JP4399800B2 - Rotation holding device - Google Patents

Description

  The present invention relates to a rotation holding device, and more particularly, to a rotation holding device suitable for use in ion implantation used to form a plurality of regions having different ion implantation amounts in a semiconductor wafer.

  In the ion implantation method, impurities are ionized, electrically accelerated as an ion beam, and implanted into a wafer such as silicon (Si). Since impurities can be introduced into a fine region with high accuracy, Widely used in manufacturing processes.

  In this ion implantation method, (1) an ion beam is deflected by applying an electric field, and electrostatic scanning is performed to scan the wafer surface. (2) an ion beam is deflected by applying a magnetic field, and the wafer surface is deflected. Magnetic field scanning for scanning, (3) mechanical scanning for scanning the ion beam by moving the wafer side placed on the holder by a motor, etc. are performed, and any one of (1) to (3) The scanning method is applied to scanning in the X and Y directions orthogonal to each other within the wafer surface.

If the ion implantation method as described above is used, ions can be uniformly implanted over the entire surface of the wafer. In addition, when a wafer on which a mask is formed in advance using a photoresist is used, desired impurities can be selectively and accurately injected into a desired region (see Patent Document 1).
JP 2003-86530 A

  Here, in the rotation holding device that performs the above-described (3) mechanical scan, an operation is performed in which ion beam implantation is performed at a certain angle in a vacuum atmosphere, and then the implantation is performed by changing the angle. For this reason, there is a request to rotate the wafer quickly between injections, but there is a request to avoid dust generation as much as possible so as not to impair the vacuum atmosphere. However, although it is desired to index at high speed in order to increase the throughput, a general-purpose motor does not have sufficient torque and cannot cope with high acceleration / deceleration, so a reduction gear is required. Therefore, one problem is how to suppress dust generation when a reduction gear is used.

  Then, in view of the subject of this prior art, an object of this invention is to provide the rotation holding | maintenance apparatus which can suppress dust generation effectively.

In order to achieve the above-mentioned object, the rotation holding device of the present invention is a rotation holding device used in an environment outside the atmosphere.
A movable housing;
A motor attached to the housing;
A speed reducer having a rotating body to which power is transmitted from the rotating shaft of the motor;
A turntable connected to the rotating body and supporting a processing object;
A cover member attached to the housing and covering the speed reducer,
The space sandwiched between the cover member and the rotating body passes through the radially inward side of the rotating body when the rotating shaft of the motor is a starting point, and communicates with the outside. .

  Since the turntable supports the object to be processed, it needs to be arranged outside the space covered by the cover member and the housing. Therefore, the cover member or the housing needs to be provided with an opening for connecting the rotary body of the speed reducer and the rotary base. However, for example, when an opening is provided in the cover member and the rotating body is exposed to the outside, the cover member is stationary, and the rotating body rotates. Attempting to seal is problematic because it generates dust by sliding.

  Therefore, it can be said that it is desirable to make the opening as small as possible in order to suppress dust generation. However, in consideration of component accuracy and assembly accuracy, there is a limit to reducing such an opening. On the other hand, according to the rotation holding device of the present invention, the space sandwiched between the cover member and the rotating body is located on the radially inner side of the rotating body when the rotation axis of the motor is the starting point. And communicates with the outside. In general, when power is transmitted from the rotating shaft of the motor to the rotating body, dust is generated at the sliding portion on the rotating shaft side. According to the present invention, dust is generated on the rotating shaft side. Foreign matter such as dust is not released outside unless it moves inward in the radial direction of the rotating body in the space between the cover member and the rotating body. At this time, the surface of the rotating body The dust or the like adhering to the surface receives a force outward in the radial direction by centrifugal force, and is prevented from moving inward in the radial direction. Therefore, according to the present invention, dust generation to the outside can be effectively suppressed, and a rotation holding device that does not impair the environment even when used in a vacuum atmosphere can be provided.

  When the cover member has a flange portion extending in the axial direction so as to surround the rotation axis of the rotating body, dust generation to the outside can be further suppressed by the flange portion. Further, by providing such a flange, the necessary rigidity at the time of processing the cover member can be secured, so that the flatness of the cover member can be processed higher, and for example, the gap with the gear can be designed small.

