JP6827289B2 - Wafer processing method and polishing equipment - Google Patents

Description

The present invention relates to a wafer processing method and a polishing apparatus.

In the electronic device manufacturing process, a plurality of regions are divided by scheduled division lines called streets arranged in a grid pattern on the surface of a silicon substrate or the like having a substantially disk shape, and ICs (Integrated Circuits) are used in each of the regions. A device such as an LSI (Large-Scale Integration) is formed. By dividing the wafer in which a plurality of devices are formed in this way along the street, individual devices are formed. In order to reduce the size and weight of the device, the back surface of the wafer is usually ground to a predetermined thickness prior to cutting the wafer along the street to divide individual regions.

When the back surface of the wafer as described above is ground, a grinding strain layer of about 1 μm composed of microcracks is generated on the back surface of the device. Further, since the bending strength of the device is lowered by the grinding strain layer, the back surface of the wafer is ground to form a predetermined thickness, and then the back surface of the wafer is polished, etched, etc. to be generated on the back surface of the wafer. The grinding strain layer is removed to prevent a decrease in the bending strength of the device.

On the other hand, when the strain layer on the back surface is removed, the gettering effect is reduced and metal ions such as copper contained inside the wafer move to the front surface side where the device is formed, which may cause a current leak. .. In order to solve such a problem, a grinding strain layer (gettering layer) is formed on the back surface of the wafer.

However, in order to carry out the above, a polishing means and a gettering layer forming means are required, and there is a problem that the apparatus configuration becomes complicated. In response to this problem, Patent Document 1 proposes a polishing apparatus including a polishing pad having both a polishing function and a gettering layer forming function (see, for example, Patent Document 1).

JP-A-2015-046550

From the viewpoint of improving productivity, it is desired to shift to the formation of a gettering layer immediately after polishing, but the polishing pad after polishing contains a polishing liquid, and the gettering layer is not formed immediately. Further, even if the polishing is completed to the value as designed, the polishing pad containing the polishing liquid comes into contact with the wafer, and the wafer may be eroded beyond the design value.

Therefore, an object of the present invention is to provide a wafer processing method and a polishing apparatus capable of promptly shifting to gettering layer formation after polishing and processing the wafer as designed.

In order to solve the above-mentioned problems and achieve the object, the processing method of the waiha of the present invention uses a polishing pad having abrasive grains having a higher moth hardness than the waiha, and the waiha in which a device is formed on the surface of the waiha. It is a method of processing a waiha that forms a gettering layer on the back surface of the waha, in which a protective member is attached to the surface of the waha and the protective member side is held on the holding surface of the chuck table, and the polishing pad is polished. A strain layer removing step of removing a strain layer from the back surface of a waiha by polishing the back surface of the waiha with the polishing pad while rotating the polishing pad while supplying a liquid and removing the strain layer. After performing the process , the rinse liquid supplied from the rinse liquid supply source is supplied to the polishing pad from the nozzle, and the abrasive liquid supplied from the liquid supply source is supplied to the back surface of the wafer from the nozzle to perform the polishing. a polishing liquid removing step of removing the residual polishing solution contained in the pad, along with supplying liquid without containing abrasive grains is supplied from the liquid supply source from the nozzle to the rear surface of 該U Eha, the rinse to the polishing pad The polishing pad is rotated while the rinse liquid supplied from the liquid supply source is supplied from the nozzle, and the back surface of the wafer is polished by the polishing pad while rotating the chuck table to form a gettering layer on the back surface. It is characterized by including a gettering layer forming step.

The gettering layer forming step may be performed while moving the chuck table horizontally with respect to the polishing pad.

The polishing device of the present invention is a polishing device for polishing a waha, and a chuck table for rotatably holding the waha and a waha held on the chuck table are polished to form a gettering layer on the polished waha. A polishing means having a polishing pad, a polishing liquid supply source for supplying a polishing liquid to the wafer and the polishing pad, and a liquid supply source for supplying a liquid containing no abrasive grains different from the polishing liquid to the wafer and the polishing pad. At least the polishing means and the chuck table are controlled to polish the wafer while supplying the polishing liquid, and then the control means for forming the gettering layer while supplying the liquid containing no abrasive grains and the chuck. Adjacent to the table, it includes a nozzle that supplies a rinse solution for removing the polishing solution toward the polishing pad, and the control means further polishes the wafer and then shifts to the gettering layer formation. , and when forming the gettering layer, the nozzle with that teapot subjected rinsing liquid toward the polishing pad from the nozzle, a liquid which does not contain the supplied the abrasive grains from the liquid supply source to the back surface of the wafer It is characterized by controlling to supply from .

