JP4966069B2 - Processing equipment - Google Patents

Description

  The present invention relates to a processing apparatus that performs grinding processing or polishing processing on a substrate such as a semiconductor wafer, and more particularly to a processing apparatus capable of adjusting the angle of a holding surface that holds a substrate.

  A semiconductor substrate (hereinafter referred to as a substrate) used as a material for a semiconductor or an electronic component includes, for example, a single crystal material such as silicon or a compound having a plurality of elements. These substrates are formed in an ingot state, then sliced into a substrate shape with a wire saw or the like, and further processed flat and thin by lapping, double-head grinding, surface grinding, or the like. After the surface grinding, both surfaces of the substrate are polished by using a double-side polishing method in which both surfaces are polished. A method for manufacturing such a substrate is known from Patent Document 1, for example.

  In the surface grinding described in Patent Document 1, for example, grinding with a configuration in which an annular wheel having a fine mesh grindstone made of fine abrasive grains is rotated and pressed against a substrate held on a rotating chuck table. A processing device is used. However, when the substrate is ground using such a grinding apparatus, the processed substrate has a thickness of the outer peripheral portion due to insufficient processing power of the wheel or a peripheral speed difference between the center and the outer periphery due to the rotation of the substrate. Tends to become thicker, or conversely thin, and flat processing to make the thickness uniform is difficult.

  Therefore, as a method for grinding the substrate flatly, for example, a method of grinding the substrate by tilting the rotation axis of the chuck table holding the substrate using the apparatus described in Patent Document 2 can be considered. In this case, by tilting the rotation axis of the chuck table to an angle suitable for the grinding tendency, the grinding amount of the substrate can be made uniform at each point, so that the substrate after grinding can be formed flat. it can.

  Further, when a fine mesh grindstone is used in the grinding process, such a grindstone has a small machining force, and therefore can only feed a workpiece of about 0.2 μm per second to the workpiece. Therefore, in order to shorten the working time, an air cut operation is performed to bring the grindstone as close as possible to the machining start position immediately before the work surface of the substrate at a speed of 10 times or more of the machining feed so as to minimize the feeding distance at a low speed. .

JP-A-10-308368 Japanese Patent Laid-Open No. 2002-1653

  By the way, when the rotation axis of the chuck table is tilted as described above, the highest position (highest position) of the region to be ground of the substrate changes. FIG. 6 shows this state. In FIG. 6, reference numeral 20 denotes a vacuum suction chuck table, and 36 denotes a grindstone wheel. This chuck table 20 has a structure in which a frame 22 is provided around a porous adsorption area 21, and the substrate 1 is adsorbed and held on the upper surface 21 a of the adsorption area 21. The grindstone wheel 36 has a grindstone 37 and grinds the substrate 1 held on the upper surface 21a of the suction area 21 by descending toward the chuck table 20 while rotating at high speed. 6A, the upper surface 21a of the suction area 21, which is the upper surface of the chuck table 20, and the upper surface 22a of the frame 22 are horizontal, and the processing surface of the grindstone 37 is also set to be horizontal. At this time, the surface 1a to be ground of the substrate 1 is horizontal and the height position is h and uniform. The air cut operation is performed by lowering the grindstone wheel 36 at a high speed based on air cut position data indicating the height h in advance. However, when the chuck table 20 is tilted as shown in FIG. 6B, the highest position h ′ of the ground surface 1a of the substrate 1 differs from h (in the figure, h ′ is higher than h). If the air cut operation based on the height h is performed in this state, the grindstone collides with the substrate 1 at a high speed, causing a problem that the substrate 1 is damaged. On the contrary, the highest position of the region to be ground of the substrate 1 may be located below h, and at this time, the machining feed speed (for example, 0.2 μm / second) is set between h and the highest position. The grindstone will be processed. This is a significant loss of working time because the grindstone is lowered at a very low speed without processing.

  Therefore, according to the present invention, when the rotation axis of the chuck table is inclined at an arbitrary angle, the machining start position of the machining means is appropriately corrected according to the angle, and the air cut operation is performed until just before contacting the substrate. An object of the present invention is to provide a processing apparatus capable of preventing the substrate and the grindstone from colliding and reducing the main processing time as much as possible.

