an assembly failure of the chuck table, the voltage can be applied. It is difficult to judge whether or not

The present invention has been made in view of such problems, and an object thereof is to provide a plasma etching apparatus capable of easily grasping a suction state of a workpiece.

In order to solve the above-mentioned problems and to achieve the object, a plasma etching apparatus of the present invention includes an electrostatic attraction table that electrostatically attracts and fixes a workpiece on a holding surface, and an electrostatic attraction table that holds the workpiece. A gas supply unit for supplying a plasma-processed gas to the workpiece, a chamber accommodating the electrostatic adsorption table and the gas supply unit and having an opening for loading/unloading the workpiece, and decompressing the chamber. A depressurizing unit, a carrying unit that holds the workpiece with a carrying pad and carries it in and out of the electrostatic adsorption table of the chamber, and a charging inspection unit that inspects the charged state of the holding surface. The electrification inspection unit is mounted on the transfer pad, and compares the surface electrometer for measuring the electrification amount of the facing holding surface with a comparison between the measured value of the surface electrometer and a preset allowable range of the electrification amount. And a notification unit that notifies that the measured value exceeds the allowable range.

In the plasma etching apparatus, if the measured value exceeds the allowable range, a voltage supply unit for adjusting the voltage supplied to the electrostatic adsorption table to adjust the charge amount of the holding surface to be within the allowable range is provided. May be.

In the plasma etching apparatus, when the measured value exceeds the allowable range, ionized air is supplied to the holding surface of the electrostatic adsorption table and the amount of charge on the holding surface is adjusted to be within the allowable range. Part may be provided.

The plasma etching apparatus of the present invention has an effect that the suction state of the workpiece can be easily grasped.

FIG. 1 is a diagram showing a configuration example of the plasma etching apparatus according to the first embodiment. FIG. 2 is a cross-sectional view of a main part of the electrostatic adsorption pad of the plasma etching apparatus shown in FIG. FIG. 3 is a plan view of a transfer pad of the plasma etching apparatus shown in FIG. FIG. 4 is a side view showing a state in which the charge inspection unit of the plasma etching apparatus shown in FIG. 1 measures the amount of charge on the holding surface of the electrostatic adsorption table. FIG. 5 is a side view showing a state in which the transfer unit of the plasma etching apparatus shown in FIG. 1 transfers a workpiece to the holding surface of the electrostatic adsorption table. FIG. 6 is a plan view of a transfer pad of the plasma etching apparatus according to the second embodiment. FIG. 7 is a diagram showing a state in which the ionized air supply unit of the plasma etching apparatus according to the second embodiment discharges the holding surface of the electrostatic adsorption table.

Modes (embodiments) for carrying out the present invention will be described in detail with reference to the drawings. The present invention is not limited to the contents described in the embodiments below. Further, the constituent elements described below include those that can be easily conceived by those skilled in the art and those that are substantially the same. Furthermore, the configurations described below can be appropriately combined. In addition, various omissions, substitutions, or changes in the configuration can be made without departing from the scope of the present invention.

[Embodiment 1]
A plasma etching apparatus according to Embodiment 1 of the present invention will be described with reference to the drawings. FIG. 1 is a diagram showing a configuration example of the plasma etching apparatus according to the first embodiment. FIG. 2 is a cross-sectional view of a main part of the electrostatic adsorption pad of the plasma etching apparatus shown in FIG. FIG. 3 is a plan view of a transfer pad of the plasma etching apparatus shown in FIG.

The plasma etching apparatus 1 according to the first embodiment is an apparatus that plasma-etches a workpiece 200. In the first embodiment, the workpiece 200 is a wafer such as a disk-shaped semiconductor wafer or an optical device wafer having a substrate of silicon, sapphire, gallium arsenide, or the like. In the workpiece 200, devices are formed in regions defined in a grid by a plurality of planned dividing lines formed in a grid on the surface. Further, in the present invention, the workpiece 200 is not limited to the wafer.