According to the present invention, by shortening the time required for transition from polishing to gettering layer formation, productivity can be improved and processing can be performed as designed.

FIG. 1 is a perspective view showing a wafer to be processed in the wafer processing method according to the first embodiment. FIG. 2 is a perspective view of a configuration example of a grinding and polishing apparatus used in the wafer processing method according to the first embodiment. FIG. 3 is a perspective view showing a configuration example of a polishing means of the grinding and polishing apparatus shown in FIG. FIG. 4 is a flowchart showing a flow of a wafer processing method according to the first embodiment. FIG. 5 is a cross-sectional view of a wafer in which a BG tape is attached to the surface of the wafer holding step of the wafer processing method according to the first embodiment. FIG. 6 is a diagram showing a strain layer removing step of the wafer processing method according to the first embodiment. FIG. 7 is a diagram showing a polishing liquid removing step of the wafer processing method according to the first embodiment. FIG. 8 is a diagram showing a gettering layer forming step of the wafer processing method according to the first embodiment. FIG. 9 is a diagram showing an individualization step of the wafer processing method according to the first embodiment. FIG. 10 is a diagram showing a strain layer removing step of the wafer processing method according to the second embodiment. FIG. 11 is a diagram showing a polishing liquid removing step of the wafer processing method according to the second embodiment. FIG. 12 is a diagram showing a gettering layer forming step of the wafer processing method according to the second embodiment. FIG. 13 is a diagram showing a polishing liquid removing step of the wafer processing method according to the first modification of the second embodiment.

An embodiment (embodiment) for carrying out the present invention will be described in detail with reference to the drawings. The present invention is not limited to the contents described in the following embodiments. In addition, the components described below include those that can be easily assumed by those skilled in the art and those that are substantially the same. Further, the configurations described below can be combined as appropriate. In addition, various omissions, substitutions or changes of the configuration can be made without departing from the gist of the present invention.

[Embodiment 1]
The method of processing the wafer according to the first embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a perspective view showing a wafer to be processed in the wafer processing method according to the first embodiment. FIG. 2 is a perspective view of a configuration example of a grinding and polishing apparatus used in the wafer processing method according to the first embodiment. FIG. 3 is a perspective view showing a configuration example of a polishing means of the grinding and polishing apparatus shown in FIG.

The method for processing a wafer according to the first embodiment is a method in which a gettering layer G is formed on the back surface WR of the wafer W and the wafer W is divided into device chips DT (indicated by a dotted line in FIG. 1). As shown in FIG. 1, the wafer W is a disk-shaped semiconductor wafer or optical device wafer using silicon as a base material. In the wafer W, the device DV is formed in a region partitioned by a plurality of streets S formed in a grid pattern on the surface WS. That is, in the wafer W, a plurality of device DVs are formed on the surface WS. In the wafer W, the back surface WR on the back side of the front surface WS is subjected to grinding or the like to be thinned to a predetermined thickness, and then a gettering layer G is formed on the back surface WR side. The gettering layer G is a layer in which crystal defects, strains, etc. (called gettering sites) are formed on the back surface WR of the wafer W, that is, the back surface WR of each device DV, and the gettering sites capture impurities that cause metal contamination. , A layer that sticks. In the first embodiment, the wafer W is divided into a device chip DT including the device DV after the gettering layer G is formed on the back surface WR side, but the wafer W is divided into the device chip DT including the device DV, but is on the front surface WS side before being ground by the grinding device 1. A gettering layer G may be formed on the back surface WR side after a groove that does not reach the back surface WR is formed and divided into device chip DTs by the grinding and polishing device 1.

As the method for processing the wafer according to the first embodiment, at least the grinding and polishing apparatus 1 as the polishing apparatus shown in FIG. 2 is used. The grinding and polishing apparatus 1 grinds the back surface WR of the wafer W to make it thinner, flattens the back surface WR of the ground wafer W with high accuracy, and provides a gettering layer G on the back surface WR side of the wafer W. It is polished to form. As shown in FIG. 2, the grinding and polishing apparatus 1 includes an apparatus main body 2, a first grinding means 3, a second grinding means 4, a polishing means 5, and four, for example, four installed on a turntable 6. It mainly includes a chuck table 7, cassettes 8 and 9, an alignment means 10, a carry-in means 11, a cleaning means 13, a carry-in / out means 14, and a control means 100.

