JP2018018923A - Processing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent a metal post from being dragged, by suppressing excessive wear of an abrasive grindstone while preventing processing cost from being increased when exposing an end face of the metal post from an encapsulation layer.SOLUTION: The present invention relates to a processing method including: a holding step of holding an encapsulation wafer W with a chuck table 2 in a state where an encapsulation layer W2 is exposed; a rough grinding step of grinding and thinning the encapsulation layer W2 into thickness that does not reach an end face of a metal post P, while using a rough grinding wheel 44 comprising a rough abrasive grindstone 440; and a finish grinding step of exposing the end face of the metal post P by grinding the encapsulation layer W2 while using a finish abrasive grindstone 340 containing abrasive grains of a small grain size. In the rough grinding step, the rough grinding of the encapsulation layer W2 is implemented while supplying pure water to a processing point where the encapsulation layer W2 is brought into contact with the rough abrasive grindstone 440. In the finish grinding step, the finish grinding of the encapsulation layer W2 is implemented while supplying a process liquid containing an abrasive material to a processing point where the encapsulation layer W2 is brought into contact with the finish abrasive grindstone 340.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a processing method for grinding a sealed wafer on which a sealing layer is formed.

  In recent years, in a semiconductor manufacturing process, as a technique for further integrating and downsizing devices and the like, for example, a package technique called WLCSP (Wafer Level Chip Size Package) and a through electrode (metal post) called TSV (Through Silicon Via) A three-dimensional mounting technique or the like for connecting a plurality of device chips stacked on a substrate using the above is used. In WLCSP, after forming a redistribution layer and a metal post connected to the electrode in the device via the redistribution layer on the surface of the wafer, the metal post on the device side and the device are sealed with resin to form a sealing layer To do. On the other hand, the TSV wafer is configured by resin-sealing a plurality of device chips stacked on a substrate, and the plurality of device chips are connected by through electrodes.

  In WLCSP, a metal post is exposed on the surface of the sealing layer, and then external terminals called electrode bumps are formed on the end face of the metal post. Thereafter, the wafer is cut with a cutting blade or the like and divided into individual chips. As a method for exposing the metal post to the surface of the sealing layer, for example, there is a method in which the sealing layer is roughly ground with a grinding wheel and then finished with a cutting tool (for example, see Patent Document 1).

  In the TSV wafer manufacturing process, it is necessary to ensure that the through electrodes are in contact with the surfaces of the device chips that are in contact with each other so that poor contact of the through electrodes does not occur. It is important to form a flat surface. Therefore, after curing the sealing resin that seals the device chip mounted on the substrate and before dividing the substrate, the sealing layer is thinned by grinding using, for example, a grinding device The surfaces where the device chips contact each other are formed in a uniform plane (see, for example, Patent Document 2).

JP 2013-008898 A JP 2011-040511 A

  Therefore, in the TSV wafer manufacturing process and WLCSP, the resin sealing layer in which the metal post is embedded is ground. However, for example, the processing method described in Patent Document 1 requires two types of processing devices, that is, a grinding device and a bite turning device, which increases the processing cost.

  On the other hand, when the sealing layer is ground only with a grinding wheel to expose the metal post, there are the following problems. For example, when forming a sealing layer, a filler (fine particles) for adjusting physical properties such as a coefficient of thermal expansion may be mixed, and damage of the package at the time of heating caused by a difference in coefficient of thermal expansion due to the filler. Is preventing. And the hardness of a filler is usually higher than the hardness of the hardened resin used as the base of a sealing layer. For this reason, for example, when grinding the sealing layer with a grinding wheel, the grinding wheel is more consumed by contacting the filler with the grinding wheel of the grinding wheel than when grinding a silicon wafer or the like.

  It is also possible to suppress the grinding wheel consumption of the grinding wheel by grinding using a grinding wheel containing abrasive grains having a relatively large abrasive grain size. However, when the sealing layer is ground until the end face of the metal post is exposed with a grinding wheel containing relatively large abrasive grains, the metal post is often dragged by the grinding wheel due to the ductility of the metal post and the processing heat of the processing point. To do. And there exists a problem that the metal post dragged with the grinding stone will contact with the adjacent metal post, and will short-circuit.

