Plasma Etching Apparatus and Plasma Etching Method

Abstract

To provide a technique of adjusting a thickness of a substrate.SOLUTION: A plasma etching device comprises: a substrate holding part; a plasma generation part; a nozzle; an electrode; a high-frequency power supply: a movement part; and a control part. The substrate holding part holds the substrate in an inner part of a processing chamber. The plasma generation part turns an etching gas into a plasma in an external part of the processing chamber. The nozzle supplies the etching gas to one part of the substrate held by the substrate holding part. The electrode is provided to the substrate holding part. The high-frequency power supply applies a high-frequency power for a bias to the electrode. The movement part moves a supply position of the etching gas that was turned into the plasma in the substrate. The control part controls the plasma generation part, the high-frequency power supply, and the movement part. The control part changes a voltage of the high-frequency power in accordance with the supply position.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present disclosure relates to a plasma etching apparatus and a plasma etching method.

Background Art

[0002] The plasma etching apparatus described in Patent Document 1 includes a vacuum chamber, an electrostatic chuck table, a nozzle, nozzle swinging means, and control means. The electrostatic chuck table holds a workpiece in the vacuum chamber. The nozzle supplies a plasma etching gas to a part of the workpiece held by the electrostatic chuck table. The nozzle swinging means swings the nozzle so as to draw a horizontal arc-shaped locus. The control unit controls the rotation amount of the electrostatic chuck and the position of the nozzle to supply the plasma etching gas to an arbitrary part of the workpiece.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] One aspect of the present disclosure provides a technique for adjusting the thickness of a substrate.

Means for Solving the Problems

[0005] A plasma etching apparatus according to an aspect of the present disclosure includes a substrate holding unit, a plasma generation unit, a nozzle, an electrode, a high-frequency power source, a moving unit, and a control unit. The substrate holding unit holds a substrate inside a processing chamber. The plasma generation unit plasmatizes an etching gas for etching the substrate outside the processing chamber. The nozzle supplies the plasmatized etching gas to a part of the substrate held by the substrate holding unit. The electrode is provided on the substrate holding unit. The high-frequency power source applies bias high-frequency power to the electrode. The moving unit moves the supply position of the plasmatized etching gas on the substrate. The control unit controls the plasma generation unit, the high-frequency power source, and the moving unit. The control unit changes the voltage of the high-frequency power according to the supply position.

Effect of the Invention

[0006] According to one aspect of the present disclosure, the thickness of the substrate can be adjusted.

Brief Description of the Drawings

[0007]

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Embodiments for Carrying out the Invention

[0008] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. In each drawing, the same or corresponding components are denoted by the same reference numerals, and the description thereof may be omitted. In this specification, the X-axis direction, the Y-axis direction, and the Z-axis direction are perpendicular to each other. The X-axis direction and the Y-axis direction are horizontal directions, and the Z-axis direction is a vertical direction.

[0009] First, with reference to FIGS. 1 and 2, a plasma etching apparatus 1 according to an embodiment will be described. The plasma etching apparatus 1 etches a substrate W with a plasma-etched etching gas. The plasma etching apparatus 1 is a vacuum plasma apparatus in the present embodiment, but may be an atmospheric pressure plasma apparatus.

[0010] The plasma etching apparatus 1 includes, for example, a processing container 10, an exhaust unit 15, a substrate holding unit 20, a plasma generation unit 30, a nozzle 40, an electrode 50, a high-frequency power source 51, a moving unit 60, and a control unit 90.

[0011] The processing container 10 has a processing chamber 11 inside. The processing container 10 has a loading / unloading port 12 for the substrate W and a gate valve 13 for opening and closing the loading / unloading port 12.

[0012] The exhaust unit 15 evacuates the gas in the processing chamber 11 to reduce the pressure in the processing chamber 11. The exhaust unit 15 includes a pipe 16 connected to the processing container 10. Although not shown, the exhaust unit 15 includes an opening / closing valve provided in the middle of the pipe 16 and a pressure controller provided in the middle of the pipe 16.

