TW201834787A - Wafer polishing method and polishing apparatus capable of suppressing processing time - Google Patents

Abstract

The subject of this invention is to provide a wafer polishing method and a polishing apparatus capable of suppressing processing time. The wafer polishing method includes: a protective member adhering step ST1 for adhering a protective member to the surface of a wafer on which devices are formed in a plurality of regions partitioned by grid-like predetermined cutting lines formed on the surface; and a polishing step ST2 of holding the wafer with a chuck table via the protective member and polishing the back surface of the wafer with a polishing pad. In the polishing step ST2, a polishing pad having a diameter larger than that of the wafer is used, and polishing is carried out while heating with hot air blown onto the region of the lower surface of the polishing pad exposed without contacting the wafer.

Description

Wafer polishing method and polishing device

The invention relates to a wafer polishing method and a polishing device.

Various wafers such as silicon wafers with semiconductor elements formed on the surface, or optical element wafers with optical elements consisting of sapphire, SiC (silicon carbide), etc. are formed on the surface. To thin. Thereafter, the wafer is polished with a polishing pad in order to remove the crushed layer of the surface to be ground (back surface) generated by grinding and to increase the bending strength when the wafer is formed (for example, refer to Patent Document 1). [Habitual technical literature] [patent literature]

[Patent Document 1] Japanese Patent Laid-Open No. 2003-243345

[Problems to be Solved by the Invention] In addition to CMP (Chemical Mechanical Polishing) polishing method for polishing wafers, dry processing using abrasive pads containing softer abrasive pads is also called dry polishing processing method. . Dry polishing involves pressing the polishing pad against the surface to be polished of the wafer and rotating the wafer and the polishing pad at the same time, removing a predetermined thickness of the wafer, and removing a broken layer formed on the surface to be polished. The broken layer exists in a thickness of several μm, and grinding is performed in order to completely remove that area. However, dry polishing requires longer processing time as the removal amount is set more.

An object of the present invention is to provide a wafer polishing method and a polishing apparatus capable of suppressing processing time.

[Technical means to solve the problem] In order to solve the above-mentioned problems and achieve the object, the wafer polishing method of the present invention includes a protective member sticking step, which attaches the protective member to the surface of the wafer, and the wafer is formed on the surface. Elements are formed in a plurality of regions divided by a grid-like dividing plan; and a polishing step of holding the wafer by the protective member at a chuck table, and polishing a back surface of the wafer with a polishing pad, wherein In the step, using the polishing pad having a larger diameter than the wafer, polishing is performed while blowing hot air to the lower surface area of the polishing pad exposed without contacting the wafer to heat.

In the aforementioned wafer polishing method, in the polishing step, the lower surface of the polishing pad that is exposed without contacting the wafer may be selectively heated.

In the aforementioned wafer polishing method, the temperature of the lower surface of the polishing pad exposed without contacting the wafer may be measured in the polishing step, and the temperature or amount of hot air may be adjusted according to the measured temperature of the polishing pad.

The polishing apparatus of the present invention is characterized by comprising: a chuck table that holds a wafer; and a polishing unit that polishes and holds the chuck table with a polishing pad having a diameter larger than the diameter of the wafer and mounted on the lower end of the spindle. The wafer; and a temperature adjustment unit that adjusts the temperature of the polishing pad in the wafer polishing process, wherein the temperature adjustment unit is provided with a hot air blow to a lower surface area of the polishing pad that is exposed without contacting the wafer Hot air jet unit.

In the aforementioned polishing apparatus, the temperature adjustment unit may further include a selective spraying unit that selectively blows hot air to a desired region of the lower surface of the polishing pad that is not exposed from the wafer.

In the aforementioned polishing device, the temperature adjustment unit may further include: a temperature measuring device that measures a temperature of a lower surface area of the polishing pad that is exposed without being in contact with the wafer; and a control unit according to the temperature measuring device. Measurement result, adjust the hot air injection temperature or quantity of the hot air injection unit.

[Effect of the Invention] The wafer polishing method and polishing apparatus of the present invention can exhibit the effect of suppressing the processing time.

Referring to the drawings, the embodiments (embodiments) for implementing the present invention will be described in detail. The present invention is not limited by the contents described in the following embodiments. In addition, the constituent elements described below include those that can be easily considered or substantially the same by those skilled in the art. The configurations described below can be combined as appropriate. Various configurations can be omitted, replaced, or changed without departing from the scope of the technical idea of the present invention.

First Example A wafer polishing method and a polishing apparatus according to the first embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a perspective view of a configuration example of a polishing apparatus according to Embodiment 1. FIG. FIG. 2 is a perspective view showing a wafer to be polished in the wafer polishing method according to the first embodiment. FIG. 3 is a perspective view of the wafer shown in FIG. 2 as viewed from the back side.