  Therefore, in the case where a plurality of metal posts are formed on the wafer and a sealing wafer containing a filler and having a sealing layer covering the metal posts is ground to expose the end faces of the metal posts, the device configuration There is a problem that an increase in processing cost due to the above is suppressed, excessive wear of the grinding wheel is suppressed, and occurrence of dragging of the metal post is suppressed.

  In order to solve the above problems, the present invention provides a metal post formed by grinding a sealing wafer in which a plurality of metal posts are formed on a wafer and a filler is contained and a sealing layer covering the metal posts is formed. And a rough grinding wheel including a rough grinding wheel after the holding step, and a holding step for holding the sealing wafer with the sealing layer exposed by a chuck table. A rough grinding step for grinding and thinning the sealing layer of the sealing wafer held by the chuck table to a thickness that does not reach the end face of the metal post, and after performing the rough grinding step, a rough grinding wheel The sealing layer of the sealing wafer held by the chuck table is ground by a finish grinding wheel including a finish grinding wheel containing abrasive grains having a particle size smaller than that of the abrasive grains. A finish grinding step for exposing an end face of the metal post, and in the rough grinding step, the grinding of the sealing layer is performed while supplying pure water to a processing point where the sealing layer and the rough grinding wheel are in contact with each other. In the finish grinding step, the finish grinding of the sealing layer is performed while supplying a working fluid containing an abrasive to a working point where the sealing layer and the finish grinding grindstone are in contact with each other. .

  In the finish grinding step, it is preferable to perform finish grinding of the sealing layer while supplying the grinding waste liquid generated in the rough grinding step as the working liquid.

  The processing method according to the present invention includes a holding step for holding a sealed wafer with a sealing layer exposed by a chuck table, and holding the chuck wafer by a rough grinding wheel equipped with a rough grinding wheel after performing the holding step. After performing the rough grinding step and the rough grinding step, the grain size of the sealing layer of the sealed wafer is smaller than the grain size of the coarse grinding wheel. A finish grinding step of grinding a sealing layer of a sealing wafer held by a chuck table by a finish grinding wheel including a finish grinding wheel containing abrasive grains to expose an end face of a metal post, and in a rough grinding step The sealing layer is coarsely ground while supplying pure water to the processing point where the sealing layer and the rough grinding wheel are in contact with each other. By applying the finishing fluid to the sealing layer while supplying the processing fluid containing the abrasive to the processing point that comes into contact with the surface, excessive wear of the finish grinding wheel is suppressed and the occurrence of dragging of the metal post is suppressed. Meanwhile, the end face of the metal post can be exposed from the sealing layer. Moreover, in this processing method, since it is not necessary to use a tool turning device, an increase in processing cost caused by the device configuration can be suppressed.

  Also, in the finish grinding step, by performing the finish grinding of the sealing layer while supplying the grinding waste liquid generated in the rough grinding step as the processing liquid, the processing cost can be reduced by using the grinding waste liquid as the processing liquid, Clean processing that is easier to the environment can be implemented.

It is a perspective view showing an example of a grinding device provided with rough grinding means and finish grinding means. It is sectional drawing which shows the state which hold | maintained the sealing wafer in the state which exposed the sealing layer with the chuck table. While supplying pure water to the processing point where the sealing layer of the sealing wafer contacts with the rough grinding wheel, the sealing layer is ground and thinned to a thickness that does not reach the upper end surface of the metal post by a rough grinding wheel. It is sectional drawing which shows a state. It is sectional drawing which shows the state by which the sealing layer of the sealing wafer was ground and thinned to the thickness which does not reach the upper end surface of a metal post. Grinding the sealing layer of the sealing wafer held on the chuck table by the finishing grinding wheel while grinding the sealing layer held on the chuck table by supplying the processing fluid containing the abrasive to the processing point where the sealing layer and the finishing grinding wheel contact. It is sectional drawing which shows the state which exposes an end surface. It is sectional drawing which shows the sealing wafer of the state in which finish grinding was given and the upper end surface of the metal post was exposed.

