JP2023104444A - Processing method for work-piece - Google Patents

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 The present invention relates to a method of processing a plate-shaped workpiece to grind it to a predetermined thickness.

2. Description of the Related Art In electronic equipment represented by mobile phones and personal computers, device chips having devices such as electronic circuits are essential components. Device chips are obtained by, for example, dividing a wafer made of a semiconductor material such as silicon into a plurality of regions along planned division lines (streets), forming devices in each region, and then dividing this wafer along the planned division lines. be done. By thinning the wafer before dividing it, thin device chips can be finally manufactured.

In the process of thinning the wafer, the wafer is ground with an annular grinding wheel to which a grinding wheel containing abrasive grains is fixed, and then the uneven shape generated on the surface to be processed of the wafer is removed by grinding. For this purpose, the wafer is polished with a polishing pad (see Patent Document 1). A grinding and polishing apparatus including a grinding unit and a polishing unit is used for thinning the wafer.

Furthermore, the grinding and polishing apparatus performs grinding 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. is carried out. Rough grinding uses a grinding wheel containing relatively large diameter abrasive grains to achieve high speed grinding. In the finish grinding, a grinding wheel containing abrasive grains with a relatively small diameter is used in order to planarize the surface to be processed with high precision while removing the damaged layer generated in the workpiece by rough grinding.

JP-A-2002-283243

Grinding and polishing equipment removes hard layers such as oxide films formed on wafers in order to manufacture reclaimed wafers from wafers with defects in the device manufacturing process or wafers used for test processing. It can be used for removal purposes. In the grinding and polishing apparatus, a grinding wheel containing abrasive grains with a particularly large grain size is used for rough grinding in order to sufficiently remove a hard layer formed on the surface to be processed of the workpiece and for other purposes. Alternatively, rough grinding may be performed under high-intensity conditions.

However, in these cases, the damage caused to the surface to be processed and the outer peripheral edge of the workpiece by rough grinding becomes large. Therefore, it is necessary to perform finish grinding for a long time in order to sufficiently remove the damaged layer, and the processing speed of the grinding and polishing apparatus decreases. In addition, the quality of the workpiece may deteriorate due to insufficient removal of the damaged layer by finish grinding.

The present invention has been made in view of these problems, and its object is to reduce the damage caused to the workpiece by grinding, and to produce a workpiece that can be processed in a short time and with high quality. It is to provide a processing method.

According to one aspect of the present invention, there is provided a processing method for processing a work piece, comprising: a first polishing step of polishing the work piece by bringing a polishing pad into contact with a work surface of the work piece; and a first grinding step of grinding the workpiece by bringing a grinding wheel comprising a first grinding wheel into contact with the workpiece surface of the workpiece after performing the first polishing step. A method of machining a workpiece is provided.

Preferably, the method further comprises a second polishing step of polishing the surface of the workpiece after the first grinding step.

More preferably, in the second polishing step, the polishing pad is used to polish the surface of the workpiece.

More preferably, after the first grinding step and before the second polishing step, a grinding wheel comprising a second grinding wheel is brought into contact with the surface of the workpiece to grind the workpiece. wherein the particle size of the abrasive grains contained in the second grinding wheel is smaller than the grain size of the abrasive grains contained in the first grinding wheel.

Alternatively, preferably, after the first grinding step, a second grinding step of grinding the workpiece by bringing a grinding wheel having a second grinding wheel into contact with the workpiece surface of the workpiece. Further, 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.

Preferably, an oxide film is formed on the surface of the workpiece to be polished in the first polishing step.

In the method for processing a workpiece according to one aspect of the present invention, after polishing the workpiece by bringing the polishing pad into contact with the surface to be processed of the workpiece, the workpiece is ground with a grinding wheel having a first grinding wheel. Grind the surface to be processed. In this case, since the surface layer of the surface of the workpiece to be ground has been removed by polishing in advance, the workpiece is ground with a weaker strength than in the case of grinding without previously polishing the surface to be ground. The surface to be processed can be ground. That is, it is possible to reduce the damage caused to the workpiece by grinding, and to process the workpiece in a short time with high quality.

Therefore, according to one aspect of the present invention, there is provided a method for processing a workpiece that can reduce damage caused to the workpiece by grinding and process the workpiece with high quality in a short period of time.