As shown in FIG. 1, the plasma etching apparatus 1 according to the first embodiment includes an electrostatic adsorption table 10, an upper electrode 20, a gas supply unit 30, a chamber 40, a decompression unit 50, and a transfer unit 60. The charging inspection unit 70 and the control unit 100 are provided.

The electrostatic adsorption table 10 electrostatically adsorbs and fixes the workpiece 200 on the holding surface 11. The electrostatic attraction table 10 is made of an insulating material and includes a cylindrical shaft portion 12 and a disk-shaped table portion 13 connected to the upper end of the shaft portion 12. The shaft portion 12 is inserted into the lower wall 42 that constitutes the chamber 40, and is sealed and held by the insulator 14. Further, in the electrostatic adsorption table 10, a cooling water circulation passage 15 is provided in the lower portion of the table portion 13 and the shaft portion 12, and the cooling water circulation passage 15 circulates the cooling water supplied from the cooling water supply means 16.

In the electrostatic adsorption table 10, the upper surface of the table portion 13 is a flat holding surface 11 along the horizontal direction, and the lower electrode 17 is provided inside the table portion 13. As shown in FIG. 2, the lower electrode 17 is connected to the positive electrode of the DC power supply 80 via the switch 81.

In the first embodiment, in the electrostatic adsorption table 10, the workpiece 200 is placed on the holding surface 11, and a positive voltage is applied to the lower electrode 17 from the DC power supply 80, so that the lower portion of the electrostatic chuck table 10 is lowered as shown in FIG. The upper side of the electrode 17 is charged with a positive charge 18, the lower surface 201 side of the workpiece 200 is charged with a negative charge, and the upper surface 202 side of the workpiece 200 is charged with a positive charge. The electrostatic attraction table 10 charges the holding surface 11 of the electrostatic attraction table 10 and the lower surface 201 of the workpiece 200 to electric charges having different polarities, so that the workpiece 200 is electrostatically attracted to the holding surface 11. Hold by adsorption. In the present invention, the negative electrode of the DC power supply 80 may be connected to the lower electrode 17, and the voltage applied to the lower electrode 17 may be a negative voltage.

Further, in the first embodiment, the plasma etching apparatus 1 is provided with the voltage adjustment unit 82 that adjusts (changes) the voltage value of the positive voltage applied by the DC power supply 80 to the lower electrode 17 between the switch 81 and the DC power supply 80. ing. The voltage adjustment unit 82 is configured to include, for example, a variable resistor or the like.

The upper electrode 20 is disposed above the electrostatic adsorption table 10 and at a position facing the holding surface 11 of the electrostatic adsorption table 10, and is connected to the ground. The upper electrode 20 includes a columnar shaft portion 22 and a disc-shaped plate portion 23 connected to the lower end of the shaft portion 22. The shaft portion 22 is inserted into an upper wall 41 that constitutes the chamber 40, is sealed by an insulator 29, and is held so as to be able to move up and down. In the plate-shaped portion 23, the lower surface 21 faces the holding surface 11 and a plurality of gas ejection holes 24 are opened.

The upper electrode 20 can be moved up and down by being driven by the elevating means 25. The elevating means 25 is composed of a cylinder 26, a piston rod 27, and a bracket 28 connected to the piston rod 27. The bracket 28 supports the shaft portion 22 of the upper electrode 20, and the cylinder 26 moves the piston rod 27 up and down to move the upper electrode 20 supported by the bracket 28 up and down.

The gas supply unit 30 supplies the processed gas that has been turned into plasma to the workpiece 200 held on the electrostatic adsorption table 10. The gas supply unit 30 includes the gas ejection hole 24 of the upper electrode 20, the gas flow passage 31 communicating with the gas ejection hole 24, the opening/closing valve 32 provided in the gas flow passage 31, the gas flow passage 31 and the opening/closing. A processing gas supply source 33 for supplying a processing gas into the chamber 40 via the valve 32 and a high frequency power source 35 connected to the electrostatic adsorption table 10 via a switch 34 are provided. The processing gas supply source 33 supplies, for example, SF ₆ gas into the chamber 40 as a processing gas. The high frequency power supply 35 applies a high frequency voltage to the electrostatic adsorption table 10.