The first grinding means 3 is a Z parallel to the back surface WR of the wafer W held on the chuck table 7 at the rough grinding position B while the grinding wheel 31 having the grinding wheel mounted on the lower end of the spindle is rotated. It is for rough grinding the back surface WR of the wafer W by being pressed along the axial direction. Similarly, the second grinding means 4 is a rough-ground wafer W held on a chuck table 7 located at the finish grinding position C while the grinding wheel 41 having a grinding wheel mounted on the lower end of the spindle is rotated. The back surface WR of the wafer W is finished and ground by being pressed by the back surface WR along the Z-axis direction.

The polishing means 5 has a polishing pad 51 that polishes the wafer W held on the chuck table 7 and forms a gettering layer G on the wafer W. In the first embodiment, as shown in FIG. 3, the polishing means 5 arranges the polishing pad 51 mounted on the lower end of the spindle 54 so as to face the holding surface 7a of the chuck table 7. The polishing means 5 is a polishing feeding means 53 along the Z-axis direction to the back surface WR of the finish-ground wafer W held on the holding surface 7a of the chuck table 7 located at the polishing position D while the polishing pad 51 is rotated. Pressed by. The polishing means 5 is for polishing the back surface WR of the wafer W by pressing the polishing pad 51 against the back surface WR of the wafer W along the Z-axis direction.

The polishing pad 51 of the polishing means 5 contains 20 to 50% by weight of abrasive grains having an average particle size of 0.35 to 1.7 (μm) [median]. The average particle size means the particle size at an integrated value of 50% in the particle size distribution obtained by the laser diffraction / scattering method. The particle size at an integrated value of 50% means the particle size when the number of particles is counted from the smallest particle size to 50% of the total number of particles. The abrasive grains contained in the polishing pad 51 have a higher Mohs hardness than the silicon constituting the wafer W, and examples of the abrasive grains suitable for forming the gettering layer G include GC (green silicon carbide). WA (white array) and diamond can be used. Further, as the abrasive grains contained in the polishing pad 51, for example, silica (SiO ₂ ), zirconia (ZrO ₂ ) or ceria (CeO ₂ ) can be used as the abrasive grains suitable for the polishing process. In the first embodiment, the polishing pad 51 contains both abrasive grains suitable for forming a gettering layer G such as GC and abrasive grains suitable for polishing processing such as silica.

The polishing means 5 supplies the polishing pad 51 from the polishing liquid supply source 15 via the switching valve 12 to the back surface WR of the wafer W from the nozzle 16 which is separate from the polishing pad 51. After polishing the back surface WR of the wafer W using the method, a liquid L (pure water in the first embodiment) containing no abrasive grains from the liquid supply source 17 is applied from the nozzle 16 to the wafer W via the switching valve 12. The gettering layer G is formed on the back surface WR side of the wafer W by using the polishing pad 51 while supplying the back surface WR. At that time, the bending strength of the wafer W is maintained. In the first embodiment, the bending strength of the wafer W is maintained at 1000 MPa or more, but the present invention is not limited to this, and a value may be set so as to obtain a desired device strength. Here, the liquid containing no abrasive grains may be a liquid that does not react with the wafer W, and when the wafer W is made of silicon, pure water or pure water may contain additives, and the wafer W is substantially used. Any liquid that does not react with can be used.

As described above, the polishing liquid supply source 15 supplies the polishing liquid GL to the wafer W and the polishing pad 51. The liquid supply source 17 supplies the wafer W and the polishing pad 51 with a liquid L that does not contain abrasive grains different from the polishing liquid GL.

The polishing means 5 is a rinse liquid CL (pure water in the first embodiment) for removing the polishing liquid GL from the polishing pad 51 from the rinse liquid supply source 19 after the polishing process is applied to the back surface WR of the wafer W. Is supplied from the nozzle 20 to the rotating polishing pad 51. The rinse liquid CL may be a liquid that does not react with the wafer W, and if the wafer W is made of silicon, it may contain additives in pure water or pure water, and may be a liquid that does not substantially react with the wafer W. Just do it. Further, as shown in FIG. 3, the polishing means 5 moves the polishing pad 51 together with the spindle 54 in the X-axis direction 52 which is orthogonal to the Z-axis direction and parallel to the width direction of the apparatus main body 2. Be prepared. The nozzle 20 is provided adjacent to the chuck table 7 at the polishing position D, supplies the rinse liquid CL toward the polishing pad 51, and has a slit-shaped discharge shape.

