TW201941292A - Grinding apparatus - Google Patents

Abstract

A grinding apparatus includes a table having a holding surface, a grinding unit grinding a wafer held on the holding surface, a notification portion notifying an operator of information, an imaging unit illuminating a ground surface of the wafer which is held and ground with an illumination and imaging the ground surface, a detecting portion detecting a cross line in an imaged picture, a memory storing an X-axis and Y-axis coordinate position of an intersection point of the cross line detected, a spotlight illuminating the holding surface at the X-axis and Y-axis coordinate position stored, and a controller causing the notification portion to notify the operator that the cross line has been detected and stopping grinding operations of the grinding apparatus.

Description

Grinding device

The present invention relates to a grinding device for grinding a workpiece such as a semiconductor wafer.

The grinding wafer grinding device grinds a wafer on a holding surface formed of a porous material held on a holding table by a grinding surface of a rotating grinding stone. The grinding stone is parallel to the holding surface. When an attachment such as grinding chips or abrasive grains is sandwiched between the holding surface of the holding table and the lower surface of the wafer, and the wafer held on the holding surface is ground with a grinding stone in this state, the directly above the attachment is Crossed cracks can form on the ground surface of the wafer. Then, in order to prevent cross cracks from being formed on the wafer, the holding surface before the suction and holding of the wafer is cleaned by the cleaning device described in Patent Document 1 or 2.

[Xizhi technical literature]
[Patent Literature]
[Patent Document 1] Japanese Patent No. 4079289.
[Patent Document 2] Japanese Patent No. 5538971.

[Problems to be Solved by the Invention]
However, when an adhered substance remains on the holding surface after being cleaned by using the cleaning device, a cross crack is formed. Therefore, before sucking and holding the wafer on the holding surface of the holding table, it is necessary to confirm whether there is any attachment on the holding surface. Here, the conventional method is to use a photographing camera to photograph the holding surface, but it has a problem that it is difficult for an operator to judge from the formed photographed image that it is a pattern of porous ceramics or an attachment.

Here, there is a problem in the grinding device: if a cross crack is found on the wafer after grinding, then the position of the holding surface of the holding table corresponding to the position where the cross crack is formed on the wafer (adhesion adheres to the holding surface) The position) allows the operator to immediately grasp and remove the position of attachments, and prevents cross cracks in the wafer during subsequent wafer grinding.

[Technical means to solve the problem]
According to the present invention, there is provided a grinding apparatus including: a holding table including a porous plate having a holding surface for holding a wafer; a holding table rotating means for rotating the holding table with the center of the holding table as an axis; The grinding stone grinds the wafer held on the holding surface; the notification means notifies the operator of various information; the photographing means illuminates the ground surface of the wafer with an illuminator and photographs the ground surface, and the wafer system is held in the holding And grinding by the grinding millstone; detecting means for detecting cross lines in an image captured by the photographing means; memory means for memorizing X-axis and Y-axis coordinate positions of intersections of the cross lines detected by the detecting means; spotlights, Irradiate the holding surface at the X-axis and Y-axis coordinate position memorized by the memory means; and control means to cause the notification means to notify an operator that the detection means detects a crosshair, and at the same time, stop the grinding operation of the device.

[Inventive effect]
According to the present invention, if a cross crack is generated on the wafer after grinding, a spotlight can be used to illuminate the holding surface directly below the cross crack, and after the wafer is removed from the holding surface, the operator can immediately grasp the holding surface. Where the grinding dust or abrasive particles are attached. Then, the operator can remove the attachments on the irradiated holding surface at this place, and can immediately remove the attachments that cause cross cracks from the holding surface.

The grinding device 1 shown in FIG. 1 is a device that performs a grinding process on the wafer W sucked and held by the holding table 30. The wafer W shown in FIG. 1 is, for example, a circular plate-shaped semiconductor wafer made of a silicon base material. A plurality of elements are formed on the front surface Wa of the wafer W facing downward in FIG. The film T is stuck and protected. The back surface Wb of the wafer W which faces upward becomes a grinding surface to be ground. On the outer periphery of the wafer W, a groove N, which is a mark indicating the crystal orientation, is formed in a state of being recessed inward in the radial direction toward the center of the wafer W.

On the front side (-X direction side) of the base 10 of the grinding apparatus 1, an input means 19 for inputting processing conditions and the like to the grinding apparatus 1 by an operator is provided. On the front side of the susceptor 10, a first cassette 331 for accommodating the wafer W before grinding and a second cassette 332 for accommodating the wafer W after grinding are arranged. A robot 330 having a multi-joint arm is arranged between the first cassette 331 and the second cassette 332. The multi-joint arm carries the wafer W before the grinding from the first cassette 331, and the grinding will end at the same time. The wafer W is carried into the second cassette 332.