In the gas supply unit 30, the opening/closing valve 32 is opened to supply the processing gas into the chamber 40 through the gas ejection holes 24, and the switch 34 is closed to supply a high-frequency voltage to the electrostatic adsorption table 10 so that the chamber 40 The processing gas supplied into the chamber 40 is converted into plasma, and the plasma-processed processing gas is supplied to the workpiece 200 held on the holding surface 11.

The chamber 40 accommodates the holding surface 11 of the electrostatic adsorption table 10 and the gas ejection holes 24 of the upper electrode 20, and has a loading/unloading opening 44 for the workpiece 200. The chamber 40 is formed in a box shape by the upper wall 41, the lower wall 42, and the side wall 43, and a loading/unloading opening 44 is formed in one side wall 43. The loading/unloading opening 44 can be opened and closed by a shutter 45. The shutter 45 is driven by the shutter opening/closing means 46 to move up and down. The shutter opening/closing means 46 includes a cylinder 47 and a piston rod 48 which is connected to the shutter 45 and is driven by the cylinder 47 to move up and down.

The decompression unit 50 decompresses the inside of the chamber 40. The decompression unit 50 is connected to an opening 51 provided in the lower wall 42 of the chamber 40, and can suck the gas in the chamber 40 and evacuate the gas through the opening 51.

The transport unit 60 holds the workpiece 200 with the transport pad 61, and carries the workpiece 200 into and out of the electrostatic attraction table 10 in the chamber 40. The transport unit 60 takes the workpiece 200 into and out of the chamber 40 through the loading/unloading opening 44 provided in the side wall 43 of the chamber 40, and a temporary placement chuck table 62 and an electrostatic adsorption table provided outside the chamber 40. The workpiece 200 is conveyed to and from 10.

The transport unit 60 includes a transport pad 61, an arm 63, and a drive unit 64. As shown in FIG. 3, the transfer pad 61 is made of a conductive material, is opposed to the temporary-placed chuck table 62, and is made of a porous ceramic that holds the upper surface 202 of the workpiece 200 by suction. A portion 65 and a frame body 66 that surrounds the outer edge of the suction holding portion 65 are provided. The transport pad 61 suction-holds the upper surface 202 of the workpiece 200 by the suction-holding portion 65 when the suction-holding portion 65 is sucked by a suction source (not shown). Further, in the first embodiment, the transfer pad 61 is connected to the ground via a switch (not shown).

The tip of the arm portion 63 is connected to the transport pad 61. The drive unit 64 includes an elevating/lowering moving means 68 for elevating and lowering the arm portion 63 in the vertical direction 68-1 (shown in FIG. 2), and an arm portion for moving the transfer pad 61 into and out of the chamber 2 through the loading/unloading opening 44. And a moving means 69 for moving 63 in the horizontal direction 69-1 (shown in FIG. 2).

The charge inspection unit 70 is for inspecting the charge state of the holding surface 11 of the electrostatic adsorption table 10. The charging inspection unit 70 includes a surface electrometer 71, as shown in FIGS. 1, 2, and 3. The surface electrometer 71 is mounted on the transport pad 61 and measures the amount of charge on the holding surface 11 of the electrostatic adsorption table 10 facing the surface.

As shown in FIG. 3, the surface electrometer 71 is attached to the outer peripheral surface of the frame portion 67 of the transfer pad 61, and in the first embodiment, is supported by the drive unit 64 of the arm portion 63 on the outer peripheral surface of the frame portion 67. It is located farthest from the base end. The lower surface of the surface electrometer 71 is arranged on the same plane as the surface of the suction holding unit 65 of the transport pad 61. The surface electrometer 71 is arranged such that its lower surface is directly above the holding surface 11 of the electrostatic adsorption table 10 and is spaced apart from the holding surface 11 by a predetermined distance 300 (shown in FIG. 2). Of the positive charge 18 is detected, and information corresponding to the amount of charge, which is the charged state of the holding surface 11, is output to the control unit 100.