The polishing apparatus shown in FIG. 1 of the first embodiment performs polishing by planarizing the back surface 202 of the wafer 201 shown in FIG. 2, which is thinned by a grinding apparatus, with high accuracy. The wafer 201 is a disc-shaped semiconductor wafer made of silicon as a base material, or an optical element wafer composed of sapphire, SiC (silicon carbide), or the like. The wafer 201 is, as shown in FIG. 2, an element 205 is formed in a plurality of regions divided by a grid-like dividing line 204 formed on the front surface 203. The wafer 201 is as shown in FIG. 3, and the back surface 202 is polished in a state where the front surface 203 is attached with the protective member 206.

As shown in FIG. 1, the grinding device 1 mainly includes a device body 2, a chuck table 7, a grinding unit 5, cassettes 8 and 9, a registration unit 10, a carry-in unit 11, a cleaning unit 13, a carry-in and carry-out unit 14, The hot-air spraying unit 15, the temperature measuring device 16, and the control unit 100.

The chuck table 7 holds the wafer 201 on the holding surface 7-1 via the protective member 206 to hold the wafer 201. The chuck table 7 is connected to a vacuum suction source (not shown) through a vacuum suction path (not shown), and attracts and holds the crystal pattern 201 placed on the holding surface 7-1. The portion constituting the holding surface 7-1 is formed by A disc shape formed by a porous ceramic material or the like. Also. The chuck table 7 is supported by a support base 7-2 that can rotate freely around an axis parallel to the Z-axis direction. The Z-axis direction is parallel to the vertical direction.

In addition, the chuck table 7 is provided so that a processing feed unit (not shown) spans the loading / unloading position 101 near the loading / unloading unit 11 and the loading / unloading unit 14 and the grinding position 104 below the grinding unit 5 in the Y axis. Free to move in the direction. The Y-axis direction is parallel to the horizontal direction.

The wafer cassettes 8 and 9 have a plurality of grooves and are storage containers for accommodating the wafer 201. The wafer cassette 8 on one side contains the wafer 201 with the protective member 206 (shown in FIG. 3) adhered to the front surface 203 before the grinding process, and the wafer cassette 9 on the other side contains the wafer 201 after the grinding process. In addition, the alignment unit 10 is a table for temporarily positioning the wafer 201 taken out from the wafer cassette 8 and aligning the center thereof.

The carry-in unit 11 has a suction pad and suction-holds the wafer 201 before the polishing process, which is aligned by the holding alignment unit 10, to carry in the chuck table 7 located at the carry-in / out position 101. The carry-in unit 11 sucks and holds the polished wafer 201 held on the chuck table 7 located at the carry-in / out position 101, and carries the wafer 201 out to the cleaning unit.

The loading / unloading unit 14 is, for example, a mechanical pick-up device including a U-shaped hand 14-1, and the wafer 201 is held by the U-shaped hand 14-1 and held and transferred. Specifically, the loading and unloading unit 14 transfers the wafer 201 before polishing processing from the wafer cassette 8 to the positioning unit 10, and loads the wafer 201 after polishing processing from the cleaning unit 13 into the wafer cassette 9. The cleaning unit 13 cleans the wafer 201 after grinding and removes contamination such as grinding debris attached to the grinding and grinding process surface.

Next, the polishing unit 5 will be described with reference to the drawings. FIG. 4 is a side view showing a state of a grinding unit of the grinding apparatus shown in FIG. 1 during a grinding process. FIG. 5 is a plan view showing a positional relationship between the polishing pad and the wafer shown in FIG. 4. FIG. 6 is a side view showing the positional relationship between the polishing pad and the wafer shown in FIG. 5.

As shown in FIG. 1, the polishing unit 5 is supported by a pillar 18 erected from the apparatus body 2, and a polishing pad 52 of a polishing tool 51 is mounted on the lower end of the main shaft 50 as shown in FIG. 4. The polishing unit 5 places the polishing pad 52 of the polishing tool 51 on the holding surface 7-1 of the chuck table 7 opposite to the polishing position 104. The polishing unit 5 presses the back surface 202 of the wafer 201 held on the holding surface 7-1 of the chuck table 7 along the Z axis by the Z-axis moving unit 5-1 while rotating the polishing tool 51 by the main shaft 50. The chuck table 7 is located at the grinding position 104 and is rotated by the supporting base table 7-2. The polishing unit 5 is used to press the back surface 202 of the wafer 201 along the Z-axis direction with the polishing pad 52 of the polishing tool 51 to polish the back surface 202 of the wafer 201 with the polishing pad 52.

The grinding unit 5 includes a spindle housing 53 provided to move in the Z-axis direction by a Z-axis moving unit 5-1 provided at the pillar 18, a spindle 50 provided to rotate freely about an axis in the spindle housing 53, and A grinding tool 51 attached to the lower end of the main shaft 50. The main shaft 50 is arranged parallel to the Z-axis direction, and is rotated around the axis by a main shaft motor 54 shown in FIG. 1. The spindle 50 is mounted with a disc-shaped tool mounting member 50-1 for mounting the polishing tool 51 on the lower end.