In the movable area of the machine tool 330, a temporary table 333a for temporarily processing the wafer W before processing is provided, and an alignment means 333b is provided in the temporary table 333a. The alignment means 333b aligns the wafer W carried out from the first cassette 331 and placed on the temporary table 333a (center correction) with a reduced diameter alignment pin at a predetermined position.

A groove detection unit 333c for detecting the groove N of the wafer W is disposed on the side of the temporary table 333a. The notch detection unit 333c is configured by, for example, a light-reflective or transmissive optical sensor. As the temporary stage 333a holding the center-corrected wafer W is rotated, the outer periphery of the wafer W is detected by the notch The detection area (lower) of the portion 333c can detect the groove N formed on the outer peripheral edge of the wafer W. Incidentally, the groove detection portion 333c may be constituted by a camera or the like, and the groove detection portion 333c may image-process the photographed image captured by the camera to detect the outer periphery of the wafer W. The groove N.

A cleaning means 334 is provided in the movable region of the machine tool 330 to clean the wafer W after the grinding. The cleaning means 334 is, for example, a leaf-type rotary cleaning device.

A first conveyance means 335 is provided near the alignment means 333b, and a second conveyance means 336 is provided near the cleaning means 334. The first transfer means 335 transfers the wafer W before the center correction and grinding to the holding table 30 shown in FIG. 1, and the second transfer means 336 holds the wafer W on any of the holding tables 30. The finished wafer W is transferred to the cleaning means 334.

A turntable 34 is arranged on the rear side of the first conveyance means 335 on the base 10, and on the turntable 34, for example, four holding tables 30 are provided in the circumferential direction at equal intervals (only shown in the figure). Figure 2). The turntable 34 is rotatable around the axis center in the Z-axis direction on the base 10. By the rotation of the turntable 34, any one of the holding tables 30 is positioned near the first conveyance means 335 and the second conveyance means 336.

As shown in FIG. 2, the holding table 30 has, for example, a circular shape, and includes a porous plate 300 that adsorbs the wafer W and a frame 301 that supports the porous plate 300. The perforated plate 300 is a suction source 39 that communicates with a vacuum generating device and the like. The attraction force generated by the suction source 39 is transmitted to the holding surface 300a, which is the exposed surface of the orifice plate 300, and the holding table 30 holds the wafer W at On the holding surface 300a. The holding surface 300a is formed as a conical surface with a very gentle incline with its rotation center as the apex.

A holding table rotation means 37 is connected to the lower surface side of the holding table 30. The holding table 30 is rotatable about the axis of the Z-axis direction by the holding table rotation means 37 on the turntable 34 shown in FIG.
A tilt adjustment mechanism 38 is provided below the holding table 30 via a coupler or the like. The tilt adjustment mechanism 38 can adjust the tilt with respect to the horizontal plane of the holding surface 300 a of the holding table 30.

The holding table rotation means 37 is, for example, a pulley mechanism, which includes: a main shaft 370 whose axial direction is the Z-axis direction and whose lower end is connected to the lower surface of the housing 301 of the holding table 30; and a motor 371 serving as a driving source for holding the table 30 The center is an axis, and the holding table 30 is rotated. A drive pulley 372 is assembled on the shaft of the motor 371, and an endless belt 373 is wound around the drive pulley 372. A driven pulley 374 is assembled to the main shaft 370, and an endless belt 373 is also wound around the driven pulley 374. The driving pulley 372 is rotationally driven by the motor 371, and the endless belt 373 is rotated with the rotation of the driving pulley 372, and the driven pulley 374 and the main shaft 370 are rotated by the rotation of the endless belt 373.
For example, a rotation encoder 379 that detects a rotation angle of the motor 371, that is, a rotation angle of the holding table 30 is connected to the motor 371.

As shown in FIG. 1, a column body 11 is erected on the rear side (+ X direction side) of the base 10, and a front surface of the column body 11 is arranged side by side: a rough grinding feed means 35 for rough grinding The means 31 performs a grinding feed on the wafer W held by the holding table 30; and a fine grinding feeding means 36 that causes the fine grinding means 32 to perform a grinding feed on the wafer W held by the holding table 30.

The rough grinding feed means 35 is composed of a ball screw (not shown) having a vertical axis (Z-axis direction), a pair of guide rails 351 arranged in parallel with the ball screw, and a motor 352 that connects the ball screw and Rotate the ball screw; and the lifting part 353, the internal nut is screwed with the ball screw, and the side part slides to the guide rail 351; as the motor 352 rotates the ball screw, the lifting part 353 supporting the rough grinding means 31 will be moved by the guide rail 351 Guide and lift.