It is a perspective view which shows a grinding-polishing apparatus and a to-be-processed object typically. FIG. 4 is a cross-sectional view schematically showing a first polishing step; It is a sectional view showing a 1st grinding step typically. FIG. 5 is a cross-sectional view schematically showing a second grinding step; FIG. 4 is a cross-sectional view schematically showing a second polishing step; 4 is a flow chart showing the flow of each step of a method for machining a workpiece;

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/polishing device 2 used in the method for processing a workpiece according to this embodiment. The front-rear direction (X-axis direction), the left-right direction (Y-axis direction), and the vertical direction (Z-axis direction) used in the following description are perpendicular to each other.

FIG. 2 includes a cross-sectional view schematically showing the workpiece 11 to be processed by the workpiece processing method 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.

A workpiece 11 in which a surface 11a side is partitioned into a plurality of small regions by a plurality of dividing lines (streets) that intersect each other, and a device such as an IC (Integrated Circuit) is formed in each small region is a workpiece according to the present embodiment. It may be processed by the processing method of the processed product. The back surface 11b side of the workpiece 11 is processed as the surface to be processed. An oxide film, a nitride film, or other functional layers may be formed on the surface to be processed. The oxide film and nitride film are, for example, films composed of oxides or nitrides of elements contained in the workpiece 11 as main components, or films composed of oxides or nitride films of other elements. On the surface 11a side of the workpiece 11, a film-like protective member 13 (see FIG. 2, etc.) or the like is attached for protecting the device.

In addition, the workpiece 11 to be processed is a wafer used for test processing when examining the conditions of processing performed by the grinding and polishing apparatus 2, or a wafer that was not processed appropriately in the device manufacturing process. Wafers may also be used. Then, in the method for processing a workpiece according to the present embodiment, a reclaimed wafer (reclaimed wafer) may be manufactured by processing such a workpiece 11 . An oxide film, a nitride film, or other functional layers may be formed on the back surface 11b side, which is the surface to be processed, of the object 11 to be processed to become a reclaimed wafer.

However, the material, shape, structure, size, etc. of the workpiece 11 are not limited. For example, the workpiece 11 may be a substrate or the like formed using other materials such as semiconductors, ceramics, resins, and metals. Similarly, there are no restrictions on the type, quantity, shape, structure, size, arrangement, etc. of the device. Devices may not be formed on the workpiece 11 . In that case, the protective member 13 may not be attached to the front surface 11a of the workpiece 11 .

Next, the grinding/polishing device 2 will be described in detail. As shown in FIG. 1, the grinding/polishing apparatus 2 includes 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 transport mechanism 6 for transporting a disk-shaped workpiece 11 (see FIG. 2) is provided in the opening 4a. .

Cassette tables 8a and 8b are provided in front of the opening 4a. Cassettes 10a and 10b that can accommodate a plurality of workpieces 11 are placed on the cassette tables 8a and 8b, respectively. A position adjusting mechanism 12 for adjusting the position of the workpiece 11 is provided obliquely behind the opening 4a.

The position adjustment mechanism 12 includes, for example, a table 12a configured to support the central portion of the workpiece 11, and a region outside the table 12a configured to approach and separate from the table 12a. and a plurality of pins 12b. When the workpiece 11 unloaded from the cassette 10a by the transport mechanism 6 is placed on the table 12a, the center of the workpiece 11 is aligned with the center of the table 12a by the plurality of pins 12b.

A carrying-in mechanism 14 capable of holding and rotating the workpiece 11 is provided near the position adjusting mechanism 12 . The carrying-in mechanism 14 includes a suction pad capable of sucking the entire upper surface of the workpiece 11, and conveys the workpiece 11 whose position has been adjusted by the position adjusting mechanism 12 to the rear. A turntable 16 is provided behind the loading mechanism 14 .

The turntable 16 is connected to a drive source (not shown) such as a motor, and rotates around a rotation axis substantially 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 approximately equal angular intervals. The number of chuck tables 18 provided on the turntable 16 is not limited.

The loading mechanism 14 sucks the workpiece 11 with a suction pad and loads it onto a chuck table 18 arranged at a loading/unloading position near the loading mechanism 14 . Each chuck table 18 can be moved by rotating the turntable 16 .

Each chuck table 18 is connected to a drive source (not shown) such as a motor, and rotates around a rotation axis generally parallel to the vertical direction (or slightly inclined with respect to the vertical direction). A part of the upper surface of each chuck table 18 serves as a support surface capable of supporting the workpiece 11 by suction.