In the first embodiment, the polishing pad 51 contains both abrasive grains suitable for forming a gettering layer G such as GC and abrasive grains suitable for polishing processing such as silica, but in the present invention. The polishing pad 51 may contain at least one of abrasive grains suitable for forming a gettering layer G such as GC and abrasive grains suitable for polishing processing such as silica. When the polishing pad 51 contains only abrasive grains suitable for forming a gettering layer G such as GC as abrasive grains, polishing of silica or the like in the polishing liquid GL supplied from the polishing liquid supply source 15. Abrasive grains suitable for processing may be contained, and when the polishing pad 51 contains only abrasive grains suitable for polishing processing such as silica as abrasive grains, the liquid L supplied from the liquid supply source 17 May contain abrasive grains suitable for forming a gettering layer G such as GC.

Further, in the first embodiment, the rinse liquid CL supplied from the rinse liquid supply source 19 is pure water, but in the present invention, it may be two fluids in which pure water and high-pressure gas are mixed.

The turntable 6 is a disk-shaped table provided on the upper surface of the apparatus main body 2, is rotatably provided in a horizontal plane, and is rotationally driven at a predetermined timing. On the turntable 6, for example, four chuck tables 7 are arranged at equal intervals with a phase angle of, for example, 90 degrees. These four chuck tables 7 have a chuck table structure in which the wafer W is rotatably held and the holding surface 7a is provided with a vacuum chuck, and the wafer W placed on the holding surface 7a is evacuated. Adsorb and hold. These chuck tables 7 are rotationally driven in a horizontal plane by a rotational drive mechanism with an axis parallel to the vertical direction as a rotational axis during grinding and polishing. As described above, the chuck table 7 has a holding surface 7a that rotatably holds the wafer W as the workpiece. Such a chuck table 7 is sequentially moved to the carry-in / carry-out position A, the rough grinding position B, the finish grinding position C, the polishing position D, and the carry-in / carry-out position A by the rotation of the turntable 6.

The cassettes 8 and 9 are accommodators for accommodating a wafer W having a plurality of slots. One cassette 8 accommodates a wafer W to which a protective member BG (Back Grind) tape T (shown in FIG. 5) is attached to the surface WS before grinding and polishing, and the other cassette 9 is ground and polished. Accommodates the processed wafer W. Further, the alignment means 10 is a table on which the wafer W taken out from the cassette 8 is temporarily placed and the center alignment thereof is performed.

The carry-in means 11 has a suction pad, sucks and holds the wafer W before grinding and polishing, which is aligned by the alignment means 10, and carries it onto the chuck table 7 located at the carry-in / carry-out position A. The carry-in means 11 sucks and holds the wafer W after grinding and polishing processing held on the chuck table 7 located at the carry-in / carry-out position A and carries it out to the cleaning means 13.

The carry-in / out means 14 is, for example, a robot pick provided with a U-shaped hand 14a, and the wafer W is sucked and held by the U-shaped hand 14a for transportation. Specifically, the carry-in / out means 14 carries out the wafer W before the grinding / polishing process from the cassette 8 to the positioning means 10, and carries in the wafer W after the grinding / polishing process from the cleaning means 13 to the cassette 9. The cleaning means 13 cleans the wafer W after the grinding and polishing process, and removes contamination such as grinding debris and polishing debris adhering to the ground and polished surface.

The control means 100 controls each of the above-mentioned components constituting the grinding and polishing apparatus 1. That is, the control means 100 causes the grinding and polishing apparatus 1 to perform a processing operation on the wafer W, and at least controls the polishing means 5 and the chuck table 7 to polish the wafer W while supplying the polishing liquid GL. Then, the gettering layer G is formed while supplying the liquid L containing no abrasive grains. The control means 100 is a computer capable of executing a computer program. The control means 100 includes an arithmetic processing device having a microprocessor such as a CPU (central processing unit), a storage device having a memory such as a ROM (read only memory) or a RAM (random access memory), and an input / output interface device. And have. The CPU of the control means 100 executes a computer program stored in the ROM on the RAM to generate a control signal for controlling the grinding apparatus 1. The CPU of the control means 100 outputs the generated control signal to each component of the grinding / polishing device 1 via the input / output interface device. Further, the control means 100 is connected to a display means (not shown) composed of a liquid crystal display device for displaying a processing operation state, an image, or the like, or an input means used by an operator when registering processing content information or the like. .. The input means is composed of at least one of a touch panel provided on the display means, a keyboard and the like.