The polishing tool 51 includes an annular support base 55 and an annular polishing pad 52. The support abutment 55 is made of an aluminum alloy. The polishing pad 52 is mounted on the lower surface of the support base 55 and is used to polish the wafer 201 held on the chuck table 7. The polishing pad 52 is formed of abrasive grains such as felt grindstones, in which abrasive grains are dispersed and fixed on polyurethane or felt.

The polishing tool 51 is such that the support abutment 55 is superposed on the lower surface of the tool mounting member 50-1 mounted on the lower end of the spindle 50 and the support abutment 55 is mounted on the tool mounting member 50-1 by bolts (not shown). Instead, it is mounted on the tool mounting member 50-1. In the first embodiment, as shown in FIGS. 5 and 6, the diameter of the polishing pad 52 of the polishing tool 51 is larger than the diameter of the wafer 201.

In the first embodiment, when the wafer 201 is polished with the polishing pad 52, the polishing unit 5 chemically reacts the abrasive grains of the polishing pad 52 with the wafer 201 without supplying a polishing liquid. Dry polishing. That is, in the first embodiment, the polishing pad 52 of the polishing tool 51 is suitable for dry polishing.

Further, in Embodiment 1, the axis center of the rotation center of the polishing tool 51 of the polishing unit 5 and the axis center of the rotation center of the chuck table 7 as the polishing position 104 are parallel to each other and spaced in the horizontal direction. Configuration. In addition, in Embodiment 1, the polishing unit 5 is as shown in FIGS. 4, 5 and 6. The polishing pad 52 covers the entire back surface 202 of the wafer 201. A part of the area 56-1 of the front surface 56 is exposed without coming into contact with the back surface 202 of the wafer 201. Furthermore, in the first embodiment, in a plan view of the polishing apparatus 1, as shown in FIG. 5, the region 56-1 is arranged between the chuck table 7 and the column 18 at the polishing position 104 in the Y-axis direction.

The hot-air spraying unit 15 blows hot air to the area 56-1 exposed on the lower surface 56 of the polishing pad 52 without contacting the wafer 201 during polishing. As shown in FIG. 4, the hot-air spray unit 15 is provided at a position 56-1 in the Z-axis direction with respect to the polishing pad 52 in the polishing process of the device body 2. In the embodiment, as shown in FIG. 5, the hot-air spraying unit 15 is disposed between the chuck table 7 and the column 18 at the grinding position 104 in the Y-axis direction.

The hot air injection unit 15 includes a supply pipe 151 that supplies hot air (ie, heated gas) from a hot air supply source (not shown), and a plurality of injection ports 152 provided in the supply pipe 151. The length direction of the supply pipe 151 is parallel to the X-axis direction orthogonal to the Y-axis direction. The X-axis direction is parallel to the horizontal direction. The injection ports 152 are arranged at intervals along the longitudinal direction of the supply pipe 151, that is, the X-axis direction. The hot-air spraying unit 15 sprays hot air supplied from a hot-air supply source from the spray port 152 toward the region 56-1 of the polishing pad 52 during polishing. In addition, the hot air supplied from the hot air injection unit 15 to the region 56-1 is a gas heated by a temperature higher than the normal temperature. In addition, in Embodiment 1, the temperature of the hot air is desirably the melting temperature of the under-protection member 206, for example, 70 ° C.

The temperature measuring device 16 measures the temperature of the region 56-1 exposed from the lower surface 56 of the polishing pad 52 without contacting the wafer 201 during polishing. The temperature measuring device 16 is provided at a position 56-1 of the polishing pad 52 during the polishing process with respect to the apparatus body 2 in the Z-axis direction. In the embodiment, as shown in FIG. 5, the temperature measuring device 16 is disposed between the chuck table 7 and the column 18 at the polishing position 104 in the Y-axis direction.

The temperature measuring device 16 is attached to a front end of a setting member 161 provided on the apparatus body 2. The installation member 161 is formed in a rod shape whose length direction is parallel to the X-axis direction orthogonal to the Y-axis direction. The temperature measuring device 16 is provided at the front end of the polishing unit 5 side of the setting member 161. The temperature measuring device 16 is composed of a radiation thermometer, a thermographer, or a pyrometer. The temperature measuring device 16 outputs a measurement result to the control unit 100.

The control unit 100 individually controls the above-described constituent elements configured as the polishing apparatus 1. That is, the control unit 100 causes the polishing apparatus 1 to perform a polishing process on the wafer 201. The control unit 100 is a computer that can execute a computer program. The control unit 100 has a calculation processing device having a microprocessor such as a CPU (central processing unit); a memory device having such as a ROM (read only memory) or a RAM (random access memory); Random access memory); and input and output interface devices. The CPU of the control unit 100 executes a computer program stored in the ROM on the RAM, and generates a control signal for controlling the grinding apparatus 1. The CPU of the control unit 100 outputs the generated control signal to each constituent element of the polishing apparatus 1 through an input / output interface device.

In addition, the control unit 100 is connected to a display unit (not shown) constituted by a liquid crystal display device or the like that displays the status or screen of the processing operation, or an input unit for the operator to register, for example, processing content information. The input unit is composed of at least one of a touch panel and a keyboard provided on the display unit.

