Processing method of workpiece

Abstract

To reduce damages which occur in a work-piece due to grinding, so as to process the work-piece in a short time and with a high quality.SOLUTION: A processing method for processing a work-piece comprises a first polishing step of polishing the work-piece, while making a polishing pad contact a surface to be processed of the work-piece and a first grinding step of grinding the work-piece while making a grinding wheel comprising a first grinding stone contact the surface to be processed of the work-piece. Preferably the processing method includes a second polishing step of polishing the surface to be processed of the work-piece, after the first grinding step. More preferably, in the second polishing step, the surface to be processed of the work-piece is polished using the polishing pad.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to a method for processing a workpiece, which grinds a plate-shaped workpiece to thin it to a predetermined thickness.

Background Art

[0002] In electronic devices represented by mobile phones and personal computers, a device chip having devices such as electronic circuits is an essential component. The device chip is obtained, for example, by dividing a wafer made of a semiconductor material such as silicon into a plurality of regions by a dicing line (street), forming devices in each region, and then dividing the wafer along the dicing line. And if the wafer is thinned before dividing the wafer, a thin device chip can be finally manufactured.

[0003] In the process of thinning the wafer, the wafer is ground with an annular grinding wheel having a grinding stone containing abrasive grains, and then the wafer is polished with a polishing pad for the purpose of removing the uneven shape generated on the processed surface of the wafer by grinding (see Patent Document 1). And for the processing of thinning the wafer, a grinding and polishing apparatus including a grinding unit and a polishing unit is used.

[0004] Furthermore, in the grinding and polishing apparatus, grinding is performed in two stages: rough grinding, which is a process of grinding a workpiece such as a wafer at a high speed, and finish grinding, which is a process of grinding the workpiece at a low speed with high precision. In rough grinding, a grinding stone containing abrasive grains having a relatively large diameter is used in order to perform grinding at a high speed. And in finish grinding, a grinding stone containing abrasive grains having a relatively small diameter is used in order to flatten the processed surface with high precision while removing the damaged layer generated on the workpiece by rough grinding.

Prior Art Documents

Patent Documents

[0005] [[ID=**********]]

Patent Document 1

[0006] Grinding and polishing equipment is sometimes used to remove hard layers such as oxide films formed on wafers in order to produce reclaimed wafers from wafers that have been defective in the device manufacturing process or wafers that have been used for test processing, etc. In addition, grinding and polishing equipment may use grinding wheels containing particularly large abrasive grains for rough grinding or perform rough grinding under high-intensity conditions in order to thoroughly remove hard layers formed on the workpiece surface of the workpiece or for other purposes.

[0007] However, in these cases, rough grinding causes significant damage to the workpiece surface and outer edges. Therefore, finish grinding needs to be performed for a long time to sufficiently remove the damaged layer, which reduces the processing speed of the grinding and polishing equipment. In addition, the quality of the workpiece may deteriorate if the damaged layer cannot be sufficiently removed during finish grinding.

[0008] This invention has been made in view of the above problems, and its objective is to provide a method for processing a workpiece that reduces damage to the workpiece caused by grinding and enables processing of the workpiece in a short time and with high quality. [Means for solving the problem]

[0009] According to one aspect of the present invention, a machining method for machining a workpiece, wherein a polishing pad is placed on the workpiece surface of the workpiece. In the formed layer Bring the workpiece into contact with it. The layer formed on the workpiece surface polish and remove A first polishing step, and after the first polishing step, bringing a grinding wheel equipped with a first grinding wheel into contact with the workpiece surface. The layer was removed. A first grinding step of grinding the workpiece, Following the first grinding step, a second polishing step is performed to polish the workpiece surface, A method for processing a workpiece is provided, characterized by comprising the following features.

[0011] More preferably, the second polishing step involves using the polishing pad to polish the workpiece surface.

[0012] More preferably, after the first grinding step and before the second polishing step, a second grinding step is further comprising grinding the workpiece by bringing a grinding wheel equipped with a second grinding wheel into contact with the workpiece surface of the workpiece, wherein the particle size of the abrasive grains contained in the second grinding wheel is smaller than the particle size of the abrasive grains contained in the first grinding wheel.

[0013] According to another aspect of the present invention, a processing method for processing a workpiece, comprising: a first polishing step of bringing a polishing pad into contact with a layer formed on the workpiece surface, and polishing and removing the layer formed on the workpiece surface; and a first grinding step of, after performing the first polishing step, bringing a grinding wheel equipped with a first grinding wheel into contact with the workpiece surface, and grinding the workpiece from which the layer has been removed. Following the first grinding step, a second grinding step is performed in which a grinding wheel equipped with a second grinding wheel is brought into contact with the workpiece surface to grind the workpiece. And, equipped with, The particle size of the abrasive grains contained in the second grinding wheel is smaller than the particle size of the abrasive grains contained in the first grinding wheel. A method for processing a workpiece is provided, characterized by the following features. .

