GRINDING APPARATUS, METHOD OF GRINDING WORKPIECE, AND METHOD OF MANUFACTURING SUBSTRATE

BACKGROUND OF THE INVENTION
Field of the Invention

The present invention relates to a grinding apparatus for grinding a workpiece having a modified layer present on one surface side thereof, a method of grinding the one surface side of the workpiece, and a method of manufacturing a substrate having a thickness less than a predetermined thickness from an ingot having the predetermined thickness.

Description of the Related Art

Semiconductor device chips are manufactured, in general, by use of a substrate that is made of a single crystal made of silicon (Si), silicon carbide (SiC), gallium nitride (GaN), lithium tantalate (LiTaO₃: LT), lithium niobate (LiNbO₃: LN), or the like. This substrate is manufactured by being sliced from an ingot with use of, for example, a wire saw.

A cutting margin formed when the substrate is sliced from the ingot with use of the wire saw is substantially 300 μm, which is relatively large. In addition, a front surface of the substrate thus sliced has surface irregularities formed thereon, and this substrate is warped in whole (a warp is generated in the substrate). Hence, when chips are manufactured with use of this substrate, the substrate is required to have its front surface lapped, etched, and/or polished in order to have the front surface planarized.

In this case, a final amount of a material that is expected to be used for the substrates is substantially ⅔ of the total amount of the ingot. In other words, substantially ⅓ of the total amount of the ingot is discarded when the substrate is cut out from the ingot and the front surface of the substrate is planarized. Hence, reduction in productivity is caused in a case in which the wire saw is used to manufacture the substrate.

In view of this problem, there has been proposed a method of manufacturing a substrate from an ingot by use of a laser beam having a wavelength transmittable through a material of the ingot (see, for example, Japanese Patent Laid-Open No. 2016-111143). More specifically, according to this method, first, in a state in which a focused spot of the laser beam is positioned in the ingot, the ingot and the focused spot are moved relative to each other.

As a result, layers (modified layers) arising from a disordered crystal structure of the material of the ingot are formed in the ingot, and cracks that extend from the modified layers are formed in the ingot. Further, according to this method, an external force is applied to the ingot in such a manner as to further extend these cracks. Consequently, with the modified layer as an initiating point, the ingot is separated, and the substrate is manufactured therefrom.

SUMMARY OF THE INVENTION

When the substrate is manufactured from the ingot as described above, the ingot and the substrate (hereinafter, which may also collectively be referred to as a “workpiece”) each have modified layers remaining on one surface side thereof. Hence, after the substrate is manufactured from the ingot in the manner described above, it is common to remove the modified layer and grind the one surface side of the workpiece in order to planarize the one surface side.

However, a thickness of the modified layer remaining on the one surface side of the workpiece may vary depending on individual differences. Hence, when the one surface side of the workpiece is ground, grinding is excessively carried out in such a manner that the whole of the modified layer is reliably removed (for example, such that the modified layer is removed by an amount several times greater than an estimated thickness of the modified layer), in many cases. In this case, as the productivity of the semiconductor devices that are produced with use of the workpiece is reduced, its throughput is also lowered.

In light of this, an object of the present invention is to prevent reduction in productivity and throughput when semiconductor devices are produced with use of a workpiece.

In accordance with an aspect of the present invention, there is provided a grinding apparatus for grinding one surface side of a workpiece in which modified layers are present on the one surface side, including a holding unit for holding the workpiece such that the one surface side is exposed, a grinding unit for grinding the one surface side of the workpiece held by the holding unit, a capturing unit for capturing the one surface side of the workpiece held by the holding unit, and a controller that determines whether grinding of the one surface side of the workpiece is to be terminated, with reference to information regarding the modified layers obtained by capturing of the one surface side of the workpiece that is performed in a state in which grinding of the one surface side of the workpiece is performed in parallel or is suspended.

