JP3773561B2 - Wafer processing equipment - Google Patents

Description

[0001]
[Industrial application fields]
The present invention relates to a wafer processing apparatus, and more particularly to a wafer processing apparatus provided with a vacuum processing chamber and lift pins.
In a wafer processing apparatus, it is important that the degree of vacuum in the processing chamber can be maintained with high reliability.
[0002]
[Prior art]
FIG. 8 shows an example of a conventional wafer processing apparatus 10. Reference numeral 11 denotes a processing chamber, and an electrostatic chuck 12 is provided. A lift pin 13 is slidably provided in the cylindrical guide 14. An O-ring 15 is provided between the lift pin 13 and the guide 14 so that the vacuum in the processing chamber 11 is maintained.
The lower end of the lift pin 13 is mechanically connected to the air actuator 16.
When the air actuator 16 is actuated, the lift pins 13 are moved up against the springs 17 as shown by two-dot chain lines, and the wafer 18 is lifted from the electrostatic chuck 12 and supported.
[0003]
[Problems to be solved by the invention]
In general, the O-ring 15 is vulnerable to high temperatures. On the other hand, wafer processing has been performed at higher temperatures. For this reason, the O-ring 15 deteriorates relatively quickly, and as a result, the degree of vacuum in the processing chamber 11 decreases.
When the degree of vacuum in the processing chamber 11 decreases, inconvenience occurs in wafer processing.
Further, in the electrostatic check 12, even after the supply of current is cut off, the electric charge remains for a certain time and the wafer 18 is attracted. On the other hand, since the lift pin 13 is mechanically coupled to the air actuator 16, the lift pin 13 always moves up when the air actuator 16 is operated. For this reason, when the air actuator 16 is operated when the wafer 18 is relatively strongly adsorbed by the residual charge, a strong force is applied to the wafer 18 and the wafer 18 is broken.
[0004]
Therefore, an object of the present invention is to provide a wafer processing apparatus that solves the above-described problems.
[0005]
[Means for Solving the Problems]
FIG. 1 shows a principle configuration diagram of the present invention. The wafer processing apparatus 30 has a wafer processing chamber 32 in which a stage 31 is accommodated, a lift pin 33, and a bottomed cylindrical shape, extends downward from the wafer processing chamber 32, and accommodates the lift pin 33. The lift pin accommodating part 34, the raising / lowering means 35 which moves up and down along the lift pin accommodating part 34, and the magnetic coupling means 36 which magnetically couples the raising / lowering means 35 and the lift pin 33 are provided. When the lifting / lowering means 35 moves up, the lift pin 33 moves up in the lift pin accommodating portion 34 via the magnetic coupling means 36.
[0006]
[Action]
The lift pin accommodating portion 34 acts to maintain the airtightness of the wafer processing chamber 32.
[0007]
【Example】
FIG. 2 shows a wafer processing apparatus 40 according to an embodiment of the present invention.
In the wafer processing chamber 41, an electrostatic chuck 42 as a stage and a plasma generator (not shown) for etching are provided.
[0008]
Reference numeral 43 denotes a lift pin housing portion which includes a cylindrical body 44 and a bottom plate 45 which is welded to the lower end and closes the lower end of the cylindrical body 44 and is attached to the lower surface of the wafer processing chamber 41 and extends downward. I'm out. The cylinder 44 is aligned with the hole 46 of the electrostatic chuck 42. The cylinder body 44 and the bottom plate 45 are both made of stainless steel, which is nonmagnetic, in relation to a magnetic coupling device described later.
[0009]
Reference numeral 50 denotes a lift pin, which includes a Teflon (registered trademark) lift pin main body 51, an iron intermediate column portion 52, and a Teflon (registered trademark) auxiliary body 53, as shown in FIG. 4. The lift pin main body 51 and the auxiliary body 53 are screwed on both sides of the intermediate column portion 52. Lift pin body 51 and the auxiliary body 53, the diameter is d1, the diameter d ₂ of the intermediate pillar portion 52 is slightly less than d _1. The lift pin 50 is slidably accommodated in the hole 46 and the cylindrical portion 44. As shown in FIG. 3, there is a gap 54 between the outer peripheral surface of the intermediate column portion 52 and the inner peripheral surface of the cylindrical body 44.