  A grinding apparatus 1 shown in FIG. 1 holds a plurality of (three in the illustrated example) chuck tables 2 that can hold and rotate the sealing wafer W, and the sealing wafers W held on the chuck table 2. Rough grinding means 4 for performing rough grinding, finish grinding means 3 for finish grinding the sealing wafer W coarsely ground by the rough grinding means 4, and first grinding feed means for grinding and feeding the rough grinding means 4 in the vertical direction 6 and a second grinding feed means 5 for grinding and feeding the finish grinding means 3 in the vertical direction.

  The sealing wafer W shown in FIGS. 1 and 2 includes, for example, a silicon wafer W1 made of silicon and having an outer diameter of a disc shape. The silicon wafer W1 shown in FIG. 2 is thinned to a predetermined thickness by, for example, grinding the back surface W1b in advance, and the surface W1a of the silicon wafer W1 is formed by a plurality of division lines S that are formed in a lattice shape. A device D such as an LSI is formed in each partitioned area. A rewiring layer (not shown) is formed on the surface W1a, and a plurality of metal posts P that are electrically connected to the electrodes of the device D are formed on the rewiring (not shown). The height position of the upper end surface of each metal post P is substantially the same. On the surface W1a of the silicon wafer W1, a sealing layer W2 made of a cured resin or the like is formed so as to cover each metal post P. The sealing layer W2 includes an inorganic filler F such as SiC that plays a role such as increasing the strength of the sealing layer W2. Note that the sealing wafer W may be a TSV wafer or the like.

  The front (on the −Y direction side) on the base 1A of the grinding apparatus 1 shown in FIG. 1 is an attachment / detachment region where the sealing wafer W is attached to and detached from the chuck table 2 by the robot 73. The rear side (+ Y direction side) on 1A is a grinding region, which is a region where the sealing wafer W held on the chuck table 2 is ground by the rough grinding means 4 or the finish grinding means 3.

  On the front side of the base 1 </ b> A, a first cassette 71 for storing the unsealed sealing wafer W and a second cassette 72 for storing the ground sealing wafer W are provided. In the vicinity of the first cassette 71 and the second cassette 72, the unsealed sealing wafer W is carried out from the first cassette 71 and the ground sealing wafer W is carried into the second cassette 72. A robot 73 having a function is provided.

  The robot 73 has a configuration in which a holding unit 731 that holds the sealing wafer W is provided at the tip of a bendable arm unit 730. The holding wafer 731 has a movable area where the sealing wafer W before processing is placed. Positioning means 74 for positioning at a predetermined position and cleaning means 75 for cleaning the ground sealing wafer W are provided. The cleaning means 75 is, for example, a single-wafer type spinner cleaning apparatus, and includes a holding table 750 that holds the ground sealed wafer W by suction.

  A first transport unit 11 a is disposed in the vicinity of the alignment unit 74, and a second transport unit 11 b is disposed in the vicinity of the cleaning unit 75. The first transport unit 11a has a function of transporting the unsealed sealed wafer W placed on the positioning unit 74 to one of the chuck tables 2, and the second transport unit 11b It has a function of transporting the ground sealing wafer W held on the chuck table 2 to the cleaning means 75.

  A column 1B is erected on the rear side (+ Y direction side) on the base 1A, and the first grinding feed means 6 and the second grinding feed means 5 are provided on the side surface of the column 1B on the −Y direction side. Are arranged side by side.

  On the base 1A, a concave portion having a rectangular shape in a plan view surrounded by the wall portion 130 standing on the base 1A and the column 1B is formed, and the turntable 12 is disposed in the concave portion. . The concave portion serves as a grinding water storage portion 13 that receives used grinding water flowing down from the chuck table 2 and the turntable 12. On the upper surface of the turntable 12, for example, three chuck tables 2 are arranged at equal intervals in the circumferential direction. A rotation shaft (not shown) for rotating the turntable 12 is disposed at the center of the turntable 12, and the turntable 12 can be rotated about the rotation shaft. The plurality of chuck tables 2 are supported by the turntable 12 so as to be able to rotate and revolve, and by rotation of the turntable 12, any one of the chuck tables 2 is in the vicinity of the first transfer means 11a and the second transfer means 11b. It is configured to be positioned.