Preferably, the grinding apparatus according to the present invention may further include a processing chamber cover that surrounds a processing chamber capable of accommodating the workpiece held by the holding unit, the grinding unit, and the capturing unit, and the processing chamber cover may include a partition wall for partitioning the processing chamber into a grinding space in which grinding of the one surface side of the workpiece is performed and a capturing space in which capturing of the one surface side of the workpiece is performed. More preferably, the grinding apparatus according to the present invention may further include a grinding liquid supplying unit for supplying a grinding liquid to a region to be ground of the one surface side of the workpiece, and a fluid jetting unit for jetting fluid to the one surface side of the workpiece, in order to prevent the grinding liquid from entering a region to be captured of the one surface side of the workpiece.

Still more preferably, the holding unit may have a chuck table for holding the workpiece on a holding surface, a motor for rotating the chuck table with a straight line passing through a center of the holding surface as a rotational axis, and an encoder that detects a rotational angle of the chuck table, and the controller may identify that an element linearly extending along a direction which changes according to the rotational angle in the workpiece captured by the capturing unit is the modified layer. In addition, preferably, the controller may change a grinding condition with reference to the information when grinding of the one surface side of the workpiece is performed.

In accordance with another aspect of the present invention, there is provided a method of grinding a workpiece which grinds one surface side of the workpiece in which modified layers are present on the one surface side, including a holding step of holding the workpiece such that the one surface side thereof is exposed, and a grinding step of grinding the one surface of the workpiece after the holding step is performed, in which a determination as to whether the grinding step is to be terminated is made with reference to information regarding the modified layers obtained by capturing of the one surface side of the workpiece that is performed in a state in which grinding of the one surface side of the workpiece is performed in parallel or is suspended.

In accordance with a further aspect of the present invention, there is provided a method of manufacturing a substrate having a thickness less than a predetermined thickness from an ingot having the predetermined thickness, the method including a modified layer forming step of moving, relative to each other, the ingot and a focused spot on which a laser beam with a wavelength transmittable through a material of the ingot is focused, in a state in which the focused spot is positioned in the ingot, thereby forming modified layers in the ingot, a substrate manufacturing step of, after the modified layer forming step is performed, with the modified layer as an initiating point, separating the ingot, thereby manufacturing the substrate having on one surface side thereof the modified layer remaining thereon, and a grinding step of, after the substrate manufacturing step is performed, grinding the one surface side of the substrate, in which a determination as to whether the grinding step is to be terminated is made with reference to information regarding the modified layers obtained by capturing of the one surface side of the substrate that is performed in a state in which grinding of the one surface side of the substrate is performed in parallel or is suspended.

According to the present invention, a determination as to whether grinding of the one surface side of the workpiece is to be terminated is made with reference to information regarding the modified layers obtained by capturing of the one surface side of the workpiece that is performed in a state in which grinding of the one surface side of the workpiece is performed in parallel or is suspended. In this case, it is possible to remove the one surface side of the workpiece by an appropriate thickness in just the right amount.

More specifically, in this case, without grinding the one surface side of the workpiece excessively, it is possible to terminate grinding of the one surface side of the workpiece, for example, at a time point at which a determination that the whole of the modified layer has been removed is made. Hence, according to the present invention, it is possible to prevent reduction in productivity of semiconductor devices manufactured with use of the workpiece and reduction in throughput thereof.

The above and other objects, features and advantages of the present invention and the manner of realizing them will become more apparent, and the invention itself will best be understood from a study of the following description and appended claims with reference to the attached drawings showing some preferred embodiments of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view schematically illustrating an example of a grinding apparatus;

FIG. 2 is a view schematically illustrating an elevational cross-section of a chuck table and other components included in a holding unit of the grinding apparatus which is positioned at a grinding position;

FIG. 3 is a view schematically illustrating an upper surface of the chuck table and other components included in the holding unit of the grinding apparatus which is positioned at the grinding position;

FIG. 4A is a block diagram schematically illustrating a controller for controlling the holding unit, a capturing unit, and a grinding unit of the grinding apparatus;

FIG. 4B is a block diagram schematically illustrating functional sections implemented by the controller when one surface side of a workpiece is ground;

FIG. 5 is a flowchart schematically indicating an example of a method of grinding the one surface side of the workpiece in the grinding apparatus;

FIG. 6A is a partial cross sectional side view schematically illustrating the manner of performing a holding step indicated in FIG. 5;

FIG. 6B is a partial cross sectional side view schematically illustrating the manner of performing a grinding step indicated in FIG. 5;

