JP2013084688A - Flattening method of sapphire substrate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method and device for manufacturing a thin and warpage-free processed substrate by flattening a sapphire substrate on an optimal processing condition meeting a market demand for a throughput of 20 sheets/hour or more.SOLUTION: After performing a grinding process by a grinder comprising grind stone heads 34h, 34h, and 34hof three axes, a lapping process is performed using a lapping board including work suction heads 22 and 22 of two tables, and a slurry with diamond abrasive grain dispersed therein, thereby manufacturing a sapphire substrate having a surface roughness (Ra) with 20nm or less.

Description

  The present invention provides a planarization method for obtaining a sapphire substrate having a surface roughness (Ra) of 20 nm or less with a very small warpage by planarizing the surface of a sapphire substrate having a thickness of 400 to 525 μm to reduce the thickness to 5 to 90 μm. About. As the sapphire substrate to be planarized, a sapphire substrate on the back surface of an optical device substrate in which an optical device layer is formed on the surface of the sapphire substrate is also included as an object.

The sapphire substrate used for the LED is prepared through the following steps S01 to S09 as disclosed in Japanese Patent Application Laid-Open No. 2007-137736 (Patent Document 1).
(S01) Pull up the crystal rod of the sapphire ingot.
(S02) The surface of the ingot is annealed.
(S03) The crystal orientation of the ingot is cut so that the C-axis end face is a vertical plane to form an ingot block.
(S04) The outer peripheral surface of the ingot block is cylindrically ground to obtain a cylindrical block having a smooth surface.
(S05) The crystal orientation of the cylindrical block is measured with an X-ray orientation measuring device (XRD machine), and an orientation flat is formed on the ingot block with a grindstone.
(S06) The ingot block on which the orientation flat is formed is wire-cut into a plane perpendicular to the C axis to obtain a large number of 400 to 525 μm thick sapphire substrates.
(S07) The surface of the sapphire substrate is ground or lapped to flatten the surface. The sapphire substrate whose surface is flattened is etched or annealed.
(S08) The treated sapphire substrate is polished on one side (polished) to flatten the surface.
and,
(S09) The polished sapphire substrate is washed.

  JP 2009-263534 A (Patent Document 2) discloses a polishing agent slurry in which a diamond abrasive having a particle size of 0.05 to 10 μm and an ester polishing accelerator dispersion of a fatty acid and a polyhydric alcohol are dispersed in a base oil. A method is proposed in which a sapphire substrate having a surface roughness (Ra) of 3 to 5 nm is obtained by polishing a sapphire substrate with a polishing pad.

JP 2010-514581 A (Patent Document 3) holds a sapphire substrate obtained by wire cutting on a suction chuck, and rough-grinds the surface of the sapphire substrate using a rough grinding wheel to increase the surface thickness to 30 μm or more. After removal, the surface of the sapphire substrate is removed by 5 μm or more using a finish grinding wheel to obtain a sapphire substrate having a surface roughness Ra of 0.1 μm or less, and further, the finish grinding surface is subjected to CMP polishing using a polishing pad. A surface having a crystal orientation selected from the group consisting of an r-plane, an m-plane, and a c-plane orientation and having an nTTV of about 0.037 μm / cm ² or less and a roughness Ra of 10.0 mm or less. A method for manufacturing a sapphire substrate is proposed.

  Japanese Patent Laying-Open No. 2010-46744 (Patent Document 4) discloses a grinding method for grinding a back surface (sapphire substrate surface) of a sapphire wafer in which a semiconductor layer in which a plurality of optical devices are partitioned by a dividing line is stacked on a sapphire substrate. A stress distribution step of dispersing the stress by cutting all or part of the dividing line of the semiconductor layer, and a protective tape attaching step of attaching a protective adhesive easy-release tape to the surface of the semiconductor layer; And a grinding step of holding the sapphire wafer on the chuck table of the grinding apparatus with the protective tape side down and grinding the back surface of the sapphire wafer with a grinding wheel. suggest.

  JP 2011-44473 A (Patent Document 5) discloses a chuck table that is rotatable while holding a sapphire substrate with a protective adhesive easy-release tape affixed to the optical device layer side facing the sapphire substrate surface upward, A sapphire substrate back surface grinding device comprising a grinding means for rotatably supporting a grinding wheel having a grinding wheel for grinding a sapphire substrate surface held by the chuck table, the chuck table sucking the sapphire substrate A suction plate having a holding surface for holding; and a frame body having a bottom portion that surrounds other than the holding surface of the suction plate and supports the opposite surface of the holding surface; The suction groove is formed so as to be denser in the central portion compared to the outer peripheral portion so that the suction force in the central portion is stronger than the suction force in the outer peripheral portion. Suction plate, characterized in that it communicates with the suction source through a suction groove formed in the frame body, proposes a backside grinding apparatus of the sapphire substrate.

Furthermore, Japanese Patent Application Laid-Open No. 2011-151151 (Patent Document 6) measures the amount of warpage (about 120 μm) of a sapphire substrate (thickness: 1,000 μm) on which an n-type semiconductor layer containing a group III nitride semiconductor is stacked. A warping amount measuring step,
A ceramic substrate support plate is affixed with wax to the n-type semiconductor layer surface of the sapphire substrate, the substrate support plate of the sapphire substrate is placed on the suction chuck, and the abrasive number (JIS general abrasive grain size) is 270 to 1. , Grinding the sapphire substrate surface to a thickness of about 160 μm over about 5 to 120 minutes using a # 800 metal bond cup wheel type grindstone,
Next, the sapphire substrate is placed on a lapping surface plate with the surface of the sapphire substrate to be ground facing downward, and a load of 50 to 300 g / cm ² is applied to the ceramic substrate support plate of the sapphire substrate with a weight to rotate the sapphire substrate. A sapphire substrate having a thickness of about 120 μm is obtained by rubbing the surface of the sapphire substrate to be ground on the surface plate for about 5 to 120 minutes while supplying a slurry in which diamond abrasive grains having a grain size of 1 to 15 μm are dispersed on a lapping plate. A first lapping step to
The surface to be ground of the sapphire substrate lapped by the first lapping step is ground on the lapping platen that rotates under a load (30 to 230 g / cm ² ) according to the warp amount of the sapphire substrate. While supplying a slurry in which diamond abrasive grains having a particle diameter of 1 to 15 μm are dispersed, the surface of the sapphire substrate to be ground is rubbed on a surface plate for 10 seconds to 5 minutes at a lapping speed of 0.5 to 5 μm / min. Is further reduced by 0.1 to 4.5 μm to reduce the amount of warpage (about 70 μm),
A method for planarizing a surface of a sapphire substrate having a metal layer is proposed.