  A rotatable holding means having a holding surface for sucking and holding the substrate, an inclination adjusting means for adjusting the inclination of the rotation axis of the holding means from a basic angle to an arbitrary angle, and a basic angle disposed opposite to the holding surface of the holding means The processing means having a rotation axis parallel to the rotation axis of the holding means in the state, the holding means and the processing means are moved relative to each other along the rotation axis of the processing means to approach and separate from each other, and the processing means when approaching Based on the feeding means for performing desired processing on the substrate and the processing start position data stored in advance, the processing means moves from the standby position to the processing start position of the substrate at a higher speed than the feed speed at the time of substrate processing. And a feed operation control means for controlling the feed means, the feed operation control means stores the rotation based on the tilt angle of the rotation axis of the holding means adjusted by the tilt adjustment means. It is characterized in that it comprises a machining start position correcting means for correcting the machining start position data that.

  In the present invention, the processing start position of the processing means is preferably a position as close as possible to the substrate surface held by the holding means. This is because the processing means shortens the distance and time from the processing start position to the actual contact with the substrate and starts processing, thereby reducing unnecessary processing feed. When processing the substrate by the processing means, an air cut operation in which the processing means moves to the processing start position at a high speed based on the processing start position data stored in the feed operation control means can be considered first. Thereafter, the processing means processes the substrate while moving in the direction of the substrate at a predetermined processing speed. When processing the substrate, the chuck table is tilted as necessary as described above. At that time, the highest position of the substrate surface tilted together with the chuck table changes, and if the machining means performs an air cut operation based on the normal machining start position data, the machining means collides with the substrate or conversely. The distance between the processing means and the substrate is too large. Therefore, in the present invention, the machining start position correction unit automatically corrects the machining start position data to appropriate data corresponding to the adjustment amount of the tilt angle of the chuck table. As a result, the processing means that has performed the air-cut operation can move to an appropriate processing start position as close as possible to the substrate surface displaced by the inclination of the chuck table, and then shifts to actual processing. As a result, even if the chucking table is adjusted to adjust the tilt angle and the processing means is air-cut, the processing means collides with the substrate or the distance between the substrate and the processing means is too large. Processing feed can be prevented. As a result, the total substrate processing time can be shortened as much as possible, and the production efficiency can be improved.

  According to the present invention, the processing start position of the processing means can be corrected to an appropriate position according to the tilt angle of the chuck table, thereby suppressing the collision of the processing means with the substrate and unnecessary processing feed. Can do. As a result, there is an effect that the apparatus can be safely operated and the production efficiency can be improved.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
[1] Grinding apparatus FIG. 2 shows a grinding apparatus to which the present invention is applied. The grinding device (processing device) 10 grinds the surface of a semiconductor wafer such as a silicon wafer (hereinafter abbreviated as a wafer). FIG. 1 shows an example of a wafer to be ground. This wafer (substrate) 1 is obtained by slicing a raw material ingot, adjusted in thickness by lapping, and then formed on both sides formed by lapping. The material stage is obtained by removing the mechanical damage layer by etching. A V-shaped notch 2 indicating a crystal orientation is formed on the outer peripheral edge of the wafer 1. The thickness of the wafer 1 is, for example, about 800 μm, but the thickness is not uniform, and there is an in-plane thickness variation of about 2 to 3 μm due to etching. Accordingly, the wafer 1 is removed by the grinding apparatus 10 to a thickness of about 10 to 20 μm, for example.

FIG. 2 shows the entire grinding apparatus 10, which includes a rectangular parallelepiped base 11 having a horizontal upper surface. In FIG. 2, the longitudinal direction, the width direction, and the vertical direction of the base 11 are shown as a Y direction, an X direction, and a Z direction, respectively. A column 12 is erected on one end of the base 11 in the Y direction. On the base 11, a processing area 11A for grinding the wafer 1 is provided on the column 12 side in the Y direction, and the wafer 1 before processing is supplied to the processing area 11A on the side opposite to the column 12, and An attachment / detachment area 11B for collecting the processed wafer 1 is provided.
Hereinafter, the grinding area 11A and the attachment / detachment area 11B will be described.