In addition, the control unit 100 adjusts the hot-air spraying temperature or amount of the hot-air spraying unit 15 according to the measurement result of the temperature measuring device 16. In the first embodiment, although the control unit 100 changes both the temperature of the hot air and the amount of hot air sprayed by the hot air injection unit 15 to the area 56-1, in the present invention, only the temperature of the hot air or the amount of the hot air is adjusted to at least one of them. One is fine. In Embodiment 1, the control unit 100 changes the temperature of the area 56-1 of the lower surface 56 of the polishing pad 52 detected by the temperature measuring device 16 during the polishing process to a preset temperature, and changes the area of the hot air spray unit 15 to the area. 56-1 The temperature of the hot air sprayed and the amount of hot air. In this way, the hot-air spraying unit 15, the temperature measuring device 16, and the control unit 100 are configured as a temperature adjustment unit 17 that adjusts the temperature of the polishing pad 52 in the polishing wafer 201.

Next, a wafer polishing method according to the first embodiment will be described. 7 is a flowchart showing a flow of a wafer polishing method according to the first embodiment.

As shown in FIG. 7, the wafer polishing method (hereinafter simply referred to as a polishing method) according to the first embodiment includes a protective member sticking step ST1 and a polishing step ST2.

The protective member attaching step ST1 is a step of attaching the protective member 206 to the front surface 203 of the wafer 201 as shown in FIG. 3. In Embodiment 1, the protective member sticking step ST1 is, for example, an operator attaches the protective member 206 to the front surface 203 of the wafer 201, and stores the wafer 201 with the protective member 206 attached to the front surface 203 in the wafer cassette 8. The wafer 201 to which the protective member 206 is adhered is a grinding step (not shown), and the back surface 202 is ground to be thin.

The polishing step ST2 is a step of holding the wafer 201 with the protective member 206 adhered to the chuck table 7 by the protective member 206 after the grinding step, and polishing the back surface 202 of the wafer 201 with the polishing pad 52. The polishing step ST2 is performed by the polishing apparatus 1 shown in FIG. 1. The polishing step ST2 is performed while the wafer cassette 8 and the wafer cassette 9 are mounted on the device body 2 (where the wafer cassette 8 accommodates the wafer 201 that the operator attaches the protective member 206 before the polishing process to the front surface 203, and the wafer The cassette 9 does not contain the wafer 201), the operator registers the processing information to the control unit 100, and the operator inputs an instruction to start the processing operation to the polishing apparatus 1.

In the polishing step ST2, the control unit 100 of the polishing apparatus 1 causes the loading and unloading unit 14 to remove the wafer 201 from the wafer cassette 8 and unload it to the positioning unit 10, so that the positioning unit 10 positions the center of the wafer 201. Then, the carrying-in unit 11 brings the aligned front side 203 side of the wafer 201 into position on the chuck table 7 in the carrying-in and carrying-out position 101.

In the polishing step ST2, the control unit 100 of the polishing apparatus 1 holds the front surface 203 side of the wafer 201 on the chuck table 7 by the protective member 206, and exposes the back surface 202. The processing feed unit will hold the wafer 201 The chuck table 7 moves to the grinding position 104. In the polishing step ST2, the control unit 100 of the polishing device 1 presses the polishing pad 52 of the grinder 51 of the polishing unit 5 while rotating the chuck table 7 of the polishing position 104 and the polishing tool 51 of the polishing unit 5 around the axis. To the back surface 202 of the wafer 201 to polish the back surface 202 of the wafer 201. In this manner, a polishing pad 52 having a larger diameter than the wafer 201 is used in the polishing step ST2.

In addition, in the polishing step ST2, the control unit 100 of the polishing apparatus 1 blows hot air from the hot air spraying unit 15 to the area 56-1 on the lower surface 56 of the polishing pad 52 to heat and polish, while using a temperature measuring device 16 The temperature of the area 56-1 of the lower surface 56 of the polishing pad 52 is measured, and the temperature or amount of hot air is adjusted according to the measured temperature of the polishing pad 52.

In the polishing step ST2, the control unit 100 of the polishing apparatus 1 stops the hot-air spraying from the hot-air spraying unit 15 while raising the polishing unit 5 and stopping the rotation of the chuck table 7 around the axis after the polishing process is finished. In the polishing step ST2, the control unit 100 of the polishing apparatus 1 moves the chuck table 7 to the carry-in / out position 101, and the wafer 201 is carried into the cleaning unit 13 by the carrying-in unit 11, and the cleaning unit 13 cleans and cleans The subsequent wafer 201 is carried into the wafer cassette 9 by the carrying-in and carrying-out unit 14. Next, the polishing method performs a polishing step ST2 on the next wafer 201. The control unit 100 of the polishing apparatus 1 performs a polishing process on all the wafers 201 in the wafer cassette 8 and ends the polishing step ST2, that is, the polishing method.