The lapping feed means 36 is composed of a ball screw (not shown) having a vertical axis; a pair of guide rails 361 arranged in parallel with the ball screw; a motor 362 that connects the ball screw and rotates the ball screw; And the lifting part 363, the internal nut is screwed with the ball screw, and the side part slides to the guide rail 361; as the motor 362 rotates the ball screw, the lifting part 363 supporting the precision grinding means 32 is guided by the guide rail 361 and lifted.

The rough grinding means 31 includes a rotation shaft 310 whose axis direction is vertical; a housing 311 that rotatably supports the rotation shaft 310; a motor 312 that rotates the rotation shaft 310; a mounting member 313 that is assembled at a lower end of the rotation shaft 310; and grinding The wheel 314 is detachably connected to the mounting member 313. A plurality of rough grinding stones 314 a having a substantially rectangular parallelepiped shape are arranged annularly on the bottom surface of the grinding wheel 314. The rough grinding stone 314a is formed by fixing diamond abrasive grains and the like with a predetermined adhesive. The rough grinding stone 314a is, for example, a grinding stone having relatively large abrasive grains included in the grinding stone.

For example, a flow path system (not shown) connected to the grinding water supply source and serving as a channel for the grinding water is formed inside the rotary shaft 310 and penetrates the axial direction of the rotary shaft 310. The flow path is formed on the bottom surface of the grinding wheel 314. The grinding water 314a is opened toward the rough grinding stone 314a.

The fine grinding means 32 can perform fine grinding for improving the flatness of the wafer W thinned by rough grinding. That is, the fine grinding means 32 further grinds the back surface Wb of the wafer W ground by the rough grinding means 31 by a grinding wheel 314 provided with a grinding grinding stone 324 a and rotatably mounted. The abrasive grains included in the fine grinding stone 324a are smaller than the grain size of the abrasive particles included in the coarse grinding stone 314a. The structure other than the fine grinding stone 324 a in the fine grinding method 32 is the same as the structure of the rough grinding method 31.

Above the moving path of the holding table 30, a cleaning means 8 for cleaning the holding surface 300a of the holding table 30 is provided. As shown in FIG. 2, this cleaning means 8 includes: a rotating shaft 80 having a vertical axis; a casing 81 rotatably supporting the rotating shaft 80; a washing grindstone 82 disposed at a lower end of the rotating shaft 80; and lifting Means 83, raising and lowering the casing 81. Then, the cleaning means 8 is reciprocally movable in the Y-axis direction by the Y-axis moving means 89 shown in FIG. 1.

The Y-axis moving means 89 shown in FIG. 1 includes, for example, a ball screw 890 having an axis center in the Y-axis direction; a bridge portion 891 that supports the ball screw 890; a movable portion 892 that has an internal nut-threaded ball screw 890, The ball screw 890 is reciprocated in the Y-axis direction; and a motor (not shown) connects one end of the ball screw 890 and rotates the ball screw 890. A cleaning device 8 is disposed in front of the movable portion 892.

The cleaning grindstone 82 is, for example, a resin bonded grindstone, a resin material, or a ceramic material formed into a circular plate shape, and contaminants such as grinding debris adhering to the holding surface 300a of the holding table 30 are removed. Incidentally, the cleaning means 8 may be provided with a cleaning brush instead of the cleaning grindstone 82.
The raising and lowering means 83 includes a rail 830 on which the casing 81 slides, and a motor or the like provided inside the casing 81, for example, and can raise and lower the casing 81.

The grinding apparatus 1 includes imaging means 40 that irradiates the grinding surface Wb of the wafer W with an illuminator 400 (see FIG. 2) and photographs the grinding surface Wb. The wafer W is held on the holding surface 300 a of the holding table 30 and Grinded by the fine grinding stone 324a; and the spotlight 41 irradiates the holding table 300a of the holding table 30.

The photographing means 40 is, for example, a line sensor camera, and is disposed on the side surface of the housing 81 of the cleaning means 8, and can move with the cleaning means 8 in the Y-axis direction and the Z-axis direction. As shown in FIG. 2, the imaging means 40 includes, for example, a rectangular parallelepiped case 401 that blocks external light, and a side surface of the case 401 is provided with an illuminator 400 that irradiates the wafer W from above the wafer W. The lighting fixture 400 is, for example, an LED or a xenon lamp, and the light generated by the lighting fixture 400 is transmitted to the inside of the housing 401 through a transmission optical system such as an optical fiber (not shown). The amount of light emitted by the luminaire 400 can be adjusted by an adjuster (not shown) or the like.