(I) Grinding area A rectangular pit 14 is formed in the grinding area 11A. In this pit 14, a disc-shaped turntable 13 having a rotation axis parallel to the Z direction and having an upper surface horizontal is rotatably provided. The turntable 13 is rotated in the arrow direction by a rotation drive mechanism (not shown). A plurality of (in this case, two) disk-shaped chuck tables (holding means) 20 are rotatably arranged at equal intervals in the circumferential direction on the outer peripheral portion of the turntable 13.

  These chuck tables 20 are of a generally known vacuum chuck type, and suck and hold the wafer 1 placed on the upper surface. As shown in FIG. 3B, the chuck table 20 has a circular adsorption area 21 made of porous ceramic on the upper surface, and the wafer 1 is adsorbed on the upper surface (holding surface) 21a of the adsorption area 21. To be held. An annular frame 22 is formed around the suction area 21, and an upper surface 22 a of the frame 22 is continuous with the upper surface 21 a of the suction area 21 and forms the same plane. Each chuck table 20 is independently rotated or rotated in one direction or both directions by a rotation drive mechanism (not shown) provided in the turntable 13, and revolves when the turntable 13 rotates. It becomes a state. As shown in FIG. 5, the turntable 13 is provided integrally with the frame 14. The chuck table 20 is integrally provided at the upper end portion of the cylindrical body 24. The body 24 is provided with a flange 23, and the body 24 and the chuck table 20 are supported on the frame 14 via an inclination adjusting means 100 so that the angle of the rotation shaft 20a can be adjusted.

  5 includes a motor 101, a bolt member 102, an adjustment lever 103, an adjustment block 105, and a fulcrum block 106 (see Japanese Patent Application Laid-Open No. 2002-1653). . The adjustment lever 103 has a fulcrum part 103a fixed to the support block 106, an action point part 103b to which the adjustment block 105 is fixed, and a force point part 103c to which the bolt member 102 is fixed. The force is applied to the action point portion 103b by the applied force. Further, a fulcrum neck 104 is formed at the end of the adjustment lever 103 on the fulcrum part 103a side, and is structured to be slightly bent by the movement of the force application part 103c. The bolt member 102 passes through the frame 14 of the turntable 13, the motor 101 fixed to the frame 14 of the turntable 13 is connected to one end, and the adjusting lever 103 is fixed to the other end. The bolt member 102 transmits force to the adjusting lever 103 as the motor 101 rotates. The fulcrum block 106 is fixed to the frame 14 of the turntable 13, and the fulcrum neck 104 is fixed to the upper surface 106a. One end of the adjustment block 105 is fixed to the adjustment lever 103 and supports the chuck table 20 via the flange 23 and the body 24.

  As shown in FIG. 4, the flange 23 is provided with a fixed support portion 23a and movable support portions 23b and 23c. A fixed shaft shaft 107 fixed to the frame 14 passes through the fixed support portion 23a. The fixed shaft 107 is fixed to the flange 23 by bolting or the like, and thereby the fixed support portion 23 a is fixedly supported on the frame 14 of the turntable 13. On the other hand, the movable support portions 23 b and 23 c are supported by the adjustment block 105 of the inclination adjusting means 100. Each support part 23a, 23b, 23c is arrange | positioned in the circumferential direction equal part of the outer peripheral part of the flange 23, as shown in FIG. According to the tilt adjusting means 100, the motor 101 rotates and the power point portion 103c of the adjusting lever 103 swings upward or downward. As a result, the movable support portions 23b and 23c move up and down, and as a result, the chuck table 20 tilts with the fixed support portion 23a as a fulcrum.

  As shown in FIG. 2, in a state where the two chuck tables 20 are arranged in the Y direction, a grinding unit (processing means) 30 is disposed immediately above the chuck table 20 on the column 12 side. Each chuck table 20 is positioned at two positions, that is, a grinding position below the grinding unit 30 and an attachment / detachment position closest to the attachment / detachment area 11 </ b> B by rotation of the turntable 13.