Furthermore, JP 2011-171324 A (Patent Document 7)
A room for installing the flattening processing equipment outdoors. A loading / unloading stage chamber for Greek letter Γ-shaped substrates is placed on the left side of the front part where a plurality of substrate storage cassettes are installed. The processing stage chamber and the back substrate grinding processing stage chamber are divided into three chambers by a partition wall, and the partition wall between the stage chambers is provided with an opening through which a substrate leading to an adjacent stage chamber can be taken in and out, A compound semiconductor substrate planarization apparatus provided with a load port communicating with a storage cassette of the plurality of substrates on a front left side wall of a loading / unloading stage chamber,
The substrate loading / unloading stage chamber is provided with a second substrate cleaning machine and a second temporary placement table from the back of the load port toward the interior of the chamber, and has a polishing agent liquid supply mechanism, a suction pad, and a reversing function. It has an articulated substrate transfer robot with an arm, a vertical suction pad cleaner and a first temporary mounting table, and a first substrate cleaner and a rotary suction pad.
In the lap processing stage chamber of the substrate, there is provided a lap surface plate equipped with a conditioner ring for conditioning the lap surface plate polisher surface in the center, and a template having a suction mechanism in front of the lap surface plate and a pendulum swing and A second substrate suction chuck mechanism capable of moving up and down and a second substrate suction chuck cleaning mechanism for cleaning a template having the suction mechanism, and a template having a suction mechanism behind the lap surface plate and swinging the pendulum and moving up and down A first substrate suction chuck mechanism and a first substrate suction chuck cleaning mechanism for cleaning a template having the suction mechanism,
In the substrate grinding stage chamber, there is provided a substrate suction chuck surface plate in which three sets of substrate suction chuck tables are rotatably provided on the same circumference at an equal interval on one index type turntable. The numerical value control device stores the index of the substrate suction chuck table as the loading / unloading stage chuck (s ₁ ), substrate rough grinding stage chuck (s ₂ ), substrate finishing grinding chuck (s ₃ ) position, and A brush cleaning device and a chuck cleaning device are provided above the loading / unloading stage chuck (s ₁ ) so as to be laterally movable, vertically movable, and rotatable, and above the substrate rough grinding stage chuck (s ₂ ), a cup wheel type. A rough grinding wheel is provided so that it can be moved up and down and rotated and rotated. A cup wheel type finishing grinding wheel is provided above the cutting stage chuck (s ₃ ) so that it can be moved up and down and rotated and rotated.
The substrate stored in the storage cassette is sucked by the suction pad of the articulated substrate transfer robot provided in the center of the loading / unloading stage chamber, and transferred to the first driving table, the first temporary mounting table Transfer the upper substrate onto the loading / unloading stage chuck (s ₁ ) in the grinding stage chamber, suck the substrate on the first substrate cleaning machine, and transfer it to the first substrate suction chuck mechanism in the lapping stage chamber. , Picks up the substrate on the first substrate cleaning machine, transfers it to the second substrate suction chuck mechanism in the lapping stage chamber, transfers it, receives the substrate sucked on the first substrate suction chuck mechanism, and transfers it to the second substrate cleaning machine Receive the substrate adsorbed by the second substrate adsorption chuck mechanism, transport it to the second substrate cleaning machine, adsorb the substrate on the second substrate cleaning machine and place it temporarily Conveying upward, the task of conveying to the second provisional table the substrate on the adsorbed substrate storage cassettes performed,
The compound semiconductor substrate on the loading / unloading stage chuck (s ₁ ) is adsorbed by using a rotary suction pad in the loading / unloading stage chamber and rotated to place the compound semiconductor substrate on the first substrate cleaning machine. Transport,
A flattening apparatus for a compound semiconductor substrate is proposed.

The applicant of the present application applies the sapphire substrate surface flattening method described in Patent Document 6 to satisfy the throughput of 30 sapphire substrates of 4 inch diameter or 6 inch diameter required by a semiconductor substrate processing manufacturer. As a surface flattening apparatus for a sapphire substrate, in Japanese Patent Application No. 2011-174463 (Patent Document 8),
The room in which the flattening machine is installed is directed from the front part to the rear part, the front left half of the room is divided into the work transfer room and work washing room, the front right half is divided into the work lapping room, and the rear part is divided. Three sections with the workpiece grinding room
The workpiece transfer chamber / work washing chamber has a plurality of workpiece storage cassettes in the front row from the front to the rear,
In the second row, an articulated arm type work transfer robot in the center,
In the third row, from left to right,
In the first row on the left side, a workpiece suction transporter that can slide the second guide rail on the upper wall of the club room,
A temporary mounting table in front of the second row, a roll rotary work surface washer in the rear of the second row,
An arm washer for an articulated arm type work transfer robot behind the articulated type work transfer robot in the third row,
In the 4th row, there is a spin cleaner on the back side of the lapping workpiece and a Bergrin cleaner for the lapping workpiece surface.
In the fourth row, from left to right,
Provided on the right side of the workpiece adsorption transporter and behind the roll rotary workpiece surface cleaner is a ground workpiece spinner cleaner,
A temporary table with a centering device is provided on the right side of the spinner cleaner for the ground workpiece and behind the arm cleaner for the articulated arm-type workpiece transfer robot,
A work entrance window is provided on the left side wall of the four walls surrounding the lapping chamber in the right front half portion, and a lapping head for a metal rotating surface plate is provided in the lapping chamber. A pair of work pressing means provided so as to be able to swing on the lifting and rotating shafts, a pair of work suction head cleaning devices provided with a rotating brush for cleaning the lower part of the workpiece suction head, and two metal rotating surface plate rings It is equipped with a conditioner, a metal rotating surface plate washing mechanism, and a metal rotating surface plate facing device.
In the rear grinding chamber,
One index table, and a driving means for rotationally driving the rotation shaft of the index table;
Four suction chuck tables provided in four cylindrical punching spaces installed at equal intervals on the same circumference centered on the rotation axis of the index table, and the rotation shafts of the four suction chuck tables are rotated. Driving means for driving,
Of the four suction chuck tables, the first suction chuck table located near the temporary work table with the grinding work washer and centering device in the work transfer chamber / work washing chamber is positioned at the loading / unloading stage (s ₁ ). The L-shaped side wall and the ceiling of the left half of the wall surrounding the loading / unloading stage (s ₁ ) position are deleted, and an up and down arm is provided on the top of the wall. A first work transfer mechanism having a first guide rail capable of moving between a center point and the center point of the temporary table with the centering device is provided, and loading / unloading is performed by the first suction chuck table and the first work transfer mechanism. Configure stage (s ₁ )
Above the second suction chuck table, a rough grinding head in which a cup wheel type rough grinding wheel is supported on the grinding wheel shaft is provided, and the second suction chuck table and the rough grinding head constitute a rough grinding stage (s ₂ ).
The third suction chuck Above the table provided finish grinding head in which the finish grinding wheel in a cup-wheel is journalled in the wheel spindle third suction chuck table and semi-finish grinding head and a medium finish grinding stage (s ₃₎ Configure

and,
Above the fourth suction chuck table, a finish grinding head having a cup wheel type finish grinding wheel supported by a grinding wheel shaft is provided, and the fourth suction chuck table and the finish grinding head constitute a finish grinding stage (s ₄ ). Set up a stage,
Next to the first suction chuck table constituting the loading / unloading stage (s ₁ ), there is provided a pendant swing rotation type work suction transport pad mechanism in which a suction pad is supported by an arm. Installed to swing and rotate between a single chuck and the spin cleaner of the ground workpiece,
The arm of the articulated arm type workpiece transfer robot in the workpiece transfer chamber / work washing chamber described above includes a storage cassette, a temporary table with a centering device, a grinding workpiece cleaning device, a temporary table, and a lapping workpiece surface cleaning device. It is possible to move a trajectory that can transport the workpiece adsorbed to the upper workpiece and the lower part of the pair of workpiece adsorbing heads, and to move a trajectory that can transport the workpiece to these devices,
The workpiece suction and transfer device that can slide on the second guide rail in the workpiece transfer chamber and workpiece cleaning chamber is on the line connecting the center point of the temporary table, the roll rotary workpiece surface cleaner, and the center point of the spinner cleaner. Designed to move,
A sapphire substrate flattening apparatus characterized by this is proposed.