The photographing means 40 includes: a half mirror 402 disposed in the housing 401 and reflecting light emitted from the luminaire 400 downward and changing directions; an objective lens (not shown) disposed in the housing 401 And the photographing section 403 is disposed on the upper side of the half mirror 402 and performs photoelectric conversion on the reflected light reflected by the wafer W and captured by the objective lens as Image information and output.

The imaging unit 403 is configured by, for example, a plurality of light-receiving elements such as a CCD and being arranged side by side in the X-axis direction. The length of the imaging section 403 in the long axis direction (X-axis direction) is approximately the same as the length of the radius of the holding surface 300a of the holding table 30, and the imaging section has an imaging area with a length longer than the radius of the wafer W. The data transmitted by each pixel of the light receiving element according to the intensity of the reflected light is represented by, for example, a brightness value of 8 bit levels, that is, 256 levels of 0 to 255.

The spotlight 41 is, for example, an LED lamp or the like that can illuminate the holding surface 300a of the holding table 30 from above, and is assembled near the photographing means 40, that is, in the present embodiment, it is assembled on the side of the casing 81 of the cleaning means 8. . Incidentally, the incident angle of the condensing light of the spotlight 41 can be adjusted, for example, by an adjustment means (not shown), and the condensing light path can be filtered to a desired value. The arrangement of the spotlight 41 is not limited to those shown in FIGS. 1 and 2.

As shown in FIGS. 1 and 2, the grinding device 1 includes control means 9, which is composed of a memory means 90 such as a CPU and a memory, and controls the entire apparatus. The control means 9 is electrically connected to the fine grinding feed means 36, the Y-axis moving means 89, and the holding table rotation means 37 through wiring (not shown). The control means 9 controls the following operations: The movement of the fine grinding means 32 by the feed means 36 in the Z axis direction; the positioning action of the photographing means 40 by the Y axis movement means 89 in the Y axis direction; and the holding by the rotation means 37 of the holding table The table 30 rotates.

The grinding device 1 includes a notification means 17 for notifying the operator of various information. The notification means 17 displays notification information on a screen (not shown) or sends a message from a warning bell.

Hereinafter, the operation of the grinding apparatus 1 when the wafer W is ground by the grinding apparatus 1 shown in FIG. 1 will be described.
First, by rotating the turntable 34 shown in FIG. 1, the holding table 30 in a state where the wafer W is not placed is revolved, and the holding table 30 is moved to the vicinity of the first transfer means 335. The machine tool 330 pulls out a wafer W from the first cassette 331 and moves the wafer W to the temporary table 333a.

After centering the wafer W on the temporary table 333a by the alignment means 333b, the groove N formed on the outer periphery of the wafer W will be detected by the groove detecting section 333c. Then, the wafer W is rotated by the temporary stage 333a, and the groove N is positioned at a predetermined position in the circumferential direction. Next, the first transfer means 335 moves the wafer W that has been center-corrected and the groove N is positioned at a predetermined position in the circumferential direction to the holding table so that the circumferential position of the groove N that is grasped is not shifted. 30 on.

For example, a groove alignment portion (alignment mark) (not shown) may be formed on the holding table 30 to align with the groove N when the wafer W is placed. In the holding table 30, the groove N of the wafer W is aligned with the groove alignment portion of the holding table 30. In other words, the position of the groove N when the wafer W is held by the first transfer means 335 while holding the wafer W is determined when the wafer W is held and carried out from the temporary table 333a. Therefore, the position of the groove N is determined by the rotation of the holding table 30 The angle is aligned so that the position of the groove N of the wafer W held by the temporary table 333a and the groove alignment portion of the holding table 30 are the same. Then, the wafer W is placed on the holding surface 300 a with the back surface Wb facing upward so that the center of the holding table 30 is approximately the same as the center of the wafer W.

Then, the attraction force generated by the operation of the attraction source 39 (see FIG. 2) is transmitted to the holding surface 300 a of the porous plate 300, whereby the holding table 30 sucks and holds the wafer W on the holding surface 300 a. The position of the groove N of the wafer W that is attracted and held is in a state grasped by the control means 9.
Incidentally, the position of the groove N that attracts the wafer W held on the holding table 30 is grasped at least until the wafer W is removed from the holding table 30 by the second transfer means 336 described later. status. That is, when the rotation of the holding table 30 by the holding table rotation means 37 is performed, the rotary encoder 379 of the holding table rotation means 37 shown in FIG. 2 will encode the encoding signal (the number of rotations of the motor 371) to the control means 9 Do output. The control means 9 feedback-controls the rotation speed of the holding table 30 by the holding table rotation means 37 according to the received encoded signal, and grasps the positions of the grooves N of the rotating wafers W one by one.

