TW202343649A - Conveying pad capable of preventing sagging of the outer peripheral and central portions of the wafer and preventing debris from adhering to the conveying pad even if the wafer is cut within the range of the atmospheric open area - Google Patents

Abstract

Provide a conveying pad capable of stably conveying a fragile wafer by preventing occurrence of a failure resulting from the sagging or cutting of a wafer. A conveying pad (40, 70) for sucking, holding, and transporting an upper surface (92) of a fragile wafer (90) to a work chuck (14). The conveying pad (40, 70) includes: a central sucking portion (44) for sucking and holding the central portion of the wafer; a circular outer peripheral sucking portion (45, 71) for sucking and holding the outer peripheral portion of the wafer; a plate piece(41) for configuring the central sucking portion and the outer peripheral sucking portion; and an atmospheric open area (50, 72) for opening the upper surface which is not sucked by the central sucking portion and the outer peripheral sucking portion to the atmosphere.

Description

Moving pad

The present invention relates to a conveying pad.

A grinding device that uses a grindstone to grind a wafer held on a work chuck is equipped with a transfer mechanism that uses a transfer pad to attract and hold the upper surface of the wafer, and then transfers the wafer to the work chuck.

Warpage may occur on the wafer processed by the grinding device. The holding surface of the chuck of the grinding device has a conical shape that becomes higher as it goes from the outer circumference to the center. If the wafer is warped, it cannot be reliably held on the chuck. .

In order to solve this problem, the invention described in Patent Document 1 uses a transfer mechanism that combines a transfer pad that attracts and holds only the center portion of the wafer, and an annular pressing member. A shaped pressing member presses the outer peripheral part of the wafer. In this transport mechanism, the central part of the wafer is transported to the work chuck while being suctioned and held by the transport pad, and the outer peripheral part of the wafer is pressed by the pressing member to correct warpage while holding the wafer on the work chuck. Work clamp table.

There is a method of processing wafers as follows: after positioning the focusing point of the laser beam inside the front side of the wafer and forming a modified layer inside along the dicing lane (scheduled line for division), the back side of the wafer is Grinding is performed on both sides (for example, Patent Document 2).

In addition, there is a method of processing wafers as follows: using a cutting blade to form a cutting groove on the front side of the wafer that does not penetrate to the back side, and then grinding the back side of the wafer to expose the cutting grooves and separate them into multiple devices. (For example, Patent Document 3). Prior technical literature patent documents

Patent Document 1: Japanese Patent Application Publication No. 2015-098073 Patent Document 2: Japanese Patent Application Publication No. 2006-012902 Patent Document 3: Japanese Patent Application Publication No. 2003-007653

The problem to be solved by the invention

Wafers with modified layers or cutting grooves formed as mentioned above are fragile wafers that are easily cut along the modified layer or cutting grooves, so care must be taken when transporting them.

For example, a wafer with a modified layer formed thereon is likely to be bent into a shape in which one side has a central depression (the center side is a concave shape) and the other side is a middle convex (the center side is a convex shape). The transfer pad of Patent Document 1, which is configured to attract and hold only the central portion, can hold such a curved wafer.

However, since a wafer with a modified layer formed thereon is easily cut along the modified layer, when only the center portion of the wafer is attracted and held for transportation, a force will be exerted due to the influence of vibration or gravity, and the wafer will be transported. Doubts about cutting the wafer along the modified layer. If the wafer is cut in an area that is not attracted and held by the transfer pad (outside the central part), there will be the following problems: the outer peripheral part of the wafer will sag, and the wafer cannot be properly transferred to be attracted and held on the work chuck.

Furthermore, in order to prevent the outer peripheral portion of the wafer from sagging, it is conceivable to use a transfer pad of a type that uses a suction surface to suction and hold the entire upper surface of the wafer. However, if the entire upper surface of the wafer is held by suction, the bent wafer will become flat, but at this time, there is a risk that the wafer will be cut along the modified layer due to the force of the flattening. . As a result, there will be the following problem: debris will be generated during cutting, and the debris will adhere to the suction surface of the transfer pad. When the next wafer is attracted, the debris will come into contact with the wafer on the wafer and the wafer will The corners are damaged.

The present invention was made in view of the above-mentioned points, and an object thereof is to provide a method for stably transporting fragile wafers while preventing the occurrence of malfunctions caused by wafer sagging or wafer cutting. pad. means to solve problems

One aspect of the present invention is to suction and hold the upper surface of a fragile wafer, and transport it to the transfer pad of the work chuck, and is provided with: a central suction part to suction and hold the central part of the wafer; and an annular outer peripheral suction part. part to attract and hold the outer peripheral part of the wafer; a plate for arranging the central suction part and the outer peripheral suction part; and an atmospheric open area to conduct the upper surface of the wafer that is not attracted by the central suction part and the outer peripheral suction part. The atmosphere is open.

The outer peripheral suction portion includes: an arc-shaped annular portion protruding downward from the lower surface of the plate and extending in the circumferential direction in an arc-shaped manner, and a plurality of them are arranged in the circumferential direction; and an outer peripheral suction port. The inner side of the arc-shaped annular portion is opened on the lower surface of the plate and can be connected to the suction source; and the outer peripheral suction path connects the outer peripheral suction port to the suction source.

The central suction part has a contact part. When the wafer is suctioned, the contact part is in contact with the upper surface of the wafer to prevent the wafer from being deformed in the suctioned area. Invention effect

According to the transfer pad of the present invention, the upper surface of the wafer can be attracted and held by the central suction part and the outer peripheral suction part, thereby preventing the outer peripheral part and the central part of the wafer from sagging. In addition, by setting the transfer pad except for the central suction part and the outer peripheral suction part as an open air area, cutting of the wafer can be suppressed, and even if the wafer has been cut within the open air area, it is difficult for debris to adhere to the area. Moving pad. Therefore, it is possible to obtain a transfer pad that can stably transfer fragile wafers by preventing the occurrence of problems caused by wafer sagging or wafer breakage.

Form used to implement the invention

Hereinafter, the conveying pad of this embodiment will be described with reference to the attached drawings. Figure 1 shows a grinding device that uses a transfer pad to transfer wafers. 2 to 4 show the structure of the transfer pad according to the first embodiment. 5 to 8 illustrate the operation of transferring the wafer to the work chuck using the transfer pad according to the first embodiment. 9 and 10 show the structure of the transfer pad according to the second embodiment. Figures 11 to 13 show the steps of forming a modified layer on a wafer and the wafer with the modified layer formed on it.

The grinding device 1 shown in FIG. 1 is an example of a processing device equipped with a transfer pad. The grinding device 1 performs grinding processing on the wafer 90 which is fragile and prone to being cut by external force. First, the fragile wafer 90 will be described with reference to FIGS. 11 to 13 .