  The chuck table 2 that holds the sealing wafer W has, for example, a circular outer shape, and includes a suction portion 29 that sucks the sealing wafer W made of a porous member and the like, and a frame body 28 that supports the suction portion 29. Prepare. The suction unit 29 communicates with the suction source 27, and the suction force generated by the suction of the suction source 27 is transmitted to the holding surface 29a that is the exposed surface of the suction unit 29, so that the chuck table 2 holds the holding 29a. The sealing wafer W is sucked and held above.

  The first grinding feed means 6 includes a ball screw 60 having a vertical axis, a pair of guide rails 61 arranged in parallel to the ball screw 60, and a motor 62 connected to the ball screw 60 and rotating the ball screw 60. The inner nut is screwed into the ball screw 60 and the side portion is slidably in contact with the guide rail 61. The elevating portion 63 is guided by the guide rail 61 as the motor 62 rotates the ball screw 60. It is configured to move up and down. The elevating part 63 supports the coarse grinding means 4, and the coarse grinding means 4 is also raised and lowered by raising and lowering the elevating part 63.

  The second grinding feed means 5 includes a ball screw 50 having a vertical axis, a pair of guide rails 51 arranged in parallel to the ball screw 50, and a motor 52 connected to the ball screw 50 and rotating the ball screw 50. The inner nut is screwed into the ball screw 50 and the side portion is composed of an elevating portion 53 slidably contacting the guide rail 51, and the elevating portion 53 is guided by the guide rail 51 as the motor 52 rotates the ball screw 50. It is configured to move up and down. The elevating part 53 supports the finish grinding means 3, and the finish grinding means 3 is also raised and lowered by raising and lowering the elevating part 53.

  The rough grinding means 4 includes a spindle 40 having a vertical axis, a housing 41 that rotatably supports the spindle 40, a motor 42 that rotationally drives the spindle 40, and a circular shape connected to the lower end of the spindle 40. A mount 43 and a rough grinding wheel 44 detachably connected to the lower surface of the mount 43 are provided. The rough grinding wheel 44 includes an annular wheel base 441 and a plurality of rough grinding wheels 440 having a substantially rectangular parallelepiped shape arranged annularly on the bottom surface of the wheel base 441. The rough grinding wheel 440 is formed by fixing diamond abrasive grains or the like with a resin bond or a metal bond, for example. In addition, the shape of the rough grinding wheel 440 may be integrally formed in an annular shape. The rough grinding wheel 440 is a grindstone used for rough grinding, and the particle size of the abrasive grains contained in the grindstone is relatively large, for example, than the particle size of the filler F contained in the sealing layer W2 shown in FIG. Is also big.

  The spindle 40 is formed, for example, in a hollow shape, and a flow path 40 a for circulating grinding water is formed in the shaft center of the spindle 40. A grinding water supply means 80 for supplying pure water as the grinding water to the rough grinding means 4 is connected to the upper end side of the flow path 40a via a pipe 400a. The grinding water supply means 80 includes a pure water source 800 in which pure water is stored, and a pure water feed unit 801 including a pump or the like that causes the pure water stored in the pure water source 800 to flow into the pipe 400a. The lower end side of the flow path 40 a passes through the mount 43 and opens downward in the rough grinding wheel 44.

  The pure water supplied from the grinding water supply means 80 to the rough grinding means 4 passes through the flow path 40a in the spindle 40 and is discharged downward from the rough grinding wheel 44, and the rough grinding wheel 440, the sealing wafer W, Reaches the processing point where it contacts, and cools and cleans the processing point.

  As shown in FIG. 1, the grinding water storage portion 13 that stores the used grinding water does not mix the grinding water used in the rough grinding means 4 and the grinding water used in the finish grinding means 3. The boundary part 14 for standing up is erected. And the grinding water accommodating part 13 is divided by the boundary part 14 into the 1st accommodation area | region 13a and the 2nd accommodation area | region 13b. In addition, for example, a partition portion is provided on the turntable 12 that extends radially outward from the rotation center of the turntable 12 to partition each chuck table 2, so that the grinding water derived from rough grinding and the grinding water derived from finish grinding are provided. And may not be mixed.