[0014] good More specifically, the workpiece surface of the workpiece that is polished in the first polishing step The layer that is formed and removed in the first polishing step is an oxide film , nitride film, or functional layer ru. Preferably, the layer formed on the workpiece surface being polished in the first polishing step and removed in the first polishing step is harder than the workpiece. [Effects of the Invention]

[0015] In one aspect of the present invention, a workpiece is processed by bringing a polishing pad into contact with the workpiece surface to polish it, and then grinding the workpiece surface with a grinding wheel equipped with a first grinding wheel. In this case, since the workpiece surface to be ground has its surface layer removed by polishing beforehand, the workpiece surface can be ground with less force than when grinding is performed without prior polishing of the workpiece surface. That is, damage to the workpiece caused by grinding can be reduced, and the workpiece can be processed quickly and with high quality.

[0016] Therefore, according to one aspect of the present invention, a method for processing a workpiece is provided that reduces damage to the workpiece caused by grinding and allows for processing of the workpiece in a short time and with high quality. [Brief explanation of the drawing]

[0017] [Figure 1] It is a perspective view schematically showing a grinding and polishing apparatus and a workpiece. [Figure 2] It is a cross-sectional view schematically showing a first polishing step. [Figure 3] It is a cross-sectional view schematically showing a first grinding step. [Figure 4] It is a cross-sectional view schematically showing a second grinding step. [Figure 5] It is a cross-sectional view schematically showing a second polishing step. [Figure 6] It is a flowchart showing the flow of each step of a method for processing a workpiece.

Mode for Carrying Out the Invention

[0018] Embodiments of the present invention will be described with reference to the accompanying drawings. FIG. 1 is a perspective view showing a configuration example of a grinding and polishing apparatus 2 used in a method for processing a workpiece according to the present embodiment. The front-back direction (X-axis direction), left-right direction (Y-axis direction), and vertical direction (Z-axis direction) used in the following description are perpendicular to each other.

[0019] FIG. 2 includes a cross-sectional view schematically showing a workpiece 11 processed by the method for processing a workpiece according to the present embodiment. The workpiece 11 is, for example, a disk-shaped wafer formed using a semiconductor. More specifically, the material of the workpiece 11 is Si (silicon), SiC (silicon carbide), sapphire, or the like.

[0020] A workpiece 11 having a surface 11a divided into multiple sub-regions by multiple intersecting division lines (streets), with devices such as ICs (Integrated Circuits) formed in each sub-region, may be the target of the workpiece processing method according to this embodiment. The back surface 11b of this workpiece 11 is processed as the workpiece surface. An oxide film, a nitride film, or other functional layer may be formed on this workpiece surface. The oxide film and nitride film are, for example, films composed of oxides or nitrides of elements that are mainly contained in the workpiece 11, or films composed of oxides or nitrides of other elements. A film-like protective member 13 (see Figure 2, etc.) for protecting the devices is attached to the surface 11a of the workpiece 11.

[0021] Furthermore, the workpiece 11 to be processed may be a wafer used for test processing when examining the processing conditions performed by the grinding and polishing apparatus 2, or a wafer that was not properly processed in the device manufacturing process. In the workpiece processing method according to this embodiment, a reclaimed wafer may be manufactured by processing such a workpiece 11. On the back surface 11b of the workpiece 11 that becomes a reclaimed wafer after processing, an oxide film, a nitride film, or other functional layer may be formed.

[0022] However, there are no restrictions on the material, shape, structure, size, etc., of the workpiece 11. For example, the workpiece 11 may be a substrate formed using other semiconductor, ceramic, resin, metal, or other materials. Similarly, there are no restrictions on the type, quantity, shape, structure, size, arrangement, etc., of the devices. The workpiece 11 does not need to have any devices formed on it. In that case, the protective member 13 does not need to be attached to the surface 11a side of the workpiece 11.

[0023] Next, the grinding and polishing apparatus 2 will be described in detail. As shown in Figure 1, the grinding and polishing apparatus 2 is equipped with a base 4 that supports each structure. An opening 4a is formed on the front end side of the upper surface of the base 4, and a conveying mechanism 6 for conveying a disc-shaped workpiece 11 (see Figure 2) is provided inside the opening 4a.

[0024] Cassette tables 8a and 8b are provided in front of the opening 4a. Cassette tables 8a and 8b are each fitted with cassettes 10a and 10b, which can accommodate multiple workpieces 11. A position adjustment mechanism 12 for adjusting the position of the workpieces 11 is provided diagonally behind the opening 4a.

[0025] The position adjustment mechanism 12 includes, for example, a table 12a configured to support the central portion of the workpiece 11, and a plurality of pins 12b configured to move closer to and further away from the table 12a in an area outside the table 12a. When the workpiece 11, which has been discharged from the cassette 10a by the transport mechanism 6, is placed on the table 12a, the plurality of pins 12b align the center of the workpiece 11 with the center of the table 12a.

[0026] Near the position adjustment mechanism 12, a loading mechanism 14 is provided that can hold and rotate the workpiece 11. The loading mechanism 14 is equipped with a suction pad that can hold the entire upper surface of the workpiece 11 and transports the workpiece 11, whose position has been adjusted by the position adjustment mechanism 12, to the rear. Behind the loading mechanism 14, a turntable 16 is provided.