This support surface is connected to a suction source (not shown) through a channel (not shown) or the like formed inside the chuck table 18 . The workpiece 11 carried into the chuck table 18 is sucked on the lower side by the negative pressure of the suction source acting on the support surface. FIG. 2 includes a cross-sectional view schematically showing the workpiece 11 held by suction on the chuck table 18. As shown in FIG. In this embodiment, the front surface 11a side of the workpiece 11 is supported by the chuck table 18 via the protective member 13 so that the back surface 11b side of the workpiece 11 is exposed upward.

The grinding and polishing apparatus 2 comprises two grinding units 34 for grinding the workpiece 11 . A columnar support structure 20 is provided on the rear side of the turntable 16 to support the grinding units 34 respectively. A vertical movement mechanism 22 is provided on the front side (turntable 16 side) of each support structure 20 . Each vertical movement mechanism 22 has a pair of guide rails 24 generally parallel to the vertical direction, and a movement plate 26 is slidably attached to the pair of guide rails 24 .

A nut (not shown) constituting a ball screw is fixed to the back side (rear side) of each moving plate 26, and a screw shaft 28 substantially parallel to the guide rail 24 can rotate on this nut. is screwed in. 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 moving plate 26 moves vertically along the guide rail 24 .

A fixture 32 is provided on the surface (front surface) of each moving plate 26 . Each fixture 32 supports a grinding unit 34 for grinding the workpiece 11 . Each grinding unit 34 includes a spindle housing 36 secured to fixture 32 .

Each spindle housing 36 rotatably accommodates a spindle 38 that serves as a rotation axis generally parallel to the vertical direction (or slightly inclined with respect to the vertical direction). A drive source (not shown) such as a motor is connected to the upper end of each spindle 38, and each spindle 38 is rotated by the power of this drive source. A lower end of each spindle 38 is exposed from the lower surface of the spindle housing 36 . A disk-shaped mount 40 is fixed to the lower end of the spindle 38 .

Grinding wheels (processing tools for grinding) 42a and 42b are attached to the lower surface of the mount 40 of each grinding unit 34, respectively. Grinding wheels 42a and 42b have wheel bases formed of a metal material such as stainless steel or aluminum to have approximately the same diameter as mount 40. As shown in FIG. A plurality of grinding wheels 43a and 43b containing abrasive grains made of diamond or the like are fixed to the lower surface of the wheel base (see FIG. 3, etc.).

One of the grinding wheels 42 a and 42 b is used for rough grinding of the workpiece 11 and the other of the grinding wheels 42 a and 42 b is used for finish grinding of the workpiece 11 . The grain size of the abrasive grains contained in the grinding wheels 43a and 43b for finish grinding is generally smaller than the grain size of the abrasive grains contained in the grinding wheels for rough grinding.

In the vicinity of each of the grinding wheels 42a and 42b, liquid supply nozzles (not shown) are provided for supplying a liquid (grinding liquid) such as pure water to regions (processing points) of the workpiece 11 in contact with the grinding wheels 43a and 43b. ) are placed. A contact-type or non-contact-type thickness gauge (not shown) for measuring the thickness of the workpiece 11 is arranged near each of the grinding wheels 42a and 42b. An opening for supplying liquid may be provided in each grinding wheel 42a, 42b and used as a liquid supply nozzle.

The grinding and polishing apparatus 2 includes a polishing unit 66 that polishes 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 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 slidable manner. ing.

A nut (not shown) that constitutes a ball screw is fixed to the rear surface side (support structure 44 side) of the first moving plate 50 . A screw shaft 52 is screwed in such a manner that it can 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 moving plate 50 moves forward and backward along the first guide rail 48 .

A pair of second guide rails 56 that are substantially parallel to the vertical direction are provided on the surface side of the first moving plate 50 . A second moving plate 58 is slidably attached to the pair of second guide rails 56 . A nut (not shown) constituting a ball screw is fixed to the back side of the second moving plate 58 (on the side of the first moving plate 50). A generally parallel threaded shaft 60 is threaded in a rotatable manner.

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 moving plate 58 moves vertically along the second guide rail 56 . A fixture 64 is provided on the surface of the second moving plate 58 . A polishing unit 66 for polishing the workpiece 11 is supported by the fixture 64 .

Polishing unit 66 includes a spindle housing 68 secured to fixture 64 . The spindle housing 68 rotatably accommodates a spindle 70 serving as a rotation axis generally parallel to the vertical direction (or slightly inclined with respect to the vertical direction). A drive source (not shown) such as a motor is connected to the upper end side of the spindle 70, and the spindle 70 is rotated by the power of this drive source.