The wafer 90 is a semiconductor wafer made of, for example, silicon, and has a front surface 91 and a back surface 92 . On the front surface 91 side of the wafer 90, a wafer 94 serving as an electronic device is formed in a plurality of areas divided by a plurality of planned dividing lines 93 in a grid shape (see FIG. 13). A protective tape 95 covering the entire front surface 91 of the wafer 90 is attached.

The modified layer 96 is formed on the wafer 90 by the laser processing device 80 . As shown in FIG. 11 , the laser processing apparatus 80 has a chuck 81 that attracts and holds the wafer 90 , and a laser irradiation part 82 that irradiates the laser beam L toward the wafer 90 on the chuck 81 . The work chuck 81 can move in the horizontal direction and rotate about an axis facing up and down. The laser irradiation unit 82 is provided with a condenser 83 that condenses and irradiates the laser beam L emitted from a laser light source (not shown). The laser beam L is a pulsed laser beam penetrating the material of the wafer 90 .

In the modified layer forming step using the laser processing apparatus 80, the wafer 90 is placed on the holding surface of the work chuck 81 with the protective tape 95 (front surface 91) side and is held (see FIG. 11). That is, the wafer 90 is held with the back surface 92 facing upward. The suction source (not shown) connected to the suction hole on the holding surface of the work chuck 81 is actuated, so that the wafer 90 is sucked and held on the holding surface of the work chuck 81 . The laser beam irradiation position is calibrated in such a manner that the laser beam L can be irradiated along the planned dividing line 93 formed on the wafer 90 by using a photographing device or the like.

One end of a predetermined planned division line 93 among the plurality of planned division lines 93 is positioned directly below the condenser 83 of the laser irradiation part 82 (see FIG. 11 ). Then, the focusing point P of the laser beam L irradiated from the condenser 83 is aligned at a predetermined position inside the thickness of the wafer 90 .

Next, while irradiating the laser beam L from the condenser 83 of the laser irradiation unit 82 to the focusing point P in the wafer 90 , the work chuck 81 is moved in the processing feed direction M at a predetermined feed speed. . As shown in FIG. 12 , when the irradiation position irradiated by the condenser 83 of the laser irradiation part 82 reaches the other end of the planned division line 93 , the irradiation of the laser beam L from the laser irradiation part 82 is stopped, and The movement of the work chuck 81 in the processing feed direction M is stopped.

Thereby, a modified layer 96 for modifying the wafer 90 along the planned division line 93 is formed inside the wafer 90 . Modification means: through the irradiation of the laser beam L, the density, refractive index, mechanical strength and other physical properties inside the wafer 90 are changed into a state different from the surrounding state, and the result of modification , the modified layer 96 will become an area with lower strength than the surrounding area.

After the modified layer 96 is formed along one planned division line 93 , the positional relationship between the work chuck 81 and the laser irradiation part 82 is changed, and one end of the next planned division line 93 is positioned to the focus of the laser irradiation part 82 Just below the optical device 83. Then, the modified layer 96 is formed along the next planned dividing line 93 . By proceeding in this manner, the modified layer 96 is formed along all the planned dividing lines 93 in the grid shape, thereby forming the wafer 90 shown in FIG. 13 . When a predetermined external force is applied to the wafer 90 in this state, the wafer 90 will be cut along the planned dividing line 93 whose strength has been reduced by the modified layer 96 , and the wafer 90 will be divided into divided parts including individual wafers 94 . That is, the wafer 90 becomes fragile and can be easily cut.

Furthermore, the modified layer 96 is formed inside the wafer 94 near the front surface 91 of the wafer 90 on which the device is formed. Therefore, the fragile wafer 90 is formed into a shape in which the front surface 91 side has a central convex shape (the central side has a convex shape), and the back surface 92 side has a central depression (the central side has a concave shape) (see FIG. 5 ). .

Furthermore, the formation of fragile wafers is not limited to the above processing method. For example, as a process for obtaining a fragile wafer, in addition to forming the modified layer 96 by irradiation with the laser beam L, a half-cut process using a cutting blade on the front side of the wafer may also be performed. A cutting groove is formed that does not penetrate to the back surface. Cutting grooves are formed by half-cut processing along all the planned division lines 93 , so that the wafer becomes fragile and easily cut along the planned division lines 93 .

The fragile wafer 90 that has undergone the modified layer formation step using the laser processing device 80 is transported to the grinding device 1 shown in FIG. 1 , and the back surface 92 is ground until it reaches a predetermined thickness. . The grinding device 1 is configured to perform a series of operations including loading processing, grinding processing, cleaning processing, and unloading processing on the wafer 90 which is a workpiece in a fully automatic manner. The wafer 90 is loaded into the grinding device 1 in a state of being accommodated in the cassette C.

The X-axis direction, the Y-axis direction, and the Z-axis direction in the grinding device 1 are in a mutually perpendicular relationship. The X-axis direction and the Y-axis direction are approximately horizontal directions, and the Z-axis direction is an up-down direction (vertical direction). In the double-arrow line indicating the direction of the X-axis, let the side of the text with an X attached to it be the front, and let the side of the text without the X axis be the rear. In the double-arrow line indicating the Y-axis direction, set the side of the text with Y to the left, and set the side of the text without Y to the right. In the double-arrow line indicating the direction of the Z axis, set the side of the text with Z attached to it as the upper side, and set the side of the text without the Z axis as the lower side.

A cassette C capable of accommodating a plurality of wafers 90 is mounted on the front side of the base 10 of the grinding device 1 . Behind the cassette C, a robot 11 for taking out and placing the wafers 90 in the cassette C is provided. A temporary workbench 12 for placing the wafer 90 before processing, and a rotating cleaning mechanism 13 for cleaning the processed wafer 90 (ground wafer 90) are provided at the left and right oblique rear of the robot 11 .

The robot hand 11 is configured by providing a hand 112 at the front end of an arm 111 composed of a multi-section link. The robot 11 can transport the pre-processed wafer 90 from the cassette C to the temporary workbench 12 , and transport the processed wafer 90 from the rotating cleaning mechanism 13 to the cassette C.

The wafer 90 that has been transported to the temporary stage 12 by the robot 11 is positioned so that its center coincides with the center of the temporary stage 12 .

The rotating cleaning mechanism 13 is provided with a nozzle 132 that sprays cleaning water and dry air toward the rotating table 131 . In the spin cleaning mechanism 13 , the wafer 90 held on the spin table 131 is sprayed with cleaning water from the nozzle 132 to clean the wafer 90 , and dry air is sprayed from the nozzle 132 after cleaning. The wafer is dried at 90%.