[0010]
Reference numeral 60 denotes a driving body as an elevating means. As shown in FIG. 3, a permanent magnet assembly 63 is incorporated in the center of a stainless steel block 62 having a through hole 61, and Teflon (registered trademark) is provided on the upper and lower sides. ) Made of bearing members 64 and 65 made of. The drive body 60 is slidably fitted to the outside of the cylindrical body 44. An inner diameter d ₁₀ of a permanent magnet 70 to be described later is slightly larger than an inner diameter d ₁₁ of the bearing members 64 and 65, and there is a gap 68 between the permanent magnet 70 and the cylindrical body 44. The driving body 60 is screwed to the arm 67 of the air actuator 66.
[0011]
As shown in FIG. 5, the permanent magnet assembly 63 includes a cylindrical permanent magnet 70 that is magnetized so that a plurality of magnetic poles are arranged in the circumferential direction and both ends in the axial direction are different from each other. And a cylindrical yoke 71 surrounding the. The permanent magnet 70 generates a magnetic field. A magnetic field represented by magnetic lines 73 is generated on the inner side, and a magnetic field represented by magnetic lines 74 is generated on the outer side.
[0012]
As shown in FIG. 3, the magnetic force line 73 passes through the cylindrical body 44 and reaches the intermediate column portion 52, and the permanent magnet 70 and the intermediate column portion 52, that is, the driving body 60 and the lift pin 50, by the magnetic force line 73. Are magnetically coupled. Here, the magnetic coupling force is determined to be smaller than the force required to break the wafer. Further, the presence of the yoke 71 prevents the magnetic field from reaching the outside of the driving body 60.
[0013]
The magnetic field lines 73 constitute the magnetic coupling means of claim 1.
As shown in FIG. 2, the wafer processing apparatus 40 includes a CPU 80, drive control circuits 81 and 82, a buzzer 83, an operation unit 84, and a sensor 85 that measures the distance to the wafer 90.
[0014]
Next, the operation of the wafer processing apparatus 40 configured as described above will be described.
FIG. 2 shows a state in which the wafer 90 is attracted to the electrostatic chuck 42 and plasma etching is performed.
When this process is completed, the energization to the electrostatic chuck 42 is cut off. Thereafter, the air actuator 66 is driven via the drive control circuit 81 in accordance with a command from the CPU 80, and the drive body 60 moves up in the Z1 direction. The lift pins 50 are magnetically coupled to the drive body 60 and move upward in the Z1 direction integrally with the drive body 60 to support the wafer 90 away from the electrostatic chuck 42 as indicated by a two-dot chain line. After the wafer 90 is unloaded from the wafer processing chamber 41 by a robot (not shown), the air actuator 66 operates in a direction to return to the original state, and the lift pins 50 move downward in the Z2 direction. That is, the lift pin 50 repeats up and down movement inside the lift pin accommodating portion 43. Therefore, the degree of vacuum in the wafer processing chamber 41 is maintained at a good level over a long period of time, even if the lift pins 50 are repeatedly opened and closed many times.
[0015]
Here, an operation when the air actuator 66 is activated when the wafer 90 is relatively strongly attracted by the residual charge will be described.
Since the wafer 90 is relatively strongly adsorbed by the residual charge, the upward movement of the lift pins 50 in the Z1 direction is relatively strongly restricted. For this reason, when the driving body 60 starts to move upward by the air actuator 66, the lift pin 50 does not move, the driving body 60 moves away from the intermediate column portion 52, and the magnetic coupling is released. Thereafter, the drive body 60 moves up in a state where no force in the Z1 direction is applied to the lift pin 50. Therefore, an accident that breaks the wafer 90 is prevented.