Incidentally, the position of the groove N of the wafer W in the holding table 30 is grasped when the edge alignment of the wafer W is performed by using the imaging means 40, and the edge alignment of the wafer W may be performed at the same time. When the edge alignment is performed, the holding table 30 is rotated so that the outer periphery of the wafer W held on the holding table 30 is imaged by the imaging means 40 in a plurality of places. Then, for example, the coordinates of three points separated at the outer periphery are detected, and the correct center coordinates of the wafer W on the holding table 30 are obtained by a geometric calculation process based on the coordinates of the three points. The coordinate position of the groove N is also grasped from the formed captured image.

After the holding table 30 attracts and holds the wafer W, the turntable 34 shown in FIG. 1 rotates clockwise when viewed from the + Z direction. Then, the holding table 30 holding the wafer W is revolved, and the rotation center of the rough grinding stone 314a of the rough grinding means 31 is shifted horizontally by a predetermined distance from the rotation center of the wafer W, so that rough grinding The rotation track of the stone 314a passes the rotation center of the wafer W so that the wafer W is positioned. In addition, the inclination of the holding table 30 is adjusted by the inclination adjustment mechanism 38 (see FIG. 2) so that the holding surface 300a of the gentle conical surface is parallel to the grinding surface (lower surface) of the rough grinding stone 314a, Therefore, the back surface Wb of the wafer W that is attracted and held along the holding surface 300a is parallel to the grinding surface of the rough grinding stone 314a.

The rough grinding means 31 is fed in the -Z direction by the rough grinding feed means 35, and the rough grinding grind stone 314a which is rotated contacts the back surface Wb of the wafer W held by the stage 30, thereby performing rough grinding. In addition, as the holding table rotation means 37 rotates the holding table 30 at a predetermined speed, the wafer W on the holding surface 300a also rotates. Therefore, the rough grinding stone 314a performs rough grinding processing on the entire back surface Wb of the wafer W. . During grinding, the grinding water is supplied to the contact portion between the rough grinding stone 314a and the back surface Wb of the wafer W, and the contact portion is cleaned and cooled.

After the wafer W is roughly ground to a thickness before the fine grinding, the rough grinding feed means 35 raises the rough grinding means 31 and separates from the wafer W.
Next, the turntable 34 rotates clockwise as viewed from the + Z direction, so as to attract the holding table 30 holding the wafer W to move below the fine grinding means 32. After the fine grinding grindstone 324a is aligned with the wafer W, the fine grinding grinding means 32 is fed downward by the fine grinding feed means 36, and the rotating fine grinding grindstone 324a abuts the back surface Wb of the wafer W, and As the holding table 30 rotates, the entire back surface Wb of the wafer W is finely ground.

After the fine grinding means 32 is separated from the wafer W to be ground to a finished thickness and the flatness of the back surface Wb is improved, the turntable 34 rotates clockwise as viewed from the + Z direction, whereby the wafer W moves to Near the second conveyance means 336. Then, the second transfer means 336 transfers the wafer W on the holding table 30 to the cleaning means 334. After the wafer W is cleaned in the cleaning means 334, the machine tool 330 carries the wafer W out of the cleaning means 334, and then carries the wafer W into the second cassette 332. In the grinding apparatus 1, a series of grinding operations are repeated in this manner, and a plurality of wafers W are ground.

As described above, when the wafer W is ground, the grinding chips or the dropped abrasive particles enter between the holding surface 300a of the holding table 30 shown in FIG. 1 and the protective film T adhered to the wafer W, so that the grinding chips or Abrasive particles adhere to the holding surface 300a. When the wafer W is ground in this state, a cross-shaped crack (cross line) is generated on the wafer W. In the state where the adhered substance remains on the holding surface 300a, the next wafer W is attracted and held on the holding surface 300a. When the back surface Wb of the next wafer W is ground, the next wafer W is generated. Cross-shaped crack.

Here, the cleaning means 8 is moved in the Y-axis direction by the Y-axis moving means 89 to position the cleaning grindstone 82 above the holding surface 300 a of the holding table 30 for carrying out the wafer W. Then, the holding table rotation means 37 rotates the holding table 30, and at the same time, the lifting and lowering means 83 lowers the rotating cleaning grindstone 82, and presses the cleaning grindstone 82 to the holding surface 300a. In this way, the grinding chips and the like protruding upward from the holding surface 300a are removed, and the holding surface 300a is cleaned.

For example, when the operation of cleaning the holding surface 300a of the holding table 30 using the cleaning means 8 is added at an appropriate timing, while a plurality of wafers W and the like are continuously ground, the cleaning performed by the cleaning means 8 is performed. Attachment remains on the holding surface 300a. In this case, a cross line is formed on the back surface Wb of the wafer W held by the holding surface 300a by grinding.
Therefore, it is necessary to prevent grinding of a plurality of wafers W while the wafer W is formed with a cross hair, and the grinding apparatus 1 of the present invention performs operations as described below.