A first conveying mechanism 15 and a second conveying mechanism 16 are provided in the Y-axis direction between the temporary stage 12 and the rotating cleaning mechanism 13. The first conveying mechanism 15 moves the wafer 90 before processing from the temporary The workbench 12 is loaded into the work chuck 14 , and the aforementioned second transport mechanism 16 unloads the processed wafer 90 from the work chuck 14 to the rotating cleaning mechanism 13 . The first transport mechanism 15 and the second transport mechanism 16 are each provided with a transport pad 40 that attracts and holds the wafer 90 . The detailed structure of the first conveyance mechanism 15 and the second conveyance mechanism 16 including the conveyance pad 40 will be described later.

A rectangular opening extending in the X-axis direction is formed on the upper surface of the base 10 on the rear side of the grinding device 1 . This opening is covered by a movable plate 17 that can move in the X-axis direction together with the work clamp 14 and a bellows-shaped waterproof cover 18. A work table moving mechanism (not shown) for moving the work clamp table 14 in the X-axis direction is provided below the waterproof cover 18 . The table moving mechanism has a ball screw extending in the X-axis direction. When the ball screw is rotated, the moving plate 17 advances or retreats in the X-axis direction.

The work chuck 14 is connected to the workbench rotating assembly (not shown), and can be rotated around an axis facing the Z-axis direction by being driven by the workbench rotating assembly. As shown in FIG. 8 , the work chuck 14 includes a frame 141 and a disk-shaped porous plate 142 installed in a recessed portion on the upper surface side of the frame 141 .

The porous plate 142 is made of a porous material such as ceramics, and has fine pores covering the entire plate. By inserting the porous plate 142 into the recess of the frame 141, the upper surface of the frame 141 and the upper surface of the porous plate 142 become flush. The upper surface of the porous plate 142 will form a holding surface 143 that attracts and holds the wafer 90 . The holding surface 143 has a conical shape that becomes higher as it goes from the outer peripheral side in the radial direction toward the center.

A flow path 144 connected to the porous plate 142 is formed in the frame 141 . The flow path 144 is connected to the suction source 20 , the air supply source 21 and the water supply source 22 through the on-off valves 201 , 211 and 221 .

When the on-off valve 201 is opened and the suction source 20 is activated, the air on the side of the porous plate 142 can be sucked through the flow path 144, and the suction force acting on the holding surface 143 can suck and hold the wafer 90 from below.

When the on-off valve 211 is opened and the air supply source 21 is activated, the air supplied via the flow path 144 is ejected from the holding surface 143 . When the on-off valve 221 is opened and the water supply source 22 is activated, the water supplied through the flow path 144 is ejected from the holding surface 143 . The air supply source 21 and the water supply source 22 may be operated simultaneously to eject a mixed fluid of air and water from the holding surface 143 .

A lifting mechanism 25 is provided on the support 23 erected at the rear of the base 10 . The lifting mechanism 25 moves the grinding mechanism 24 in a direction (Z-axis direction) that approaches and separates the work chuck 14 .

The lifting mechanism 25 is provided with: a pair of parallel guide rails 251 arranged on the front surface side of the pillar 23 and extending in the Z-axis direction; a lifting table 252 provided so as to be slidable in the Z-axis direction relative to the pair of guide rails 251; The ball screw 253 extends in the Z-axis direction and is screwed to a screwed portion (not shown) of the lifting table 252 . The ball screw 253 is rotated by the driving force of the motor 254 connected to one end of the ball screw 253, thereby moving the lifting table 252 in the Z-axis direction.

The grinding mechanism 24 is installed on the front surface of the elevating table 252 through the housing 241, and is configured to rotate the grinding wheel 243 with the spindle unit 242. The spindle unit 242 may be, for example, an air spindle, and rotatably supports the spindle shaft 244 through high-pressure air inside the housing. The spindle axis 244 is an axis extending in the Z-axis direction.

A mounting base 245 is connected to the front end (lower end) of the spindle shaft 244, and a grinding wheel 243 is mounted on the mounting base 245. A plurality of grinding stones 246 are provided annularly on the lower surface side of the grinding wheel 243 . The grinding mechanism 24 uses the grinding stone 246 to grind the back surface 92 of the wafer 90 that is attracted and held on the work chuck 14 .

The grinding device 1 is provided with a control unit 30 that integrates various parts of the control device. The control unit 30 is composed of a processor, a memory, etc. that execute various processes. The control unit 30 controls, for example, the grinding feed amount of the grinding mechanism 24 in the Z-axis direction, the grinding feed speed, the rotation speed of the grinding wheel 243, etc., and allows grinding to be performed until the thickness of the wafer 90 reaches the finished product thickness. So far. In addition, the control unit 30 controls the transportation operation of the wafer 90 by the robot 11, the first transportation mechanism 15 and the second transportation mechanism 16, or the cleaning operation of the wafer 90 by the rotation cleaning mechanism 13. wait.

The operation of each part of the grinding device 1 described below is assumed to be controlled by the control signal transmitted from the control unit 30 unless the subject of control is clearly described.

In the grinding device 1 configured as above, the robot 11 transports the wafer 90 (which has the modified layer 96 formed by the laser processing device 80 ) from the cassette C to the temporary holding work. Taiwan 12. Next, with the back surface 92 of the wafer 90 being suctioned and held by the transfer pad 40 of the first transfer mechanism 15 , the wafer 90 is transferred from the temporary stage 12 to the work chuck 14 by the first transfer mechanism 15 . When the wafer 90 is transferred from the transfer pad 40 of the first transfer mechanism 15 , the work chuck 14 is positioned at a transfer position near the first transfer mechanism 15 (closer to the front in the X-axis direction) by the movement of the moving plate 17 .

As shown in FIG. 8 , the wafer 90 transported by the first transport mechanism 15 is placed on the holding surface of the work chuck 14 with the modified layer 96 (front surface 91 ) side facing downward and the back surface 92 side facing upward. 143 on. That is, during processing on the grinding device 1 , the protective tape 95 is the lower surface and the back surface 92 is the upper surface. The on-off valve 201 is opened to allow the suction source 20 to communicate with the flow path 144, so that the suction force acts on the holding surface 143 of the work chuck 14. The wafer 90 can be attracted and held on the holding surface 143 by this attractive force.