FIG. 7 is a flowchart schematically indicating an example of processes that are performed by the controller for making a determination as to whether a grinding condition used when the one surface side of the workpiece is ground is to be changed and as to whether this grinding process is to be terminated, in the grinding step indicated in FIG. 5;

FIG. 8A is a plan view schematically illustrating the one surface side of the workpiece that has not undergone the grinding step;

FIG. 8B is a plan view schematically illustrating the one surface side of the workpiece having some of the modified layers removed by grinding;

FIG. 8C is a plan view schematically illustrating the one surface side of the workpiece having most of the modified layers removed by grinding;

FIG. 8D is a plan view schematically illustrating the one surface side of the workpiece having all of the modified layers removed by grinding;

FIG. 9 is a partial cross sectional side view schematically illustrating an example of a grinding apparatus including a capturing unit with a structure different from that of the capturing unit illustrated in FIG. 2 and FIG. 3;

FIG. 10A is a partial cross sectional side view schematically illustrating an example of a grinding apparatus which can capture the one surface side of the workpiece in a state in which a capturing space is filled with liquid;

FIG. 10B is a partial cross sectional side view schematically illustrating the manner of the grinding step indicated in FIG. 5 that is performed in the grinding apparatus illustrated in FIG. 10A;

FIG. 11A is a partial cross sectional side view schematically illustrating another example of the grinding apparatus which can capture the one surface side of the workpiece in a state in which the capturing space is filled with liquid;

FIG. 11B is a partial cross sectional side view schematically illustrating the manner of the grinding step indicated in FIG. 5 that is performed in the grinding apparatus illustrated in FIG. 11A;

FIG. 12 is a flowchart schematically indicating an example of a method of manufacturing a substrate;

FIG. 13 is a perspective view schematically illustrating the manner of a modified layer forming step indicated in FIG. 12;

FIG. 14A is a side view schematically illustrating the manner of a substrate manufacturing step indicated in FIG. 12; and

FIG. 14B is a side view schematically illustrating the manner of the substrate manufacturing step indicated in FIG. 12.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

With reference to the attached drawings, embodiments of the present invention will be described. FIG. 1 is a perspective view schematically illustrating an example of a grinding apparatus. Note that an X-axis direction (front-back direction) and a Y-axis direction (left-right direction) illustrated in FIG. 1 are directions orthogonal to each other on a horizontal plane. In addition, a Z-axis direction (upper-lower direction) is a direction (vertical direction) orthogonal to each of the X-axis direction and the Y-axis direction.

A grinding apparatus 2 illustrated in FIG. 1 has a base 4 that supports components. On an upper surface of the base 4, there is formed a rectangular parallelepiped recess 4a that extends along the X-axis direction. Also, inside the recess 4a, there is provided a holding unit 6 that holds a workpiece 11.

The workpiece 11 is a substrate manufactured by being separated from an ingot, for example, with modified layers as initiating points, or a remaining ingot obtained after this substrate is manufactured. Note that a method of manufacturing such a substrate will be described later. The modified layers remain on one surface 11a side of this workpiece 11 (more specifically, a surface side that is newly exposed due to separation of the ingot).

Also, the presence of the modified layers causes the one surface 11a of the workpiece 11 to be rougher than the other surface 11b. Moreover, a side surface of the workpiece 11 has an orientation flat 11c for indicating a crystal orientation of a material (for example, a single crystal made of Si, SiC, GaN, LT, LN, or the like) formed thereon.

The holding unit 6 has a chuck table 8 for holding the workpiece 11 on a holding surface. Also, the chuck table 8 is movable between a position at which the workpiece 11 is loaded onto the holding surface and the workpiece 11 is unloaded therefrom (loading/unloading position) and a position at which grinding of the workpiece 11 held on the holding surface is performed (grinding position).

Note that, in FIG. 1, the grinding apparatus 2 is illustrated as being in a state in which the chuck table 8 is positioned at the loading/unloading position. Also, the grinding position is a position spaced apart from the loading/unloading position in the X-axis direction, i.e., a rearward position in the X-axis direction, as viewed from the loading/unloading position.