[0016]
Note that the sensor 85 detects that the wafer 90 is not lifted off the electrostatic chuck 42 even though the air actuator 66 is operated, and further, according to a command from the CPU 80, the buzzer 83 via the drive control circuit 82. Pronounces. The operator who has heard the buzzer operates the operation unit 84 to operate the air actuator 66 in the reverse direction. As a result, the driving body 60 moves down to the original position, and is magnetically coupled to the lift pins 50 again, so that the wafer processing apparatus 40 operates normally.
[0017]
Further, when the lift pin 50 moves up and down, only the portions 51 and 53 made of Teflon (registered trademark) move while contacting the inner surface of the cylindrical body 44, and the iron intermediate column portion 52 moves relative to the inner surface of the cylindrical body 44. And move while maintaining a non-contact state. For this reason, the lift pin 50 moves smoothly without generating dust. Therefore, the inside of the wafer processing chamber 44 is prevented from being contaminated by dust.
[0018]
Similarly, the driving body 60 is also moved while the Teflon (registered trademark) bearing members 64 and 65 are in contact with the outer surface of the cylindrical body 44 and the permanent magnet 70 is kept in a non-contact state with respect to the outer surface of the cylindrical body 44. To do. For this reason, the drive body 600 moves smoothly without generating dust. Therefore, the wafer processing apparatus 40 is prevented from being contaminated with dust.
[0019]
Further, as shown in FIG. 3, the magnetic lines of force 74 pass through the yoke 71, and the magnetic flux does not leak to the outside of the driving body 60. For this reason, even if magnetic coupling is adopted, plasma etching is not affected at all and is normally performed.
The lift pin main body 51 and the auxiliary body 53 are not limited to Teflon (registered trademark) and may be made of a high-purity material that does not contain metal impurities such as quartz and ceramic. Next, another embodiment of the present invention will be described.
[0020]
FIG. 6 is a diagram corresponding to FIG. Instead of the permanent magnet assembly 63 of FIG. 3, an electromagnet assembly 100 is provided.
The electromagnet assembly 100 includes a coil 102 wound around a bobbin 101 having an inner diameter d ₁₀ similar to the inner diameter of the permanent magnet 70, a power source 103, a variable resistor 104, and a switch 105 connected in series to the coil 102. And a switch control device 106 that controls opening and closing of the switch 105.
[0021]
As shown in FIG. 7, the switch 105 is turned off during the plasma etching process. As a result, no magnetic flux is generated during the plasma etching process, and the plasma etching is performed normally.
When the plasma etching process is completed, the switch 105 is turned on by the switch control device 106, the coil 102 is energized, and the driver 60A is magnetically coupled to the lift pin 50. Here, by appropriately adjusting the variable resistor 106, the strength of the magnetic force generated by the electromagnet assembly 100 is adjusted within a range of about 5,000 G to 12,000 G, and the driving body 60A and the lift pin 50 are adjusted. The strength of the magnetic coupling force is determined according to the strength of the wafer being processed.
[0022]
【The invention's effect】
As described above, according to the first aspect of the present invention, since the lift pins are housed in the bottomed cylindrical lift pin accommodating portion, the degree of vacuum in the wafer processing chamber can be maintained satisfactorily. In addition, the lift pin has a structure in which an iron pillar is attached to a non-metallic lift pin body, and the magnetic coupling means is magnetically coupled to the iron pillar, and the strength of the magnetic coupling. However, since the force that pushes up the wafer acting on the lift pins reaches the force that breaks the wafer before reaching the force that breaks the wafer, the wafer is not forced to be pushed up. Can prevent accidents. In addition, this is particularly effective when an electrostatic chuck is used as the stage. Further, since the iron pillar portion has a diameter smaller than that of the lift pin body, the iron pillar portion is not in contact with the lift pin housing portion, and the lift pin moves up and down smoothly without generating dust. Is called.