The control unit 100 controls each of the above-mentioned constituent elements of the plasma etching apparatus 1. That is, the control unit 100 causes the plasma etching apparatus 1 to execute the processing operation on the workpiece 200. The control unit 100 includes an arithmetic processing device having a microprocessor such as a CPU (central processing unit), a storage device having a memory such as a ROM (read only memory) or a RAM (random access memory), and an input/output interface device. And a computer program capable of executing a computer program.

The arithmetic processing unit of the control unit 100 executes the computer program stored in the ROM on the RAM to generate control signals for controlling each component of the plasma etching apparatus 1. The arithmetic processing unit of the control unit 100 outputs the generated control signal to each component of the plasma etching apparatus 1 via the input/output interface unit. Further, the control unit 100 is connected to a display unit (not shown) configured by a liquid crystal display device for displaying a state of a machining operation, an image and the like, and an input unit used when an operator registers machining content information and the like. .. The input unit includes at least one of a touch panel provided on the display unit and a keyboard.

The control unit 100 also includes a comparison unit 101 and a supply voltage adjustment unit 102, as shown in FIG. The comparison unit 101 and the supply voltage adjustment unit 102 form a charging inspection unit 70. The comparison unit 101 compares the charge amount of the holding surface 11 which is the measurement result of the surface electrometer 71 with a preset allowable range of the charge amount, and the charge amount of the holding surface 11 is outside the allowable range of the charge amount. Determine if there is.

When the comparison unit 101 determines that the charge amount of the holding surface 11 is outside the preset charge amount allowable range, that is, when the charge amount of the holding surface 11 exceeds the allowable range, the supply voltage adjusting unit 102 The voltage adjuster 82 is controlled to adjust the voltage supplied from the DC power supply 80 to the electrostatic adsorption table 10 so that the amount of charge on the holding surface 11 falls within the allowable range.

Specifically, the supply voltage adjusting unit 102 has a relationship between the information according to the charge amount of the holding surface 11 which is the measurement result of the surface electrometer 71 in advance and the voltage value applied to the electrostatic adsorption table 10 by the DC power supply 80. , And the target voltage value of the positive voltage applied by the DC power supply 80 is stored in the electrostatic adsorption table 10. The target voltage value of the positive voltage applied to the electrostatic adsorption table 10 by the DC power supply 80 is a preset value, and the charging amount of the holding surface 11 is within the allowable range, and the supply voltage It is a voltage value of a positive voltage applied to the electrostatic attraction table 10 by the DC power supply 80 before adjustment by the adjustment unit 102.

The supply voltage adjusting unit 102 uses the positive voltage applied to the electrostatic adsorption table 10 by the DC power supply 80 based on the above-mentioned relationship from the information according to the charge amount of the holding surface 11 which is the measurement result of the surface electrometer 71. Calculate the voltage value of. The supply voltage adjusting unit 102 calculates the difference between the target voltage value of the positive voltage stored in advance and the calculated voltage value of the positive voltage applied to the electrostatic attraction table 10 by the DC power supply 80. The supply voltage adjusting unit 102, if the calculated positive voltage voltage applied to the electrostatic adsorption table 10 by the DC power supply 80 is larger than the target voltage value of the positive voltage stored in advance, the voltage adjusting unit 82. Is controlled to apply a positive voltage with a reduced voltage value by the calculated difference from the DC power supply 80 to the electrostatic adsorption table 10. Further, the supply voltage adjusting unit 102 adjusts the voltage when the calculated DC voltage 80 applied to the electrostatic attraction table 10 is smaller than the target voltage value of the positive voltage stored in advance. By controlling the unit 82, a positive voltage obtained by increasing the calculated positive voltage by the difference is applied from the DC power supply 80 to the electrostatic adsorption table 10.