JP 2007-137736 A JP 2009-263534 A Japanese Translation of PCT International Publication No. 2010-514581 JP 2010-46744 A JP 2011-44473 A JP 2011-151151 A JP 2011-171324 A Japanese Patent Application No. 2011-174463 (not disclosed)

  Unlike single crystal silicon, which is the material of the silicon substrate, the sapphire substrate is a hexagonal crystal. Therefore, when grinding with a grindstone, the sapphire substrate that has been ground by the frictional heat that the substrate and the grindstone rub against each other tends to warp. is there. Therefore, the one-stage grinding method of Patent Document 1 and Patent Document 6 can be obtained by grinding so as to employ the two-stage grinding process of the rough grinding process and the finish grinding process described in Patent Document 2 and Patent Document 7. A sapphire substrate is preferred because of its small warpage.

  The sapphire substrate in which the protective adhesive easy-release tape of Patent Document 4 and Patent Document 5 is pasted on the surface of the optical device layer, and the sapphire substrate in which the ceramic substrate support plate of Patent Document 6 is pasted on the surface of the optical device layer with wax This is preferable for further reducing the degree of warpage of the sapphire substrate.

  In the surface flattening apparatus for sapphire substrate described in Patent Document 6, the throughput of a sapphire substrate having a diameter of 4 inches and 6 inches is 20 sheets / hour, which does not satisfy the market requirement of 30 sheets / hour. Moreover, since the replacement time (lifetime) of a grinding wheel is short from the semiconductor substrate manufacturer, provision of a grinding wheel having a longer life is desired. The flattening apparatus for a sapphire substrate described in Patent Document 8 divides the grinding process into three stages to shorten the throughput time per sapphire substrate, and a 4 inch diameter sapphire substrate has a throughput of 30 sheets / hour or more, 6 The sapphire substrate with an inch diameter has the advantage of satisfying market demands of throughput of 20 sheets / hour or more, and reducing the amount of grinding wheel wear during grinding per sapphire substrate, thereby extending the life of the wheel (the time for changing the wheel). .

  The first object of the present invention is to select a grinding wheel for processing a sapphire substrate with a small warp and a surface roughness (Ra) of 20 nm or less, using the sapphire substrate flattening apparatus described in Patent Document 8. And the sapphire substrate which selected the abrasive slurry and determined the optimum processing conditions to satisfy the market requirement of the throughput of 30 sheets / hour or more with a 4 inch diameter sapphire substrate and the throughput of 20 sheets / hour or more with a 6 inch diameter sapphire substrate A flattening method is provided.

  The second object of the present invention is that some semiconductor manufacturing equipment manufacturers require a sapphire substrate having a surface roughness (Ra) of 6 nm or less, and therefore a polishing process for reducing the thickness of 10 μm or more after the lapping process. In addition, the present invention provides a method for producing a sapphire substrate having a surface roughness (Ra) of 2 to 6 nm. The inventors of the present application experimented with the conditions of the flattening process in the order of the grinding process, polishing process, and lapping process. When lapping was performed after polishing of the sapphire substrate, the lapping process speed was reduced and 4 inches It was confirmed that only a sapphire substrate with a surface roughness (Ra) of 20 to 36 nm was obtained while the throughput was 25 sheets / hour or less with a sapphire substrate having a diameter.

The invention of claim 1 provides a method for flattening a sapphire substrate, characterized in that the surface of the sapphire substrate is flattened through the following steps to reduce the thickness of the sapphire substrate.
1). A sapphire substrate (workpiece) having an easily peelable adhesive tape or wax-attached substrate support plate attached to the surface is transferred onto the first suction chuck table, and the easily peelable adhesive tape surface of the workpiece or the substrate support plate is The workpiece is placed on the first suction chuck table so that the sapphire substrate surface is the upper surface on the lower surface.
2). The index table is rotated 90 degrees to move the first chuck table on which the workpiece at the loading / unloading stage (s ₁ ) position is mounted to the second chuck table position at the first grinding stage (s ₂ ) position.
3). Rotating the second chuck table, and then rotating and lowering the first grindstone shaft for bearing the diamond abrasive cup wheel type metal bond grinding wheel having an abrasive number of 280 to 360, the diamond abrasive cup wheel type metal The bond grinding wheel is brought into contact with the sapphire substrate surface of the workpiece and rubbed to start the first grinding process, and the diamond abrasive cup wheel type metal bond grinding wheel is lowered to perform in-feed grinding of the sapphire substrate surface. Perform the first grinding process.
4). The index table is rotated 90 degrees to move the second chuck table at the first grinding stage (s ₂ ) position to the third chuck table position at the second grinding stage (s ₃ ) position.
5). Rotating the third chuck table, and then rotating and lowering the second grindstone shaft that supports the diamond abrasive cup wheel type metal bond grinding wheel having an abrasive number of 680 to 800, the diamond abrasive cup wheel type metal The bond grinding wheel is brought into contact with the sapphire substrate surface of the workpiece and rubbed to start the second grinding process. Further, the diamond abrasive cup wheel type metal bond grinding wheel is lowered to perform in-feed grinding of the sapphire substrate surface. Perform the second grinding process.
6). The index table is rotated 90 degrees clockwise to move the third chuck table at the second grinding stage (s ₃ ) position to the fourth chuck table position at the finish grinding stage (s ₄ ) position.
7). Rotating the fourth chuck table, and then rotating and lowering the third grindstone shaft that supports the diamond abrasive cup wheel type metal bond grindstone having an abrasive number of 680 to 800, the diamond abrasive cup wheel type metal The bond grinding wheel is brought into contact with the sapphire substrate surface of the workpiece and rubbed to start the third grinding process, and the diamond abrasive cup wheel type metal bond grinding wheel is lowered to infeed grinding the sapphire substrate surface. Perform third grinding.
8). The index table is rotated 90 degrees clockwise or 270 degrees counterclockwise to move the fourth chuck table at the third grinding stage (s ₄ ) position to the loading / unloading stage (s ₁ ) position. Move to a certain first chuck table position.
9). The ground workpiece mounted on the first chuck table at the position of the loading / unloading stage (s ₁ ) is subjected to spin cleaning.
10). The to-be-ground sapphire substrate that has been subjected to spin cleaning is moved onto the metal lap rotating surface plate so that the to-be-ground sapphire surface faces the surface of the metal wrap rotating surface plate.
11). Applying a load of 50 to 300 g / cm ^{2 to} the tape surface or substrate support plate surface of the sapphire substrate to be ground on a metal rotating surface plate, and a grain size of 1 to 15 μm on the rotating lap surface plate A sapphire substrate having a thickness of 5 to 90 μm and a surface roughness (Ra) of 20 to 36 nm is obtained by rubbing the surface of the sapphire substrate to be ground with the metal rotating surface plate while supplying a slurry in which diamond abrasive grains are dispersed. A lapping process is performed.