[0013] When a decompression source such as a vacuum pump operates and the opening / closing valve opens the pipe 16, the pipe 16 sucks the gas in the processing chamber 11. The gas pressure in the processing chamber 11 is controlled by a pressure controller. The pressure controller includes a pressure adjustment valve such as a butterfly valve, for example.

[0014] The substrate holding unit 20 holds the substrate W inside the processing chamber 11. The substrate holding unit 20 is, for example, an electrostatic chuck. The electrostatic chuck can adsorb the substrate W under a reduced pressure atmosphere. When the plasma etching apparatus 1 etches the substrate W under atmospheric pressure, the substrate holding unit 20 may be a vacuum chuck.

[0015] The plasma generation unit 30 plasmatizes the etching gas for etching the substrate W outside the processing chamber 11. The plasmatized etching gas contains radicals. The radicals contain, for example, ions. The radicals collide with the first main surface Wa of the substrate W to etch the substrate W. Although not shown, the plasma generation unit 30 includes, for example, an electrode for plasma generation and a high-frequency power supply that supplies high-frequency power to the electrode.

[0016] The plasma generation unit 30 plasmatizes the etching gas with microwaves, for example. The frequency of the microwaves is, for example, 2.45 GHz. The plasma is not limited to microwave plasma and may be capacitively coupled plasma, inductively coupled plasma, or the like. As long as radicals are generated. The high-frequency power for plasma generation has a frequency of, for example, 450 kHz to 2.45 GHz and a voltage of, for example, 0.5 kV to 5 kV.

[0017] Although not shown, the plasma generation unit 30 has a gas supply chamber provided with an electrode for plasma generation, and plasmatizes the etching gas in the gas supply chamber. The etching gas may be a mixed gas, for example, a mixed gas of SF6 gas and O2 gas. In addition to the etching gas, a dilution gas for diluting the etching gas may be supplied to the gas supply chamber. As the dilution gas, an inert gas such as Ar gas is used.

[0018] The plasma generation unit 30 includes, for example, an individual pipe, an on-off valve provided in the middle of the individual pipe, and a flow controller provided in the middle of the individual pipe for each type of gas. When the on-off valve opens the individual pipe, gas is supplied from the supply source to the gas supply chamber. The supply amount is controlled by the flow controller. On the other hand, when the on-off valve closes the individual pipe, the supply of gas from the supply source to the gas supply chamber is stopped.

[0019] The nozzle 40 supplies the etching gas turned into plasma by the plasma generation unit 30 to a part of the substrate W held by the substrate holding unit 20. The nozzle 40 has a discharge nozzle 41 that discharges the plasma-etched etching gas. The discharge nozzle 41 discharges the plasma-etched etching gas, for example, perpendicularly to the first main surface Wa of the substrate W. The discharge nozzle 41 has a discharge port 41a at its lower end.

[0020] The flow rate and supply time of the plasma-etched etching gas are controlled, for example, using the flow controller and on-off valve of the plasma generation unit 30. The higher the flow rate of the plasma-etched etching gas, the faster the etching rate. Also, the longer the supply time of the plasma-etched etching gas, the larger the etching amount.

[0021] The nozzle 40 may have a suction nozzle 42 surrounding the discharge nozzle 41. The discharge nozzle 41 and the suction nozzle 42 form a double pipe. The suction nozzle 42 narrows the area to be etched on the substrate W by sucking the plasma-etched etching gas. The suction port 42a at the lower end of the suction nozzle 42 is installed, for example, below the discharge port 41a at the lower end of the discharge nozzle 41.

[0022] The electrode 50 is provided on the substrate holding unit 20. For example, the electrode 50 is embedded inside the substrate holding unit 20. When the substrate holding unit 20 holds the substrate W horizontally, when viewed from the vertical direction, the electrode 50 has a size equal to or larger than that of the substrate W. A high-frequency power supply 51 is electrically connected to the electrode 50.