The work chuck 14 that attracts and holds the wafer 90 can be moved toward the rear side in the X-axis direction by the table moving mechanism and positioned at a processing position below the grinding mechanism 24 . Then, the grinding mechanism 24 is lowered by the lifting mechanism 25 so that the grinding stone 246 contacts the back surface 92 of the wafer 90 , and the grinding wheel 243 is rotated by the spindle unit 242 , and the grinding wheel 243 is rotated by the grinding stone 246 The back surface 92 side is ground while pressing the wafer 90 . When the back side 92 of the wafer 90 is ground to the desired thickness, the rotation of the grinding wheel 243 is stopped, and the grinding mechanism 24 is raised by the lifting mechanism 25 to remove the grinding stone 246 from the work chuck 14 The distance between the wafers 90 is increased, and the grinding process is completed.

After the grinding process, the work table 14 is moved forward in the X-axis direction by the table moving mechanism, and the work table 14 is positioned at a transfer position near the second transport mechanism 16 . The on-off valve 201 is closed to disconnect the suction source 20 so that the suction force exerted on the wafer 90 from the holding surface 143 of the chuck 14 does not act, and the wafer 90 can be removed from the chuck 14 It is delivered to the conveyance pad 40 of the 2nd conveyance mechanism 16.

In a state where the back surface 92 of the wafer 90 is sucked and held by the transport pad 40 of the second transport mechanism 16 , the air supply source 21 is actuated and the on/off valve 211 is opened, so that the surface of the wafer 90 is directed from the holding surface 143 of the chuck 14 to The lower surface (protective tape 95) is supplied with air. Alternatively, the water supply source 22 may be actuated and the on-off valve 221 may be opened to supply water from the holding surface 143 of the work chuck 14 toward the lower surface (protective tape 95 ) of the wafer 90 . Thereby, the wafer 90 can be pushed up by the pressure of the mixed fluid of air and water from the holding surface 143 side, so that the wafer 90 can be separated from the holding surface 143 .

The second transport mechanism 16 can transport the wafer 90 out of the work chuck 14 and transport the wafer 90 to the rotation cleaning mechanism 13 . When the wafer 90 is placed on the spin table 131 , the suction and holding of the wafer 90 by the transfer pad 40 of the second transfer mechanism 16 is completed, and the wafer 90 is transferred from the second transfer mechanism 16 to the spin cleaning. Institutions13. Then, the wafer 90 is cleaned by the rotating cleaning mechanism 13 .

Then, the cleaned wafer 90 will be moved out from the rotating table 131 by the robot 11 and placed in the cassette C. Furthermore, although only one cassette C is shown in FIG. 1 , the cassette C for accommodating the wafers 90 before processing and the cassette C for accommodating the wafers 90 after processing may also be provided.

By the way, the wafer 90 on which the modified layer 96 is formed is formed into the following shape as shown in FIG. 5: the back 92 side is bent into a central depression (the central side is in the shape of a depression), and the front side 91 and the protective tape 95 side are bent. It is convex in the middle (the central side is convex in shape). That is, the wafer 90 with the front surface 91 facing downward is likely to have a shape in which the outer peripheral portion is warped upward. In addition, the wafer 90 on which the modified layer 96 is formed has the fragility of being easily cut along the modified layer 96 (the planned division line 93 ) when an external force is applied. The first transport mechanism 15 and the second transport mechanism 16 in the grinding device 1 of this embodiment are equipped with transport pads 40. The transport pads 40 can stably hold the wafer 90 having such characteristics while suppressing Droop or cut one side for transportation. Hereinafter, although the first conveyance mechanism 15 will be mainly described in detail, the second conveyance mechanism 16 also has the same structure as the first conveyance mechanism 15 .

The transfer pad 40 is a transfer pad to which the first embodiment of the present invention is applied. As shown in FIGS. 2 to 4 , the transfer pad 40 has a disk-shaped plate 41 .

As shown in FIG. 2 , a cylindrical portion 42 protruding upward is provided in the center of the upper surface 411 of the plate member 41 . Furthermore, three sliding shafts 43 are provided on the upper surface 411 of the plate 41 so as to surround the cylindrical portion 42 .

As shown in FIG. 3 , a central suction part 44 that suctions and holds the central part of the wafer 90 and an annular outer peripheral suction part 45 that suctions and holds the outer peripheral part of the wafer 90 are arranged on the lower surface 412 of the plate 41 . The central suction part 44 is located at the center of the lower surface 412 , and the outer peripheral suction part 45 is located at the outer peripheral part (outer edge) of the lower surface 412 .

The central suction part 44 is formed with a central suction port 441 that opens downward, and is provided with a plurality of cylindrical contact parts 442 concentrically surrounding the central suction port 441 and an annular part outside the contact part 442 443. In this embodiment, a double-layered contact portion 442 is provided. The contact portion 442 and the annular portion 443 are formed of a material such as rubber that is elastically deformable and blocks the passage of air.

The outer peripheral suction part 45 is divided into four arc-shaped areas in the circumferential direction of the plate 41 and is provided. Each region of the outer peripheral suction portion 45 has an outer peripheral suction port 451 that opens downward, and an arc-shaped annular portion 452 surrounding the outer peripheral suction port 451. The arc-shaped annular portion 452 is a protruding portion having a shape that protrudes downward from the lower surface 412 of the plate 41 and extends in the circumferential direction in an arc-shaped manner, and surrounds the inner circumferential side and outer circumference of the outer circumferential suction port 451 sides and both ends in the circumferential direction. That is, a plurality of (four) arcuate annular portions 452 extending in the circumferential direction of the plate 41 are arranged, and a lower surface 412 opening to the plate 41 is formed inside each arcuate annular portion 452 Outer peripheral suction port 451. The arcuate annular portion 452 is formed of a material such as rubber that is elastically deformable and blocks the passage of air.

The lower surfaces (front ends) of the contact portion 442 and the annular portion 443 are located at substantially the same position as the lower surface (front end) of the arcuate annular portion 452 in the Z-axis direction.

As shown in FIG. 4 , a central suction path 46 and an outer peripheral suction path 47 are formed inside the plate 41 . The central suction path 46 is connected to the suction path 421 formed inside the cylindrical portion 42 and extending in the Z-axis direction, and a central suction port 441 is formed at the lower end of the central suction path 46 . The outer peripheral suction path 47 extends from the suction path 421 toward the outer peripheral side of the plate 41 and in the radial direction, and the front end of the outer peripheral suction path 47 is bent downward to communicate with the outer peripheral suction port 451 . The outer peripheral suction path 47 together with the outer peripheral suction port 451 and the arcuate annular portion 452 constitute the outer peripheral suction portion 45 .