The invention of claim 2 provides a method for flattening a sapphire substrate, characterized in that the surface of the sapphire substrate is flattened through the following steps to reduce the thickness of the sapphire substrate.
1). A sapphire substrate (workpiece) having an easily peelable adhesive tape or wax-attached substrate support plate attached to the surface is transferred onto the first suction chuck table, and the easily peelable adhesive tape surface of the workpiece or the substrate support plate is The workpiece is placed on the first suction chuck table so that the sapphire substrate surface is the upper surface on the lower surface.
2). The index table is rotated 90 degrees to move the first chuck table on which the workpiece at the loading / unloading stage (s ₁ ) position is mounted to the second chuck table position at the first grinding stage (s ₂ ) position.
3). Rotating the second chuck table, and then rotating and lowering the first grindstone shaft for bearing the diamond abrasive cup wheel type metal bond grinding wheel having an abrasive number of 280 to 360, the diamond abrasive cup wheel type metal The bond grinding wheel is brought into contact with the sapphire substrate surface of the workpiece and rubbed to start the first grinding process, and the diamond abrasive cup wheel type metal bond grinding wheel is lowered to perform in-feed grinding of the sapphire substrate surface. Perform the first grinding process.
4). The index table is rotated 90 degrees to move the second chuck table at the first grinding stage (s ₂ ) position to the third chuck table position at the second grinding stage (s ₃ ) position.
5). Rotating the third chuck table, and then rotating and lowering the second grindstone shaft that supports the diamond abrasive cup wheel type metal bond grinding wheel having an abrasive number of 680 to 800, the diamond abrasive cup wheel type metal The bond grinding wheel is brought into contact with the sapphire substrate surface of the workpiece and rubbed to start the second grinding process. Further, the diamond abrasive cup wheel type metal bond grinding wheel is lowered to perform in-feed grinding of the sapphire substrate surface. Perform the second grinding process.
6). The index table is rotated 90 degrees clockwise to move the third chuck table at the second grinding stage (s ₃ ) position to the fourth chuck table position at the finish grinding stage (s ₄ ) position.
7). Rotating the fourth chuck table, and then rotating and lowering the third grindstone shaft that supports the diamond abrasive cup wheel type metal bond grindstone having an abrasive number of 680 to 800, the diamond abrasive cup wheel type metal The bond grinding wheel is brought into contact with the sapphire substrate surface of the workpiece and rubbed to start the third grinding process, and the diamond abrasive cup wheel type metal bond grinding wheel is lowered to infeed grinding the sapphire substrate surface. Perform third grinding.
8). The index table is rotated 90 degrees clockwise or 270 degrees counterclockwise to move the fourth chuck table at the third grinding stage (s ₄ ) position to the loading / unloading stage (s ₁ ) position. Move to a certain first chuck table position.
9). The ground workpiece mounted on the first chuck table at the position of the loading / unloading stage (s ₁ ) is subjected to spin cleaning.
10). The to-be-ground sapphire substrate that has been subjected to spin cleaning is moved onto the metal lap rotating surface plate so that the to-be-ground sapphire surface faces the surface of the metal wrap rotating surface plate.
11). Diamond grinding with a grain size of 1 to 15 μm is applied to the rotating lap platen by applying a load of 50 to 300 g / cm ^{2 to} the tape surface or substrate support plate surface of the sapphire substrate to be ground on a metal rotating platen. A lapping step of forming a sapphire substrate having a thickness of 5 to 90 μm and a surface roughness (Ra) of 20 to 36 nm by sliding the surface of the sapphire substrate to be ground on the metal rotating surface plate while supplying slurry in which grains are dispersed. I do.
12). Polishing apparatus by holding the tape surface or substrate support plate surface of the sapphire substrate to be ground / lapped by a suction chuck and then lowering and rotating the sapphire surface to be ground / lapped of the workpiece The surface roughness is reduced by reducing the thickness of the sapphire substrate by 10 to 30 μm by supplying a polishing slurry in which diamond abrasive grains having a particle size of 0.05 to 3 μm are dispersed on the polishing surface plate. A polishing process for forming a sapphire substrate with a thickness (Ra) of 2 to 6 nm is performed.

  In order to prevent the effect of warping of the workpiece due to the thermal history accumulated in the workpiece in the grinding process stage, the grinding stage is divided into three stages to reduce the initial extinction at each grinding stage and make it easy to peel. The occurrence of warpage is further reduced by backing the workpiece with an adhesive tape or a substrate support plate.

  Since the diamond abrasive cup wheel type metal bond grinding wheel grinding requires less wear during grinding of the sapphire substrate than the diamond abrasive cup wheel type vitrified bond grinding wheel, the replacement time of the grinding wheel can be delayed.

  The substrate thickness removal allowance is faster in lapping than in polishing, but a sapphire substrate with a mirror surface (with a smaller Ra value) can be obtained in lapping than lapping.

FIG. 1 is a plan view of a flattening apparatus for a sapphire substrate. FIG. 2 is a right side view of the work suction / conveyor capable of sliding on the first guide rail. FIG. 3 is a right side view of the articulated arm type work transfer robot and the temporary table. FIG. 4 is a right side view of the articulated arm type work transfer robot and the lapping machine. FIG. 5 is a right side view in which a part of the lapping machine in the lapping chamber is cut away. FIG. 6 is a rear view of the lapping machine with a part cut away when viewed from behind. FIG. 7 is a front view in which a part of the grinding apparatus is cut away.

Hereinafter, the present invention will be described in more detail with reference to the drawings.
The sapphire substrate flattening apparatus 1 shown in FIG. 1 has a room 2 in which the flattening apparatus is installed facing from the front part to the rear part, the front left half of the room 2 is the work transfer chamber / work washing room 2a, and the front part. The right half is divided into a lapping chamber 2c for workpieces, and the rear portion is divided into three sections with a workpiece grinding chamber 2b.

  By making the grinding chamber 2b with a large amount of generated grinding scraps backward and bringing the lapping chamber of the final process forward, the chance of processing scraps adhering to the final workpiece is reduced.

  From the front to the rear, the workpiece transfer chamber / work washing chamber 2a has a plurality of workpiece storage cassettes 3 and 3 in the front row, and an articulated arm type workpiece transfer in the center in the second row. From the left side to the right side in the third row, the robot 4 is provided with a workpiece suction transfer device 7 having a suction pad 7a that can slide on the second guide rail 7b on the upper wall of the chamber in the first left side column, A temporary table 9 in front of the second row, a roll rotary work surface cleaner 8 in the rear of the second row, and an articulated arm type behind the articulated workpiece transfer robot 4 in the third row. The arm cleaning device 10 for the suction arm 4a of the workpiece transfer robot is provided with a spin cleaning device 11a on the back surface of the lapping workpiece and a berlin cleaning device 11b for the spin cleaning device in the fourth row. The workpiece is attracted from the right side A spinner cleaner 6 for a ground workpiece is provided on the right side of the feeder 7 and behind the roll-rotating workpiece surface cleaner 8, and the spinner cleaner 6 for the ground workpiece is provided. And a temporary table 5 with a centering device is provided behind the arm washer 10 for the articulated arm type work transfer robot. The storage cassettes 3 and 3 are installed on the tilt mechanism base 3a in order to easily carry out and carry in the work by the arm 4a of the articulated arm type work transfer robot 4.