  Hereinafter, a comparative example and a preferred embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a perspective view of a wafer scanning mechanism portion of an ion beam implantation apparatus using the rotation holding device of the present embodiment. A motor M is attached to the lower part of the vertically long casing H, and a screw shaft S connected to the motor M extends in the vertical direction inside the casing H and is a nut ( (Not shown). The moving table T is connected to a support bracket B that supports the rotation holding device 200. That is, when the screw shaft S is rotated by driving the motor M, the support bracket B is moved up and down together with the nut and the moving table T, whereby the rotation holding device 200 is also moved up and down.

Here, the ion beam implantation apparatus scans the beam in the horizontal direction in a vacuum in the state shown in FIG. 1, and implants ions into the entire wafer by scanning the wafer up and down with respect to this beam. At this time, in order to adjust the implantation angle, the attitude of the wafer with respect to the beam is determined by the tilt axis and the twist axis. Therefore, the wafer can be scanned by the ion beam I irradiated in the horizontal direction in a vacuum of about 10 ⁻⁵ to 10 ⁻⁶ Pa, and by performing appropriate ion beam implantation, As, A semiconductor can be manufactured by controlling the implantation amount of impurities such as P and B.

  FIG. 2 is a cross-sectional view of the rotation holding device 200 according to the present embodiment. In FIG. 2, a disk-shaped first housing 201 is fixed to a base (not shown). A second housing 204 is attached to the upper surface of the first housing 201. The motor 203 is bolted to the outer edge of the cylindrical stay 212 bolted to the second housing 204. A small gear 203 a formed on the rotation shaft of the motor 203 meshes with the ring gear 215. The small gear 203a and the ring gear 215 constitute a speed reducer, and the ring gear 215 constitutes a rotating body.

  On the other hand, a cylindrical portion 204a is formed at the center of the upper surface of the second housing 204, and a hollow support shaft 206 is disposed around the cylindrical portion 204a. The support shaft 206 has a pedestal 202 attached to its upper end with bolts. A ring gear 215 is fixed to the support shaft 206 with a bolt on the outer side in the radial direction of the lower end of the pedestal 202. Here, the support shaft 206 and the pedestal 202 constitute a support shaft.

  Inner rings of angular contact ball bearings 207 and 211 are fitted and arranged on the outer periphery of the support shaft 206 with a spacer 218 interposed therebetween, and are fixed by a bearing restraint 231. On the other hand, the outer ring of the angular contact ball bearings 207 and 211 is fitted and disposed on the outer periphery of the stay 212 with the spacer 219 interposed therebetween. Accordingly, the support shaft 206 is rotatably supported with respect to the first housing 201, the second housing 204, and the stay 212 constituting the housing by the outer ring fixed and inner ring rotating angular contact ball bearings 207 and 211. The stay 212 is attached to the support bracket B (see FIG. 1) as will be described later. Further, a cover member 220 attached to the stay 212 is disposed above the ring gear 215.

  By tightening the bolt B1, the bearing holder 231 presses the inner rings of the angular contact ball bearings 207 and 211 with the spacer 218 sandwiched between the flange b of the support shaft 206. On the other hand, by tightening the bolt B <b> 2, the outer rings of the angular contact ball bearings 207 and 211 are pushed between the bearing holder 232 and the second housing 204 with the spacer 219 interposed therebetween. A preload can be applied to the angular contact ball bearings 207 and 211 by adjusting the thicknesses (lengths in the axial direction) of the spacers 218 and 219. The support shaft 206, the bearing holders 231 and 232, the second housing 204, and the bolts B1 and B2 constitute a preload mechanism.

  Between the cylindrical portion 204a of the second housing 204 and the support shaft 206, which are radially inward of the angular contact ball bearings 207, 211, a cooling water seal 210, a vacuum seal 209, and Is arranged. The cooling water seal 210 seals the passage of cooling water, and the vacuum seal 209 has a function of isolating the atmosphere outside the atmosphere from the atmosphere inside the atmosphere. A differential exhaust seal can also be used.

  The disk-like pedestal 202 attached to the upper end of the support shaft 206 has a holder 216 attached to its upper surface with bolts. A holder 216 serving as a turntable for electrostatically attracting and holding a wafer (not shown) as a processing target has a space 216a for flowing cooling water therein, and a circular hole-like supply opened on the lower surface thereof. It has a mouth 216b and an annular outlet 216c surrounding it.