As described above, in the polishing method and the polishing apparatus 1 according to the first embodiment, in the polishing step ST2, the polishing pad 52 is heated by the hot air sprayed from the hot air spraying unit 15, so that the reaction speed between the abrasive particles of the polishing pad 52 and the wafer 201 can be increased. . As a result, the polishing method and the polishing apparatus 1 can increase the removal amount of the wafer 201 per unit time (referring to the reduced thickness of the wafer 201), and can improve the throughput (throughput) of the polishing process. As a result, the polishing method and the polishing apparatus 1 can suppress the processing time.

In addition, in the polishing method and polishing apparatus 1 of Embodiment 1, in the polishing step ST2, the temperature of the region 56-1 of the lower surface 56 of the polishing pad 52 is measured, and the temperature and amount of the hot air are adjusted according to the measurement results to a preset temperature. , And the temperature of the lower surface 56 of the polishing pad 52 can be maintained at a preset temperature.

Second Example A wafer polishing method and a polishing apparatus according to a second embodiment of the present invention will be described with reference to the drawings. Fig. 8 is a perspective view of a configuration example of a polishing apparatus according to a second embodiment. In FIG. 8, the same portions as those in the first embodiment are denoted by the same reference numerals, and descriptions thereof are omitted.

The point difference between the polishing device 1-2 of the second embodiment and the polishing device 1 of the first embodiment is further provided with a plurality of chuck tables 7, a first grinding unit 3, and a second grinding unit provided on the rotary table 6. 4.

The rotary table 6 is a disk-shaped table provided on the upper surface of the apparatus body 2 and is provided to be rotatable in a horizontal plane and driven to rotate at a predetermined timing. In this rotary table 6, in the second embodiment, four chuck tables 7 are arranged at equal intervals at a phase angle of 90 degrees, for example. In the second embodiment, the chuck table 7 is sequentially moved from the loading / unloading position 101, the rough grinding position 102, the finishing grinding position 103, and the grinding position 104 to the loading / unloading position 101 by rotation of the rotary table 6.

The first grinding unit 3 rotates an unillustrated grinding wheel (having a grinding grinding stone attached to the lower end of the main shaft) while pressing the grinding wheel in the Z-axis direction parallel to the vertical direction to the position held by the rough grinding position 102. The back surface 202 of the wafer 201 on the chuck table 7 is subjected to rough grinding processing on the back surface 202 of the wafer 201. Similarly, the second grinding unit 4 is a card that is held in the finishing grinding position 103 by rotating an unillustrated grinding wheel (having a grinding grindstone mounted on the lower end of the spindle) in the Z axis direction while rotating. The back surface 202 of the wafer 201 that has been roughly ground on the tray table 7 is finely ground.

The wafer polishing method according to the second embodiment (hereinafter simply referred to as a polishing method) is a grinding step in which a rough grinding process and a fine grinding process are applied to the back surface 202 of the wafer 201, and then the same polishing steps ST2 as in the first embodiment are performed, and The polishing method of the first embodiment is the same.

In the polishing method and the polishing apparatus 1-2 of the second embodiment, in the polishing step ST2, the polishing pad 52 is added by the hot air sprayed from the hot-air spraying unit 15, so that the processing time can be suppressed similarly to the first embodiment.

Third Example A wafer polishing method and a polishing apparatus according to a third embodiment of the present invention will be described with reference to the drawings. Fig. 9 is a perspective view of a main part of a polishing apparatus according to a third embodiment. Fig. 10 is a plan view of a main part of a polishing apparatus according to a third embodiment. 11 is a flowchart showing a flow of a wafer polishing method according to the third embodiment. FIG. 12 is a side view showing a state in which a wafer thickness on a measurement path is measured in a measurement step before polishing of the wafer polishing method shown in FIG. 11. FIG. 13 is a side view showing a wafer polished in a test polishing step of the wafer polishing method shown in FIG. 11. FIG. 14 is a side view of the wafer after the polishing step of the wafer polishing method shown in FIG. 11. In FIGS. 9 to 14, the same portions as those in the first embodiment are denoted by the same reference numerals, and descriptions thereof are omitted.

The polishing apparatus 1-3 of Embodiment 3 is equipped with the measuring unit 12 as shown in FIG. The measurement unit 12 is arranged relatively to the holding surface 7-1 of the chuck table 7 located in the loading / unloading position 101, and is provided to be movable in a direction parallel to the holding surface 7-1 by a horizontal moving unit (not shown). The moving path 207 indicated by the one-dot line in FIG. 1 of the horizontal moving unit of the measuring unit 12 is a linear shape passing through the center of the holding surface 7-1 of the chuck table 7 located at the carry-in / out position 101 and the chuck table The diameter direction of 7 is parallel. In addition, the moving path 207 of the horizontal moving unit of the measuring unit 12 is formed by sandwiching the center of the holding surface 7-1 of the chuck table 7 between the two outer edges.