Next, the method of processing the wafer according to the first embodiment will be described. FIG. 4 is a flowchart showing a flow of a wafer processing method according to the first embodiment. FIG. 5 is a cross-sectional view of a wafer in which a BG tape is attached to the surface of the wafer holding step of the wafer processing method according to the first embodiment. FIG. 6 is a diagram showing a strain layer removing step of the wafer processing method according to the first embodiment. FIG. 7 is a diagram showing a polishing liquid removing step of the wafer processing method according to the first embodiment. FIG. 8 is a diagram showing a gettering layer forming step of the wafer processing method according to the first embodiment. FIG. 9 is a diagram showing an individualization step of the wafer processing method according to the first embodiment.

As shown in FIG. 4, the waha processing method (hereinafter, simply referred to as a processing method) includes a waha holding process ST1, a rough grinding process ST2, a finish grinding process ST3, a strain layer removing process ST4, and a polishing liquid removal. The process includes a step ST5, a gettering layer forming step ST6, and an individualization step ST7.

The wafer holding step ST1 is a step of attaching the BG tape T to the surface WS of the wafer W and sucking and holding the BG tape T side on the holding surface 7a of the chuck table 7. In the wafer holding step ST1, as shown in FIG. 5, the operator attaches the BG tape T to the surface WS of the wafer W before grinding and polishing, turns the BG tape T downward, and puts the wafer W in the cassette 8. Contain. The operator attaches the cassette 8 containing the wafer W before grinding and polishing processing and the cassette 9 not containing the wafer W to the apparatus main body 2, and registers the processing information in the control means 100. The operator inputs a machining operation start instruction to the grinding / polishing device 1, and the control means 100 starts the machining operation of the grinding / polishing device 1.

In the wafer holding step ST1, the control means 100 of the grinding and polishing apparatus 1 takes out the wafer W from the cassette 8 and carries it out to the alignment means 10, and the alignment means 10 aligns the center of the wafer W. Then, the carry-in means 11 carries the surface WS side of the aligned wafer W onto the chuck table 7 located at the carry-in / carry-out position A, and the chuck table 7 sucks and holds the wafer W. In this way, in the wafer holding step ST1, the back surface WR of the wafer W is exposed by sucking and holding the BG tape T on the chuck table 7. The control means 100 of the grinding / polishing apparatus 1 conveys the wafer W to the rough grinding position B, the finish grinding position C, the polishing position D, and the carry-in / carry-out position A in this order on the turntable 6. In the control means 100 of the grinding and polishing apparatus 1, every time the turntable 6 rotates 90 degrees, the wafer W before the grinding and polishing process is carried into the chuck table 7 at the carry-in / carry-out position A.

In the rough grinding step ST2, the control means 100 of the grinding and polishing apparatus 1 rough grinds the back surface WR of the wafer W at the rough grinding position B using the first grinding means 3, and in the finish grinding step ST3, the finish grinding position. At C, the back surface WR of the waha W is finish-ground by using the second grinding means 4.

In the strain layer removing step ST4, the back surface WR of the wafer W is polished by the polishing pad 51 while rotating the polishing pad 51 while supplying the polishing liquid GL to the polishing pad 51 and rotating the chuck table 7, thereby polishing the back surface WR of the wafer W. This is a step of removing the strain layer from the WR. In the strain layer removing step ST4, the control means 100 of the grinding and polishing apparatus 1 rotates the chuck table 7 and the polishing pad 51 at the polishing position D, and as shown in FIG. 6, the switching valve 12 is switched to the back surface WR of the wafer W. While supplying the polishing liquid GL from the polishing liquid supply source 15 from the nozzle 16, the polishing pad 51 is brought into contact with the back surface WR of the wafer W to polish the back surface WR of the wafer W. In the first embodiment, in the strain layer removing step ST4, the control means 100 of the grinding and polishing apparatus 1 rotates the chuck table 7 at a rotation speed of 505 rpm, and the polishing pad 51 is the same as the chuck table 7 at a rotation speed of 500 rpm. While rotating in the direction, the polishing pad 51 is pressed by the polishing feeding means 53 so that a polishing pressure of 300 g / cm ² acts on the back surface WR of the wafer W, but the processing conditions of the polishing process are not limited to this.

The polishing liquid removing step ST5 is a step of supplying the rinse liquid CL from the nozzle 20 toward the polishing pad 51 and removing the residual polishing liquid GL contained in the polishing pad 51 after the strain layer removing step ST4 is performed. In the polishing liquid removing step ST5, the control means 100 of the grinding and polishing apparatus 1 rotates the chuck table 7 and the polishing pad 51 at the polishing position D, and as shown in FIG. 7, the back surface WR of the wafer W of the polishing pad 51. The rinse liquid CL supplied from the rinse liquid supply source 19 is supplied from the nozzle 20 to the portion protruding from the wafer, and the liquid L supplied from the liquid supply source 17 via the switching valve 12 is supplied to the back surface WR of the wafer W through the nozzle 16. The polishing pad 51 is brought into contact with the back surface WR of the wafer W while being supplied from.