  The workpiece can be gripped by the arm 4a of the articulated arm-type workpiece transfer robot 4 by vacuum suction by the arm 4a having a vacuum hole in the lower surface of the arm, or the workpiece outer periphery can be gripped by both arm claws provided at the tip of the arm 4a. This type of multi-joint arm-type workpiece transfer robot can also be used.

  The spin cleaner 11a rotates the workpiece with a spinner while spraying line clean water from the nozzle to the lower surface and upper surface of the workpiece to clean the front and back of the workpiece, and the Berglin cleaner 11b advances a cleaning brush on the workpiece upper surface to move the workpiece upper surface. Clean the scrub.

The left side wall of the fourth wall surrounding the lapping chamber 2c of the front right half portion, the workpiece carry-in port window 2c _l is provided, this lapping chamber, work for one of the metal rotation plate 21 A pair 24, 24 of work pressing means provided with the suction head 22 so that it can be moved up and down and rotated on the rotary shaft 23, and a pair 25, 25 of a work suction head washer comprising a rotating brush 25a for cleaning the lower part of the work suction head. And a lapping machine 20 having two metal rotating surface plate ring conditioners 26, 26, a metal rotating surface plate cleaning mechanism 27, and a single metal rotating surface plate facing device 28. ing.

  As the metal of the metal rotating surface plate 21 material, there can be used a casting surface plate made of copper, tin, brass, iron or the like, or a mixed casting of these metal powder and resin, for example, a chemet surface plate.

  In the rear grinding chamber 2b, there is one index table 31, driving means 33 for rotationally driving the rotary shaft 32 of the index table, and on the same circumference with the rotational axis of the index table as the center point. Provided with four suction chuck tables 34a, 34b, 34c, 34d provided in four hollow cylindrical spaces installed at equal intervals, and driving means 36 for rotationally driving the rotation shafts 35 of the four suction chuck tables. To do.

Of the four suction chuck tables 34a, 34b, 34c, 34d, the first suction chuck table is located close to the grinding workpiece cleaner 6 and the temporary table 5 with a centering device in the workpiece transfer chamber / work cleaning chamber 2a. 34 a is a loading / unloading stage (s ₁ ) position, and the L-shaped side wall and ceiling of the left half 2 b _l of the wall surrounding the loading / unloading stage (s ₁ ) position are deleted, and the top of the wall Includes a claw that can move back and forth to hold a work that can be moved up and down, or a transport pad mechanism 39 having an arm 39a that includes a suction pad. The center point of the first suction chuck table 34a and the center point of the temporary table 5 with the centering device A second guide rail 39b that moves between the transport pad mechanism 39 and the first suction Make up the the loading / unloading Rohde queuing stage _{(s 1)} in the Yakkuteburu 34a.

Above the second suction chuck table 34b, there is provided a rough grinding head 34h _c that is supported by a first grindstone shaft 34o that bears a diamond abrasive cup wheel type metal bond grinding wheel 34g _c having a grinding number of 280 to 360. constituting the second suction chuck table 34b and the rough grinding head 34h _c and the first grinding stage Te _{(s 2).} The first grindstone shaft 34o is rotationally driven by a built-in motor 34m.

Above the third suction chuck table 34c, the finish grinding head 34h _m in abrasive numbered were journalled to the second wheel spindle 34o to journalled diamond abrasive cup wheel type metal bond grinding grindstone 34g _m of No. 680-800 It provided the third constitutes a suction chuck table 34c and the semi-finish grinding head 34h _m and in the second grinding stage _{(s 3)} and.

Above the fourth suction chuck table 34d, a finish grinding head 34h _f is provided which is supported by a third grindstone shaft 34o for bearing a diamond abrasive cup wheel type metal bond grinding wheel 34g _f having a grinding number of 680 to 800. constituting the third grinding stage in the fourth suction chuck table 34c and the finish grinding head 34h _f Te _{(s 3).}

A pendant that can swing and swing an arm 34k that supports a workpiece suction / conveying pad 34p around a rotation axis near the first suction chuck table 34a constituting the loading / unloading stage (s ₁ ) and outside the index table 31. A workpiece suction / transport pad mechanism 34t of the type is provided, and the workpiece suction / transport pad 34t is installed so as to swing and rotate between the first suction chuck table 34a and the spin cleaner 6 of the ground workpiece. To do.

  The arm of the articulated arm-type workpiece transfer robot 4 in the workpiece transfer chamber / work washing chamber 2a includes a storage cassette 4, a temporary table 5 with a centering device, a grinding workpiece cleaner 6, a temporary table 9, and It is possible to move the trajectory on which the workpiece on the cleaner 25 on the lapping workpiece surface and the workpiece adsorbed to the lower part of the pair of workpiece suction heads 22 and 22 can be transported, and the trajectory on which the workpiece can be transferred to these devices. Is.

  The above-described workpiece adsorption / conveyance device capable of sliding on the second guide rail in the workpiece conveyance chamber / work washing chamber 2a is the center point of the temporary table 9, the center of the roll rotary type workpiece surface cleaning device 8, and the center of the spinner cleaning device 6. It is designed to be able to move on the line connecting the points.

  Although the polishing apparatus is not shown in FIG. 1, it is a polishing apparatus comprising a polishing pad surface plate with a polishing cloth affixed to the surface of a metal surface plate, a substrate suction head, and a nozzle for supplying abrasive slurry. A polishing machine “600s” (trade name) of Machine Tool Works can be used.

  The chamfering allowance of the sapphire substrate in each process is 35-60% of the total machining allowance in the first grinding process, 15-25% of the total machining allowance in the second grinding process, 15 to 25% of the machining allowance, 10 to 25% of the total machining allowance in the lapping process, and 10 to 25 μm in the polishing process are preferable for achieving the throughput.

Example 1
The step of flattening the sapphire substrate surface of the sapphire substrate having a thickness of 500 μm and a diameter of 6 inches to which the easily peelable adhesive tape is attached using the above-described sapphire substrate flattening apparatus 1 is performed through the following steps. .

A workpiece obtained by attaching an easily peelable adhesive tape to the surface of a 6-inch diameter sapphire substrate that has been wire cut to a thickness of 500 μm is used. Easy-release adhesive tapes include Q-chuck (trade name) of Maruishi Sangyo Co., Ltd., FIXFILM (trade name) series of Fuji Copian Co., Ltd., STD1, STD2, HG1, HG2 (grade name), etc. and adhesive layer The peel force (conforming to JIS K-6854) is 10 mN / 12.7 mm width or less, and the shear force between the sapphire substrate and the adhesive layer when the suction pad that adsorbs the workpiece is shifted laterally is 1.0 N / What is cm < ² > or more is preferable.

  1) The sapphire substrate (work) w with the easily peelable adhesive tape in the storage cassette 3 attached to the surface is adsorbed to the arm 4a of the articulated arm type work transfer robot 4 and placed on the temporary table 5 with a centering device. The arm is depressurized and the work is placed on the temporary table 5 with the centering device.