[0025]
According to the invention of claim 2 , the leakage of the magnetic flux to the outside is limited by the yoke, and the wafer processing can be prevented from being affected. Further, since the permanent magnet is not in contact with the lift pin housing portion, the vertical movement of the elevating means is performed smoothly without generating dust.
According to the invention of claim 3, since no magnetic flux is generated during the wafer processing, the wafer processing can be performed normally. Further, since the bobbin is not in contact with the lift pin housing portion, the vertical movement of the elevating means is performed smoothly without generating dust.
[Brief description of the drawings]
FIG. 1 is a principle configuration diagram of the present invention.
FIG. 2 is a diagram showing a wafer processing apparatus according to a first embodiment of the present invention.
FIG. 3 is a diagram for explaining magnetic coupling between a driving body and a lift pin in FIG. 1;
FIG. 4 is an exploded perspective view of a lift pin.
FIG. 5 is a view showing a permanent magnet assembly in FIG. 3;
FIG. 6 is a view showing a main part of a wafer processing apparatus according to another embodiment of the present invention.
7 is a diagram illustrating the opening / closing timing of the switch in FIG. 6. FIG.
FIG. 8 is a diagram showing an example of a conventional wafer processing apparatus.
[Explanation of symbols]
30, 40 Wafer processing apparatus 31 Stages 32, 41 Wafer processing chambers 33, 50 Lift pins 34, 43 Lift pin accommodating portion 35 Driving means 36 Magnetic coupling means 42 Electrostatic chuck (stage)
44 Cylindrical body 45 Bottom plate 46 Hole 51 Lift pin body 52 Intermediate column 53 Auxiliary body 54, 68 Clearance 60, 60A Drive body (lifting means)
61 Through-hole 62 Block 63 Permanent magnet assembly 64, 65 Bearing member 66 Air actuator 67 Arm 70 Permanent magnet 71 Yoke 73 Line of magnetic force (magnetic coupling means)
74 Magnetic field line 80 CPU
81, 82 Drive control circuit 83 Buzzer 84 Operation unit 85 Sensor 90 Wafer 100 Electromagnet assembly 101 Bobbin 102 Coil 103 Power supply 104 Variable resistance 105 Switch 106 Switch control device

Claims (3)

A wafer processing chamber having a stage for supporting the wafer inside;
A non-metallic lift pin body is a structure in which an iron pillar having a diameter smaller than the diameter of the lift pin body is attached, and lift pins that move up and push the wafer up from the stage;
A lift pin accommodating portion that has a bottomed cylindrical shape, extends downward from the wafer processing chamber, and accommodates the lift pins;
Elevating means that moves up and down along the lift pin accommodating portion;
Magnetic coupling means for magnetically coupling the lifting means and the iron pillar portion of the lift pin with a predetermined strength ;
The predetermined strength by the magnetic coupling means is a strength at which the magnetic coupling is released before the force that pushes up the wafer acting on the lift pins reaches the force that breaks the wafer,
When the elevating means moves up, the lift pins move up in the lift pin accommodating portion via the magnetic coupling means to support the wafer apart from the stage,
When the wafer is strongly attracted to the stage, the wafer processing apparatus is configured such that when the lifting means is moved up, the magnetic coupling is released and the lift pins are not moved up . The wafer processing apparatus according to claim 1,
The elevating means has a bearing member that slides on the outer periphery of the lift pin accommodating portion, and a permanent magnet assembly,
The permanent magnet assembly includes a cylindrical permanent magnet and a cylindrical yoke surrounding the permanent magnet, and the inner diameter of the permanent magnet is larger than the inner diameter of the bearing member. apparatus. The wafer processing apparatus according to claim 1,
The elevating means has a bearing member that slides on the outer periphery of the lift pin housing portion, and an electromagnet assembly.
The electromagnet assembly includes a coil wound around a bobbin, a power source for supplying current to the coil, and means for controlling supply of current to the coil when a wafer is being processed in the wafer processing chamber. The wafer processing apparatus is characterized in that the bobbin has an inner diameter larger than the inner diameter of the bearing member .

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