For example, a plurality of wafers W to be scheduled are ground to the finished thickness by precision grinding, then the precision grinding means 32 shown in FIG. 1 is separated from the wafer W, and then the turntable 34 is viewed from the + Z direction. In order to rotate clockwise, the Y-axis moving means 89 moves the imaging means 40 in the Y-axis direction, so that the imaging means 40 can photograph the back surface Wb of the wafer W held by the holding table 30, so that the wafer W Align with shooting means 40. That is, as shown in FIGS. 3 and 4, alignment is performed so that the imaging unit 403 linearly spans from above the center Wc of the wafer W to above the outer periphery. Incidentally, in FIGS. 3 and 4, the configuration other than the imaging section 403 of the imaging means 40 is omitted.

Next, the holding table rotation means 37 rotates the holding table 30 by a predetermined angle under the control of the control means 9. For example, as shown in FIG. 4, it passes through the imaginary of the center Wc of the wafer W and the groove N. The line L1 is parallel to the X-axis direction, and the groove N is positioned at a position on the + X-direction side (the 0-degree position, that is, the shooting start position).
In addition, when the to-be-photographed means 40 is operated, focusing of an objective lens (not shown) is performed by the up-and-down movement of the photographed means 40 by the elevating means 83 shown in FIG. 2. At the time when the objective lens is in focus on the back surface Wb of the wafer W, the elevating means 83 stops the vertical movement of the imaging means 40.

In this state, as shown in FIGS. 3 and 4, the holding table rotation means 37 rotates the holding table 30 in a counterclockwise direction when viewed from the + Z direction side at a predetermined rotation speed, for example. In addition, the illuminator 400 (see FIG. 2) of the imaging means 40 irradiates the back surface Wb of the wafer W through the half mirror 402, and the reflected light from the back surface Wb of the wafer W is captured by an objective lens (not shown) and is incident To the light receiving element of the imaging section 403. Then, the back surface Wb of the wafer W that is relatively rotated with respect to the imaging means 40 is continuously photographed for each line by the imaging means 40 from the center Wc of the wafer W to its outer periphery.

The imaging unit 403 transmits the captured images in line units to the control means 9 shown in FIGS. 1 and 2 one by one. The captured images in this line unit are sequentially memorized to the storage means 90 of the control means 9 so that the entire captured back surface Wb of the wafer W can be formed. In addition, the control means 9 captures an image of a line on the back surface Wb of the wafer W based on the encoded signal received from the rotary encoder 379 (see FIG. 2) of the holding table rotation means 37 that rotates the holding table 30. , And the rotation angle of the holding table 30 from the shooting start position (0 degree position) when the captured image of the line is captured, establishes relevance and memorizes to the memory means 90 in order.
Then, when the holding table rotation means 37 rotates the holding table 30 360 degrees so that the photographing means 40 bypasses the upper surface Wb of the wafer W by one turn (the groove N returns to the shooting start position), a developing wafer W is formed. The captured image of the entire back surface Wb, and the rotation of the holding table 30 is stopped.

The light amount (received light amount) of the reflected light which has entered the light receiving elements of the imaging unit 403 differs when the back surface Wb of the wafer W has a crosshair. That is, among the light receiving elements of the imaging unit 403, the places where the back surface Wb of the wafer W has a crosshair will increase the amount of light received, and its brightness value will be close to 255 and close to white. Otherwise, the back surface Wb of the wafer W has no crosshairs. The area of the line will reduce the amount of light received, and its brightness value will be close to 0 and close to black. Therefore, in the captured image G showing the entire surface of the back surface Wb of the wafer W displayed on the virtual output screen of a predetermined resolution shown in FIG. 5, the cross line C of the back surface Wb of the wafer W is, for example, White is shown, and the back surface Wb of the wafer W around it is shown in gray.
Incidentally, binary processing may also be performed on the captured image G, so that the crosshair C and its surroundings can be more clearly distinguished.

As shown in FIGS. 1 and 2, the grinding device 1 includes detection means 91 that detects a cross line C in a captured image G captured by the imaging means 40. The detection means 91 is, for example, incorporated in the control means 9. The detection means 91 systematically displays the sum of the Y-axis direction of the white pixels and the sum of the X-axis directions of the white pixels in the back surface Wb of the wafer W in the captured image G shown in FIG. To detect the crosshair C and calculate the size of the crosshair C at the same time. Pixels at the intersections of the cross lines C are specified.