[0027] The turntable 16 is connected to a drive source (not shown), such as a motor, and rotates around a rotation axis that is generally parallel to the vertical direction. Four chuck tables 18 for supporting the workpiece 11 during machining are provided on the upper surface of the turntable 16 at generally equal angular intervals. There are no restrictions on the number of chuck tables 18 provided on the turntable 16.

[0028] The loading mechanism 14 uses a suction pad to pick up the workpiece 11 and loads it onto a chuck table 18 located near the loading / unloading position of the loading mechanism 14. By rotating the turntable 16, each chuck table 18 can be moved.

[0029] Each chuck table 18 is connected to a drive source (not shown), such as a motor, and rotates around a rotation axis that is generally parallel to the vertical direction (or slightly inclined to the vertical direction). A portion of the upper surface of each chuck table 18 is a support surface that can attract and support the workpiece 11.

[0030] This support surface is connected to a suction source (not shown) through a flow path (not shown) formed inside the chuck table 18. The workpiece 11, when placed on the chuck table 18, is sucked from the bottom side by the negative pressure of the suction source acting on the support surface. Figure 2 includes a schematic cross-sectional view showing the workpiece 11 held by suction on the chuck table 18. In this embodiment, the front surface 11a of the workpiece 11 is supported by the chuck table 18 via a protective member 13 so that the back surface 11b of the workpiece 11 is exposed upwards.

[0031] The grinding and polishing apparatus 2 comprises two grinding units 34 for grinding the workpiece 11. Columnar support structures 20 are provided on the rear side of the turntable 16 to support each of the grinding units 34. A vertical movement mechanism 22 is provided on the front side (turntable 16 side) of each support structure 20. Each vertical movement mechanism 22 is equipped with a pair of guide rails 24 that are generally parallel to the vertical direction, and a movable plate 26 is mounted on the pair of guide rails 24 in a manner that allows it to slide.

[0032] A nut (not shown) that constitutes a ball screw is fixed to the back side (rear side) of each movable plate 26, and a screw shaft 28 that is roughly parallel to the guide rail 24 is screwed into this nut in a manner that allows it to rotate. A pulse motor 30 is connected to one end of each screw shaft 28. By rotating the screw shaft 28 with the pulse motor 30, the movable plate 26 moves vertically along the guide rail 24.

[0033] A fixing device 32 is provided on the surface (front) of each movable plate 26. Each fixing device 32 supports a grinding unit 34 for grinding the workpiece 11. Each grinding unit 34 is equipped with a spindle housing 36 that is fixed to the fixing device 32.

[0034] Each spindle housing 36 houses a spindle 38 whose axis of rotation is approximately parallel to (or slightly inclined to) the vertical direction, in a manner that allows it to rotate. A drive source (not shown), such as a motor, is connected to the upper end of each spindle 38, and each spindle 38 rotates due to the power of this drive source. The lower end of each spindle 38 is exposed from the lower surface of the spindle housing 36. A disc-shaped mount 40 is fixed to the lower end of each spindle 38.

[0035] Each grinding unit 34 has a grinding wheel (grinding tool) 42a or 42b mounted on the underside of its mount 40. The grinding wheels 42a and 42b are equipped with a wheel base made of a metal material such as stainless steel or aluminum, and are approximately the same diameter as the mount 40. Multiple grinding wheels 43a and 43b containing abrasive grains made of diamond or the like are fixed to the underside of the wheel base (see Figure 3, etc.).

[0036] One of the grinding wheels 42a and 42b is used for rough grinding of the workpiece 11, and the other of the grinding wheels 42a and 42b is used for finish grinding of the workpiece 11. Generally, the particle size of the abrasive grains contained in the grinding wheels 43a and 43b used for finish grinding is smaller than the particle size of the abrasive grains contained in the grinding wheels used for rough grinding.

[0037] Near each grinding wheel 42a, 42b, a liquid supply nozzle (not shown) is positioned to supply a liquid (grinding fluid) such as pure water to the area (processing point) of the workpiece 11 that comes into contact with the grinding wheels 43a, 43b. Also, near each grinding wheel 42a, 42b, a contact-type or non-contact-type thickness measuring instrument (not shown) is positioned to measure the thickness of the workpiece 11. Alternatively, openings for supplying liquid may be provided on each grinding wheel 42a, 42b and used as liquid supply nozzles.

[0038] The grinding and polishing apparatus 2 includes a polishing unit 66 for polishing the workpiece 11. A support structure 44 for supporting the polishing unit 66 is provided on the side of the turntable 16. A moving mechanism 46 is provided on the turntable 16 side of the support structure 44. The moving mechanism 46 includes a pair of first guide rails 48 that are generally parallel to the front-rear direction, and a first moving plate 50 is attached to the pair of first guide rails 48 in a manner that allows it to slide.