In the gettering layer forming step ST6, the back surface WR of the wafer W is formed by the polishing pad 51 while rotating the polishing pad 51 and rotating the chuck table 7 while supplying the polishing pad 51 and the wafer W with the liquid L containing no abrasive grains. This is a step of forming a gettering layer G on the back surface WR by polishing.

In the gettering layer forming step ST6, the control means 100 of the grinding and polishing apparatus 1 rotates the chuck table 7 and the polishing pad 51 at the polishing position D, and as shown in FIG. 8, switches to the back surface WR of the wafer W. The abrasive-free liquid L supplied from the liquid supply source 17 via the liquid 12 was supplied from the nozzle 16 and was supplied from the rinse liquid supply source 19 to the portion of the polishing pad 51 protruding from the back surface WR of the wafer W. While supplying the rinse liquid CL from the nozzle 20, the polishing pad 51 is brought into contact with the back surface WR of the wafer W to generate a gettering layer G on the back surface WR side of the wafer W. The arithmetic mean roughness (Ra) of the back surface WR of the wafer W after carrying out the gettering layer forming step ST6 is 0.8 to 4.5 nm.

As described above, when the control means 100 polishes the wafer W and then shifts to the formation of the gettering layer G by supplying the rinse liquid CL in the polishing liquid removing step ST5 and the gettering layer forming step ST6, the nozzle The grinding and polishing apparatus 1 is controlled so as to supply the rinse liquid CL from 20 toward the polishing pad 51 and remove the polishing liquid GL remaining on the polishing pad 51. In the first embodiment, in the gettering layer forming step ST6, the control means 100 of the grinding and polishing apparatus 1 rotates the chuck table 7 at a rotation speed of 505 rpm, and the polishing pad 51 and the chuck table 7 at a rotation speed of 500 rpm. While rotating in the same direction, the polishing feed means 53 presses the polishing pad 51 so that a polishing pressure of 50 g / cm ² acts on the back surface WR of the wafer W, but the processing conditions for forming the gettering layer G are Not limited to this.

In implementation embodiment 1, the outer diameter of the wafer W is a 300 mm, the outer diameter of the polishing pad 51 is 450 mm. In the strain layer removing step ST4 and the gettering layer forming step ST6, the polishing pad 51 is positioned so that the outer periphery of the polishing pad 51 covers the center of the wafer W and protrudes from the outer edge of the wafer W.

After the gettering layer forming step ST6, the control means 100 of the grinding / polishing apparatus 1 positions the wafer W on which the gettering layer forming step ST6 is carried out at the carry-in / carry-out position A, carries it into the cleaning means 13 by the carry-in means 11, and cleans it. The wafer W is washed by the means 13 and the washed wafer W is carried into the cassette 9 by the carry-in / out means 14.

In the individualization step ST7, the wafer W is taken out from the cassette 9, the BG tape T is peeled off from the surface WS, and then polyvinyl alcohol (PVA) or polyvinylpyrrolidone (PVP) is applied to the surface WS of the wafer W. A protective film (not shown) composed of a water-soluble resin containing the like and the like is formed, and the back surface WR side of the wafer W is held on the chuck table 33 of the laser processing machine 30 shown in FIG. In the individualization step ST7, as shown in FIG. 9, the laser light LR is irradiated to the street S from the laser light irradiation unit 32 while the laser light irradiation unit 32 of the laser processing machine 30 is relatively moved along the street S. Then, the street S is subjected to ablation processing, and the waiha W is separated into individual device chip DTs along the street S. In the individualization step ST7, after the wafer W is individualized into individual device chip DTs, a protective film (not shown) is removed, the surface WS of the wafer W is washed, and the protective film is washed and removed together with debris. In the first embodiment, the back surface WR of the wafer W is directly sucked and held by the chuck table 33, but in the present invention, the wafer W is attached to a dicing tape fixed to the inner circumference of a ring frame (not shown) on the back surface WR. , It may be sucked and held on the chuck table 33 via the dicing tape.

In the first embodiment, in the individualization step ST7, the wafer W is individualized into individual device chip DTs by ablation processing using the laser light LR, but in the present invention, the individualization step ST7 uses the laser light. The modified layer may be formed inside the waha W by irradiation to separate the waha W into individual device chip DTs, or the waha W may be made into individual device chip DTs by ablation processing using laser light LR. In the case of individualizing, after half-cutting by ablation processing, an external force may be applied to individualize into individual device chip DTs. The wafer W may be individualized into individual device chip DTs by cutting with a cutting blade.