The measuring unit 12 receives the light reflected by the back surface 202 by irradiating the back surface 202 of the wafer 201 held on the holding surface 7-1 of the chuck table 7 located in the carry-in / out position 101 with light or ultrasonic waves. Or, it moves on the moving path 207 by ultrasonic waves, and measures the thickness of each position of the wafer 201 on the moving path 207 at a predetermined predetermined distance. In this specification, the movement path 207 of the measurement unit 12 is hereinafter referred to as a measurement path 207. The measurement unit 12 outputs a measurement result to the control unit 100. In addition, in the first embodiment, the measurement unit 12 is a non-contact irradiated light or an ultrasonic non-contact type for measuring the thickness of each position of the wafer 201 on the moving path. However, the measurement unit 12 may be a contact type having a contact terminal that contacts the back surface 202 of the wafer 201. In addition, in Embodiment 3, although the measurement unit 12 is provided in the polishing apparatus 1, in the present invention, the thickness of the wafer 201 may be measured using a measurement apparatus different from the polishing apparatus 1-3.

In addition, as shown in FIG. 10, the temperature adjustment unit 17 of the polishing apparatus 1-3 includes a selective ejection unit 153 that selectively blows hot air to a desired region of the region 56-1 of the lower surface 56 of the polishing pad 52. In the third embodiment, the selective injection portions 153 are provided corresponding to the injection ports 152, respectively, and are gate mechanisms capable of opening and closing the corresponding injection ports 152. The selective spraying section 153 is provided with a plurality of hot air spraying units 15. Each of the selective injection sections 153 opens and closes the injection ports 152 independently of each other by the control unit 100.

Next, a wafer polishing method according to the third embodiment will be described. The wafer polishing method (hereinafter simply referred to as a polishing method) according to Embodiment 3 includes a protective member sticking step ST1 and a polishing step ST2 as shown in FIG. 11, and a selection step ST3 is performed by a polishing device 1-3.

The selection step ST3 is a step performed after the protective member sticking step ST1 and before the polishing step ST2. The selection step ST3 is a step of selecting a region where the hot air is blown from the region 56-1 of the lower surface 56 of the polishing pad 52 in the polishing step ST2 in order to suppress the thickness deviation of the wafer 201 after the polishing step ST2, and is to select an open jet Steps of selecting the injection section 153 of the port 152 and closing the selection of the injection section 153 of the injection port 152. As shown in FIG. 11, the selection step ST3 includes a pre-polishing measurement step ST31, a test polishing step ST32, an acquisition step ST33, and a selection step ST34.

In the pre-polishing measurement step ST31 in the selection step ST3, the control unit 100 of the polishing device 1-3 causes the carry-in and carry-out unit 14 to take out the wafer 201 from the wafer cassette 8 (in addition, the wafer 201 that has been ground and grinded in the selection step ST3) , Hereinafter referred to as test wafer 201-1), carried out to the alignment unit 10, so that the alignment unit 10 will align the center of the test wafer 201-1, so that the carry-in unit 11 will be used for the alignment test The front side 203 side of the wafer 201-1 is carried in position above the chuck table 7 in the carry-in / out position 101.

In the measurement step ST31 before polishing, the control unit 100 of the polishing device 1-3 holds the front surface 203 side of the test wafer 201-1 on the chuck table 7 via the protection member 206. In the measurement step ST31 before polishing, the control unit 100 of the polishing device 1-3 is shown in FIG. 12, and the measurement unit 12 is moved along the measurement path 207 to each position of the test wafer 201-1 on the measurement path 207. The thickness is measured. Furthermore, as shown in FIG. 12, the test wafer 201-1 positioned at the carry-in / out position 101 has a thinner center thickness and a thicker outer edge in Embodiment 3, and a thicker thickness between the center and the outer edge of the center. Generally, the thickness is deviated. In addition, FIG. 12 shows that the thickness deviation is larger than the actual thickness, and the thickness deviation is exaggerated.

The test polishing step ST32 is to polish the test wafer 201-1 held on the chuck table 7 with the polishing pad 52 of the polishing unit 5. The test wafer 201-1 has been obtained as the wafer 201 in the measurement step ST31 before polishing. The thickness of each position on the movement path 207 of the thickness information. In the test polishing step ST32, the control unit 100 of the polishing apparatus 1-3 moves the chuck table 7 holding the test wafer 201-1 to the polishing position 104, and rotates the chuck table 7 around the axis at the polishing position 104 When the polishing tool 51 is rotated around the axis, the polishing pad 52 is pressed against the wafer 201 held on the chuck table 7 to polish the back surface 202 of the wafer 201. The control unit 100 of the polishing apparatus 1-3 proceeds to the acquisition step ST33 after the test polishing step ST32 ends.

Furthermore, as shown in FIG. 13, the test wafer 201-1 after polishing is in Embodiment 3. The thickness of the center and the thickness of the outer edge are thin, and the thickness of the center and the center of the outer edge is generally thick. Deviation. In addition, FIG. 13 is the same as FIG. 12 and is described as having a larger thickness deviation than the actual one, and the thickness deviation is exaggerated.