Next, the X-axis Y-axis coordinate position of the pixel at the intersection of the detected cross line C will be determined by the detection means 91. The coordinate position of the center Wc of the wafer W which is approximately the same as the rotation center of the holding table 30 is determined as the origin coordinate (0, 0), and an imaginary line L2 is drawn, and the imaginary line L2 is connected to indicate the origin coordinate. (0,0) pixels at the intersection with the specified cross line C. The angle θ1 between the imaginary line L1 and the imaginary line L2 is the same as the angle at which the holding table 30 is rotated from the shooting start position when the captured image of the line unit drawn with the cross line C is captured, and is memorized in the memory means 90 Known value.
The length of the imaginary line L2 is calculated from the pixel statistics of the pixels from the origin coordinate (0, 0) to the intersection of the cross lines C (for example, let the calculated value be r). Then, the X-axis Y-axis coordinate position (x, y) of the pixel at the intersection of the detected cross line C is determined as (rcosθ1, -rsinθ1). Then, the X-axis Y-axis coordinate position (rcosθ1, -rsinθ1) of the intersection of the cross line C is memorized to the memory means 90.

Incidentally, the determination of the X-axis Y-axis coordinate position (x, y) of a pixel at the intersection of the detected cross lines C is not limited to those in the above embodiment. For example, an imaginary line L3 (not shown in FIG. 5) perpendicular to the imaginary line L1 is drawn from pixels at the intersection of the cross line C. The X-axis coordinate of the intersection of the imaginary line L1 and the imaginary line L3 is drawn from The pixel coordinates of the point coordinates (0, 0) to the intersection of the imaginary line L1 and the imaginary line L3 are determined. Then, in order to further perform pixel statistics from the intersection of the imaginary line L1 and the imaginary line L3 to the intersection of the cross line C, the position of the Y-axis coordinate of the intersection of the cross line C can be determined, and finally the intersection of the cross line C can be determined. The X-axis Y-coordinate position of the pixel (x, y).

When the X-axis Y-axis coordinate position (rcosθ1, -rsinθ1) of the intersection of the cross line C is memorized to the memory means 90, the spotlight 41 shown in Figs. Y-axis coordinate position (rcosθ1, -rsinθ1). That is, under the control by the control means 9, the movement of the spotlight 41 by the Y-axis moving means 89 in the Y-axis direction and the movement of the spotlight 41 by the lifting means 83 in the Z-axis direction are performed. The movement and / or adjustment of the incident angle of the spotlight irradiated by the spotlight 41 by an adjustment means (not shown), so that the spotlight 41 irradiates the stored X-axis Y of the back surface Wb of the wafer W with a predetermined spot diameter Axis coordinate position (rcosθ1, -rsinθ1). Incidentally, the diameter of the spot of the spotlight irradiated by the spotlight 41 is, for example, the diameter of the vertical and horizontal lengths of the crosshair C.

As described earlier, when the cross-line C is detected by the detection means 91, the control signal is transmitted from the control means 9 to the notification means 17, and the notification means 17 notifies the operator that the cross-line C is detected on the wafer W. Under the control by the control means 9, the grinding operation is stopped, that is, the operation such as described later is stopped: the wafer W is carried in by the first transfer means 335 to the crystal holding the cross line C formed. The holding table 30 other than the holding table 30 having a circle W; rough grinding processing (fine grinding processing) is performed on the wafers W held by the other holding tables 30; and the wafer W having the cross line C is transferred from the second transfer means 336 from Conveyance of the holding table 30 to the cleaning means 334; and rotation of the turntable 34. As a result, the operator removes the wafer W on which the reticle C is formed from the holding table 30, and the grinding apparatus 1 is in a state capable of removing the adhered matter on the holding surface 300 a of the holding table 30.
Incidentally, when the cross line C is not detected on the wafer W, the wafer W is moved to the vicinity of the second transfer means 336 by the rotation of the turntable 34 as described above, and the second transfer means 336 transfers the wafer W on the holding table 30 to the cleaning means 334.

As described above, after the grinding operation of the grinding apparatus 1 is stopped, the wafer W having the cross line C is detected. After the wafer W is held by the holding table 30, the wafer W is operated as a wafer that is not suitable for a product wafer. The worker moves out of the holding table 30. Therefore, the spotlight 41 (refer to FIG. 2) that irradiates the memorized X-axis Y-axis coordinate position (rcosθ1, -rsinθ1) in the back surface Wb of the wafer W with a predetermined spot diameter is formed by irradiating the crossline C with the spotlight. The holding surface 300 a directly below the X-axis Y-axis coordinate position (rcosθ1, -rsinθ1) of the wafer W. That is, the attached matter on the holding surface 300 a which is the cause of the formation of the cross line C on the wafer W will be in a state where the spotlight 41 is accurately irradiated with the light spot.