  The grinding unit 30 is fixed to a slider (feeding means) 40 attached to the column 12 so as to be movable up and down. The slider 40 is slidably mounted on a guide rail (feed means) 41 extending in the Z direction, and is moved in the Z direction by a ball screw type feed mechanism (feed means) 43 driven by a servo motor (feed means) 42. It is possible to move to. The grinding unit 30 grinds the exposed surface of the wafer 1 held by the chuck table 20 by a feed operation that moves up and down in the Z direction by the feed mechanism 43 and descends and approaches the chuck table 20.

  As shown in FIG. 3, the grinding unit 30 includes a cylindrical spindle housing 31 whose axial direction extends in the Z direction, a spindle shaft 32 coaxially and rotatably supported in the spindle housing 31, and a spindle housing. The motor 33 is fixed to the upper end of 31 and rotationally drives the spindle shaft 32, and the disk-shaped flange 34 is coaxially fixed to the lower end of the spindle shaft 32. A cup wheel 35 is detachably attached to the flange 34 by attachment means such as screwing.

  The cup wheel 35 is configured such that a plurality of grindstones 37 are annularly arranged and fixed to the lower end surface of an annular frame 36 over the entire outer periphery of the lower end surface. A cup wheel 35 in which a grindstone 37 includes fine mesh abrasive grains made of fine abrasive grains, for example, is attached to the flange 34 of the grinding unit 30 for grinding disposed above the grinding position. The flange 34 and the cup wheel 35 are provided with a grinding water supply mechanism (not shown) for supplying grinding water for cooling and lubrication of the grinding surface or discharging grinding scraps, and a water supply line is connected to the mechanism. Yes. The grinding wheel outer diameter of the cup wheel 35, that is, the diameter of the outer peripheral edge of the plurality of grindstones 37 is set to be at least equal to or larger than the radius of the wafer 1 and generally equal to the diameter of the wafer.

  As shown in FIG. 6, the grinding unit 30 has a processing feed rate (for example, 0.2 μm / mm) when the wafer 1 is actually ground from the standby position P set above the chuck table 20 to the processing start position h. "Air cut operation" sent at a speed 10 times or more of the second). After this air cut operation, processing feed is performed and the wafer 1 is ground. Such a feed operation of the grinding unit 30 is controlled by the feed operation control means 110. The feed operation control means 110 controls the operation of the servo motor 42 based on the machining start position data inputted in advance, and performs the air cut operation up to the machining start position h. The processing start position h is the highest position in the region to be ground of the wafer 1, and the height changes according to the tilt angle of the chuck table 20. Accordingly, the machining start position data is corrected to appropriate data by the machining start position correcting unit 111, so that the machining start position h is positioned as close as possible to the surface to be ground of the wafer 1 according to the tilt angle of the chuck table 20. Is set. The machining start position correcting unit 111 is according to the present invention and will be described in detail later.

  Reference numeral 50 in FIG. 2 is a thickness measuring gauge for measuring the thickness of the wafer. As shown in FIG. 3, the thickness measurement gauge 50 includes a combination of a reference side height gauge 51, a wafer side height gauge 52, and a gauge stand 53. The reference-side height gauge 51 and the wafer-side height gauge 52 are disposed on a plate-like table 53 b that extends horizontally from the support column 53 a of the gauge stand 53 to the chuck table 20. As shown in FIG. 3A, the reference-side height gauge 51 is configured such that the tip of the swinging reference probe 51a contacts the upper surface 22a of the frame 22 of the chuck table 20 that is not covered with the wafer 1, The height position is detected. The wafer-side height gauge 52 detects the height position of the upper surface of the wafer 1 when the tip of the oscillating variable probe 52 a contacts the upper surface of the wafer 1 held by the chuck table 20, that is, the surface to be ground. . According to the thickness measurement gauge 50, the thickness of the wafer 1 is measured based on a value obtained by subtracting the measurement value of the reference height gauge 51 from the measurement value of the wafer height gauge 52. In the thickness measurement gauge 50 of this embodiment, the height gauge is separately provided on the reference side and the wafer side, but both the measurement value on the reference side and the measurement value on the wafer side are measured with one height gauge. You may use what can.