The suction path 421 is connected to the suction source 48 through the on-off valve 481, and is connected to the air supply source 49 through the on-off valve 491. By opening the on/off valve 481, the central suction port 441 and the peripheral suction port 451 are connected to the suction source 48. By opening the on-off valve 491, the central suction port 441 and the peripheral suction port 451 are connected to the air supply source 49. When the suction source 48 is driven with the on-off valve 481 opened, air is sucked from the central suction port 441 and the peripheral suction port 451 toward the central suction path 46 and the peripheral suction path 47 . When the air supply source 49 is driven with the on-off valve 491 opened, air can be ejected from the central suction port 441 and the peripheral suction port 451 through the central suction path 46 and the outer peripheral suction path 47 .

On the lower surface 412 side of the plate 41, an atmosphere opening area 50 is formed in the area between the central suction part 44 and the outer peripheral suction part 45. As shown in FIG. 3 , the atmosphere open area 50 is an area surrounded by the lower surface 412 of the plate 41 , the outer peripheral surface of the annular portion 443 , and the inner peripheral surface of the arcuate annular portion 452 . The atmosphere open area 50 communicates with the atmosphere on the outer peripheral side of the plate member 41 through the gaps 51 between the arcuate annular portions 452 that are divided into four and provided in the circumferential direction.

In a state where the central suction part 44 and the outer peripheral suction part 45 are in contact with the wafer 90 ( FIGS. 6 to 8 ), the atmosphere open area 50 is connected to the central suction port 441 and the outer peripheral suction port 451 through the annular part. 443 and the arc annular portion 452 are separated. Therefore, when air is sucked from the central suction port 441 and the peripheral suction port 451 , the wafer 90 is only sucked at the central suction part 44 and the peripheral suction part 45 , and the suction force does not act in the atmosphere open area 50 . In addition, since the atmosphere open area 50 is connected to the atmosphere through the gap 51, even if the suction force from the central suction port 441 or the peripheral suction port 451 leaks slightly, the internal pressure of the atmosphere open area 50 will not change significantly. It is possible to maintain the state in which the attraction force does not act on the atmospheric open area 50.

The first conveying mechanism 15 is provided with a moving mechanism 60 that moves the conveying pad 40 . The movement of the transfer pad 40 by the moving mechanism 60 is a lifting movement in the Z-axis direction and a rotating movement centered on a vertical axis extending in the Z-axis direction. By the revolving operation of the moving mechanism 60, the transfer pad 40 can be moved to a position above the temporary workbench 12 and at an intersection position with the work chuck 14 (the work chuck 14 on the front side in the X-axis direction). ) above the position. In addition, by lifting and lowering the moving mechanism 60 , the transfer pad 40 can be moved closer to or further apart from the temporary table 12 and the work chuck 14 in the Z-axis direction.

The moving mechanism 60 is provided with the arm 61 which supports the conveyance pad 40. The arm 61 extends in the horizontal direction, and a ring portion 611 surrounding the cylindrical portion 42 of the transfer pad 40 is provided on the front end side of the arm 61 (see FIG. 2 ). The ring portion 611 is formed with three through holes 612 penetrating in the Z-axis direction (only two are shown in FIGS. 4 to 8 ). The three through holes 612 are provided at substantially equal intervals in the circumferential direction centered on the vertical axis passing through the center of the transfer pad 40 . The sliding shaft 43 penetrates each through hole 612 . The upper end of the sliding shaft 43 has a head 431 with a larger diameter, and the head 431 can contact the upper surface of the ring portion 611 .

A cylindrical coil spring 62 surrounding each sliding shaft 43 is arranged between the upper surface 411 of the plate 41 in the transfer pad 40 and the lower surface of the ring portion 611 in the arm 61 . Each coil spring 62 imparts potential energy downward to the conveying pad 40 with respect to the arm 61 and presses the head 431 of the sliding shaft 43 against the upper surface of the ring portion 611 . Thereby, the transfer pad 40 is maintained at a certain position in the Z-axis direction with respect to the arm 61 . In addition, when the transfer pad 40 receives a pressing force from below, the transfer pad 40 can be brought closer to the arm 61 (move upward) while contracting the coil spring 62 .

An arm support portion 63 extending in the Z-axis direction is connected to an end portion of the arm 61 opposite to the ring portion 611 . The arm support part 63 is moved up and down in the Z-axis direction by a lift drive part. As shown in FIGS. 5 to 8 , the lift drive unit includes a guide 64 , a ball screw 65 , a motor 66 , and an encoder 67 .

The guided portion 631 of the arm support portion 63 is supported movably in the Z-axis direction relative to the guide portion 64 extending in the Z-axis direction. The screw portion 632 of the arm support portion 63 is screwed to the ball screw 65 extending in the Z-axis direction. The ball screw 65 is rotated by the driving force of a motor 66 connected to one end of the ball screw 65 . When the ball screw 65 rotates and applies force to the screw portion 632 , the arm support portion 63 moves in the Z-axis direction along the guide portion 64 .

The driving direction and driving amount of the motor 66 are detected through the encoder 67 . The detection signal of the encoder 67 is input to the control unit 30 .

The transfer of the wafer 90 by the first transfer mechanism 15 equipped with the transfer pad 40 will be described with reference to FIGS. 5 to 8 . This transfer is performed until the wafer 90 placed on the temporary stage 12 is transferred to the work chuck 14 .

As shown in FIG. 5 , the wafer 90 is placed on the temporary workbench 12 with the front side 91 attached with the protective tape 95 facing downward and the back side 92 facing upward. The wafer 90 on which the modified layer 96 is formed has a curved shape in which the back surface 92 side has a central depression, the front surface 91 (protective tape 95) side has a central convex shape, and the outer peripheral portion is curved upward.

The transfer pad 40 is positioned above the temporary stage 12 on which the wafer 90 is placed. Then, the motor 66 of the moving mechanism 60 is driven to rotate the ball screw 65 to move the arm 61 and the arm support portion 63 downward. By this movement, the transfer pad 40 will descend and approach the back surface 92 of the wafer 90 placed on the temporary table 12 .

When the transfer pad 40 is lowered, the contact portion 442 and the annular portion 443 of the central suction portion 44 of the transfer pad 40 and the arcuate annular portion 452 of the outer peripheral suction portion 45 will contact the back surface 92 (upper surface) of the wafer 90 . From the time point when the contact portion 442 , the annular portion 443 , and the arc-shaped annular portion 452 are in contact with the back surface 92 of the wafer 90 , the arm 61 and the arm support portion 63 are further moved downward by the moving mechanism 60 . Thereby, as shown in FIG. 6 , the arm 61 will move downward along the sliding shaft 43 , so that the distance between the lower surface of the ring portion 611 and the upper surface 411 of the plate 41 becomes smaller, and the coil spring 62 contracts, and The wafer 90 is pressed on the temporary stage 12 by the transfer pad 40 .