  A drainage port 15 for discharging the grinding water (coarse grinding waste liquid) used in the coarse grinding means 4 to the outside is disposed in the first storage region 13a, and the drainage port 15 is connected via the drainage pipe 15a. It communicates with a rough grinding waste liquid recovery tank 820 for storing the rough grinding waste liquid drained from the drain port 15. The rough grinding waste liquid recovery tank 820 is a part of the processing liquid supply means 82 that supplies the rough grinding waste liquid as the processing liquid to the finish grinding means 3. The processing liquid supply means 82 includes a filter 821 formed of a mesh material or the like. And a machining fluid feed unit 822 for pumping the machining fluid from the rough grinding waste fluid recovery tank 820. The machining fluid feed unit 822 communicates with an upper end side of a flow path 30a of the spindle 30 described later via a pipe 300a. The filter 821 may be disposed in the drain pipe 15a.

  The finish grinding means 3 includes a spindle 30 having a vertical axis, a housing 31 that rotatably supports the spindle 30, a motor 32 that rotationally drives the spindle 30, and a circular shape connected to the lower end of the spindle 30. A mount 33 and a finish grinding wheel 34 detachably connected to the lower surface of the mount 33 are provided. The finish grinding wheel 34 includes a wheel base 341 and a plurality of finish grinding wheels 340 having a substantially rectangular parallelepiped shape arranged annularly on the bottom surface of the wheel base 341. The finish grinding wheel 340 is formed by fixing diamond abrasive grains or the like with, for example, a resin bond or a metal bond. In addition, the shape of the finish grinding wheel 340 may be integrally formed in an annular shape. The finish grinding wheel 340 is a grindstone used for finish grinding, and the abrasive grains contained in the grindstone are abrasive grains having a smaller particle diameter than the abrasive grains contained in the rough grinding grindstone 440.

  The spindle 30 is formed, for example, in a hollow shape, and a flow path 30 a through which the machining fluid is circulated is formed at the center of the spindle 30, and the lower end side of the flow path 30 a passes through the mount 33 and is a finish grinding wheel. 34 is opened downward.

  The machining liquid supplied from the machining liquid supply means 82 to the finish grinding means 3 passes through the flow path 30a in the spindle 30 and is discharged downward from the finish grinding wheel 34, and the finish grinding wheel 340, the sealing wafer W, Reaches the processing point where it contacts, and cools and cleans the processing point. The machining fluid used in the finish grinding means 3 is discharged to the outside from the drain port 16 formed in the second accommodation region 13b.

  Below, each step of a processing method and operation | movement of the grinding device 1 in the case of implementing the processing method which concerns on this invention using the grinding device 1 shown in FIG. 1 are demonstrated.

(1) Holding Step First, when the turntable 12 shown in FIG. 1 rotates, the chuck table 2 in a state where the sealing wafer W is not placed is revolved, and the chuck table 2 is the first transfer means 11a. Move to the vicinity. The robot 73 pulls out one sealing wafer W from the first cassette 71, moves the sealing wafer W to the alignment means 74, and places it with the sealing layer W2 facing upward. Next, after the sealing wafer W is positioned at a predetermined position in the alignment unit 74, the first transfer unit 11 a moves the sealing wafer W on the alignment unit 74 onto the chuck table 2. Then, as shown in FIG. 2, the sealing wafer W is placed on the holding surface 29a with the back surface W1b side down so that the center of the chuck table 2 and the center of the sealing wafer W substantially coincide with each other. . Then, the suction force generated by the suction source 27 is transmitted to the holding surface 29a, whereby the chuck table 2 sucks and holds the sealing wafer W with the sealing layer W2 exposed upward.

(2) Rough grinding step For example, when the turntable 12 shown in FIG. 1 rotates in the clockwise direction when viewed from the + Z-axis direction, the chuck table 2 holding the sealing wafer W revolves and the sealing wafer W It moves below the rough grinding means 4 to align the rough grinding wheel 44 provided in the rough grinding means 4 with the sealing wafer W held on the chuck table 2. For example, as shown in FIG. 3, the rotation center of the coarse grinding wheel 44 is shifted in the + Y direction by a predetermined distance with respect to the rotation center of the chuck table 2, and the rotation trajectory of the coarse grinding wheel 440 is aligned with the chuck table 2. This is done through the center of rotation.