[0039] A nut (not shown) that constitutes a ball screw is fixed to the back side (support structure 44 side) of the first movable plate 50, and a screw shaft 52, which is generally parallel to the first guide rail 48, is screwed into this nut in a manner that allows it to rotate. A pulse motor 54 is connected to one end of the screw shaft 52. By rotating the screw shaft 52 with the pulse motor 54, the first movable plate 50 moves in the front-rear direction along the first guide rail 48.

[0040] A pair of second guide rails 56, which are generally parallel to the vertical direction, are provided on the surface side of the first movable plate 50. The second movable plate 58 is mounted on the pair of second guide rails 56 in a manner that allows it to slide. A nut (not shown) that constitutes a ball screw is fixed to the back side (the side facing the first movable plate 50) of the second movable plate 58, and a screw shaft 60, which is generally parallel to the second guide rail 56, is screwed into this nut in a manner that allows it to rotate.

[0041] A pulse motor 62 is connected to one end of the screw shaft 60. By rotating the screw shaft 60 with the pulse motor 62, the second movable plate 58 moves vertically along the second guide rail 56. A fixing device 64 is provided on the surface of the second movable plate 58. A polishing unit 66 for polishing the workpiece 11 is supported by the fixing device 64.

[0042] The polishing unit 66 includes a spindle housing 68 fixed to a fixture 64. The spindle housing 68 houses a spindle 70 that has a rotation axis that is approximately parallel to (or slightly inclined to) the vertical direction, in a manner that allows it to rotate. A drive source (not shown), such as a motor, is connected to the upper end of the spindle 70, and the spindle 70 rotates due to the power of this drive source.

[0043] The lower end of the spindle 70 is exposed from the lower surface of the spindle housing 68. A disc-shaped mount 72 is fixed to the lower end of the spindle 70. An abrasive pad (a polishing tool) 74, made of a resin such as foamed polyurethane or a nonwoven fabric, is attached to the lower surface of the mount 72.

[0044] The diameter of the polishing pad 74 is less than or equal to the radius of the chuck table 18. Therefore, even when the polishing pad 74 is in contact with the workpiece 11 and the workpiece 11 is being machined, a portion of the workpiece 11 is exposed upwards. Furthermore, when the polishing pad 74 is in contact with the workpiece 11 and the workpiece 11 is being machined, the polishing pad 74 (or the chuck table 18) is moved horizontally to prevent uneven machining.

[0045] However, the diameter of the polishing pad 74 used in the grinding and polishing apparatus 2 is not limited to this. That is, the diameter of the polishing pad 74 may exceed the radius of the workpiece 11, or it may exceed the diameter of the workpiece 11. In this case, when polishing the workpiece 11 with the polishing pad 74, it is not necessary to move the polishing pad 74 or the like along the horizontal direction.

[0046] Furthermore, the polishing pad 74 may be provided with an opening for supplying a liquid containing dispersed abrasive particles (polishing fluid) to the area (processing point) of the workpiece 11 that comes into contact with the polishing pad 74. When polishing the workpiece 11, the polishing fluid may be supplied between the workpiece 11 and the polishing pad 74.

[0047] Alternatively, abrasive grains may be dispersed and fixed on the polishing pad 74. Furthermore, when polishing the workpiece 11, it is not necessary to supply polishing fluid to the workpiece 11. In other words, the grinding and polishing apparatus 2 may perform wet polishing or dry polishing on the workpiece 11.

[0048] Furthermore, the grinding and polishing apparatus 2 may be equipped with a thickness measuring device near the polishing unit 66 for measuring the thickness of the workpiece 11. In the grinding and polishing apparatus 2, the thickness of the workpiece 11 being polished by the polishing unit 66 and the thickness distribution of the workpiece surface may be monitored, and the workpiece 11 may be polished by the polishing unit 66 until a predetermined thickness is reached.

[0049] As shown in Figure 1, a discharge mechanism 80 is provided to the side of the loading mechanism 14, capable of holding and rotating the workpiece 11 after it has been processed by the grinding unit 34 and the polishing unit 66. In front of the discharge mechanism 80 and behind the opening 4a, a cleaning mechanism 82 is positioned to clean the workpiece 11 that has been discharged by the discharge mechanism 80. The workpiece 11 that has been cleaned by the cleaning mechanism 82 is transported by the transport mechanism 6 and, for example, stored in a cassette 10b.

[0050] A control unit is connected to each of the components described above. The control unit controls the operation of each component so that the workpiece 11 can be processed appropriately. Typically, the control unit consists of a computer including a processing unit such as a CPU (Central Processing Unit) and a storage device such as flash memory. Various functions of the control unit are realized by operating the processing unit and other components according to the software stored in the storage device.

[0051] Here, we will further explain the workpiece 11 that is to be processed by the grinding and polishing apparatus 2. In the series of processes for forming a device on the surface of a wafer, some processes may not be performed properly, resulting in failure to form a normal device. In this case, even if the wafer is divided as is, a normal device chip cannot be manufactured. Therefore, it is desirable to process the wafer as a workpiece 11 using the grinding and polishing apparatus 2 to remove unnecessary layers and create a wafer that can be used to manufacture a new device chip.