For example, when the target voltage value of the positive voltage is 6000 V (volts) and the calculated DC power source 80 applies the positive voltage voltage value of 6100 (volts) to the electrostatic adsorption table 10, the voltage is supplied. The voltage adjusting unit 102 controls the voltage adjusting unit 82 to apply a positive voltage of 5900 V (volt) to the electrostatic adsorption table 10. In addition, when the target voltage value of the positive voltage is 6000 V (volt) and the calculated DC power source 80 applies a positive voltage value of 5900 (volt) to the electrostatic adsorption table 10, the voltage is supplied. The voltage adjusting unit 102 controls the voltage adjusting unit 82 to apply a positive voltage of 6100 V (volt) to the electrostatic adsorption table 10.

The function of the comparison unit 101 is realized by the above-described arithmetic processing device executing a computer program stored in a storage device. The function of the supply voltage adjusting unit 102 is realized by the storage device storing the relationship and the target voltage value described above, and the arithmetic processing device executing the computer program stored in the storage device.

The charging inspection unit 70 also includes a notification unit 103. The notification unit 103 notifies that the charge amount of the holding surface 11, which is the measurement value of the surface electrometer 71, exceeds the allowable range. The notification unit 103 emits at least one of sound and light to notify the operator of the plasma etching apparatus 1 that the charge amount of the holding surface 11, which is the measurement value of the surface electrometer 71, exceeds the allowable range. When the notification unit 103 is connected to the control unit 100 and receives information indicating that the comparison unit 101 has determined that the charge amount of the holding surface 11 that is the measurement value of the surface electrometer 71 exceeds the allowable range, a sound is output. Emits at least one of light and.

Next, this specification describes a processing operation of the plasma etching apparatus 1 shown in FIG. FIG. 4 is a side view showing a state in which the charge inspection unit of the plasma etching apparatus shown in FIG. 1 measures the amount of charge on the holding surface of the electrostatic adsorption table. FIG. 5 is a side view showing a state in which the transfer unit of the plasma etching apparatus shown in FIG. 1 transfers a workpiece to the holding surface of the electrostatic adsorption table.

In the plasma etching apparatus 1, first, the operator operates the input means to register the processing content information in the control unit 100, and when the control unit 100 receives an instruction to start the processing operation from the operator, the processing operation is performed. In the processing operation, the control unit 100 of the plasma etching apparatus 1 closes the switch 81, applies a target voltage value of a positive voltage from the DC power supply 80 to the lower electrode 17, and causes the holding surface 11 to have a positive charge 18. Charge.

The control unit 100 measures the charge amount of the holding surface 11 with the charge inspection unit 70 at the charge amount measurement timing for measuring the charge amount of the holding surface 11, as shown in FIG. The charge amount measurement timing is the timing at which the charge inspection unit 70 measures the charge amount of the holding surface 11, and every time the workpiece 200 is plasma-etched by a predetermined number, or the operator operates the input means. This is the timing when the control unit 100 receives an instruction to measure the charge amount.

At the charge amount measurement timing, the control unit 100 lowers the shutter 45 by lowering the piston rod 48 to the cylinder 47 that constitutes the shutter opening/closing means 46, opens the loading/unloading opening 44, and drives the transport unit 60. The transfer pad 61 is inserted into the chamber 40 by 64, and the lower surface of the surface electrometer 71 is located immediately above the holding surface 11 of the electrostatic adsorption table 10 and at a predetermined distance 300 from the holding surface 11 as shown in FIG. Place it in the right position. The surface electrometer 71 detects the electric charge of the holding surface 11 and outputs information according to the amount of charge, which is the charged state of the holding surface 11, to the control unit 100.

The comparison unit 101 of the control unit 100 compares the charge amount of the holding surface 11 that is the measurement result of the surface electrometer 71 with a preset allowable range of the charge amount, and the charge amount of the holding surface 11 is preset. It is determined whether the charge amount is out of the allowable range. The supply voltage adjusting unit 102 supplies a positive voltage from the DC power supply 80 to the electrostatic attraction table 10 when the comparing unit 101 determines that the charge amount of the holding surface 11 is outside the preset charge amount allowable range. Is adjusted so that the amount of charge on the holding surface 11 falls within the allowable range.