As described above, in the processing method according to the first embodiment, after the strain layer removing step ST4 is carried out, the polishing liquid removing step ST5 for supplying the rinse liquid CL from the nozzle 20 toward the polishing pad 51 is carried out, so that it is gettered. Since the polishing liquid GL remaining on the polishing pad 51 can be efficiently removed in the layer forming step ST6, excessive erosion of the back surface WR of the wafer W by the polishing liquid GL can be suppressed, and the gettering layer G can be quickly eroded. You can move on to formation.

[Embodiment 2]
The method of processing the wafer according to the second embodiment of the present invention will be described with reference to the drawings. FIG. 10 is a diagram showing a strain layer removing step of the wafer processing method according to the second embodiment. FIG. 11 is a diagram showing a polishing liquid removing step of the wafer processing method according to the second embodiment. FIG. 12 is a diagram showing a gettering layer forming step of the wafer processing method according to the second embodiment. In FIGS. 10 to 12, the same parts as those in the first embodiment are designated by the same reference numerals, and the description thereof will be omitted.

The wafer processing method according to the second embodiment (hereinafter, simply referred to as a processing method) includes the configuration of the polishing means 5 for carrying out the strain layer removing step ST4, the polishing liquid removing step ST5, and the gettering layer forming step ST6. It is the same as the first embodiment except that it is different from the above.

In the processing method according to the second embodiment, the polishing means 5 for carrying out the strain layer removing step ST4, the polishing liquid removing step ST5 and the gettering layer forming step ST6 is a polishing liquid as shown in FIGS. 10, 11 and 12. A supply passage 18 for supplying the polishing liquid GL from the supply source 15 or the liquid L from the liquid supply source 17 to the center of the polishing surface in contact with the back surface WR of the wafer W of the polishing pad 51 is provided at the center. Further, in the processing method according to the second embodiment, the outer diameter of the wafer W may be 300 mm, and the outer diameter of the polishing pad 51 may be 300 mm or more, and in this example, it is 450 mm. In the strain layer removing step ST4 and the polishing liquid removing step ST5, the polishing pad 51 is positioned so that the entire polishing pad 51 covers the entire back surface WR of the wafer W.

Further, in the processing method according to the second embodiment, in the gettering layer forming step ST6, the outer edge portion of the polishing pad 51 protrudes from the outer edge of the wafer W as shown in FIG. 12, and the polishing pad 51 is shown in FIG. The chuck table 7 is moved horizontally with respect to the polishing pad 51 over the position where the entire back surface WR of the wafer W is covered. In the second embodiment, in the gettering layer forming step ST6, the control means 100 of the grinding and polishing apparatus 1 causes the X-axis moving means 52 to move the polishing pad 51 together with the spindle 54 in the horizontal X-axis direction to the chuck table. 7 is moved horizontally with respect to the polishing pad 51.

In the processing method according to the second embodiment, similarly to the first embodiment, after the strain layer removing step ST4, the polishing liquid removing step ST5 for supplying the rinse liquid CL from the nozzle 20 toward the polishing pad 51 is carried out. In the gettering layer forming step ST6, since the polishing liquid GL remaining on the polishing pad 51 can be suppressed, excessive erosion of the back surface WR of the wafer W by the polishing liquid GL can be suppressed, and the gettering layer G is quickly formed. can do. As a result, the processing method according to the first embodiment can immediately shift to the formation of the gettering layer G after polishing, can form the gettering layer G as designed, and can process the wafer W as designed. ..

[Modification example]
The method of processing the wafer according to the first modification of the second embodiment of the present invention will be described with reference to the drawings. FIG. 13 is a diagram showing a polishing liquid removing step of the wafer processing method according to the first modification of the second embodiment. In FIG. 13, the same parts as those in the second embodiment are designated by the same reference numerals, and the description thereof will be omitted.

The method for processing the wafer according to the first modification of the second embodiment (hereinafter, simply referred to as the processing method) is the suction source 40 of the polishing pad 51 through the supply passage 18 as shown in FIG. 13 in the polishing liquid removing step ST5. It is the same as the second embodiment except that the residual polishing liquid GL of the polishing pad 51 is sucked by applying a suction force.

Similar to the second embodiment, the processing method according to the first modification of the second embodiment is the polishing liquid removing step ST5 in which the rinse liquid CL is supplied from the nozzle 20 toward the polishing pad 51 after the strain layer removing step ST4 is performed. Since this is carried out, it is possible to immediately shift to the formation of the gettering layer G after polishing, the gettering layer G as designed can be formed, and the wafer W can be processed as designed.