[0023] The high-frequency power supply 51 applies high-frequency power to the electrode 50. The high-frequency power is the power for drawing the radicals of the plasma-etched etching gas into the substrate W, and is the power for bias for controlling the energy of the radicals. The high-frequency power for bias has a frequency of, for example, 0.1 MHz to 100 MHz and a voltage of, for example, 0.5 kV to 5 kV. The high-frequency power for bias is controlled independently of the high-frequency power for plasma generation.

[0024] The high-frequency power supply 51 generates a sheath region in the vicinity of the first main surface Wa of the substrate W by applying high-frequency power to the electrode 50. The sheath region is a region where radicals such as ions repeatedly collide with the first main surface Wa of the substrate W. Due to the collision of the radicals, the first main surface Wa of the substrate W is etched. The higher the voltage of the high-frequency power, the higher the energy of the radicals and the faster the etching rate.

[0025] The moving unit 60 moves the supply position of the plasma-etched etching gas on the substrate W. The moving unit 60 has, for example, a rotational moving unit 61 and a linear moving unit 62. The rotational moving unit 61 rotates the substrate holding unit 20. The rotational moving unit 61 includes, for example, a motor. The linear moving unit 62 moves the substrate holding unit 20 in a direction orthogonal to the rotation center line of the substrate holding unit 20. The linear moving unit 62 includes, for example, a motor and a ball screw that converts the rotational motion of the motor into a linear motion.

[0026] When the substrate holding unit 20 holds the substrate W horizontally, the rotational moving unit 61 rotates the substrate holding unit 20 about a vertical rotation center line, and the linear moving unit 62 moves the substrate holding unit 20 in the horizontal direction. Note that the moving unit 60 may relatively move the substrate holding unit 20 and the nozzle 40, or may move the nozzle 40. The moving unit 60 may swing-move the nozzle 40 in the same manner as in Patent Document 1.

[0027] The control unit 90 is, for example, a computer, and includes a CPU (Central Processing Unit) 91 and a storage medium 92 such as a memory. A program for controlling various processes executed in the plasma etching apparatus 1 is stored in the storage medium 92. The control unit 90 controls the operation of the plasma etching apparatus 1 by causing the CPU 91 to execute the program stored in the storage medium 92.

[0028] Next, with reference to FIG. 3, a substrate processing method using the plasma etching apparatus 1 shown in FIGS. 1 and 2 will be described. The substrate processing method includes, for example, steps S101 to S103 shown in FIG. 3. The plasma etching apparatus 1 performs step S103.

[0029] In step S101 of FIG. 3, the substrate W is thinned. The substrate W is, for example, a silicon wafer, but may be a compound semiconductor wafer. The substrate W may be a glass substrate. As shown in FIG. 4, the substrate W has a first main surface Wa and a second main surface Wb opposite to the first main surface Wa.

[0030] The first main surface Wa of the substrate W is etched by the plasma etching apparatus 1. Devices (not shown) are formed on the second main surface Wb of the substrate W. The devices are, for example, electronic circuits, and are formed for each region partitioned by a plurality of streets shown by broken lines in FIG. 4. After step S103, the substrate W is cut along the plurality of streets and divided into a plurality of chips.

[0031] A protective film F for protecting the devices may be formed on the second main surface Wb of the substrate W. The protective film F protects the devices while the substrate W is being thinned. The protective film F covers the entire second main surface Wb of the substrate W. The protective film F is removed after the substrate W is thinned. Note that, instead of forming the protective film F on the second main surface Wb of the substrate W, a second substrate different from the substrate W may be bonded. The second substrate is a silicon wafer, a compound semiconductor wafer, or a glass substrate. Devices may also be formed on the surface of the second substrate facing the substrate W.