When the comparison unit 101 determines that the charge amount of the holding surface 11 is outside the preset charge amount allowable range, the control unit 100 causes the comparison unit 101 to hold the measured value of the surface electrometer 71. Information indicating that the charge amount of the surface 11 has exceeded the allowable range is output to the notification unit 103. When the notification unit 103 receives the information indicating that the comparison unit 101 has determined that the charge amount of the holding surface 11, which is the measurement value of the surface electrometer 71, exceeds the allowable range, it outputs at least one of sound and light. Then, the operator is notified that the charge amount of the holding surface 11 is out of the allowable range.

In the control unit 100, at the charge amount measurement timing, when the comparison unit 101 determines that the charge amount of the holding surface 11 is not outside the preset allowable range of the charge amount, or the supply voltage adjustment unit 102 causes electrostatic attraction. After adjusting the voltage value of the positive voltage applied from the DC power source 80 to the table 10 so that the amount of charge on the holding surface 11 is within the allowable range, the transport unit 61 is attached to the drive unit 64 of the transport unit 60 outside the chamber 40. Move to.

The control unit 100 causes the suction holding portion 65 of the transport pad 61 of the transport unit 60 to suction-hold the upper surface 202 of the workpiece 200 on the temporary placement chuck table 62. The control unit 100 causes the drive unit 64 to insert the transfer pad 61 into the chamber 40, and as shown in FIG. 5, the workpiece suctioned and held on the transfer pad 61 is held on the holding surface 11 of the electrostatic adsorption table 10. In addition, it is arranged at a position spaced from the holding surface 11. The control unit 100 causes the drive unit 64 to cause the transport unit 60 to place the workpiece 200 on the holding surface 11 of the electrostatic attraction table 10.

Then, since the holding surface 11 of the electrostatic attraction table 10 is charged with the positive charge 18, the lower surface 201 side of the workpiece 200 is negatively charged, and the upper surface 202 side of the workpiece 200 is positively charged. Since the electrostatic attraction table 10 and the workpiece 200 are charged with electric charges having different polarities, the workpiece 200 is attracted and held on the holding surface 11 by the electrostatic attraction force. The control unit 100 releases (stops) the suction holding of the suction holding portion 65 of the transfer pad 61, and then causes the drive unit 64 to move the transfer unit 60 to the outside of the chamber 40.

The control unit 100 causes the shutter opening/closing means 46 to lower the shutter 45 to seal the inside of the chamber 40. At this time, the pressure inside the chamber 40 is atmospheric pressure. In the control unit 100, the depressurizing means 53 depressurizes the inside of the chamber 40 and the open/close valve 32 is opened to open the processing gas supply source 33 from the processing gas supply source 33 with the upper surface 202, which is the surface to be processed of the workpiece 200, exposed upward. The processing gas is sent into the gas flow passage 31, and is ejected downward from the gas ejection hole 24.

The control unit 100 closes the switch 81 and keeps the DC power supply 80 applying a positive voltage to the lower electrode 17, and then closes the switch 34 to apply a high frequency voltage from the high frequency power supply 35 between the workpiece 200 and the upper electrode 20. Apply. Then, the processing gas is turned into plasma between the electrostatic adsorption table 10 and the upper electrode 20, and the upper surface 202 of the workpiece 200 is plasma-etched by the turned processing gas.

When the upper surface 202 of the workpiece 200 is plasma-etched by a desired amount, the control unit 100 stops the supply of the processing gas from the processing gas supply source 33 into the chamber 40 and opens the switch 34 to open the electrostatic adsorption table. The application of the high frequency voltage between 10 and the upper electrode 20 is stopped, and the plasma of the processing gas is stopped. At this time, the control unit 100 maintains the state where the positive voltage (negative voltage) is applied to the lower electrode 17 while keeping the switch 81 closed.