  After the alignment of the rough grinding wheel 44 and the sealing wafer W is performed, as the spindle 40 is driven to rotate, the rough grinding wheel 44 rotates, for example, counterclockwise when viewed from the + Z direction side. Further, the coarse grinding means 4 is fed in the −Z direction by the first grinding feed means 6, and the coarse grinding wheel 440 of the rotating coarse grinding wheel 44 comes into contact with the sealing layer W <b> 2 of the sealing wafer W to make rough. Grinding is performed. During rough grinding, as the chuck table 2 rotates counterclockwise as viewed from the + Z direction side, the sealing wafer W held on the holding surface 29a also rotates, so that the rough grinding wheel 440 is sealed. The entire surface of the sealing layer W2 is roughly ground together with the filler F in the stop layer W2. Further, the grinding water supply means 80 supplies pure water to the processing point which is a contact portion between the rough grinding wheel 440 and the sealing layer W2 of the wafer W through the flow path 40a in the spindle 40, and the rough grinding wheel 440 A processing point with the sealing layer W2 is cooled and washed. A separate nozzle for allowing pure water to flow is disposed on the side of the chuck table 2, and pure water is introduced into the nozzle from the grinding water supply means 80, so that the machining point is externally applied to the machining point. Pure water may be supplied.

  The rotating rough grinding wheel 44 moves in the -Z direction at a predetermined grinding feed rate until the bottom surface of the rough grinding wheel 440 reaches the position Z1 shown in FIG. 3 where the bottom surface of the metal post P is slightly above the + Z direction. By being sent, the sealing layer W2 is ground to a thickness where the upper surface of the sealing layer W2 of the sealing wafer W does not reach the upper end surface of the metal post P as shown in FIG.

  The pure water supplied from the grinding water supply means 80 shown in FIG. 1 to the processing points of the rough grinding wheel 440 and the sealing layer W2 of the wafer W cools the processing points and removes grinding dust generated at the processing points. Then, it becomes grinding waste liquid and flows down from the chuck table 2 and the turntable 12 to the first accommodation area 13 a together with the grinding waste, and is drained from the drain port 15. The grinding scrap generated at the processing point includes abrasive grains shed from the coarse grinding wheel 440 and filler F derived from the sealing layer W2. Grinding waste liquid drained from the drain port 15 including the abrasive grains and filler F that have been shed from the coarse grinding wheel 440 passes through the drain pipe 15a, and the inside of the rough grinding waste liquid recovery tank 820 is used as a processing liquid used in the finishing grinding step described later. It is stored in.

(3) Finish grinding step After the sealing layer W2 is ground to a thickness where the upper surface of the sealing layer W2 of the sealing wafer W does not reach the upper end surface of the metal post P, the rough grinding means 4 moves upward and seals. Separated from the wafer W. Next, when the turntable 12 shown in FIG. 1 rotates in the clockwise direction as viewed from the + Z direction, the chuck table 2 holding the sealing wafer W after the rough grinding revolves, and the chuck table 2 becomes the finish grinding means 3. Move down below. After the positioning of the finish grinding wheel 34 and the sealing wafer W is performed, the finish grinding means 3 is sent in the -Z direction by the second grinding feed means 5, and the finish grinding rotates as shown in FIG. The grinding wheel 340 comes into contact with the sealing layer W <b> 2 of the sealing wafer W to perform finish grinding. During finish grinding, as the chuck table 2 rotates counterclockwise as viewed from the + Z direction side, the sealing wafer W held on the holding surface 29a also rotates, so that the finish grinding wheel 340 is sealed. The finish cutting of the entire surface of the sealing layer W2 is performed together with the filler F in the stop layer W2.

  During the finish grinding, the working fluid supply means 82 shown in FIG. 1 supplies the working fluid stored in the rough grinding waste liquid recovery tank 820 to the finish grinding means 3. That is, the machining fluid feed unit 822 pumps up the machining fluid from the rough grinding waste fluid recovery tank 820 into the machining fluid feed unit 822, and causes the pumped machining fluid to flow into the pipe 300a. The machining fluid passes through the filter 821 when moving from the rough grinding waste fluid recovery tank 820 to the machining fluid feed unit 822. The mesh size of the filter 821 is set such that, for example, the abrasive grains of the coarse grinding wheel 440 are not allowed to pass therethrough, and the filler F included in the sealing layer W2 of the sealing wafer W illustrated in FIG. Therefore, the processing liquid supplied from the processing liquid supply means 82 to the finish grinding means 3 does not include abrasive grains of the coarse grinding wheel 440 or grinding waste derived from the resin of the sealing layer W2, and a filler derived from the sealing layer W2. F is included.