  The pedestal 202 serving as a part of the support shaft has a plurality of transmission passages extending in the axial direction. More specifically, a first transmission passage 202c is provided at the center of the pedestal 202, and a second transmission passage 202d is provided around the first transmission passage 202c. One end of the first transmission passage 202 c communicates with a central first through hole 204 b formed in the second housing 204, and the other end is open to the supply port 216 b of the holder 216. One end of the second transmission passage 202 d communicates with a second through hole 204 c formed in the second housing 204, and the other end is open to the discharge port 216 c of the holder 216.

  An O-ring that separates the first through hole 204b and the second through hole 204c is not provided between the pedestal 202 and the second housing 204, and a clearance between the pedestal 202 and the support shaft 206 is provided around them. Only an O-ring OR is provided for sealing. However, the upper end of the second housing 204 is a convex portion 204d protruding so as to surround the first through-hole 204b, and a predetermined gap is formed in a concave portion 202e formed at the center of the bottom surface of the base 202 so as to face this. The gap is inserted to form a clearance seal.

  The first through hole 204b of the second housing 204 communicates with the inlet passage 201b of the first housing 201, and a pipe connected to a cooling water supply unit (not shown) is connected to the inlet passage 201b. On the other hand, the second through hole 204c of the second housing 204 communicates with the outlet passage 201c of the first housing 201, and a pipe connected to a cooling water discharge unit (not shown) is connected to the outlet passage 201c. Yes.

  By driving the motor 203 while holding the wafer (not shown) by the holder 216, the wafer can be rotated together with the holder 216 connected to the support shaft 206 and the pedestal 202 via the small gear 203a and the ring gear 215. it can. At this time, even if the support shaft 206 and the pedestal 202 rotate, cooling water can be supplied from the first housing 201 to the holder 216 and discharged from the holder 216 to the first housing 201.

  More specifically, the cooling water supplied from the cooling water supply unit via the pipe enters the first through hole 204b of the second housing 204 through the inlet passage 201b, and from here, the first of the base 202 is inserted. It passes through the transmission passage 202c and enters the space 216a inside the holder 216 through the supply port 216b. The cooling water that has entered the space 216 a exchanges heat with the wall surface of the holder 216, thereby cooling the wafer held by the holder 216.

  The cooling water heated by heat exchange in the space 216a flows out from the discharge port 216c, and then passes through the second through hole 204c of the second housing 204 via the second transmission passage 202d of the pedestal 202, to the first housing. It will flow out to the outside cooling water discharge part via the outlet passage 201c of 201.

  3 is a perspective view of the rotation holding device 200 shown with the holder 216 removed, FIG. 4 is a perspective view of the rotation holding device 200 shown with the cover member 220 further removed, and FIG. It is a figure which expands and shows the part shown by the arrow V of the structure of FIG.

  In FIG. 3, the cover member 220 includes a disc portion 220a, an outer flange portion 220b formed on the outer peripheral edge of the disc portion 220a and extending upward in the axial direction, and an axial line formed in the vicinity of the inner periphery of the disc portion 220a. It consists of an inner flange portion 220c extending upward in the direction and a circumferential raised portion 220d provided between both flange portions 220b and 220c. An opening 220e for penetrating the pedestal 202 is formed in the center of the disc part 220a.

  The bottom surface of the cover member 220 is attached so as to be in close contact with the upper end of the stay 212. The stay 212 is rotatably supported with respect to the support bracket B by a rotation shaft RS attached to the one end side arm 212a of the stay 212, is attached to the other end side arm 212b of the stay 212, and is a motor (not shown). Is driven to rotate (tilt operation) in a direction perpendicular to the axis by the drive shaft DS coupled to the shaft.

  An optical sensor 221 having a light emitting part 221a and a light receiving part 221b is disposed on the disc part 220a, and the light shielding plate 222 (see FIGS. 2 and 5) attached to the lower surface of the holder 216 is a holder. By rotating together with H.216 and positioned between the light emitting unit 221a and the light receiving unit 221b, the light beam traveling from the light emitting unit 221a to the light receiving unit 221b is blocked, and thereby the position of the holder 216 can be detected. Further, a stopper 223 is disposed on the circumferentially raised portion 220d at a position where it can come into contact with a locking member 224 (see FIG. 2) attached to the lower surface of the holder 216. An overrun of the holder 216 is prevented.

  In FIG. 4, the small gear 203 a attached to the rotating shaft of the motor 203 meshes with the ring gear 215 in the space surrounded by the flange 212 c of the stay 212. By driving the motor 203, the ring gear 215 rotates while being decelerated at a reduction ratio corresponding to the gear ratio, and the holder 216 (see FIG. 1) is rotated via the pedestal 202. Since the rotation position of the holder 216 can be detected by the optical sensor 221 and the light shielding plate 222 described above, the motor 203 is driven and controlled according to the signal.