A lower end of the spindle 70 is exposed from the lower surface of the spindle housing 68 . A disk-shaped mount 72 is fixed to the lower end of the spindle 70 . A polishing pad (processing tool for polishing) 74 made of resin such as polyurethane foam or non-woven fabric is attached to the lower surface of the mount 72 .

The diameter of this polishing pad 74 is equal to or less than the radius of the chuck table 18 . Therefore, even when the polishing pad 74 is brought into contact with the workpiece 11 to process the workpiece 11, a part of the workpiece 11 is exposed upward. When the workpiece 11 is processed by contacting the polishing pad 74, the polishing pad 74 (or the chuck table 18) is horizontally moved so as not to cause uneven processing.

However, the diameter of the polishing pad 74 used in the grinding/polishing apparatus 2 is not limited to this. That is, the diameter of polishing pad 74 may exceed the radius of workpiece 11 or may exceed the diameter of 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.

The polishing pad 74 is provided with, for example, an opening for supplying a liquid (polishing liquid) in which abrasive grains are dispersed to a region (processing point) of the workpiece 11 that contacts the polishing pad 74. may be When polishing the workpiece 11 , a polishing liquid may be supplied between the workpiece 11 and the polishing pad 74 .

Alternatively, abrasive grains may be dispersed and fixed on the polishing pad 74 . When polishing the workpiece 11, the polishing liquid does not have to be supplied to the workpiece 11 and the like. That is, the grinding and polishing apparatus 2 may perform wet polishing or dry polishing on the workpiece 11 .

Further, the grinding and polishing apparatus 2 may be provided with a thickness measuring device for measuring the thickness of the workpiece 11 near the polishing unit 66 . In the grinding and polishing apparatus 2, while the thickness of the workpiece 11 polished by the polishing unit 66 and the thickness distribution of the surface to be processed are monitored, the polishing unit 66 polishes the workpiece 11 until it reaches a predetermined thickness. may be

As shown in FIG. 1, a carry-out mechanism 80 that can hold and turn the workpiece 11 after being processed by the grinding unit 34 and the polishing unit 66 is provided at a side position of the carry-in mechanism 14 . A cleaning mechanism 82 configured to clean the workpiece 11 carried out by the carry-out mechanism 80 is arranged in front of the carry-out mechanism 80 and behind the opening 4a. The workpiece 11 cleaned by the cleaning mechanism 82 is transported by the transport mechanism 6 and stored in, for example, the cassette 10b.

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

Here, the workpiece 11 desired to be processed by the grinding and polishing apparatus 2 will be further described. In a series of steps for forming devices on the surface of a wafer, some steps may not be performed properly, failing to form normal devices. In this case, even if the wafer is divided as it is, normal device chips cannot be manufactured. Therefore, it is desirable to process a wafer as the workpiece 11 by the grinding/polishing apparatus 2 to remove unnecessary layers, thereby fabricating a wafer that can be used for manufacturing new device chips.

In addition, in the device chip manufacturing process, each step requires appropriate processing conditions for processing the wafer as intended. Then, in order to derive the appropriate machining conditions, a large number of test machining are repeated and the machining results are evaluated. A large number of wafers are required to perform the test process, but the test process does not require the use of high quality wafers. Therefore, it is desirable to process wafers that have been used for test processing or wafers for which device formation has failed with the grinding and polishing apparatus 2 to produce wafers that can be used for test processing.

Oxide films, nitride films, and other functional layers may be formed on the back surface 11b side of the workpiece 11 that is desired to be processed by the grinding and polishing apparatus 2. Removal of the provided hard layer 15 (see FIG. 2) may be desired. Moreover, the workpiece 11 itself may be formed of a hard material.

In the grinding and polishing apparatus 2, abrasive grains having a particularly large particle size are used for the purpose of sufficiently removing the hard layer 15 formed on the back surface 11b of the workpiece 11, which is the surface to be processed, and for other purposes. Grinding wheels 43a, 43b, which include the grinding wheels, may be used for rough grinding. Alternatively, rough grinding may be performed under conditions of high strength.

However, in these cases, damage caused to the surface to be processed and the outer peripheral edge of the workpiece 11 increases due to the load due to rough grinding. Therefore, it is necessary to perform finish grinding for a long time in order to sufficiently remove the damaged layer, and the processing speed of the grinding and polishing apparatus 2 decreases. In addition, the quality of the workpiece 11 may deteriorate due to insufficient removal of the damaged layer by finish grinding.