[0032] For thinning the substrate W, for example, a grinding apparatus 100 shown in FIG. 5 is used. The grinding apparatus 100 includes, for example, a flange 101, a spindle shaft 102, a first rotation motor 103, a chuck 104, and a second rotation motor 105.

[0033] The flange 101 is provided at the lower end of the spindle shaft 102. A grinding tool D is attached to the flange 101. The grinding tool D includes, for example, a disk-shaped grinding wheel D1 and a plurality of grinding stones D2 arranged in a ring shape on the lower surface of the grinding wheel D1. The first rotation motor 103 rotates the grinding tool D by rotating the spindle shaft 102 about the rotation center line R1.

[0034] The chuck 104 holds the substrate W from below with the first main surface Wa of the substrate W facing upward. The suction surface of the chuck 104 that sucks the substrate W, that is, the upper surface of the chuck 104, may be a conical surface symmetric about the rotation center line R2 of the chuck 104. By adjusting the inclination angle of the rotation center line R2 of the chuck 104, the thickness distribution in the radial direction of the substrate W can be adjusted. The second rotation motor 105 rotates the substrate W by rotating the chuck 104 about the rotation center line R2.

[0035] As shown in FIG. 6, the orbit E of the plurality of grinding stones D2 arranged in a ring shape is set to pass through the center of the upper surface of the substrate W. Further, the substrate W is sucked to the chuck 104 such that the center of the upper surface of the substrate W passes through the rotation center line R2 of the chuck 104. As the substrate W rotates together with the chuck 104, the entire upper surface of the substrate W is ground by the grinding stones D2.

[0036] The ground substrate W has a thickness distribution. The thickness variation is represented, for example, by the difference between the maximum value and the minimum value of the thickness (TTV: Total Thickness Variation). The thickness variation is caused, for example, by the relative speed difference between the grinding stones D2 and the substrate W on the orbit E of the grinding stones D2 shown in FIG. 6. When the protective film F is used, the thickness variation increases due to the deformation of the protective film F.

[0037] Note that a laser processing apparatus (not shown) may be used to thin the substrate W. The laser processing apparatus forms a modified layer inside the substrate W. A plurality of modified layers are formed at intervals in the radial direction and the circumferential direction of the substrate W. By dividing the substrate W starting from the plurality of modified layers, the substrate W can be thinned. Also in this case, the thinned substrate W has a thickness distribution.

[0038] In step S102 of FIG. 3, the thickness distribution of the thinned substrate W is measured. To measure the thickness distribution of the substrate W, the measuring device 200 shown in FIG. 1 is used. The measurement location of the thickness distribution of the substrate W may be inside the grinding device 100 or the laser processing device, or inside the plasma etching device 1, or in the middle of the transport path for transporting the substrate W from the grinding device 100 or the laser processing device to the plasma etching device 1.

[0039] The measuring device 200 may be either non-contact type or contact type, but preferably it is non-contact type. The non-contact measuring device 200 uses, for example, infrared light transmitted through the substrate W to utilize the interference between the light reflected from the first main surface Wa of the substrate W and the light reflected from the second main surface Wb of the substrate W, and measures the thickness distribution of the substrate W. The non-contact measuring device 200 may measure the thickness distribution of the substrate W by measuring the distance to the substrate W using a capacitance-type displacement sensor or a laser displacement sensor.

[0040] The measuring device 200 transmits the measurement data of the thickness distribution of the substrate W to the plasma etching device 1. The measurement data to be transmitted includes the coordinates on the first main surface Wa of the substrate W and the thickness of the substrate W for each coordinate. The control unit 90 of the plasma etching device 1 receives the measurement data transmitted by the measuring device 200, and performs control to reduce the thickness unevenness of the substrate W by controlling the etching of the substrate based on the received measurement data of the thickness distribution of the substrate W.

[0041] In step S103 of FIG. 3, plasma etching of the substrate W is performed. For the plasma etching of the substrate W, the plasma etching apparatus 1 shown in FIGS. 1 and 2 is used. The control unit 90 of the plasma etching apparatus 1 performs control to change the voltage of the high-frequency power for bias, for example, according to the supply position of the plasma-etched etching gas. Thereby, the thickness distribution of the substrate W can be adjusted.