[0052] Furthermore, in the device chip manufacturing process, appropriate processing conditions are required at each step to process the wafer as intended. To derive these appropriate processing conditions, numerous test processing steps are repeated, and the processing results are evaluated. Many wafers are required to perform test processing, but it is not necessary to use high-quality wafers for test processing. Therefore, it is desirable to process wafers that have been used in test processing or wafers that failed to form devices using the grinding and polishing apparatus 2 to produce wafers that can be used for test processing.

[0053] Furthermore, the back surface 11b of the workpiece 11 to be processed by the grinding and polishing device 2 may have an oxide film, a nitride film, or other functional layer formed thereon, and the grinding and polishing device 2 may want to remove the hard layer 15 (see Figure 2) provided on the back surface 11b. In addition, the workpiece 11 itself may be formed from a hard material.

[0054] Furthermore, in the grinding and polishing apparatus 2, grinding wheels 43a and 43b containing particularly large abrasive grains may be used for rough grinding in order to sufficiently remove the hard layer 15, etc., formed on the back surface 11b of the workpiece 11, which is the workpiece surface, or for other purposes. Alternatively, rough grinding may be performed under high-intensity conditions.

[0055] However, in these cases, the load from rough grinding causes significant damage to the workpiece surface and outer edge of the workpiece 11. Therefore, it is necessary to perform finish grinding for a long time to sufficiently remove the damaged layer, which reduces the processing speed of the grinding and polishing device 2. In addition, the quality of the workpiece 11 may deteriorate if the damaged layer is not sufficiently removed during finish grinding.

[0056] Therefore, the workpiece processing method according to this embodiment, as described below, reduces the damage to the workpiece 11 caused by grinding while processing the workpiece 11 quickly and with high quality. The workpiece processing method according to this embodiment will be described in detail below. Figure 6 is a flowchart showing the flow of each step in the workpiece processing method according to this embodiment. However, some of the steps shown in the flowchart of Figure 6 may not be performed, and additional steps not shown in the flowchart may be performed.

[0057] The workpiece processing method according to this embodiment is mainly carried out by a grinding and polishing apparatus 2. First, a first polishing step S10 is performed in which the polishing pad 74 is brought into contact with the workpiece surface (back surface 11b) of the workpiece 11 and the workpiece 11 is polished.

[0058] In the first polishing step S10, the workpiece 11 is first removed from the cassettes 10a and 10b and placed on the upper surface of the chuck table 18. During this process, the back surface 11b of the workpiece 11, which will be the workpiece surface, is turned upward, and the position of the workpiece 11 is adjusted using the position adjustment mechanism 12, and the loading mechanism 14 is made to carry the workpiece 11 as predetermined. As a result, the center of the workpiece 11 and the center of the upper surface of the chuck table 18 coincide.

[0059] Then, the workpiece 11 is held in place by suction using the chuck table 18. A tape-like protective member 13 may be attached to the surface 11a of the workpiece 11 to protect it. That is, the workpiece 11 is held in place by suction using the chuck table 18 via the protective member 13. The turntable 16 is then rotated clockwise when viewed from above to move the chuck table 18, which holds the workpiece 11, below the polishing unit 66. Figure 2 is a schematic cross-sectional view showing the first polishing step S10.

[0060] Next, the chuck table 18 and the polishing pad 74 are rotated relative to each other so that the lower surface of the polishing pad 74 comes into contact with the back surface 11b (upper surface) of the workpiece 11 that is exposed above. As a result, the workpiece 11 is polished by the polishing pad 74. At this time, the moving mechanism 46 is operated to keep the polishing pad 74 moving in a direction that is roughly parallel to the vertical direction so that the entire back surface 11b of the workpiece 11 can be polished uniformly.

[0061] When polishing the workpiece 11, a polishing fluid containing abrasive particles may be supplied to the workpiece 11 and the polishing pad 74. Alternatively, when polishing the workpiece 11, a polishing fluid containing abrasive particles may not be supplied to the workpiece 11 and the polishing pad 74. The type of polishing pad 74 and whether or not polishing fluid is supplied should be determined according to the material of the workpiece 11 and the type of hard layer 15 to be removed.

[0062] Polishing the workpiece 11 with the polishing pad 74 can thin the workpiece 11. Also, if a hard layer 15 is formed on the workpiece surface (back surface 11b) side of the workpiece 11, the hard layer 15 can be removed by polishing. While polishing the workpiece 11 with the polishing pad 74, the thickness of the workpiece 11 should be monitored with a thickness measuring instrument, and the polishing of the workpiece 11 should be stopped when the workpiece 11 reaches a predetermined thickness.

[0063] The machining load applied to the workpiece 11 when polishing it is smaller than the machining load applied to the workpiece 11 when grinding it (the load applied to the workpiece 11 due to rough grinding). Therefore, when polishing the workpiece 11 with the polishing pad 74, a damage layer like the one that occurs on the workpiece surface when grinding the workpiece 11 does not occur on the workpiece 11.