  Here, when the small gear 203a is driven, dust is generated due to the tooth surface sliding at the meshing portion (A) with the ring gear 215. Here, if foreign matter such as generated dust enters the vacuum chamber, there is a possibility of causing a processing failure of the wafer.

  On the other hand, in the present embodiment, the small gear 203a and the ring gear 215 are shielded on both sides in the axial direction by the cover member 220 and the stay 212 and shielded radially outward by the flange 212c of the stay 212. Release of foreign matter such as generated dust to the outside is suppressed. However, only a gap communicating with the outside of the rotation holding device 200 is formed between the opening 220 e provided in the cover member 220 and the base 202.

  On the other hand, according to the present embodiment, as shown in FIG. 5, in order for foreign matter such as dust generated on the small gear 203a side to travel between the opening 220e and the pedestal 202, the radial direction of the ring gear 215 At this time, dust or the like adhering to the surface of the ring gear 215 is subjected to a force radially outward by centrifugal force, and is prevented from moving radially inward. Therefore, according to the present embodiment, dust generation can be effectively suppressed, and for example, even when used in a vacuum atmosphere, the rotation holding device 200 that does not impair the environment can be provided.

  Even if foreign matter such as generated dust reaches the clearance between the opening 220e and the pedestal 202, an inner flange portion 220c and an outer flange portion 220b are formed on the upper surface of the cover member 220. Therefore, this and the lower surface of the holder 216 form a so-called labyrinth seal. For example, as shown by a dotted line in FIG. 5, it takes a long distance for foreign matter such as dust generated from the small gear 203a to reach the outside. It has to move and effectively suppresses foreign matters such as dust generated by the movement to the outside.

  The present invention has been described above with reference to the embodiments. However, the present invention should not be construed as being limited to the above-described embodiments, and can be modified or improved as appropriate. For example, the environment outside the atmosphere includes not only a vacuum state but also a state filled with a gas different from the atmosphere. Further, the speed reducer is not limited to one using a gear train, and may be a chain / belt drive. In such a case, the sprocket or pulley connected to the turntable is the rotating body of the present invention.

It is a perspective view of the wafer scanning mechanism part of the ion beam implantation apparatus using the rotation holding device of the present embodiment. It is sectional drawing of the rotation holding | maintenance apparatus 200 concerning this Embodiment. It is a perspective view of the rotation holding device 200 shown with the holder 216 removed. It is a perspective view of the rotation holding device 200 shown with the cover member 220 removed. It is a figure which expands and shows the part shown by the arrow V of the structure of FIG.

Explanation of symbols

200 rotation holding device 201 housing 201b inlet passage 201c outlet passage 202 pedestal 202c first transmission passage 202d second transmission passage 202e concave portion 203 motor 203a small gear 204 housing 204a cylindrical portion 204b first through hole 204c second through hole 204d convex portion 206 Support shaft 207 Angular contact ball bearings 207, 211 Angular contact ball bearings 209 Vacuum seal 210 Cooling water seal 212 Stay 212a One end side arm 212b The other end side arm 212c Flange 215 Ring gear 216 Holder 216a Space 216b Supply port 216c Discharge port 218, 219 Spacer 220 Cover member 220a Disc portion 220b Both flange portions 220b Outer flange portion 220c Inner flange portion 220d Circumferentially raised portion 220e Opening 221 Optical sensor 21a light emitting portion 221b receiving section 222 light-shielding plate 223 stopper 224 engaging member 231 and 232, bearing suppressed B support bracket B1, B2 bolt DS driving shaft H housing I ion beam M motor OR ring RS rotary shaft S axis T moving table

Claims (2)

In the rotation holding device used in the environment outside the atmosphere,
A movable housing;
A motor attached to the housing;
A speed reducer having a rotating body to which power is transmitted from the rotating shaft of the motor;
A turntable connected to the rotating body and supporting a processing object;
A cover member attached to the housing and covering the speed reducer,
The space sandwiched between the cover member and the rotating body passes through the radially inward side of the rotating body when the rotation axis of the motor is a starting point, and communicates with the outside. Rotation holding device. The rotation holding device according to claim 1, wherein the cover member has a flange portion extending in an axial direction so as to surround a rotation axis of the rotating body.

Images