The obtaining step ST33 is a step of obtaining the thickness of each position of the test wafer 201-1 on the measurement path 207 (that is, the thickness of the test wafer 201-1 measured after the test polishing step ST32 is performed). At the acquisition step ST33, the control unit 100 of the polishing apparatus 1-3 stops the rotation of the chuck table 7, moves the test wafer 201-1 to the carry-in / out position 101, and moves the measurement unit 12 along the measurement path 207 The thickness of each position of the test wafer 201-1 on the measurement path 207 is measured.

In this way, in the obtaining step ST33, the control unit 100 of the polishing apparatus 1-3 obtains the thickness of each position of the test wafer 201-1 on the measurement path 207 (that is, the test wafer 201- 1 thickness).

The selection step ST34 is a step of selecting a region on the surface of the wafer 201 that has a higher polishing efficiency than other regions. In the selection step ST34, the control unit 100 of the polishing apparatus 1-3 selects the thickness of each position of the test wafer 201-1 on the measurement measurement path 207 after the polishing measured in step ST33 to be greater than the desired finishing thickness The thicker position is used as a region where the polishing efficiency is more desired on the 201 surface of the wafer than other regions. At the selection step ST34, the control unit 100 of the polishing apparatus 1-3 previously memorizes the correspondence relationship between each area of the back surface 202 of the wafer 201 and the selection ejection unit 153, and selects the wafer 201 corresponding to this correspondence relationship in advance. The selection ejection unit 153 is a region that is more likely to improve the polishing efficiency than other regions on the surface to perform the polishing step ST2.

The polishing step ST2 is a step of polishing the wafer 201 with the chuck table 7 holding a wafer 201 having the same thickness as the test wafer 201-1. In the polishing step ST2, the control unit 100 of the polishing apparatus 1 opens the injection port 152 of the selection injection portion 153 selected in the selection step ST34 as shown in FIG. 10, and closes the injection ports 152 of the other selection injection portions 153. Among the areas 56-1 of the lower surface 56 of the polishing pad 52, the desired area corresponding to the area where the polishing efficiency of the wafer 201 is desired to be polished is polished on one side. In addition, in FIG. 10, the selected injection unit 153 that opens the injection port 152 is indicated by a symbol “153O”, and the selected injection unit 153 that closes the injection port 152 is indicated by a symbol “153C”. In the polishing step ST2, the control unit 100 of the polishing apparatus 1 causes the loading / unloading unit 14 to transfer the wafer 201 (hereinafter, the wafer 201 to be ground and polished in the polishing step ST2 is referred to as a processing wafer 201-2) from the wafer. Take out from the box 8 and carry it out to the registration unit 10 so that the registration unit 10 aligns the center of the processing wafer 201-2, and the loading unit 11 aligns the front side 203 of the processed wafer 201-2. The side loading is in place above the chuck table 7 in the loading / unloading position 101.

In the polishing step ST2, the control unit 100 of the polishing apparatus 1 holds the front surface 203 side of the processing wafer 201-2 on the chuck table 7 with a protective member 206, and transfers it to the polishing position 104. In the polishing step ST2, the control unit 100 of the polishing apparatus 1 causes the selected injection portion 153 selected in the selection step ST34 to open the injection port 152, and causes the other selected injection portions 153 to close the injection port 152 so as to open the injection port 152 from one side. Hot air is blown to the area of the lower surface 56 to heat, and the back surface 202 of the processing wafer 201-2 is planarized with high accuracy as shown in FIG. 14.

The polishing device 1 positions the processing wafer 201-2 polished by the polishing unit 5 at the carry-in and carry-out position 101, and is carried in by the carry-in unit 11 to the cleaning unit 13, washed by the washing unit 13, and cleaned by the carry-in and carry-out unit 14. The processed wafer 201-2 is carried into the wafer cassette 9. After the polishing apparatus 1 performs polishing on all the processing wafers 201-2 in the wafer cassette 8, the polishing method ends.

As described above, in the polishing method and the polishing apparatus 1-3 of Embodiment 3, in the polishing step ST2, the polishing pad 52 is heated by the hot air sprayed from the hot air spraying unit 15, so that the abrasive particles of the polishing pad 52 and the wafer 201 can be raised. reaction speed. As a result, the polishing method and the polishing apparatus 1-3 can increase the removal amount of the wafer 201 per unit time (referring to the reduced thickness of the wafer 201), and can increase the throughput (throughput) of the polishing process. As a result, the polishing method and the polishing apparatus 1 can suppress the processing time.

In addition, the polishing method and polishing apparatus 1-3 of Embodiment 3 are based on the shape (thickness) of the test wafer 201-1 after the test polishing step ST32. Even if it is desired to improve the polishing efficiency in only a desired region, it is selective. A desired region among regions 56-1 of the lower surface 56 of the polishing pad 52 is heated, and the processing wafer 201-2 can be polished to a desired shape (thickness).

Next, in order to confirm the effect of the present invention, the inventor of the present invention measured the removal amount per unit time during heating of the region 56-1 from the hot air spray unit 15 to the polishing pad 52 by the hot air spray unit 15. The measurement results are shown in FIG. 15. FIG. 15 shows the amount of removal between the units when the area of the polishing pad of the polishing apparatus shown in FIG. 1 is heated.