[0064] After performing the first polishing step S10, the first grinding step S20 is performed. In the first grinding step S20, grinding wheels 42a and 42b equipped with the first grinding wheel are brought into contact with the workpiece surface (back surface 11b) of the workpiece 11 to grind the workpiece. The first grinding step S20 is performed by one of the two grinding units 34 of the grinding and polishing apparatus 2. Figure 3 is a schematic cross-sectional view showing the first grinding step S20.

[0065] When performing the first grinding step S20, the turntable 16 is rotated clockwise to move the chuck table 18, which holds the workpiece 11 by suction, below one of the two grinding units 34. For example, if a grinding unit 34 equipped with a grinding wheel 42b is used in the first grinding step S20, the chuck table 18 is moved below that grinding unit 34.

[0066] Then, while supplying grinding fluid such as pure water to the workpiece 11 and the grinding wheel 42b, the chuck table 18 and the grinding wheel 42b are rotated relative to each other, bringing the grinding wheel 43b of the grinding wheel 42b into contact with the back surface 11b (top surface) of the workpiece 11.

[0067] Here, when grinding the workpiece 11 is performed in two stages, rough grinding and finish grinding, the first grinding step S20 is performed to rough grind the workpiece 11, and after the first grinding step S20, the second grinding step S30 is performed as finish grinding of the workpiece 11. Figure 4 is a schematic cross-sectional view showing the second grinding step S30.

[0068] When performing the second grinding step S30, the turntable 16 is rotated to move the chuck table 18, which holds the workpiece 11 by suction, to the other of the two grinding units 34. In the second grinding step S30, the grinding wheels 42a and 42b, each equipped with a second grinding wheel, are brought into contact with the workpiece surface (back surface 11b) of the workpiece 11 to grind the workpiece.

[0069] For example, if a grinding unit 34 equipped with a grinding wheel 42a is used in the second grinding step S30, the chuck table 18 is moved below the grinding unit 34. Then, while supplying grinding fluid such as pure water to the workpiece 11 and the grinding wheel 42a, the chuck table 18 and the grinding wheel 42a are rotated relative to each other, bringing the grinding wheel 43a of the grinding wheel 42a into contact with the back surface 11b (top surface) of the workpiece 11.

[0070] When grinding the workpiece 11 in two stages, rough grinding is performed in the first grinding step S20 to grind the workpiece 11 at high speed, and finish grinding is performed in the second grinding step S30 to grind the workpiece 11 with high precision. In each grinding step, the thickness of the workpiece 11 is monitored with a thickness measuring instrument, and grinding of the workpiece 11 is terminated when the workpiece 11 reaches a predetermined thickness.

[0071] Then, when the workpiece 11 is thinned to a predetermined finish thickness using the grinding and polishing device 2, the majority of the total amount of material to be removed from the workpiece 11 is ground during the rough grinding (first grinding step S20). Furthermore, in the finish grinding (second grinding step S30), the workpiece 11 is thinned to a predetermined finish thickness while removing the damaged layer that occurred on the workpiece 11 during the rough grinding.

[0072] In the first polishing step S10, polishing the workpiece 11 with the polishing pad 74 allows the workpiece 11 to be thinned to a certain extent. Therefore, the amount of material removed by grinding when the workpiece 11 is finally thinned to a predetermined thickness is reduced. In other words, the amount of material removed from the workpiece 11 in rough grinding (first grinding step S20) can be reduced. In this case, since the damage layer formed on the workpiece surface of the workpiece 11 during rough grinding is reduced, the finish grinding (second grinding step S30) can also be performed quickly and with high quality.

[0073] Furthermore, if the workpiece 11 has a hard layer 15 on its work surface and this hard layer 15 is to be removed, then if the workpiece 11 is roughly ground without polishing to remove the hard layer 15, a relatively thick damaged layer will be formed on the workpiece 11 due to the rough grinding. This is because it is necessary to grind the workpiece 11 using a grinding wheel with a grinding wheel containing relatively large abrasive grains, or to grind the workpiece 11 with relatively high intensity.

[0074] In these cases, finish grinding must be performed for a long time to remove the thick damaged layer, which reduces the processing efficiency of the workpiece 11 in the grinding and polishing device 2. In addition, the damaged layer may not be sufficiently removed by finish grinding, resulting in a decrease in the quality of the workpiece 11 after finish grinding.

[0075] In contrast, in the workpiece processing method according to this embodiment, the hard layer 15 formed on the workpiece 11 is removed in the first polishing step S10. Therefore, when grinding the workpiece 11, it is not necessary to use a grinding wheel with a grinding wheel containing relatively large abrasive grains, and the workpiece 11 can be ground with relatively low intensity. In this case, the damage layer formed on the workpiece 11 during polishing is reduced, so the workpiece 11 can be ground quickly and with high quality.

[0076] In the workpiece processing method according to this embodiment, the workpiece 11 may be ground in the first grinding step S20, and then the second polishing step S40 may be performed. If the second grinding step S30 is performed after the first grinding step S20, the second polishing step S40 is performed after the second grinding step S30. In the second polishing step S40, the workpiece surface (back surface 11b) of the workpiece 11 is polished.