  2). After lowering the arm of the work first transport mechanism 39 to suck the work on the temporary table 5 with the centering device by the suction pad 39a, the arm is lifted. Next, after the arm that sucks the workpiece is moved on the first guide rail 39b and is positioned above the center point of the first suction chuck table 34a, the suction pad 39a that sucks the workpiece is lowered and the first suction chuck table is lowered. The workpiece w is placed so that the easily peelable adhesive tape surface is on the lower surface and the sapphire substrate surface is the upper surface. Thereafter, the vacuuming of the suction pad is stopped, and the suction pad is lifted away from the workpiece surface.

3). The index table 31 is rotated 90 degrees to move the first chuck table 34a on which the workpiece at the loading / unloading stage (s ₁ ) position is mounted to the second chuck table 34b position at the first grinding stage (s ₂ ) position. Let

4). The second chuck table 34b is rotated at 300 rpm, then rotate and lower the first wheel spindle 34g ₀ to journalled diamond abrasive cup wheel type metal bond grinding grindstone 34g _c abrasive numbered No. 325 in 3,000rpm The diamond abrasive cup wheel type metal bond grinding wheel 34g _c is brought into contact with and rubbed against the sapphire substrate surface of the work to start the first grinding process, and further the diamond abrasive cup wheel type metal bond grinding wheel is lowered. Then, the infeed grinding of the sapphire substrate surface is performed, and when the rough grinding allowance of 250 μm is reached, the rough grinding head 34h _c is raised to move away from the workpiece surface and the first grinding process is finished. Next, the rotation of the second chuck table 34b is stopped. While the first grinding process is being performed, a new workpiece is placed on the first chuck table 34a at the loading / unloading stage (s ₁ ) position.

5). The index table 31 is rotated 90 degrees to move the second chuck table 34b at the first grinding stage (s ₂ ) position to the third chuck table 34c position at the second grinding stage (s ₃ ) position.

6). A third chuck table 34c is rotated at 280 rpm, then the finish grinding head 34h _m in comprising a second wheel spindle 34h ₀ abrasive numbered to journalled diamond abrasive cup wheel type metal bond grinding grindstone 34g _m of No. 700 2 The diamond abrasive cup wheel type metal bond grinding wheel is brought into contact with and rubbed against the sapphire substrate surface of the workpiece to start the second grinding process, and further the diamond abrasive cup wheel type metal A second grinding process is performed in which the bond grinding wheel is lowered to perform in-feed grinding of the sapphire substrate surface. To end the second grinding away from the work surface by increasing the semi-finish grinding head 34h _m When a in the 70μm thick finish grinding allowance. Next, the rotation of the third chuck table 34c is stopped. While the second grinding process is being performed, a new workpiece is placed on the first chuck table 34a at the loading / unloading stage (s ₁ ) position, and the first grinding stage (s ₂ ) position. In the second chuck table 34b, the workpiece is first ground.

7). The index table 31 is rotated 90 degrees clockwise to move the third chuck table 34c at the second grinding stage (s ₃ ) position to the fourth chuck table position at the third grinding stage (s ₄ ) position.

8). The fourth chuck table 34d is rotated at 280 rpm, and then a finish grinding head 34h _f having a third grinding wheel shaft 34h ₀ for bearing a diamond abrasive cup wheel type metal bond grinding wheel 34g _f having a grinding number of 700 is set to 2, rotate and lowered abutting the diamond abrasive cup wheel type metal bond grinding grindstone 34g _f the sapphire substrate surface of the workpiece, the third grinding by rubbing started at 800 rpm, further wherein the diamond abrasive cup wheel type lowering the metal-bonded grinding grindstone 34g _f performs a third grinding to the infeed grinding of the sapphire substrate surface. When the allowance for finishing grinding with a thickness of 70 μm is reached, the finishing grinding head 34h _f is raised to move away from the work surface to finish the third grinding process. Next, the rotation of the fourth chuck table 34d is stopped. While this third grinding process is being performed, a new workpiece is placed on the first chuck table 34a at the loading / unloading stage (s ₁ ) position, and the first grinding stage (s ₂ ) position. The second chuck table 34b is used for the first (rough) grinding of the workpiece, and the third chuck table 34c located at the second grinding stage (s ₃ ) is used for the second (medium finish) grinding of the workpiece. Is called.

9). The index table is rotated 90 degrees clockwise or 270 degrees counterclockwise, and the fourth chuck table 34d at the third grinding stage (s ₄ ) position is at the loading / unloading stage (s ₁ ) position. Move to first chuck table 34a position.

10). The ground workpiece surface mounted on the first chuck table 34a at the loading / unloading stage (s ₁ ) position is adsorbed by the adsorption pad 34p of the workpiece adsorption / transfer pad mechanism 34t, and then the arm of the workpiece adsorption / transfer pad mechanism 34k is turned leftward and moved to the spinner cleaner 6 for the workpiece that has been ground, and then the work suction spinner cleaner is released by releasing the pressure reduction of the workpiece suction transfer pad 34p and releasing the suction of the workpiece. 6 is mounted. Then, the arm of the work suction / transport pad mechanism 34t is rotated rightward to return the arm of the work suction / transport pad mechanism to the standby position.

  11). The workpiece is spin cleaned while spraying cleaning water onto the workpiece surface ground by the workpiece spinner cleaner 6. If this spin cleaning is started before returning the arm of the workpiece suction transfer pad mechanism 34t to the standby position, the workpiece suction transfer pad 34p can be washed with water together with the workpiece spin cleaning.

  12). The suction pad 7a of the workpiece suction / conveyor 7 is retracted on the second guide rail 7b and moved onto the spinner cleaner 6 of the workpiece, and the workpiece placed on the spinner cleaner 6 is ground and cleaned. Adsorb the surface.

  13). The suction pad 7a of the workpiece suction / conveying device 7 is retracted on the second guide rail and passed over the roll-rotating workpiece surface cleaning device 8, and the easily peelable adhesive tape surface on the back surface of the workpiece is cleaned with roll rotation water.

  14). The suction pad 7a of the workpiece suction transporter 7 is further retracted on the second guide rail 7b and stopped on the temporary placement table 9, and then the pressure reduction of the suction pad 7a of the workpiece suction transporter 7 is released to release the temporary placement table 9. The workpiece is placed with the tape surface of the workpiece facing down and the grinding / cleaning sapphire substrate surface facing upward.

  15). The grinding / cleaning sapphire substrate surface is attracted to the arm 4a of the articulated arm-type workpiece transfer robot 4, and the workpiece w is attached to the tape while the workpiece is transferred to a position below the workpiece suction head 22 in the lapping chamber 2c. After the arm 4a is turned so that the surface faces upward, the work is positioned below the work suction head 22 in the lapping chamber, and the work suction head is depressurized to suck and fix the tape application surface of the work.

  16). The revolving arm of the work adsorption head 22 is rotated about the rotation axis 23 to position the work on the metal rotating surface plate 21.

  17). The workpiece w newly placed on the temporary table 9 with the grinding / cleaning sapphire substrate surface facing upward is adsorbed to the arm 4a of the articulated arm type work transfer robot 4 to adsorb the workpiece in the lapping chamber. While the workpiece is being transferred to a position below the head 22, the arm is turned so that the tape application surface of the workpiece faces upward, and then the workpiece is positioned below the empty workpiece suction head 22 in the lapping chamber. Then, the work suction head is depressurized to fix the tape application surface of the work by suction.