Therefore, the workpiece 11 is processed in a short time and with high quality while reducing the damage caused to the workpiece 11 by grinding by the method for processing the workpiece 11 according to the present embodiment described below. The method for processing a workpiece according to this embodiment will be described in detail below. FIG. 6 is a flow chart showing the flow of each step of the method for machining a workpiece according to this embodiment. However, some of the steps described in the flowchart of FIG. 6 may not be performed, and further steps not described in the flowchart may be performed.

The method for processing a workpiece according to this embodiment is mainly performed by the grinding/polishing apparatus 2 . First, a first polishing step S10 of polishing the workpiece 11 by bringing the polishing pad 74 into contact with the surface to be processed (back surface 11b) of the workpiece 11 is performed.

In the first polishing step S10, first, the workpiece 11 is unloaded from the cassettes 10a and 10b and placed on the upper surface of the chuck table . In this process, the position of the workpiece 11 is adjusted by the position adjusting mechanism 12 with the back surface 11b side of the workpiece 11 facing upward, and the carrying operation of the workpiece 11 by the loading mechanism 14 is performed. be carried out as prescribed. Then, the center of the workpiece 11 and the center of the upper surface of the chuck table 18 overlap.

Then, the chuck table 18 sucks and holds the workpiece 11 . A tape-shaped protective member 13 may be adhered to the surface 11 a of the workpiece 11 to protect the surface 11 a of the workpiece 11 . That is, the workpiece 11 is held by suction on the chuck table 18 via the protective member 13 . Then, the turntable 16 is rotated clockwise when viewed from above, and the chuck table 18 sucking and holding the workpiece 11 is sent below the polishing unit 66 . FIG. 2 is a cross-sectional view schematically showing the first polishing step S10.

Next, the chuck table 18 and the polishing pad 74 are mutually rotated to bring the lower surface of the polishing pad 74 into contact with the rear surface 11b side (upper surface side) of the workpiece 11 exposed upward. Thereby, the workpiece 11 is polished by the polishing pad 74 . At this time, the moving mechanism 46 is operated to keep moving the polishing pad 74 along a direction substantially parallel to the vertical direction so that the entire area of the back surface 11b side of the workpiece 11 can be uniformly polished.

When polishing the workpiece 11 , a polishing liquid containing abrasive grains may be supplied to the workpiece 11 and the polishing pad 74 . Alternatively, when polishing the workpiece 11 , the workpiece 11 and the polishing pad 74 may not be supplied with a polishing liquid containing abrasive grains. The type of the polishing pad 74 and whether or not to supply polishing liquid may be determined according to the material of the workpiece 11 and the type of the hard layer 15 to be removed.

By polishing the workpiece 11 with the polishing pad 74, the thickness of the workpiece 11 can be reduced. Further, when the hard layer 15 is formed on the surface to be processed (back surface 11b) 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 is monitored by the thickness gauge, and polishing of the workpiece 11 is finished when the workpiece 11 reaches a predetermined thickness. do it.

The processing load applied to the workpiece 11 when polishing the workpiece 11 is greater than the processing load applied to the workpiece 11 when grinding the workpiece 11 (the load applied to the workpiece 11 by rough grinding). small. Therefore, when the workpiece 11 is polished with the polishing pad 74 , the workpiece 11 does not have a damaged layer that occurs on the surface of the workpiece 11 when the workpiece 11 is ground.

After performing the first polishing step S10, the first grinding step S20 is performed. In the first grinding step S20, the grinding wheels 42a and 42b having the first grinding wheel are brought into contact with the surface to be processed (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 grinder 2 . FIG. 3 is a cross-sectional view schematically showing the first grinding step S20.

When performing the first grinding step S<b>20 , the turntable 16 is rotated clockwise to move the chuck table 18 sucking and holding the workpiece 11 under one of the two grinding units 34 . For example, when using the grinding unit 34 having the grinding wheel 42 b in the first grinding step S<b>20 , the chuck table 18 is moved below the grinding unit 34 .

Then, while supplying grinding water such as pure water to the workpiece 11 and the grinding wheel 42b, the chuck table 18 and the grinding wheel 42b are mutually rotated to move the back surface 11b side (upper surface side) of the workpiece 11. The grinding stone 43b of the grinding wheel 42b is brought into contact.