Therefore, the operator can immediately grasp the position where the adhering matter such as grinding chips or abrasive grains on the holding surface 300a is immediately grasped by the spotlight of the spotlight 41. Therefore, for example, the operator can use a tool for removing attachments (for example, a scraper or a cleaning brush) to immediately remove the attachments that are the cause of the crosshairs C from the holding surface 300a.

After the removal of the attachments on the holding surface 300a by the operator is performed as described above, the operator sets the grinding device 1 so that the grinding operation of the grinding device 1 can be restarted, so that the wafer W is held in the holding state. The surface 300 a is placed on the holding table 30 in a state where the next wafer W does not form the cross line C, and the aforementioned grinding is performed.

Incidentally, the grinding device 1 of the present invention is not limited to those described in the above embodiment, and the configuration of each device shown in the attached drawings is not limited to this. Change appropriately.
For example, the spotlight 41 may also be the position where the X-axis Y-axis coordinate position (rcosθ1, -rsinθ1).

1‧‧‧Grinding device

10‧‧‧ base

11‧‧‧ cylinder

17‧‧‧ Means of notification

30‧‧‧holding table

300‧‧‧ multi-well plate

300a‧‧‧ holding surface

301‧‧‧Frame

31‧‧‧Rough grinding methods

310‧‧‧Rotary shaft

311‧‧‧shell

312‧‧‧Motor

314‧‧‧grinding wheel

314a‧‧‧Rough grinding grinding stone

32‧‧‧Refined grinding methods

324a‧‧‧Refined grinding stone

330‧‧‧ Machinery

331‧‧‧First cassette

332‧‧‧Second cassette

333a‧‧‧Temporary table

333b‧‧‧Counting means

333c‧‧‧Groove detection section

334‧‧‧Cleaning means

335‧‧‧The first transfer method

336‧‧‧Second Transfer Means

34‧‧‧Turntable

35‧‧‧ Rough grinding feed

350‧‧‧ball screw

351‧‧‧rail

352‧‧‧Motor

353‧‧‧Lifting Department

36‧‧‧Refining feed

360‧‧‧ball screw

361‧‧‧rail

362‧‧‧Motor

363‧‧‧Lift

37‧‧‧Rotation means of holding table

370‧‧‧ spindle

371‧‧‧Motor

372‧‧‧Driven pulley

373‧‧‧ endless belt

374‧‧‧Driven pulley

379‧‧‧rotary encoder

38‧‧‧Tilt adjustment mechanism

39‧‧‧ Attraction Source

8‧‧‧ cleaning methods

80‧‧‧rotation axis

81‧‧‧shell

82‧‧‧washing stone

83‧‧‧ Lifting means

89‧‧‧Y-axis moving means

40‧‧‧shooting methods

400‧‧‧Lighting

401‧‧‧shell

402‧‧‧half mirror

403‧‧‧Photography Department

41‧‧‧ spotlight

9‧‧‧ control means

90‧‧‧means of memory

91‧‧‧Testing methods

W‧‧‧ Wafer

Wa‧‧‧ Back of Wafer

Grinded side of Wb‧‧‧ wafer (back side)

T‧‧‧protective film

N‧‧‧Groove

C‧‧‧ Cross

FIG. 1 is a perspective view showing an example of a grinding device.

FIG. 2 is a sectional view showing an example of a holding table, a cleaning means, and an imaging means.

FIG. 3 is a cross-sectional view showing a polished surface of a wafer held on a holding surface and ground by a grinding stone, irradiated with an illuminator, and photographed by an imaging means.

FIG. 4 is a plan view showing a ground surface of a wafer to be held on a holding surface and ground by a grinding stone, irradiated with an illuminator, and photographed by imaging means.

FIG. 5 is an explanatory diagram illustrating a situation where the detection means detects a crosshair in an image captured by the imaging means.

Claims (1)

A grinding device having: A holding table including a perforated plate having a holding surface for holding a wafer; The rotating means of the holding table rotates the holding table with the center of the holding table as an axis; Grinding means for grinding a wafer held on the holding surface with a grinding stone; Notification means to inform operators of various information; A photographing means for irradiating the ground surface of the wafer with an illuminator and shooting the ground surface, and the wafer system is held on the holding surface and ground by the grinding stone; Detecting means for detecting cross lines in an image taken by the shooting means; A memory means for memorizing the X-axis Y-axis coordinate position of the intersection of the cross lines detected by the detection means; A spotlight illuminating the holding surface at the X-axis and Y-axis coordinate position memorized by the memory means; and The control means causes the notification means to notify an operator that the detection means detects a crosshair, and at the same time, stops the grinding operation of the device.