  The processing liquid passes through the pipe 300a and the flow path 30a, and is ejected downward in the grinding wheel 34 as shown in FIG. 5, and is supplied to the processing points of the finishing grinding wheel 340 and the sealing layer W2 of the sealing wafer W. Then, the processing points of the finish grinding wheel 340 and the sealing layer W2 are cooled and washed. A separate nozzle for passing the machining fluid is provided on the side of the chuck table 2, and the machining fluid is caused to flow into the nozzle from the machining fluid supply unit 82, so that the machining point is applied to the machining point from the outside of the finish grinding unit 3. It is also possible to supply a machining fluid.

  The filler F in the machining fluid supplied to the machining point acts as an abrasive, and the grinding wheel 340 is caused by the grinding waste generated during finish grinding and the abrasive grains in the finishing grinding wheel 340 by the filler F. Clogging is eliminated. Further, the filler F promotes the grain removal of the abrasive grains in the finish grinding wheel 340, so that the drag of the metal post P when the grinding wheel 340 contacts the metal post P is suppressed. This is because the abrasive grains in the finish grinding wheel 340 are in continuous contact with the sealing layer W2 as fixed abrasive grains, whereas the filler F, which is an abrasive, is used as a free abrasive grain as the sealing layer. Since it is flowing on W2 and can contact the processing point of the finishing grinding wheel 340 and the sealing layer W2 to contribute to the processing or escape from the processing point, the processing heat is generated in the finishing grinding wheel 340. This is because it is difficult to store heat compared to abrasive grains. Therefore, it is considered that the filler F contributes to the grinding of the sealing layer W2 without increasing the ductility of the metal post P, which is one of the factors that cause the metal post P to be dragged.

  The processing liquid supplied from the processing liquid supply means 82 to the processing point of the finish grinding wheel 340 and the sealing layer W2 of the sealing wafer W cools the processing point and removes grinding waste generated at the processing point, and performs grinding. It becomes grinding waste liquid discarded together with scraps, flows down from the chuck table 2 and the turntable 12 to the second storage region 13 b shown in FIG. 1, and is discharged to the outside from the drain port 16.

  As shown in FIG. 6, when the sealing layer W <b> 2 of the sealing wafer W is ground until the upper end surface of the metal post P is exposed, the finish grinding means 3 moves upward and is separated from the sealing wafer W. Further, the rotation of the chuck table 2 is stopped, and the turn table 12 shown in FIG. 1 rotates in the clockwise direction when viewed from the + Z direction, whereby the chuck table 2 holding the sealing wafer W becomes the second transfer unit 11b. Move to the vicinity of. Then, the second transfer means 11b carries out the processed sealed wafer W from the chuck table 2.

  Thus, in the processing method according to the present invention, the sealing layer W2 of the sealing wafer W held by the chuck table 2 by the rough grinding wheel 44 including the rough grinding wheel 440 is reduced to a thickness that does not reach the end face of the metal post P. After carrying out the rough grinding step for thinning by grinding, and the rough grinding step, the sealing held by the chuck table 2 by the finishing grinding wheel 340 containing abrasive grains smaller than the abrasive grains of the rough grinding wheel 440 And a finishing grinding step for grinding the sealing layer W2 of the stationary wafer W to expose the end face of the metal post P. In the rough grinding step, the processing point where the sealing layer W2 and the rough grinding wheel 440 are in contact with each other is pure. Rough grinding of the sealing layer W2 is performed while supplying water, and in the finish grinding step, a processing liquid containing an abrasive (filler F) at a processing point where the sealing layer W2 and the finish grinding wheel 34 come into contact with each other. By performing the finish grinding of the sealing layer W2 while supplying, the end surface of the metal post P is sealed in the sealing layer while suppressing excessive wear of the finish grinding wheel 340 and suppressing the dragging of the metal post P. It can be exposed from W2. Moreover, in this processing method, since it is not necessary to use a tool turning device, an increase in processing cost due to the device configuration can be suppressed.