The control unit 100 opens the loading/unloading opening 44, discharges the processing gas from the loading/unloading opening 44 to the outside, and then lowers the shutter 45 by the shutter opening/closing means 46 to open the loading/unloading opening 44. The control unit 100 inserts the transfer pad 61 into the chamber 40 by the drive unit 64 of the transfer unit 60, and causes the transfer pad 61 to suck and hold the upper surface 202 of the workpiece 200.

The control unit 100 opens the switch 81 to stop the application of the DC power supply 80 to the lower electrode 17, releases the attraction and holding of the workpiece 200 by the electrostatic attraction table 10, and causes the drive unit 64 to transfer the transport pad 61. The workpiece 200 sucked and held by the above is conveyed to the outside of the chamber 40, and is placed on the temporary placement chuck table 62. In this way, the plasma etching apparatus 1 plasma-etches the workpieces 200 one by one.

In the plasma etching apparatus 1 according to the first embodiment, since the surface electrometer 71 is attached to the transfer pad 61 of the transfer unit 60, the charge amount of the holding surface 11 of the electrostatic adsorption table 10 is attached to the transfer pad 61. It can be measured by the surface electrometer 71. As a result, the plasma etching apparatus 1 can grasp the actual charge amount of the holding surface 11 as a result of applying the voltage to the lower electrode 17, so that it can be easily confirmed whether or not the workpiece 200 can be reliably attracted. This has an effect that the suction state of the workpiece 200 can be easily grasped.

Further, in the plasma etching apparatus 1 according to the first embodiment, since the surface electrometer 71 attached to the transfer pad 61 of the transfer unit 60 measures the charge amount of the holding surface 11 of the electrostatic adsorption table 10, the DC power supply 80 lowers There is no need to connect a measuring device to the circuit applied to the electrode 17.

[Embodiment 2]
A plasma etching apparatus according to Embodiment 2 of the present invention will be described with reference to the drawings. FIG. 6 is a plan view of a transfer pad of the plasma etching apparatus according to the second embodiment. FIG. 7 is a diagram showing a state in which the ionized air supply unit of the plasma etching apparatus according to the second embodiment discharges the holding surface of the electrostatic adsorption table. 6 and 7, the same parts as those of the first embodiment are designated by the same reference numerals and the description thereof will be omitted.

The plasma etching apparatus 1 according to the second embodiment includes the ionizer 72 that is an ionized air supply unit, and the comparison unit 101 determines that the charge amount of the holding surface 11 is outside the preset charge amount allowable range. In addition, it is the same as the first embodiment except that the ionizer 72 once removes the charge on the holding surface 11.

As shown in FIG. 6, the ionizers 72 are attached to both sides of the surface electrometer 71, and two ionizers are provided in the first embodiment. The ionizer 72 supplies ionized air 73 to the holding surface 11 of the electrostatic adsorption table 10 when the charge amount of the holding surface 11 as the measured value exceeds the allowable range, and the charge amount of the holding surface 11 falls within the allowable range. It is adjusted so that The ionizer 72 is a so-called corona discharge type static eliminator, and blows ionized air 73 capable of neutralizing the charges on the holding surface 11 downward toward the holding surface 11 to remove the electric charge from the holding surface 11.

In the plasma etching apparatus 1 according to the second embodiment, when the comparison unit 101 determines that the charge amount of the holding surface 11 is out of the preset charge amount allowable range, the control unit 100 opens the switch 81, The application of the positive voltage from the DC power supply 80 to the lower electrode 17 is stopped. The control unit 100 causes the drive unit 64 to move the transport pad 61 along the holding surface 11 while blowing the ionizing air 73 downward to the ionizer 72, and blows the ionizing air 73 onto the entire holding surface 11 to hold the holding surface 11. Remove all 11 electricity. In the first embodiment, the drive unit 64 moves the transfer pad 61 shown by the dotted line in FIG. 7 from the position on the far side of the chamber 40 to the outside of the chamber 40 through the loading/unloading opening 44 and moves the transfer pad 61 from the ionizer 72 to the ionized air. 73 is blown to the holding surface 11.