The wafer 90 is pressed toward the temporary stage 12 by the contact portion 442, the annular portion 443, and the arcuate annular portion 452 of the transfer pad 40, thereby correcting the bend. However, since the area between the annular portion 443 and the arc-shaped annular portion 452 is the open atmosphere area 50 that does not contact the wafer 90, the central portion where the contact portion 442 and the annular portion 443 are in contact with the arc The wafer 90 is not pressed by the transfer pad 40 except for the outer peripheral portion where the annular portion 452 contacts. Thereby, no force is applied to forcibly flatten the entire wafer 90 , and the occurrence of breakage in the fragile wafer 90 can be suppressed.

In addition, since the annular portion 443 and the arcuate annular portion 452 are both made of elastically deformable rubber or other materials, the annular portion 443 and the arcuate annular portion 452 can be aligned with the back surface 92 of the wafer 90 It has air-tight sealing to prevent the central suction port 441 and the peripheral suction port 451 from being connected to the atmosphere or the atmosphere open area 50, and the central suction part 44 and the peripheral suction part 45 can reliably attract and hold the wafer 90 .

When the contact portion 442, the annular portion 443 and the arcuate annular portion 452 are pressed against the wafer 90 with appropriate pressure, the driving of the motor 66 is stopped. The movement amount of the transfer pad 40 and the arm 61 until the pressing of the wafer 90 is completed is managed by detecting and controlling the driving amount of the motor 66 based on the signal from the encoder 67 .

In a state where the contact portion 442, the annular portion 443, and the arcuate annular portion 452 of the transfer pad 40 are pressed against the wafer 90, the suction source 48 is actuated and the opening and closing valve 481 is opened. Thereby, air can be sucked from the central suction port 441 and the peripheral suction port 451 through the central suction path 46 and the peripheral suction path 47, and the wafer 90 can be sucked by the suction force acting on the central suction part 44 and the peripheral suction part 45. The back surface 92 is attracted and held on the transfer pad 40 . More specifically, the back surface 92 of the wafer 90 is brought into close contact with the lower surfaces of the contact portion 442 , the annular portion 443 and the arcuate annular portion 452 through the attraction force. Since the atmosphere open area 50 is separated from the central suction port 441 and the peripheral suction port 451 by the annular portion 443 and the arc annular portion 452, and is further connected to the atmosphere through the gap 51, it is open to the atmosphere. There is no attraction effect on wafer 90 in the area of zone 50 . In this way, only the central portion and the outer peripheral portion of the wafer 90 are attracted and held by the transfer pad 40 .

Next, as shown in FIG. 7 , the motor 66 of the moving mechanism 60 is driven to rotate the ball screw 65 to move the arm 61 and the arm support portion 63 upward. By this movement, the transfer pad 40 that has attracted and held the back surface 92 of the wafer 90 rises, and the wafer 90 is separated from the temporary stage 12 .

The wafer 90 held on the transfer pad 40 and separated from the temporary stage 12 can be separated from the central part sucked and held by the central suction part 44 and the outer peripheral part sucked and held by the outer peripheral suction part 45 . It is transported with the lower part sagging.

After the first transfer mechanism 15 moves the transfer pad 40 holding the wafer 90 by suction to the upper side of the temporary stage 12 , it further performs a rotating action in the moving mechanism 60 to position the transfer pad 40 to the work chuck 14 above. At this time, the work clamp table 14 is positioned at the transfer position, which is a position close to the first conveying mechanism 15 in the X-axis direction.

When the transfer pad 40 reaches the top of the work chuck 14, the motor 66 of the moving mechanism 60 is driven to rotate the ball screw 65, thereby moving the arm 61 and the arm support portion 63 downward. Then, as shown in FIG. 8 , the downward protective tape 95 side of the wafer 90 that has been sucked and held on the transfer pad 40 is placed on the holding surface 143 of the work chuck 14 .

When the wafer 90 is placed on the holding surface 143 of the work chuck 14 , the suction source 20 is activated and the switching valve 201 is opened. In this way, the air on the porous plate 142 side will be attracted through the flow path 144 so that the attractive force acts on the holding surface 143 and the wafer 90 is attracted and held on the holding surface 143 .

In this state, the opening and closing valve 481 is closed or the operation of the suction source 48 is stopped to release the suction force acting on the central suction part 44 and the outer peripheral suction part 45 of the transfer pad 40 . In this way, the transfer pad 40 no longer attracts and holds the wafer 90 .

Furthermore, the on-off valve 491 is opened and the air supply source 49 is activated. Thereby, air can be blown out from the central suction port 441 and the peripheral suction port 451 through the central suction path 46 and the outer peripheral suction path 47, thereby releasing the wafer 90 from the transfer pad 40.

As described above, the wafer 90 is transferred from the temporary stage 12 to the work chuck 14 by the first transfer mechanism 15 equipped with the transfer pad 40 .

The transfer pad 40 attracts and holds both the central portion and the outer peripheral portion of the wafer 90 through the central suction portion 44 and the outer peripheral suction portion 45 . Thereby, since the wafer 90 is transported without sagging the central part or the outer peripheral part, the wafer 90 can be transferred from the transfer pad 40 to the holding surface 143 of the work chuck 14 without hindrance.

In addition, the transfer pad 40 does not suck and hold the wafer 90 in the atmosphere open area 50 between the central suction part 44 and the outer peripheral suction part 45 . That is, since the curvature of the wafer 90 is not corrected in the area of the atmosphere open area 50 , the load applied to the wafer 90 in the state held by the transfer pad 40 can be reduced, thereby suppressing the deflection of the wafer 90 . The modified layer 96 is cut into pieces of the wafer 90 .

Assuming that the wafer 90 is cut in an area corresponding to the atmospheric open area 50 while being held by the transfer pad 40 , the debris generated by the cutting can still be prevented from adhering without the attraction force acting on the atmospheric open area 50 on the transfer pad 40. Therefore, debris generated by cutting the wafer 90 is less likely to remain attached to the transfer pad 40 , thereby reducing the risk of damage caused by the debris when the next wafer 90 is transferred. In other words, it is not necessary to perform frequent cleaning to remove debris in the transfer pad 40 .

Different from the transfer pad 40 of this embodiment, in the transfer pad configured to transport only the central part of the wafer 90 by attracting and holding it (for example, the above-mentioned Patent Document 1), the wafer 90 except the central part easily vibrates up and down. This makes it easier to cause breakage along the modified layer 96 in the wafer 90 . Furthermore, if the wafer 90 is cut in an area not held by the transfer pad, there is a concern that the outer peripheral portion of the wafer 90 will sag, and the wafer 90 will not be properly attracted and held on the chuck 14 .