[0077] In the second polishing step S40, the workpiece surface of the workpiece 11 may be polished using the polishing pad 74 used in the first polishing step S10. Alternatively, the second polishing step S40 does not require the use of the polishing pad 74 used in the first polishing step S10, and other polishing pads may be used. In this case, for example, the workpiece 11 may be removed from the grinding and polishing apparatus 2, and the second polishing step S40 may be performed in a polishing apparatus (not shown) outside the grinding and polishing apparatus 2.

[0078] The second polishing step S40 may be performed with the aim of removing minute irregularities formed on the workpiece surface of the workpiece 11 by grinding, thereby flattening the workpiece surface and finishing it to a mirror finish. If the polishing unit 66 of the grinding and polishing apparatus 2 is suitable for the purpose of the second polishing step S40, the second polishing step S40 can be performed using the polishing unit 66. On the other hand, if the polishing unit 66 is not suitable for the purpose, the second polishing step S40 may be performed using a suitable polishing apparatus outside the grinding and polishing apparatus 2.

[0079] The second polishing step S40 will be explained below using the case where it is performed by the grinding and polishing device 2 as an example. Figure 5 is a schematic cross-sectional view showing the second polishing step S40. In the second polishing step S40, the turntable 16 is rotated to move the chuck table 18, which holds the workpiece 11 by suction, downwards to the polishing unit 66.

[0080] Next, the chuck table 18 and the polishing pad 74 are rotated relative to each other so that the lower surface of the polishing pad 74 comes into contact with the back surface 11b (upper surface) of the workpiece 11 that is exposed above. As a result, the workpiece 11 is polished by the polishing pad 74. At this time, the moving mechanism 46 is operated to keep the polishing pad 74 moving in a direction that is roughly parallel to the vertical direction so that the entire back surface 11b of the workpiece 11 can be polished uniformly.

[0081] When polishing the workpiece 11, a polishing fluid containing abrasive particles may be supplied to the workpiece 11 and the polishing pad 74. Alternatively, when polishing the workpiece 11, a polishing fluid containing abrasive particles may not be supplied to the workpiece 11 and the polishing pad 74.

[0082] Here, the polishing conditions in the second polishing step S40 do not need to be the same as the polishing conditions in the first polishing step S10. For example, the rotational speed of the polishing pad 74, the rotational speed of the chuck table 18, the descending speed of the polishing unit 66, whether or not polishing fluid is supplied and the amount supplied, the processing time, etc., may differ between the first polishing step S10 and the second polishing step S40.

[0083] When the second polishing step S40 is performed, the irregularities on the workpiece surface of the workpiece 11 are removed, and the workpiece surface is finished to a mirror finish. Then, the turntable 16 is rotated to move the chuck table 18 to a position where the unloading mechanism 80 can access the workpiece 11. The suction holding of the workpiece 11 by the chuck table 18 is then released, and the workpiece 11 is transported by the unloading mechanism 80 to the cleaning mechanism 82, where the workpiece 11 is cleaned. After that, the workpiece 11 is stored in cassettes 10a and 10b by the transport mechanism 6.

[0084] As described above, in the workpiece processing method according to this embodiment, the workpiece surface 11 is polished before grinding. As a result, the workpiece 11 is thinned. Also, if a hard layer 15 is formed on the workpiece surface 11, the hard layer 15 can be removed by polishing. Therefore, the intensity of grinding performed on the workpiece 11 is reduced, reducing damage to the workpiece 11, and the workpiece 11 can be processed quickly and with high quality.

[0085] It should be noted that the present invention is not limited to the embodiments described above and can be implemented with various modifications. For example, in the embodiments described above, the thickness of the workpiece 11 is monitored with a thickness measuring instrument in each step and the workpiece 11 is processed until it reaches a predetermined thickness, but one aspect of the present invention is not limited to this. In one aspect of the present invention, the thickness of the workpiece 11 does not need to be monitored with a thickness measuring instrument in each step.

[0086] When processing a workpiece 11, on which a hard layer 15 is formed on the back surface 11b, with a grinding and polishing device 2 to form a regenerated wafer, it is sometimes desirable to process the workpiece 11 in such a way that the hard layer 15 is removed while leaving the workpiece 11 as thick as possible. In this case, in the first polishing step S10 of the workpiece processing method according to one aspect of the present invention, the workpiece surface of the workpiece 11 should be polished until the hard layer 15 is removed.

[0087] In one aspect of the present invention, the hard layer 15 can be removed by polishing, so unlike when the hard layer 15 is removed by grinding, a thick damaged layer is not formed on the workpiece 11. Therefore, even if the amount of workpiece 11 removed by processing is not large, the processed workpiece 11 will meet a certain standard. In other words, a relatively thick recycled wafer that can be used for test processing can be manufactured.

[0088] Furthermore, although the embodiments described above mainly described the case in which the first polishing step S10, the first grinding step S20, the second grinding step S30, and the second polishing step S40 are performed, the present invention is not limited thereto. For example, in the workpiece processing method according to one embodiment of the present invention, the second polishing step S40 may be omitted.