Here, when the workpiece 11 is ground in two steps of rough grinding and finish grinding, in the first grinding step S20, the workpiece 11 is rough ground, and the first grinding step S20 is performed. Next, as finish grinding of the workpiece 11, a second grinding step S30 is performed. FIG. 4 is a cross-sectional view schematically showing the second grinding step S30.

When performing the second grinding step S<b>30 , the turntable 16 is rotated to move the chuck table 18 sucking and holding the workpiece 11 to the other of the two grinding units 34 . In the second grinding step S30, grinding wheels 42a and 42b having second grinding wheels are brought into contact with the surface to be processed (back surface 11b) of the workpiece 11 to grind the workpiece.

For example, when using the grinding unit 34 having the grinding wheel 42 a in the second grinding step S<b>30 , the chuck table 18 is moved below the grinding unit 34 .
Then, while supplying grinding water such as pure water to the workpiece 11 and the grinding wheel 42a, the chuck table 18 and the grinding wheel 42a are mutually rotated, and the back surface 11b side (upper surface side) of the workpiece 11 is rotated. The grinding stone 43a of the grinding wheel 42a is brought into contact.

When the workpiece 11 is ground in two steps, 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 accuracy. In each grinding step, the thickness of the workpiece 11 is monitored by a thickness gauge, and grinding of the workpiece 11 is finished when the workpiece 11 reaches a predetermined thickness.

When the workpiece 11 is thinned to a predetermined finish thickness by the grinding and polishing apparatus 2, most of the total amount of grinding planned for the workpiece 11 is ground in the rough grinding (first grinding step S20). . Further, in the finish grinding (second grinding step S30), the workpiece 11 is thinned to a predetermined finish thickness while removing the damaged layer generated in the workpiece 11 in the rough grinding.

Here, by polishing the workpiece 11 with the polishing pad 74 in the first polishing step S10, the thickness of the workpiece 11 can be reduced to some extent. Therefore, when the workpiece 11 is finally thinned to a predetermined thickness, the amount of the workpiece 11 to be removed by grinding is reduced. That is, the amount of grinding of the workpiece 11 in the rough grinding (first grinding step S20) can be reduced. In this case, since the damaged layer formed on the surface to be processed of the workpiece 11 by the rough grinding is reduced, the finish grinding (second grinding step S30) can also be performed in a short time and with high quality.

In addition, when the workpiece 11 has a hard layer 15 on the surface to be processed and the hard layer 15 is to be removed, it is assumed that the workpiece 11 is rough-ground without being polished. If layer 15 is removed, rough grinding will result in the formation of a relatively thick damage layer on workpiece 11 . This requires grinding the workpiece 11 using a grinding wheel to which a grinding wheel containing abrasive grains with a relatively large grain size is fixed, or grinding the workpiece 11 with relatively high strength. Because there is

In these cases, finish grinding must be performed for a long time to remove the thick damaged layer, and the efficiency of processing the workpiece 11 in the grinding and polishing apparatus 2 is lowered. In addition, the damaged layer may not be sufficiently removed by finish grinding, and the quality of the workpiece 11 after finish grinding is degraded.

In contrast, in the method for processing a workpiece according to the present embodiment, the hard layer 15 formed on the workpiece 11 is removed in the first polishing step S10. Therefore, when grinding the workpiece 11, there is no need to use a grinding wheel to which a grinding wheel containing abrasive grains with a relatively large grain size is fixed, and the workpiece 11 can be ground with relatively low strength. In this case, since the damage layer formed on the workpiece 11 by polishing is reduced, the workpiece 11 can be ground in a short period of time with high quality.

In addition, in the method for processing a workpiece according to the present embodiment, the second polishing step S40 may be performed after the workpiece 11 is ground in the first grinding step S20. 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 surface to be processed (back surface 11b) of the workpiece 11 is polished.

In the second polishing step S40, the polishing pad 74 used in the first polishing step S10 may be used to polish the surface of the workpiece 11 to be processed. Alternatively, in the second polishing step S40, the polishing pad 74 used in the first polishing step S10 may not be used, and another polishing pad may be used. In this case, for example, the workpiece 11 may be carried out of the grinding/polishing apparatus 2 and the second polishing step S40 may be performed by a polishing apparatus (not shown) outside the grinding/polishing apparatus 2 .