  Further, in the finish grinding step, the grinding waste liquid generated in the rough grinding step is supplied as the processing liquid, and the finish grinding of the sealing layer W2 is performed, thereby reducing the processing cost by using the grinding waste liquid as the processing liquid. Clean processing that is easier to the environment can be performed.

  Note that the processing method according to the present invention is not limited to the above embodiment, and the configuration of the grinding apparatus 1 illustrated in the accompanying drawings is not limited to this, and the effects of the present invention are exhibited. It can be changed as appropriate within a possible range.

  For example, the flow path 30a of the finish grinding means 3 does not communicate with the machining liquid supply means 82, but a machining liquid prepared separately from the grinding waste liquid generated in the rough grinding step (for example, a particle size similar to that of the filler F). May be communicated with the machining fluid supply means in which the abrasive material, i.e., the fluid containing loose abrasive grains) is stored. In the final grinding step, instead of using the grinding waste liquid generated in the rough grinding step as the processing liquid, the separately prepared processing liquid is supplied to the processing point where the sealing layer W2 and the final grinding wheel 340 are in contact with each other. However, finish grinding may be performed.

1: Grinding device 1A: Base 11a: First conveying means 11b: Second conveying means 12: Turntable 13: Grinding water accommodating part 130: Wall part 13a: First accommodating area 13b: Second accommodating area 14: Boundary Part 15: Drain port 15a: Drain pipe 16:
2: Chuck table 29: Suction part 29a: Holding surface 28: Frame 27: Suction source 3: Finish grinding means 30: Spindle 30a: Channel 300a: Piping 31: Housing 32: Motor 33: Mount 34: Finish grinding wheel 340 : Finish grinding wheel 341: Wheel base 4: Coarse grinding means 40: Spindle 40 a: Flow path 400 a: Pipe 41: Housing 42: Motor 43: Mount 44: Coarse grinding wheel 440: Coarse grinding wheel 441: Wheel base 5: Second grinding feed means 50: Ball screw 51: Guide rail 52: Motor 53: Lifting part 6: First grinding feed means 60: Ball screw 61: Guide rail 62: Motor 63: Lifting part 71: First cassette 72: Second cassette 73: Robot 730: Arm unit 731: Holding unit 74: Positioning 75: Cleaning means 750: Holding table 80: Grinding water supply means 800: Pure water source 801: Pure water feed part 82: Processing liquid supply means 820: Grinding waste liquid recovery tank 821: Filter 822: Working liquid feed part W: Seal Stop wafer W1: Silicon wafer W1a: Front surface of silicon wafer W1b: Back surface of silicon wafer S: Line to be divided D: Device W2: Sealing layer P: Metal post F: Filler

Claims (2)

A processing method in which a plurality of metal posts are formed on a wafer and a sealing wafer on which a sealing layer covering the metal posts is formed and containing a filler is ground to expose an end face of the metal posts,
A holding step for holding the sealed wafer with the sealing layer exposed at the chuck table;
After carrying out the holding step, the roughing wheel is thinned by grinding the sealing layer of the sealing wafer held by the chuck table to a thickness that does not reach the end face of the metal post by a rough grinding wheel having a rough grinding wheel. A grinding step;
After performing the rough grinding step, the sealing layer of the sealing wafer held by the chuck table by a finishing grinding wheel including a finishing grinding wheel containing abrasive grains having a grain size smaller than that of the coarse grinding wheel And finishing grinding to expose the end face of the metal post,
In the rough grinding step, rough sealing of the sealing layer is performed while supplying pure water to a processing point where the sealing layer and the rough grinding wheel contact each other.
In the finish grinding step, the finish grinding of the sealing layer is performed while supplying a working fluid containing an abrasive to a working point where the sealing layer and the finish grinding grindstone are in contact with each other.   The processing method according to claim 1, wherein in the finish grinding step, finish grinding of the sealing layer is performed while supplying the grinding waste liquid generated in the rough grinding step as the working fluid.

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