[0042] Specifically, for example, the control unit 90 acquires measurement data of the thickness distribution of the substrate W, and performs control to change the voltage of the high-frequency power for bias based on the acquired measurement data. The control unit 90 sets the voltage of the high-frequency power for bias higher at positions where the thickness of the substrate W is thicker, for example, with the minimum value of the thickness of the substrate W as a reference. Thereby, thickness unevenness of the substrate W can be reduced.

[0043] Note that the control unit 90 may perform control to change the flow rate or supply time of the plasma-etched etching gas instead of or in addition to the control of changing the voltage of the high-frequency power for bias. The control unit 90 sets a larger flow rate or a longer supply time at positions where the thickness of the substrate W is thicker, for example, with the minimum value of the thickness of the substrate W as a reference. Thereby, thickness unevenness of the substrate W can be reduced.

[0044] Note that the thickness distribution of the substrate W has the same tendency, for example, for each lot of the substrate W. Therefore, the control unit 90 may perform control to reduce the thickness unevenness of the substrate W by associating and storing in advance the supply position of the plasma-etched etching gas, the voltage of the high-frequency power for bias, etc., and controlling the etching of the substrate W according to the stored data.

[0045] Next, with reference to FIGS. 7 to 10, the number and arrangement of the discharge nozzles 41 will be described. In FIGS. 7 to 10, the black circles indicate the centers of the first main surface Wa of the substrate W. As shown in FIG. 7, when the number of the discharge nozzles 41 is one, rotation of the substrate W around the Z axis and movement of the substrate W in the X-axis direction are performed so that the supply position of the plasma-etched etching gas is displaced over the entire first main surface Wa of the substrate W.

[0046] As shown in FIG. 8, even when a plurality of discharge nozzles 41 are arranged in the radial direction of the substrate W, rotation of the substrate W around the Z axis and movement of the substrate W in the X-axis direction are performed. The greater the number of discharge nozzles 41, the shorter the movement distance of the substrate W in the X-axis direction can be, and the throughput can be improved. As shown in FIGS. 9 and 10, it is also possible to make the movement distance of the substrate W in the X-axis direction zero.

[0047] The plurality of discharge nozzles 41 can independently control the flow rate and supply time of the plasma-etched etching gas. The control unit 90 performs control to independently change the flow rate or supply time of the plasma-etched etching gas for each discharge nozzle 41. The control unit 90 performs control to independently change the flow rate or supply time for each discharge nozzle 41 according to the thickness of the substrate W at the discharge position of the discharge nozzle 41.

[0048] The control unit 90 sets, for example, a larger flow rate or a longer supply time for the discharge nozzle 41 arranged at a position where the thickness of the substrate W is thicker, based on the minimum value of the thickness of the substrate W. Thereby, thickness unevenness of the substrate W can be reduced. When the minimum value of the thickness of the substrate W is the target value, it is preferable to perform control not to discharge the etching gas from the discharge nozzle 41 arranged at the position where the thickness of the substrate W is the minimum value.

[0049] Note that the control unit 90 may perform control to change the voltage of the high-frequency power for bias instead of or in addition to the control to change the flow rate or supply time of the plasma-etched etching gas. Specifically, the control unit 90 performs control to set a higher voltage of the high-frequency power for bias for a position where the thickness of the substrate W is thicker, for example, based on the minimum value of the thickness of the substrate W. Thereby, thickness unevenness of the substrate W can be reduced. When the minimum value of the thickness of the substrate W is the target value, it is preferable to perform control not to discharge the etching gas from the discharge nozzle 41 arranged at the position where the thickness of the substrate W is the minimum value.