The second polishing step S40 is carried out for the purpose of removing fine irregularities formed on the surface to be processed of the workpiece 11 by grinding, planarizing the surface to be processed, and finishing the surface to be processed into a mirror surface. Sometimes. The second polishing step S40 can be performed by the polishing unit 66 when the polishing unit 66 of the grinding/polishing apparatus 2 meets the purpose of performing the second polishing step S40. On the other hand, if the polishing unit 66 is not suitable for this implementation purpose, the second polishing step S40 may be performed in a suitable polishing device external to the grinding and polishing device 2 .

The second polishing step S<b>40 will be described below by taking as an example the case where it is performed by the grinding/polishing apparatus 2 . FIG. 5 is a cross-sectional view schematically showing the second polishing step S40. In the second polishing step S<b>40 , the turntable 16 is rotated to send the chuck table 18 sucking and holding the workpiece 11 below the polishing unit 66 .

Next, the chuck table 18 and the polishing pad 74 are mutually rotated to bring the lower surface of the polishing pad 74 into contact with the rear surface 11b side (upper surface side) of the workpiece 11 exposed upward. Thereby, the workpiece 11 is polished by the polishing pad 74 . At this time, the moving mechanism 46 is operated to keep moving the polishing pad 74 along a direction substantially parallel to the vertical direction so that the entire area of the back surface 11b side of the workpiece 11 can be uniformly polished.

When polishing the workpiece 11 , a polishing liquid containing abrasive grains may be supplied to the workpiece 11 and the polishing pad 74 . Alternatively, when polishing the workpiece 11 , the workpiece 11 and the polishing pad 74 may not be supplied with a polishing liquid containing abrasive grains.

Here, the polishing conditions in the second polishing step S40 need not be the same as the polishing conditions in the first polishing step S10. For example, in the first polishing step S10 and the second polishing step S40, the rotation speed of the polishing pad 74, the rotation speed of the chuck table 18, the descent speed of the polishing unit 66, the presence or absence of supply of polishing liquid and its supply amount, the processing The time, etc. may be different.

When the second polishing step S40 is performed, the unevenness of the surface to be processed of the workpiece 11 is removed and the surface to be processed is finished to a mirror surface. After that, the turntable 16 is rotated to move the chuck table 18 to a position where the unloading mechanism 80 can access the workpiece 11 . Then, the suction holding of the workpiece 11 by the chuck table 18 is released, the carry-out mechanism 80 transports the workpiece 11 to the cleaning mechanism 82 , and the cleaning mechanism 82 cleans the workpiece 11 . Thereafter, the workpiece 11 is accommodated in the cassettes 10a and 10b by the transport mechanism 6. As shown in FIG.

As described above, in the method for processing a workpiece according to the present embodiment, the surface to be processed of the workpiece 11 is polished before being ground. Therefore, the workpiece 11 is thinned. Further, when the hard layer 15 is formed on the surface of the workpiece 11 to be processed, the hard layer 15 can be removed by polishing. Therefore, the strength of the grinding performed on the workpiece 11 is reduced, the damage caused to the workpiece 11 is reduced, and the workpiece 11 can be processed in a short time and with high quality.

It should be noted that the present invention is not limited to the description of the above-described embodiment and can be implemented with various modifications. For example, in the above-described embodiment, the thickness of the workpiece 11 is monitored by a thickness gauge in each process, and the workpiece 11 is processed until it reaches a predetermined thickness. The aspect is not limited to this. In one aspect of the present invention, the thickness of the workpiece 11 may not be monitored with a thickness gauge at each step.

When the workpiece 11 having the hard layer 15 formed on the back surface 11b side is processed by the grinding and polishing apparatus 2 to form a reclaimed wafer, the hard layer 15 is removed while the workpiece 11 remains as thick as possible. It may be desired that the workpiece 11 be machined. In this case, in the first polishing step S10 of the method for processing a workpiece according to one aspect of the present invention, the surface to be processed of the workpiece 11 may be polished until the hard layer 15 is removed.

In the method for processing a workpiece according to one aspect of the present invention, since the hard layer 15 can be removed by polishing, a thick damaged layer is formed on the workpiece 11 unlike the case where the hard layer 15 is removed by grinding. no. Therefore, even if the amount of the workpiece 11 removed by machining is not large, the workpiece 11 after machining satisfies a certain level. That is, relatively thick reclaimed wafers that can be used for test processing or the like can be manufactured.