In the control unit 100, after the static elimination of the holding surface 11 by the ionizer 72 is completed, the control unit 100 closes the switch 81 and applies a positive voltage from the DC power supply 80 to the lower electrode 17. At this time, as in the first embodiment, the supply voltage adjusting unit 102 may apply a positive voltage having a voltage value adjusted by the voltage adjusting unit 82. After that, the plasma etching apparatus 1 according to the second embodiment plasma-etches the workpiece 200 as in the first embodiment.

In the plasma etching apparatus 1 according to the second embodiment, since the surface electrometer 71 is attached to the transfer pad 61 of the transfer unit 60, the charge amount of the holding surface 11 of the electrostatic adsorption table 10 is attached to the transfer pad 61. It can be measured by the surface electrometer 71. As a result, the plasma etching apparatus 1 can grasp the actual charge amount of the holding surface 11 as a result of applying the voltage to the lower electrode 17, so that it can be easily confirmed whether or not the workpiece 200 can be reliably attracted. This has an effect that the suction state of the workpiece 200 can be easily grasped.

Further, in the plasma etching apparatus 1 according to the second embodiment, the ionizer 72 is attached to the transfer pad 61 of the transfer unit 60, and the charge amount of the holding surface 11 is outside the preset charge amount allowable range. In the case where 101 is determined, the holding surface 11 is once discharged by the ionizer 72, so that the charge amount of the holding surface 11 can be easily adjusted to be within the allowable range.

The present invention is not limited to the above embodiment. That is, various modifications can be made without departing from the gist of the present invention. For example, the plasma etching apparatus 1 of the present invention alternately repeats an etching step of etching the upper surface 202 of the workpiece 200 and a film deposition step of depositing a film on the upper surface 202 of the workpiece 200 after the etching step. The workpiece 200 may be plasma-etched by the so-called Bosch method.

DESCRIPTION OF SYMBOLS 1 Plasma etching apparatus 10 Electrostatic adsorption table 11 Holding surface 30 Gas supply unit 40 Chamber 44 Loading/unloading opening 50 Decompression unit 60 Transfer unit 61 Transfer pad 70 Charge inspection unit 71 Surface potential meter 72 Ionizer (ionized air supply part)
73 Ionized air 101 Comparison unit 102 Supply voltage adjustment unit 103 Notification unit 200 Workpiece

Claims (3)

An electrostatic attraction table that electrostatically attracts and fixes a workpiece to a holding surface, a gas supply unit that supplies a processing gas that has been turned into plasma to the workpiece held by the electrostatic attraction table, and the electrostatic attraction A chamber that contains a table and the gas supply unit and has an opening for loading and unloading a workpiece, a decompression unit that depressurizes the inside of the chamber, and a electrostatic pad of the chamber that holds the workpiece with a transfer pad. A transport unit that carries in and out the table, and a charging inspection unit that inspects the charging state of the holding surface,
The charging inspection unit is
A surface electrometer attached to the transfer pad for measuring the amount of charge on the holding surface facing the transfer pad;
A comparison unit that compares the measured value of the surface electrometer with a preset allowable range of the charge amount;
A plasma etching apparatus comprising: a notification unit that notifies that the measured value exceeds an allowable range. The supply voltage adjusting unit according to claim 1, further comprising: a supply voltage adjusting unit that adjusts a voltage supplied to the electrostatic attraction table when the measured value exceeds an allowable range so that a charge amount of the holding surface falls within an allowable range. Plasma etching equipment. When the measured value exceeds an allowable range, ionized air is supplied to the holding surface of the electrostatic adsorption table, and an ionized air supply unit is provided to adjust the charge amount of the holding surface to be within an allowable range. Alternatively, the plasma etching apparatus according to claim 2.

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