[0050] As shown in FIG. 9, a plurality of discharge nozzles 41 may be arranged in a staggered pattern, or as shown in FIG. 10, a plurality of discharge nozzles 41 may be randomly arranged. If there are discharge ports 41a with the same width as the regions A1 to A4 directly above each of the plurality of regions A1 to A4 formed by radially dividing the first main surface Wa of the substrate W, it is possible to supply the plasma-etched etching gas to the entire first main surface Wa of the substrate W only by rotating the substrate W around the Z axis.

[0051] As described above, embodiments of the plasma etching apparatus and the plasma etching method according to the present disclosure have been explained, but the present disclosure is not limited to the above embodiments. Within the scope described in the claims, various changes, modifications, substitutions, additions, deletions, and combinations are possible. Naturally, they also belong to the technical scope of the present disclosure.

Description of Reference Numerals

[0052] 1 Plasma etching apparatus 11 Processing chamber 20 Substrate holding unit 30 Plasma generation unit 40 Nozzle 50 Electrode 51 High-frequency power supply 60 Moving unit 90 Control unit W Substrate

Claims

1. a substrate holding unit that holds a substrate inside a processing chamber; a plasma generation unit that generates plasma from an etching gas for etching the substrate outside the processing chamber; a nozzle that supplies the plasma-generated etching gas to a part of the substrate held by the substrate holding unit; an electrode provided in the substrate holding unit; a high-frequency power supply that applies high-frequency power for bias to the electrode; a moving unit that moves the supply position of the plasma-generated etching gas on the substrate; a control unit that controls the plasma generation unit, the high-frequency power supply, and the moving unit; comprising a plasma etching apparatus, wherein the control unit performs control to change the voltage of the high-frequency power according to the supply position.

2. The plasma etching apparatus according to claim 1, wherein the control unit acquires measurement data of the thickness distribution of the substrate and performs control to change the voltage of the high-frequency power based on the acquired measurement data.

3. The plasma etching apparatus according to claim 1 or 2, wherein the control unit performs control to change the flow rate or supply time of the plasma-generated etching gas according to the supply position.

4. a substrate holding unit that holds a substrate inside a processing chamber; a plasma generation unit that generates plasma from an etching gas for etching the substrate outside the processing chamber; a nozzle that supplies the plasma-generated etching gas to a part of the substrate held by the substrate holding unit; a moving unit that moves the supply position of the plasma-generated etching gas on the substrate; a control unit that controls the plasma generation unit and the moving unit; comprising wherein the plasma generation unit includes a flow rate controller that controls the flow rate of the plasma-generated etching gas discharged from the nozzle; a plasma etching apparatus, wherein the control unit controls the flow rate controller to change the flow rate of the plasma-generated etching gas discharged from the nozzle according to the supply position.

5. The plasma etching apparatus according to claim 4, wherein the control unit acquires measurement data of the thickness distribution of the substrate and controls the flow rate controller to change the flow rate based on the acquired measurement data.

6. wherein the moving unit includes a rotational moving unit that rotates the substrate by rotating the substrate holding unit The plasma etching apparatus according to any one of claims 1 to 5, having a plurality of the nozzles in the radial direction of the substrate.

7. holding a substrate by a substrate holding portion inside a processing chamber; plasma-treating an etching gas for etching the substrate outside the processing chamber; discharging the plasma-treated etching gas from a nozzle and supplying it to a part of the substrate held by the substrate holding portion; applying high-frequency power for bias to an electrode provided in the substrate holding portion; moving a supply position of the plasma-treated etching gas on the substrate; changing a voltage of the high-frequency power according to the supply position; A plasma etching method comprising:

8. A plasma etching method according to claim 7, comprising: obtaining measurement data of a thickness distribution of the substrate; and changing the voltage of the high-frequency power based on the obtained measurement data.

9. The plasma etching method according to claim 7 or 8, wherein a plurality of the nozzles are arranged in the radial direction of the substrate.

10. A plasma etching method comprising etching the substrate using the plasma etching apparatus according to claim 4 or 5.

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