Further, in the above-described embodiment, the case where the first polishing step S10, the first grinding step S20, the second grinding step S30, and the second polishing step S40 are performed has been mainly described. , one aspect of the present invention is not limited to this. For example, in the method for processing a workpiece according to one aspect of the present invention, the second polishing step S40 may be omitted.

When performing the first polishing step S10, the first grinding step S20, and the second grinding step S30 in this order, first, the polishing unit 66 polishes the workpiece 11. FIG. Thereafter, the turntable 16 is rotated clockwise to move the chuck table 18, and the workpiece 11 is roughly ground by the grinding wheel 42b having the grinding wheel 43b. Then, the turntable 16 is further rotated clockwise to move the chuck table 18, and finish grinding of the workpiece 11 is performed by the grinding wheel 42a having the grinding wheel 43a.

When performing the first polishing step S10, the first grinding step S20, the second grinding step S30, and the second polishing step S40 in the grinding/polishing apparatus 2, first, the polishing unit 66 A workpiece 11 is polished. After that, the turntable 16 is rotated counterclockwise to move the chuck table 18, and the workpiece 11 is roughly ground by the grinding wheel 42a having the grinding wheel 43a. That is, in the first grinding step S20, the grinding wheel 43a is used as the first grinding wheel.

After that, the turntable 16 is rotated counterclockwise to move the chuck table 18, and the workpiece 11 is finish-ground by the grinding wheel 42b having the grinding wheel 43b. That is, in the second grinding step S30, the grinding wheel 43b is used as the second grinding wheel. After that, the turntable 16 is further rotated counterclockwise to move the chuck table 18 , and the polishing unit 66 polishes the workpiece 11 .

By switching the rotation direction of the turntable 16 of the grinding/polishing apparatus 2 in this way, various aspects of the method for processing a workpiece according to the present invention can be implemented in the grinding/polishing apparatus 2 . That is, by modifying the control program of the control unit, the method for processing a workpiece according to the present invention can be implemented even with the existing grinding and polishing apparatus 2 .

In addition, the structures, methods, and the like according to the above-described embodiments and modifications can be modified without departing from the scope of the present invention.

REFERENCE SIGNS LIST 11 workpiece 11a front surface 11b rear surface 13 protective member 15 hard layer 2 grinding and polishing device 4 base 4a opening 6 transport mechanism 8a, 8b cassette table 10a, 10b cassette 12 position adjustment mechanism 12a table 12b pin 14 loading mechanism 16 turntable 18 Chuck Table 20, 44 Support Structure 22 Vertical Movement Mechanism 24, 48, 56 Guide Rail 26, 50, 58 Movement Plate 28, 52, 60 Screw Shaft 30, 54, 62 Pulse Motor 32, 64 Fixture 34 Grinding Unit 36, 68 Spindle housing 38, 70 Spindle 40, 72 Mount 42a, 42b Grinding wheel 43a, 43b Grinding wheel 46 Moving mechanism 66 Polishing unit 74 Polishing pad 80 Unloading mechanism 82 Cleaning mechanism

Claims (6)

A processing method for processing a workpiece,
a first polishing step of contacting a polishing pad with a surface to be processed of the workpiece to polish the workpiece;
and a first grinding step of grinding the workpiece by bringing a grinding wheel comprising a first grinding wheel into contact with the workpiece surface of the workpiece after performing the first polishing step. A method of processing a workpiece characterized by: 2. The method of processing a workpiece according to claim 1, further comprising a second polishing step of polishing the surface of the workpiece after the first grinding step. 3. The method of processing a workpiece according to claim 2, wherein in the second polishing step, the surface of the workpiece is polished using the polishing pad. After the first grinding step and before the second polishing step, a grinding wheel having a second grinding wheel is brought into contact with the surface of the workpiece to grind the workpiece. further comprising 2 grinding steps;
4. The workpiece according to claim 2, wherein the grain size of the abrasive grains contained in the second grinding wheel is smaller than the grain size of the abrasive grains contained in the first grinding wheel. method of processing things. After the first grinding step, further comprising a second grinding step of grinding the workpiece with a grinding wheel comprising a second grinding wheel in contact with the surface to be processed of the workpiece;
2. The method of machining a workpiece according to claim 1, wherein the grain size of the abrasive grains contained in the second grinding wheel is smaller than the grain size of the abrasive grains contained in the first grinding wheel. . 6. The workpiece according to any one of claims 1 to 5, wherein an oxide film is formed on the surface of the workpiece to be polished in the first polishing step. processing method.

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