In order to prevent the outer peripheral part of the wafer 90 from sagging, the following method may be considered: using a transfer pad that attracts and holds only the outer peripheral part of the wafer 90 for transportation. However, when such a transfer pad is used, there is a concern that the wafer 90 may be cut into a plurality of pieces along the modified layer 96 on the inside of the outer peripheral part due to the impact given to the outer peripheral part. As a result of this cutting, there is a possibility that the central portion of the wafer 90 may sag, and the adjacent wafers 94 on the wafer 90 may come into contact with each other, causing damage (defects, etc.) to the wafers 94 .

Furthermore, in order to prevent part of the wafer 90 from sagging, it is conceivable to use a transfer pad of a type that uses a suction surface to suction and hold the entire back surface 92 of the wafer 90 . However, when such a transfer pad is used, since the entire wafer 90 is suctioned and held while correcting the curved shape to a flat shape, it is easy to increase the load on the wafer 90 and cause the wafer 90 to move along the wafer 90 . There is a high risk that the modified layer 96 will be cut. In addition, debris generated during cutting will adhere to the suction surface of the transfer pad, and there is a concern that damage caused by the debris may occur when the next wafer 90 is suctioned and held. For example, debris attached to the suction surface of the transfer pad contacts the wafer 94 on the wafer 90 and causes defects in the corners of the wafer 94 .

Unlike such a transfer pad to be compared, the transfer pad 40 of this embodiment can prevent the central part and the outer peripheral part of the wafer 90 from sagging, and can transfer the wafer 90 to the work clamp in a stable state. Taiwan 14. In addition, the transfer pad 40 having the air open area 50 between the central part and the outer peripheral part can make it difficult to cause breakage along the modified layer 96 when the wafer 90 is transferred, and even if it is assumed that the wafer 90 occurs It is also difficult for debris generated by cutting to adhere to the transfer pad 40 during dicing, thereby preventing manufacturing defects of the wafer 94 caused by debris.

The outer peripheral suction portion 45 of the transfer pad 40 prevents the outer peripheral portion of the wafer 90 from sagging by suction during transportation, and is an arc-shaped annular portion 452 that protrudes downward when the wafer 90 is placed on the work chuck 14 to press the outer peripheral portion of the wafer 90 toward the work chuck 14 . Thereby, the wafer 90 having warpage as shown in FIG. 5 can be reliably attracted and held on the work chuck 14 .

The central suction part 44 of the transfer pad 40 has a contact part 442 around the central suction port 441. When the wafer 90 is suctioned, the lower surface of the contact part 442 contacts the back surface 92 (upper surface) of the wafer 90. The contact portion 442 can suppress the deformation of the wafer 90 in the area where the suction force from the central suction port 441 acts, thereby improving the stability of the central portion of the wafer 90 . Specifically, if the central portion of the wafer 90 that receives the suction force from the central suction port 441 is recessed toward the central suction port 441 side inside the annular portion 443 , the wafer 90 may be easily damaged due to local deformation. Cutting occurs, but such local deformation of the wafer 90 can be prevented by contacting the contact portion 442 provided inside the annular portion 443 with the back surface 92 of the wafer 90 . In addition, like the contact portion 442 , the annular portion 443 also has a function of preventing local deformation of the central portion of the wafer 90 .

The entire annular portion 443 in the circumferential direction is in contact with the back surface 92 of the wafer 90 . In this way, the annular portion 443 is configured to extend entirely in the circumferential direction outside the central suction port 441 , so that the suction force from the central suction port 441 does not reach the atmospheric open area 50 . The contact portion 442 is formed to partially contact the back surface 92 of the wafer 90 in the circumferential direction. For example, the contact portion 442 may have a lower height in the Z-axis direction in a part of the circumferential direction. The contact portion 442 only needs to serve as a support to suppress the deformation when the center portion of the wafer 90 is about to deform toward the center suction port 441. Therefore, a sufficient effect can be obtained by partial contact.

Furthermore, in this embodiment, the double-layered cylindrical contact portion 442 is provided around the central suction port 441, but the number or shape of the contact portion 442 is not limited thereto. Furthermore, in this embodiment, although the contact portion 442 partially contacts the back surface 92 of the wafer 90 in the circumferential direction, the contact portion 442 may be entirely in circumferential contact with the back surface 92 of the wafer 90 .

In the above, although the conveyance pad 40 mounted on the 1st conveyance mechanism 15 was demonstrated, the same effect can be obtained also with respect to the conveyance pad 40 mounted on the 2nd conveyance mechanism 16. In the second transfer mechanism 16 , the transfer pad 40 receives the wafer 90 from the chuck 14 , and the transfer pad 40 transfers the wafer 90 to the rotary table 131 . The transport pad 40 in the first transport mechanism 15 described in FIG. 8 operates in substantially the same manner. Therefore, detailed description of the operation of the conveyance pad 40 in the second conveyance mechanism 16 is omitted.

In the second transport mechanism 16 , since the wafer 90 whose back surface 92 side has been thinned by grinding in the grinding mechanism 24 is transported out of the work chuck 14 , it becomes easier to produce the wafer 90 . The conveying pad 40 of this embodiment is conveyed in a cut state, making the conveying pad 40 of this embodiment highly useful.

Furthermore, in the present invention, the method of transporting the wafer to the work chuck includes loading the wafer into the work chuck (the function of the first transport mechanism 15) and unloading the wafer from the work chuck (the second function). The concept of both sides of the function of the transport mechanism 16).

The transfer pad 70 shown in FIGS. 9 and 10 is a transfer pad to which the second embodiment of the present invention is applied. In the transfer pad 70 , components that are common to the transfer pad 40 of the first embodiment described above are denoted by the same reference numerals as those of the transfer pad 40 , and description thereof is omitted.

As shown in FIG. 10 , an annular outer peripheral suction portion 71 for sucking and holding the outer peripheral portion of the wafer 90 is disposed on the outer peripheral portion (outer edge) of the lower surface 412 of the plate 41 . The outer peripheral suction portion 71 is configured in a complete ring shape that is continuous without interruption in the circumferential direction of the plate 41 .

More specifically, the outer peripheral suction part 71 has an outer peripheral suction port 711 that opens downward, and an annular protrusion 712 protruding from the lower surface 412 of the plate 41 and extending annularly in the circumferential direction. The annular protrusion 712 surrounds the inner peripheral side and the outer peripheral side of the outer peripheral suction port 711 . The outer peripheral suction port 711 communicates with the outer peripheral suction path in the plate 41 (the same suction path as the outer peripheral suction path 47 of the transfer pad 40). The annular protrusion 712 is formed of a material such as rubber that is elastically deformable and blocks the passage of air.