  18). The revolving arm of the work suction head 22 is rotated to position the work on the metal rotating surface plate 21.

  19). A pair of the workpiece suction heads 22 and 22 are lowered and the sapphire substrate surface of the workpiece is brought into contact with and slid on the metal rotating surface plate 21 rotating at a speed of 180 mm / min. Is started, and when the lapping process has a lapping amount of 20 μm, the rotation of the metal rotating surface plate 21 is stopped and the pair of workpiece suction heads 22 and 22 are raised, and then the workpiece suction is performed. The revolving arm of the head 22 is rotated in the opposite direction to the above and returned to the workpiece suction head standby position, and the lapping process is completed. At the time of lapping, a diamond abrasive water dispersion manufactured by Reiston Co., Ltd. is supplied to the surface of the metal rotating surface plate 21.

20). The arm 4a of the articulated arm-type workpiece transfer robot 4 is moved below the workpiece suction head 22, and the lap sapphire substrate surface of the workpiece sucked below the workpiece suction head 22 is moved by the arm 4a. After the suction, the pressure reduction of the workpiece suction head 22 is released, and then the arm of the articulated arm type work transfer robot 4 is moved onto the spin cleaner 11a on the back surface of the lapping workpiece, where the pressure of the arm 4a is reduced. cancel placed on the spinner provisional table 11a _t toward the lapping surface of the workpiece to above.

  21). The spin cleaning of the workpiece is performed while spraying cleaning water on the front and back surfaces of the workpiece using the spin cleaning device 11a and the Bergrin cleaning device 11b, and the cleaning water adhering to the workpiece is wiped off with Berglin.

  22). After moving the arm 4a of the articulated arm-type workpiece transfer robot 4 onto the spin cleaner 11a on the back surface of the lapping workpiece, the arm is decompressed to adsorb the lapping surface of the workpiece, and then the articulated arm type The arm of the workpiece transfer robot is transferred into the shelf of the storage cassette 3, where the pressure of the arm 4a is released, and a workpiece having a sapphire substrate thickness of 90 μm is stored in the storage cassette 3.

  23). The arm of the articulated arm type work transfer robot 4 is transferred onto the arm cleaner 10 for the articulated arm type work transfer robot, and the arm 4a is cleaned.

24). The arm 4a of the articulated arm-type workpiece transfer robot 4 with the arm cleaned is moved below the other workpiece suction head 22, and then the workpiece lapping sapphire sucked below the workpiece suction head. After the substrate surface is adsorbed by the arm 4a, the pressure reduction of the work adsorption head 22 is released, and then the arm 4a of the articulated arm type work transfer robot is moved onto the spin cleaner 11a on the back surface of the lapping work, , placed on a spinner provisional table 11a _t toward the lapping surface of the workpiece upward by releasing the vacuum of the arm.

  25). The spin cleaning of the work is performed while spraying the cleaning water on the front and back surfaces of the work using the spin cleaning device 11a and the Berglin cleaning device 11b, and the cleaning water adhering to the work is wiped off with Berglin.

  26). After moving the arm 4a of the articulated arm-type workpiece transfer robot 4 onto the spin cleaner 11a on the back surface of the lapping workpiece, the arm is decompressed to adsorb the lapping surface of the workpiece, and then the articulated arm type The arm 4a of the workpiece transfer robot is transferred into the shelf of the storage cassette 3, where the decompression of the arm 4a is released and a workpiece having a sapphire substrate thickness of 90 μm is stored in the storage cassette 3.

  27). The arm 4a of the articulated arm type work transfer robot 4 is transferred onto the arm cleaner 10 for the articulated arm type work transfer robot, and the arm is cleaned. After cleaning, the arm 4a is returned to the arm standby position of the articulated arm type work transfer robot.

  28). During the steps 20) to 27), the metal rotating surface plate 21 is rotated in the lapping chamber 2c, and cleaning water is supplied from the metal rotating surface plate cleaning device 27. The metal rotating surface plate is cleaned, and the lower part of the workpiece suction head 22 is cleaned by the workpiece suction head cleaner 25. Further, the grooving repair processing of the surface of the metal rotating surface plate 21 is performed by the facing device 28 while the workpiece is not lapping.

  The warpage of the 90-μm thick 6-inch diameter sapphire substrate, which was flattened and removed from the easily peelable tape, was about 20 μm, and the surface roughness (Ra) was 18 nm. The throughput was about 22 sheets / hour.

29) The surface of the sapphire substrate to be ground / lapped obtained in the above 28 steps is vacuum-adsorbed to the suction head of a polishing apparatus, and then the polishing head is rotated and lowered at 100 rpm and rotated at 120 rpm. The sapphire surface to be ground and lapped was rubbed on the surface plate and the polishing process was started while applying a pressure of 120 g / cm ^2. The polishing process was terminated when the allowance was 12 μm. During the polishing process, a 0.5 to 1.5 μm diameter diamond abrasive dispersed abrasive slurry was supplied onto the polishing surface plate. The warpage of the 6-inch diameter sapphire substrate having a thickness of 78 μm after polishing and removal of the easily peelable tape was about 18 μm, and the surface roughness (Ra) was 3.4 nm.

Example 2
The same as in Example 1 except that the sapphire substrate flattening apparatus 1 described above is used, and a sapphire substrate having a thickness of 500 μm and a 4 inch diameter with an easily peelable adhesive tape attached is used instead of the 6 inch diameter sapphire substrate. When the surface of the sapphire substrate is planarized under the above processing conditions, the warp of the 90-μm-thick 4-inch sapphire substrate is about 82 μm and the surface roughness (Ra) is about 20 nm at a rate of about 31 sheets / hour. A sapphire substrate with grinding and lapping was obtained.

  The method for planarizing a sapphire substrate according to the present invention can perform grinding, lapping, and polishing on the surface of the sapphire substrate at a high throughput without causing cracks. Further, the warping of the flattened sapphire substrate obtained is small, and an annealing process step conventionally performed after grinding or lapping is not necessary.

DESCRIPTION OF SYMBOLS 1 Substrate flattening processing device 2a Work conveyance / work washing chamber 2b Grinding chamber Lapping chamber 2c Lapping chamber 3 Storage cassette 4 Articulated transfer robot 5 Temporary table 20 with centering device Lapping machine 21 Metal rotating surface plate 22 Workpiece suction head 30 Grinding device 31 Index tables 34a, 34b, 34c, 34d Suction chuck table s ₁ Loading / unloading stage s ₂ First (coarse) grinding stage s ₃ Second (medium finish) grinding stage s ₄ Three (finishing) grinding stage 34h _c Coarse grinding wheel head 34h _m Medium finishing grinding wheel head 34h _f Finishing grinding wheel head

Claims (2)