  FIG. 4 shows the positional relationship between the rotation trajectory 37a of the grindstone 37 and the chuck table 20 as viewed from above. The suction area 21a of the chuck table 20 is formed in an umbrella shape with the center at the apex as shown in FIG. 6 by performing self-grinding to adjust the positional relationship with the grinding unit 30. Therefore, the region in which the wafer 1 and the grindstone 37 are in contact with each other and the grindstone 37 grinds the wafer 1 is limited to the range of the contact area 37b from the center to the outer periphery.

(II) Attachment / Removal Area As shown in FIG. 2, a two-bar link pickup robot 70 that moves up and down is installed at the center of the attachment / detachment area 11B. Around the pickup robot 70, a supply cassette 71, an alignment table 72, a supply means 73, a recovery means 76, a spinner type cleaning device 80, and a recovery cassette 81 are arranged counterclockwise as viewed from above. Has been. The supply means 73 includes a suction pad 74 that sucks the wafer 1 on a horizontal lower surface by a vacuum action, and a horizontal swiveling supply arm 75 having the suction pad 74 fixed to the tip. The recovery means 76 includes a suction pad 78 that sucks the wafer 1 on a horizontal lower surface by a vacuum action, and a horizontal swiveling supply arm 79 having the suction pad 78 fixed to the tip. The cassettes 71 and 81 are configured to accommodate a plurality of wafers 1 in a horizontal posture and in a stacked state at regular intervals in the vertical direction, and are set at predetermined positions on the base 11. Further, a cleaning nozzle 77 is provided between the supply unit 73 and the recovery unit 76 for cleaning the wafer 1 after grinding by spraying water onto the chuck table 20 at the attachment / detachment position.

(III) Details of Machining Start Position Correction Unit Next, the machining start position correction unit 111 according to the present invention will be described.

  The adjustment amount of the angle at which the rotation axis 20 a of the chuck table 20 is tilted by the tilt adjusting unit 100 is supplied to the machining start position correcting unit 111. The machining start position correction unit 111 stores a correction value in advance. This correction value corrects the processing start position of the grinding unit 30 that changes in accordance with the tilt angle adjustment amount of the chuck table 20 and adjusts the processing start position h to a position as close as possible to the surface of the wafer 1. It is. By setting the processing start position h to a position as close as possible to the surface of the wafer 1, it is possible to perform a lean air cut operation. The machining start position h changes according to the tilt angle of the chuck table 20 adjusted by the vertical movement of the movable support portions 23b and 23c. Therefore, the correction value is reflected in the amount of vertical movement of the movable support portions 23b and 23c. The correction value according to the change of the movable support portions 23b and 23c is determined according to the inclination angle and the inclination direction of the chuck table 20 that is inclined according to the amount of vertical movement of the movable support portions 23b and 23c. These correction values are obtained by collecting and analyzing the relationship between the tilt angle of the chuck table 20 and the highest position of the ground region of the wafer 1. The processing start position data corrected with the correction value corresponding to the adjustment amount of the tilt angle of the chuck table 20 is supplied to the feed operation control means 110, and the servo motor 42 is moved, so that an appropriate air cut operation of the grinding unit 30 is performed. And processing feed can be performed.

[2] A series of operations of the grinding apparatus The above is the configuration of the grinding apparatus 10 of the present embodiment. Next, the operation of the apparatus 10 will be described.
The wafer 1 to be ground is first taken out from the supply cassette 71 by the pick-up robot 70 and placed on the alignment table 72 to be determined at a certain position. Next, the wafer 1 is picked up from the alignment table 72 by the supply arm 73 and placed on the chuck table 20 waiting at the attachment / detachment position with the surface to be ground facing up.

  Next, each inclination adjusting means 100 rotates in the direction and the number of rotations corresponding to the inclination angle. Then, the vertical movement of the force point portion 103c of the adjusting lever 103 that swings around the fulcrum portion 103a is transmitted to the two movable support portions 23b and 23c, and accordingly, the flange 23 supported by the adjustment block 105 is fixed to the fixed shaft. The shaft 107 tilts around the fulcrum, and the rotation shaft 20a of the chuck table 20 tilts.