The invented object 1 of FIG. 15 has a preset temperature of 35.6 degrees C, and the invented object 2 has a preset temperature of 38.5 degrees C. The hot air is sprayed from the hot air spraying unit 15 and heated in the region 56-1. Inventive object 1 and Inventive object 2 together measured the amount of removal per unit time (μm / min) when the polishing process was performed for 150 seconds.

According to FIG. 15, the removal amount per unit time with respect to the object 1 of the present invention is 0.49 (μm / min), and the removal amount per unit time of the object 2 of the present invention is 0.59 (μm / min). Therefore, according to FIG. 15, it was confirmed that by increasing the temperature of the polishing pad 52, the removal amount per unit time can be increased, and the throughput of the polishing process can be increased.

The present invention is not limited to the embodiments described above. That is, various modifications can be made without departing from the spirit of the present invention.

1,1-2,1-3‧‧‧grinding device

5‧‧‧grinding unit

7‧‧‧ chuck table

15‧‧‧hot air jet unit

16‧‧‧Temperature measuring device

17‧‧‧Temperature adjustment unit

50‧‧‧ Spindle

52‧‧‧ Abrasive pad

56‧‧‧ lower surface

56-1‧‧‧Area

100‧‧‧control unit

153‧‧‧Choose the spray department

202‧‧‧Back

203‧‧‧Front

204‧‧‧ divided scheduled line

205‧‧‧Element

206‧‧‧Protective member

ST1‧‧‧Protection procedure

ST2‧‧‧Grinding steps

FIG. 1 is a perspective view of a configuration example of a polishing apparatus according to Embodiment 1. FIG. FIG. 2 is a perspective view showing a wafer to be polished in the wafer polishing method according to the first embodiment. FIG. 3 is a perspective view of the wafer shown in FIG. 2 as viewed from the back side. FIG. 4 is a side view showing a state of a grinding unit of the grinding apparatus shown in FIG. 1 during a grinding process. FIG. 5 is a plan view showing a positional relationship between the polishing pad and the wafer shown in FIG. 4. FIG. 6 is a side view showing the positional relationship between the polishing pad and the wafer shown in FIG. 5. 7 is a flowchart showing a flow of a wafer polishing method according to the first embodiment. Fig. 8 is a perspective view of a configuration example of a polishing apparatus according to a second embodiment. Fig. 9 is a perspective view of a main part of a polishing apparatus according to a third embodiment. Fig. 10 is a plan view of a main part of a polishing apparatus according to a third embodiment. 11 is a flowchart showing a flow of a wafer polishing method according to the third embodiment. FIG. 12 is a side view showing a state in which a wafer thickness on a measurement path is measured in a measurement step before polishing of the wafer polishing method shown in FIG. 11. FIG. 13 is a side view showing a wafer polished in a test polishing step of the wafer polishing method shown in FIG. 11. FIG. 14 is a side view of the wafer after the polishing step of the wafer polishing method shown in FIG. 11. FIG. 15 is a graph showing the amount of removal per unit time when the area of the polishing pad of the polishing apparatus shown in FIG. 1 is heated.

Claims (6)

A wafer polishing method, comprising: (1) a protective member attaching step, adhering the protective member to a surface of a wafer having elements formed in a plurality of regions divided by a predetermined grid-like division line formed on the surface; And a polishing step, the wafer is held by the protective member at the chuck table, and the back surface of the wafer is polished with a polishing pad, and in the polishing step, the polishing pad having a diameter larger than that of the wafer is used, The lower surface area of the polishing pad exposed by coming into contact with the wafer is heated by blowing hot air to perform polishing. The wafer polishing method according to item 1 of the scope of patent application, wherein in the polishing step, the lower surface of the polishing pad exposed without contacting the wafer is selectively heated. The wafer polishing method according to item 1 of the scope of patent application, wherein in the polishing step, the temperature of the lower surface of the polishing pad exposed without contacting the wafer is measured, and the temperature of the polishing pad is measured according to the measurement. Adjust the temperature or amount of hot air. A polishing device comprising: a chuck table that holds a wafer; and a polishing unit that grinds the crystal held on the chuck table with a polishing pad having a diameter larger than the diameter of the wafer and mounted on the lower end of the spindle. ；; and a temperature adjustment unit that adjusts the temperature of the polishing pad when the wafer is polished, 加工 wherein the temperature adjustment unit is provided with hot air that blows hot air toward the lower surface area of the polishing pad that is exposed without contacting the wafer Spray unit. The polishing device according to item 4 of the scope of patent application, wherein the temperature adjustment unit is provided with a selective spraying section that selectively blows hot air to a desired area of the lower surface of the polishing pad that is not exposed from the wafer. The polishing device according to item 4 of the scope of patent application, wherein the temperature adjustment unit is provided with: a temperature measuring device that measures a temperature of a lower surface area of the polishing pad exposed without contacting the wafer; and a control unit that According to the measurement result of the temperature measuring device, the hot air spraying temperature or quantity of the hot air spraying unit is adjusted.