[0089] When the first polishing step S10, the first grinding step S20, and the second grinding step S30 are performed in this order, first the workpiece 11 is polished by the polishing unit 66. Then the turntable 16 is rotated clockwise to move the chuck table 18, and the workpiece 11 is roughly ground with the grinding wheel 42b equipped with a grinding wheel 43b. Then the turntable 16 is rotated clockwise again to move the chuck table 18, and the workpiece 11 is finish ground with the grinding wheel 42a equipped with a grinding wheel 43a.

[0090] Furthermore, when the first polishing step S10, the first grinding step S20, the second grinding step S30, and the second polishing step S40 are performed in the grinding and polishing apparatus 2, first the workpiece 11 is polished in the polishing unit 66. Then, the turntable 16 is rotated counterclockwise to move the chuck table 18, and the workpiece 11 is roughly ground with the grinding wheel 42a equipped with a grinding wheel 43a. That is, in the first grinding step S20, the grinding wheel 43a is used as the first grinding wheel.

[0091] Subsequently, the turntable 16 is rotated counterclockwise to move the chuck table 18, and the workpiece 11 is finished grinding with the grinding wheel 42b equipped with the grinding wheel 43b. That is, in the second grinding step S30, the grinding wheel 43b is used as the second grinding wheel. Then, the turntable 16 is rotated counterclockwise again to move the chuck table 18, and the workpiece 11 is polished with the polishing unit 66.

[0092] In this way, by switching the rotation direction of the turntable 16 of the grinding and polishing apparatus 2, various embodiments of the workpiece processing method according to the present invention can be implemented in the grinding and polishing apparatus 2. That is, by modifying the control program of the control unit, the workpiece processing method according to the present invention can also be implemented in an existing grinding and polishing apparatus 2.

[0093] Furthermore, the structures, methods, etc., of the embodiments and modifications described above can be modified and implemented without departing from the scope of the present invention. [Explanation of symbols]

[0094] 11 Workpiece 11a surface 11b Back side 13 Protective components 15. Hard layer 2. Grinding and polishing equipment 4 bases 4a aperture 6. Conveying mechanism 8a, 8b Cassette Table 10a, 10b Cassette 12 Position adjustment mechanism 12a Table 12b pin 14 Loading mechanism 16 Turntables 18 Chuck Table 20,44 Support structure 22 Vertical movement mechanism 24, 48, 56 Guide rails 26, 50, 58 Movable Plate 28, 52, 60 Screw shaft 30, 54, 62 pulse motor 32,64 Fixtures 34 Grinding Unit 36,68 Spindle Housing 38.70 spindles 40,72 mount 42a, 42b Grinding Wheel 43a, 43b Grinding wheels 46 Moving mechanism 66 Polishing Units 74 Polishing Pads 80 Unloading mechanism 82 Cleaning Mechanism

Claims

1. A processing method for processing a workpiece, A first polishing step involves bringing a polishing pad into contact with a layer formed on the workpiece surface, and polishing and removing the layer formed on the workpiece surface; After the first polishing step is performed, a first grinding step is performed in which a grinding wheel equipped with a first grinding wheel is brought into contact with the workpiece surface and the workpiece from which the layer has been removed is ground, A method for processing a workpiece, characterized by comprising: a first grinding step followed by a second polishing step of polishing the workpiece surface.

2. The method for processing a workpiece according to claim 1, characterized in that the second polishing step involves polishing the workpiece surface using the polishing pad.

3. After the first grinding step and before the second polishing step, a second grinding step is further provided, in which a grinding wheel equipped with a second grinding wheel is brought into contact with the workpiece surface of the workpiece to grind the workpiece. The method for processing a workpiece according to claim 1 or 2, characterized in that the particle size of the abrasive grains contained in the second grinding wheel is smaller than the particle size of the abrasive grains contained in the first grinding wheel.

4. A processing method for processing a workpiece, A first polishing step involves bringing a polishing pad into contact with a layer formed on the workpiece surface, and polishing and removing the layer formed on the workpiece surface; After the first polishing step is performed, a first grinding step is performed in which a grinding wheel equipped with a first grinding wheel is brought into contact with the workpiece surface and the workpiece from which the layer has been removed is ground, The process includes a second grinding step, in which a grinding wheel equipped with a second grinding wheel is brought into contact with the workpiece surface to grind the workpiece, after the first grinding step, A method for processing a workpiece, characterized in that the particle size of the abrasive grains contained in the second grinding wheel is smaller than the particle size of the abrasive grains contained in the first grinding wheel.

5. A method for processing a workpiece according to any one of claims 1 to 4, characterized in that the layer formed on the workpiece surface of the workpiece to be polished in the first polishing step and removed in the first polishing step is an oxide film, a nitride film, or a functional layer.

6. The method for processing a workpiece according to any one of claims 1 to 5, characterized in that the layer formed on the workpiece surface of the workpiece being polished in the first polishing step and removed in the first polishing step is harder than the workpiece.

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