A method for planarizing a sapphire substrate, characterized in that the thickness of the sapphire substrate is reduced by flattening the surface of the sapphire substrate through the following steps.
1). A sapphire substrate (workpiece) having an easily peelable adhesive tape or wax-attached substrate support plate attached to the surface is transferred onto the first suction chuck table, and the easily peelable adhesive tape surface of the workpiece or the substrate support plate is The workpiece is placed on the first suction chuck table so that the sapphire substrate surface is the upper surface on the lower surface.
2). The index table is rotated 90 degrees to move the first chuck table on which the workpiece at the loading / unloading stage (s ₁ ) position is mounted to the second chuck table position at the first grinding stage (s ₂ ) position.
3). Rotating the second chuck table, and then rotating and lowering the first grindstone shaft for bearing the diamond abrasive cup wheel type metal bond grinding wheel having an abrasive number of 280 to 360, the diamond abrasive cup wheel type metal The bond grinding wheel is brought into contact with the sapphire substrate surface of the workpiece and rubbed to start the first grinding process, and the diamond abrasive cup wheel type metal bond grinding wheel is lowered to perform in-feed grinding of the sapphire substrate surface. Perform the first grinding process.
4). The index table is rotated 90 degrees to move the second chuck table at the first grinding stage (s ₂ ) position to the third chuck table position at the second grinding stage (s ₃ ) position.
5). Rotating the third chuck table, and then rotating and lowering the second grindstone shaft that supports the diamond abrasive cup wheel type metal bond grinding wheel having an abrasive number of 680 to 800, the diamond abrasive cup wheel type metal The bond grinding wheel is brought into contact with the sapphire substrate surface of the workpiece and rubbed to start the second grinding process. Further, the diamond abrasive cup wheel type metal bond grinding wheel is lowered to perform in-feed grinding of the sapphire substrate surface. Perform the second grinding process.
6). The index table is rotated 90 degrees clockwise to move the third chuck table at the second grinding stage (s ₃ ) position to the fourth chuck table position at the finish grinding stage (s ₄ ) position.
7). Rotating the fourth chuck table, and then rotating and lowering the third grindstone shaft that supports the diamond abrasive cup wheel type metal bond grindstone having an abrasive number of 680 to 800, the diamond abrasive cup wheel type metal The bond grinding wheel is brought into contact with the sapphire substrate surface of the workpiece and rubbed to start the third grinding process, and the diamond abrasive cup wheel type metal bond grinding wheel is lowered to infeed grinding the sapphire substrate surface. Perform third grinding.
8). The index table is rotated 90 degrees clockwise or 270 degrees counterclockwise to move the fourth chuck table at the third grinding stage (s ₄ ) position to the loading / unloading stage (s ₁ ) position. Move to a certain first chuck table position.
9). The ground workpiece mounted on the first chuck table at the position of the loading / unloading stage (s ₁ ) is subjected to spin cleaning.
10). The to-be-ground sapphire substrate that has been subjected to spin cleaning is moved onto the metal lap rotating surface plate so that the to-be-ground sapphire surface faces the surface of the metal wrap rotating surface plate.
11). Applying a load of 50 to 300 g / cm ^{2 to} the tape surface or substrate support plate surface of the sapphire substrate to be ground on a metal rotating surface plate, and a grain size of 1 to 15 μm on the rotating lap surface plate A sapphire substrate having a thickness of 5 to 90 μm and a surface roughness (Ra) of 20 to 36 nm is obtained by rubbing the surface of the sapphire substrate to be ground with the metal rotating surface plate while supplying a slurry in which diamond abrasive grains are dispersed. A lapping process is performed. A method for planarizing a sapphire substrate, characterized in that the thickness of the sapphire substrate is reduced by flattening the surface of the sapphire substrate through the following steps.
1). A sapphire substrate (workpiece) having an easily peelable adhesive tape or wax-attached substrate support plate attached to the surface is transferred onto the first suction chuck table, and the easily peelable adhesive tape surface of the workpiece or the substrate support plate is The workpiece is placed on the first suction chuck table so that the sapphire substrate surface is the upper surface on the lower surface.
2). The index table is rotated 90 degrees to move the first chuck table on which the workpiece at the loading / unloading stage (s ₁ ) position is mounted to the second chuck table position at the first grinding stage (s ₂ ) position.
3). Rotating the second chuck table, and then rotating and lowering the first grindstone shaft for bearing the diamond abrasive cup wheel type metal bond grinding wheel having an abrasive number of 280 to 360, the diamond abrasive cup wheel type metal The bond grinding wheel is brought into contact with the sapphire substrate surface of the workpiece and rubbed to start the first grinding process, and the diamond abrasive cup wheel type metal bond grinding wheel is lowered to perform in-feed grinding of the sapphire substrate surface. Perform the first grinding process.
4). The index table is rotated 90 degrees to move the second chuck table at the first grinding stage (s ₂ ) position to the third chuck table position at the second grinding stage (s ₃ ) position.
5). Rotating the third chuck table, and then rotating and lowering the second grindstone shaft that supports the diamond abrasive cup wheel type metal bond grinding wheel having an abrasive number of 680 to 800, the diamond abrasive cup wheel type metal The bond grinding wheel is brought into contact with the sapphire substrate surface of the workpiece and rubbed to start the second grinding process. Further, the diamond abrasive cup wheel type metal bond grinding wheel is lowered to perform in-feed grinding of the sapphire substrate surface. Perform the second grinding process.
6). The index table is rotated 90 degrees clockwise to move the third chuck table at the second grinding stage (s ₃ ) position to the fourth chuck table position at the finish grinding stage (s ₄ ) position.
7). Rotating the fourth chuck table, and then rotating and lowering the third grindstone shaft that supports the diamond abrasive cup wheel type metal bond grindstone having an abrasive number of 680 to 800, the diamond abrasive cup wheel type metal The bond grinding wheel is brought into contact with the sapphire substrate surface of the workpiece and rubbed to start the third grinding process, and the diamond abrasive cup wheel type metal bond grinding wheel is lowered to infeed grinding the sapphire substrate surface. Perform third grinding.
8). The index table is rotated 90 degrees clockwise or 270 degrees counterclockwise to move the fourth chuck table at the third grinding stage (s ₄ ) position to the loading / unloading stage (s ₁ ) position. Move to a certain first chuck table position.
9). The ground workpiece mounted on the first chuck table at the position of the loading / unloading stage (s ₁ ) is subjected to spin cleaning.
10). The to-be-ground sapphire substrate that has been subjected to spin cleaning is moved onto the metal lap rotating surface plate so that the to-be-ground sapphire surface faces the surface of the metal wrap rotating surface plate.
11). Diamond grinding with a grain size of 1 to 15 μm is applied to the rotating lap platen by applying a load of 50 to 300 g / cm ^{2 to} the tape surface or substrate support plate surface of the sapphire substrate to be ground on a metal rotating platen. A lapping step of forming a sapphire substrate having a thickness of 5 to 90 μm and a surface roughness (Ra) of 20 to 36 nm by sliding the surface of the sapphire substrate to be ground on the metal rotating surface plate while supplying slurry in which grains are dispersed. I do.
12). Polishing apparatus by holding the tape surface or substrate support plate surface of the sapphire substrate to be ground / lapped by a suction chuck and then lowering and rotating the sapphire surface to be ground / lapped of the workpiece The surface roughness is reduced by reducing the thickness of the sapphire substrate by 10 to 30 μm by supplying a polishing slurry in which diamond abrasive grains having a particle size of 0.05 to 3 μm are dispersed on the polishing surface plate. A polishing process for forming a sapphire substrate with a thickness (Ra) of 2 to 6 nm is performed.

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