Further, as a further modification 2 of the configuration of FIG. 13, a bypass line communicating with the supply passage 18 is provided, the liquid L is supplied from the liquid supply source 17, the polishing liquid GL is pushed out from the bypass line, and the rinse liquid supply source 19 is further provided. The rinse liquid CL may be supplied to the polishing pad 51 to remove the polishing liquid from the polishing pad 51.

According to each embodiment, the following device chip manufacturing methods can be obtained.

(Additional note)
Distortion from the back surface of the wafer by rotating the polishing pad while supplying the polishing liquid to the polishing pad of the polishing device and polishing the back surface of the wafer after grinding with the polishing pad while rotating the chuck table of the polishing device. The strain layer removal process to remove the layer and
After performing the strain layer removing step, a polishing liquid removing step of supplying a rinse liquid from a nozzle toward the polishing pad to remove the residual polishing liquid contained in the polishing pad, and a polishing liquid removing step.
A gettering layer is formed on the back surface of the wafer by rotating the polishing pad while supplying a liquid containing no abrasive grains to the polishing pad and the wafer and polishing the back surface of the wafer with the polishing pad while rotating the chuck table. Gettering layer forming process and
Includes an individualization process, which separates the wafer into individual device chips along the street.
Manufacturing method of device chip.

The present invention is not limited to the above embodiments and modifications. That is, it can be modified in various ways without departing from the gist of the present invention.

1 Grinding and polishing equipment (polishing equipment)
5 Polishing means 7 Chuck table 7a Holding surface 15 Polishing liquid supply source 17 Liquid supply source 20 Nozzle 51 Polishing pad 100 Control means W Wafer WS Front surface WR Back surface DV device G Gettering layer TBG tape (protective member)
GL polishing liquid CL rinsing liquid L liquid ST1 Wafer holding process ST4 Strain layer removing process ST5 Polishing liquid removing process ST6 Gettering layer forming process

Claims (3)

A method for processing a wafer in which a polishing pad having abrasive grains having a Mohs hardness higher than that of the wafer is used and a gettering layer is formed on the back surface of the wafer in which a device is formed on the surface of the wafer.
A wafer holding process in which a protective member is attached to the surface of the wafer and the protective member side is held on the holding surface of the chuck table.
A strain layer removing step of removing the strain layer from the back surface of the wafer by rotating the polishing pad while supplying the polishing liquid to the polishing pad and polishing the back surface of the wafer with the polishing pad while rotating the chuck table. ,
After performing the strain layer removing step , the rinse liquid supplied from the rinse liquid supply source is supplied to the polishing pad from the nozzle, and the abrasive-free liquid supplied from the liquid supply source is supplied to the back surface of the wafer from the nozzle. Then, a polishing liquid removing step of removing the residual polishing liquid contained in the polishing pad, and
The該U Eha backside with a liquid which does not contain the abrasive grains supplied from the liquid supply source with supplied from the nozzle, while the rinsing liquid supplied from the rinse liquid supply source to the polishing pad supplied from the nozzle A method for processing a wafer, comprising a gettering layer forming step of forming a gettering layer on the back surface by polishing the back surface of the wafer with the polishing pad while rotating the polishing pad and rotating the chuck table. The method for processing a wafer according to claim 1, wherein the gettering layer forming step is performed while the chuck table is horizontally moved with respect to the polishing pad. A polishing device that polishes wafers
A chuck table that holds the wafer rotatably and
A polishing means having a polishing pad for polishing a wafer held on the chuck table and forming a gettering layer on the polished wafer, and a polishing means.
A polishing liquid supply source that supplies the polishing liquid to the wafer and the polishing pad, and
A liquid supply source that supplies a liquid that does not contain abrasive grains different from the polishing liquid to the wafer and the polishing pad, and
At least the polishing means and the chuck table are controlled to polish the wafer while supplying the polishing liquid, and then the control means for forming the gettering layer while supplying the liquid containing no abrasive grains.
A nozzle provided adjacent to the chuck table and supplying a rinse liquid for removing the polishing liquid toward the polishing pad is provided.
When moving to a gettering layer formed after polishing the control means further wafer, and when forming the gettering layer, with that teapot subjected rinsing liquid toward the polishing pad from the nozzle, of the wafer A polishing device that controls the back surface to supply a liquid containing no abrasive grains supplied from the liquid supply source from a nozzle .

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