The area between the central suction part 44 and the outer peripheral suction part 71 on the lower surface 412 side of the plate 41 is the atmosphere open area 72 . Since the annular protruding portion 712 of the outer peripheral suction portion 71 is continuous without interruption in the circumferential direction, the conveying mat 70 is provided with an atmosphere opening hole 73 penetrating the plate member 41 in the thickness direction as an atmosphere opening area. 72 is connected to the composition of the atmosphere. As shown in FIGS. 9 and 10 , the atmosphere opening hole 73 is opened on the upper surface 411 and the lower surface 412 of the plate 41 , so that the atmosphere opening area 72 formed on the lower surface 412 side is connected to the upper surface 411 side of the plate 41 The atmosphere is connected.

In a state where the back surface 92 of the wafer 90 is sucked and held by the central suction part 44 and the outer peripheral suction part 71 , the atmosphere open area 72 is formed by the annular part 443 and the annular suction port 711 with respect to the central suction port 441 and the outer peripheral suction port 711 . The protrusions 712 are separated. Therefore, when the wafer 90 is sucked and held by the transfer pad 70 , the wafer 90 is sucked only by the central part having the central suction part 44 and the outer peripheral part having the outer peripheral suction part 71 , and the atmospheric open area 72 in between does not attract the suction force. effect.

In addition, since the atmosphere open area 72 is communicated with the atmosphere through the atmosphere opening hole 73, even if the suction force from the central suction port 441 or the peripheral suction port 711 leaks slightly, the internal pressure of the atmosphere open area 72 will not change significantly. Therefore, the state in which the attractive force does not act on the atmospheric open area 72 can be maintained.

The transfer pad of the present invention is suitable for transporting wafers in the grinding apparatus of the above embodiment, but it can also be applied to transporting wafers in processing apparatuses other than the grinding apparatus, or between different processing apparatuses. wafer transportation.

Furthermore, the embodiments of the present invention are not limited to the above-described embodiments or modifications, and various changes, substitutions, and modifications may be made within the scope that does not deviate from the gist of the technical idea of the present invention. In addition, if the technical idea of the present invention can be realized in other ways through technological advancement or other derived technologies, this method can also be used to implement it. Therefore, the scope of the patent application covers all implementation aspects that can be included in the scope of the technical idea of the present invention. industrial availability

As described above, the transfer pad of the present invention has the effect of stably transferring fragile wafers, and is particularly useful in a grinding device that performs grinding processing on fragile wafers.

1:Grinding device 10:Abutment 11:Manipulator 12: Temporary workbench 13: Rotating cleaning mechanism 14,81:Work clamp table 15: The first transport mechanism 16: The second transport mechanism 17:Mobile board 18: Waterproof cover 20,48: source of attraction 21,49:Air supply source 22:Water supply source 23:Pillar 24:Grinding mechanism 25:Lifting mechanism 30:Control Department 40,70:Transfer pad 41:Plate 42:Tubular part 43:Sliding shaft 44: Central Attraction Department 45,71: Peripheral suction department 46:Central Attraction Road 47: Peripheral suction road 50,72: Atmospheric open area 51: Gap 60:Mobile mechanism 61: arm 62:coil spring 63:Arm support part 64: Guidance Department 65,253: Ball screw 66,254: Motor 67:Encoder 73: Atmospheric opening hole 80:Laser processing device 82:Laser irradiation department 83: Concentrator 90:wafer 91:front 92: Backside (upper surface of wafer) 93: Split scheduled line 94:wafer 95:Protective tape 96: Modified layer 111:Arm 112:Hand 131: Rotary table 132:Nozzle 141:frame 142:Porous plate 143:Keep the surface 144:Flow path 201,211,221,481,491: On-off valve 241: Shell 242: Spindle unit 243:Grinder wheel 244:Spindle axis 245:Mounting seat 246:Grinding stone 251: Guide rail 252: Lifting workbench 411: Upper surface (upper surface of the plate) 412: Lower surface (lower surface of plate) 421: Attraction Road 431:Head 441: Central suction port 442:Contact Department 443: Annular part 451,711: Peripheral suction port 452:Arc ring part 611: Ring Department 612:Through hole 631: guided part 632:Screw joint 712: Annular protrusion C: film cassette L:Laser beam M: Processing feed direction P: focus point X,Y,Z: direction

Fig. 1 is a perspective view showing the grinding device. FIG. 2 is a perspective view of the transfer pad according to the first embodiment as viewed from above. FIG. 3 is a perspective view of the transfer pad according to the first embodiment as viewed from the lower side. Fig. 4 is a cross-sectional view of the transfer pad according to the first embodiment. FIG. 5 is a cross-sectional view showing a state where the wafer has been placed on the temporary stage. FIG. 6 is a cross-sectional view showing a state where the transfer pad has pressed the wafer on the temporary table. 7 is a cross-sectional view showing a state in which a wafer sucked and held on a transfer pad is being transferred. 8 is a cross-sectional view showing a state in which a wafer is transferred from a transfer pad to a work chuck. FIG. 9 is a perspective view of the transfer pad according to the second embodiment as viewed from above. FIG. 10 is a perspective view of the transfer pad according to the second embodiment as viewed from the lower side. FIG. 11 is a cross-sectional view showing the steps of forming a modified layer on a wafer. FIG. 12 is a cross-sectional view showing a state in which a modified layer is formed on a wafer. FIG. 13 is a perspective view of a wafer with a modified layer formed thereon.

40:Transfer pad

41:Plate

44: Central Attraction Department

45: Peripheral suction department

50: Atmospheric open area

51: Gap

412: Lower surface (lower surface of plate)

441: Central suction port

442:Contact Department

443: Annular part

451: Peripheral suction port

452:Arc ring part

Claims (3)

A transfer pad that attracts and holds the upper surface of a fragile wafer and transfers it to a work chuck. The transfer pad has: The central suction part attracts and holds the central part of the wafer; The annular peripheral suction part attracts and holds the peripheral part of the wafer; A plate for arranging the central suction part and the peripheral suction part; and The atmosphere opening area is for opening the upper surface of the wafer to the atmosphere that is not attracted by the central suction part and the peripheral suction part. For example, the transfer pad of claim 1, wherein the peripheral suction part has: Arc annular parts protrude downward from the lower surface of the plate and extend in the circumferential direction in an arc ring shape, and a plurality of them are arranged in the circumferential direction; A peripheral suction port opens on the lower surface of the plate on the inside of the arcuate annular portion and can be connected to the suction source; and The peripheral suction path connects the peripheral suction port to the suction source. The transfer pad of Claim 1, wherein the central suction part has a contact part, and when the wafer is suctioned, the contact part is in contact with the upper surface of the wafer to prevent the wafer from deforming in the suctioned area.

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