  The wafer 1 is transferred to the grinding position by the rotation of the turntable 13. When the wafer 1 is placed at the grinding position, the servo motor 42 controlled by the feed operation control means 110 is moved to feed the grinding unit 30 from the standby position P to the machining start position h at a speed 10 times or more the machining feed. At this time, the machining start position correction unit 111 corrects the machining start position data in advance based on a correction value corresponding to the adjustment amount of the tilt angle of the chuck table 20. Thus, a safe and lean air cut operation is performed. After the air cut operation is completed, the surface of the wafer 1 is ground by the grinding unit 30 from the processing start position h at a processing feed rate. When grinding the wafer 1, the grinding amount is controlled while measuring the thickness of the wafer 1 by the thickness measurement gauge 50. The wafer 1 that has been ground is returned to the attachment / detachment position by the turntable 13 rotating.

  The wafer 1 on the chuck table 20 returned to the attachment / detachment position is cleaned by the cleaning nozzle 77. Next, it is picked up by the recovery arm 76, transferred to a spinner type cleaning device 80, washed with water and dried. The wafer 1 cleaned by the spinner cleaning device 80 is transferred and accommodated in the recovery cassette 81 by the pickup robot 70. The above is the overall operation of the grinding apparatus 10 of the present embodiment, and this operation is repeated to grind many wafers 1 continuously.

  According to this embodiment, even if the tilt angle of the chuck table 20 is changed by the tilt adjusting unit 100, the machining start position data is corrected according to the tilt angle. Therefore, the processing start position h can be appropriately adjusted to a position as close as possible to the surface of the wafer displaced by the inclination of the chuck table. Thereby, even if the grinding unit 30 is air-cut after adjusting the tilt angle of the chuck table 20, the grinding unit 30 collides with the wafer 1 or the distance between the wafer 1 and the grinding unit 30 is too large. It is possible to prevent excessive machining feed due to. As a result, the processing apparatus of the present invention can be operated safely without damaging the substrate, and the processing time can be shortened as much as possible, so that the production efficiency can be improved.

It is the (a) perspective view and (b) side view of the wafer which are ground by one Embodiment of this invention. It is a perspective view of a grinding apparatus provided with the process start position correction | amendment means of this invention. It is the (a) perspective view and (b) side view which show the state which grinds the wafer surface with the grinding unit with which the grinding-work apparatus shown in FIG. 2 is equipped. It is the top view which showed the positional relationship of the rotation locus | trajectory of the grindstone of a grinding processing apparatus, and a chuck table. It is a side view of a chuck table provided with inclination adjustment means. It is a figure explaining the change of the process start position which arises when a chuck table is inclined.

Explanation of symbols

1 ... wafer (substrate)
10 ... Grinding equipment (processing equipment)
20 ... Chuck table (holding means)
20a ... Rotating shaft 21a ... Upper surface (holding surface) of the suction area
30 ... Grinding unit (processing means)
40. Slider (feeding means)
41. Guide rail (feeding means)
42 ... Servo motor (feeding means)
43 ... Feeding mechanism (feeding means)
110: Feeding operation control means 111 ... Machining start position correcting means P ... Standby position h ... Machining start position

Claims (1)

A rotatable holding means having a holding surface for sucking and holding the substrate;
Inclination adjusting means for adjusting the inclination of the rotation axis of the holding means from a basic angle to an arbitrary angle;
A processing means disposed opposite to the holding surface of the holding means and having a rotation axis parallel to the rotation axis of the holding means in the state of the basic angle;
The holding means and the processing means are moved relative to each other along the rotation axis of the processing means so as to approach and separate from each other, and a feeding means for performing desired processing on the substrate by the processing means when approaching,
Based on pre-stored processing start position data, a feed operation control means for controlling the feed means so that the processing means moves from the standby position to the processing start position of the substrate at a higher speed than the feed speed during substrate processing. In a processing apparatus having
A machining start position correction unit that corrects the machining start position data stored in the feed operation control unit based on the tilt angle of the rotation shaft of the holding unit adjusted by the tilt adjustment unit. Processing equipment.

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