FIG. 2 is a view schematically illustrating an elevational cross-section of the chuck table 8 positioned at the grinding position. Note that, in FIG. 2, components of the holding unit 6 other than the chuck table 8, and the like are illustrated in block form. In addition, FIG. 3 is a view schematically illustrating an upper surface of the chuck table 8 that is positioned at the grinding position.

The chuck table 8 has a circular plate-shaped frame body 10 formed of ceramic or the like, for example. This frame body 10 has a circular plate-shaped bottom wall 10a and a cylindrical side wall 10b erected from an outer peripheral portion of this bottom wall 10a. In other words, a circular plate-shaped recess portion defined by the bottom wall 10a and the side wall 10b is formed on an upper surface side of the frame body 10.

Further, this recess portion has a circular plate-shaped porous plate 12 formed of porous ceramic or the like fixed thereto. Note that an upper surface of the side wall 10b of the frame body 10 and an upper surface of the porous plate 12 have a shape corresponding to a side surface of a cone, functioning as the holding surface in holding the workpiece 11.

In addition, the bottom wall 10a has a flow channel 10c opened at the bottom surface of the recess portion and penetrating the bottom wall 10a. Moreover, the flow channel 10c communicates with a suction source 16athrough a valve 14a and with a fluid supply source 16bthrough a valve 14b.

The suction source 16a includes, for example, an ejector or the like. In addition, the fluid supply source 16b includes, for example, a tank for storing a high-pressure gas, a filter for removing foreign matter that is mixed in the gas supplied from the tank, and a regulator for controlling pressure of the gas supplied from the tank.

In addition, the chuck table 8 is, for example, connected to a motor 18 through a pulley (not illustrated) and a belt (not illustrated) that is wrapped around the pulley, or the like. Further, when the motor 18 is operated, with a straight line passing through the center of the holding surface of the chuck table 8 as a rotational axis, for example, the chuck table 8 is rotated in a clockwise direction (along a direction of an arrow Al illustrated in FIG. 3), in plan view.

In addition, in the vicinity of the chuck table 8, an encoder 20 is provided. The encoder 20 includes, for example, a light source which emits light (for example, visible light) toward a gauge formed on a lower surface of the bottom wall 10a of the frame body 10 of the chuck table 8, and a light-receiving element which converts the light reflected on the lower surface of the bottom wall 10a into an electric signal. Moreover, the encoder 20 detects a rotational angle of the chuck table 8 in reference to the electric signal.

In addition, the chuck table 8 is supported by an inclination adjusting mechanism (not illustrated) through a bearing (not illustrated), a table base (not illustrated), and the like. The inclination adjusting mechanism includes, for example, two movable shafts and one fixed shaft, which are disposed to be spaced at substantially equal angular intervals along a circumferential direction of the chuck table 8. Further, when at least one of the two movable shafts partially lifts the table base and the chuck table 8, an inclination of the rotational axis of the chuck table 8 is adjusted.

Inside the recess 4a formed in the upper surface of the base 4, an X-axis direction moving mechanism (not illustrated) is provided. The X-axis direction moving mechanism includes, for example, a ball screw, a motor, and the like. Moreover, when the X-axis direction moving mechanism is operated, the chuck table 8 moves between the loading/unloading position and the grinding position.

In the periphery of the chuck table 8, there is provided a rectangular parallelepiped table cover 22 that surrounds the chuck table 8 such that the holding surface thereof is exposed. The width (length along the Y-axis direction) of the table cover 22 is substantially equal to the width of the recess 4a formed in the upper surface of the base 4. In addition, on the front and rear sides of the table cover 22, there are provided dustproof droplet-proof covers 24 capable of contracting and extending along the X-axis direction.

On the upper surface of the base 4, there is provided a processing chamber cover 26 surrounding a space (processing chamber) in which the workpiece 11 is ground. The processing chamber cover 26 has a rectangular shaped top plate 28 the width (length along the Y-axis direction) of which is greater than that of the recess 4a. Note that the top plate 28 overlaps with the rear side of the recess 4a in plan view.

Moreover, the top plate 28 has a circular opening 28a formed therein. The opening 28a has a center positioned on the rear side of the top plate 28 and has, in plan view, the center of the holding surface and the rear end of the chuck table 8 positioned at the grinding position exposed.

The opening 28a enables a grinding wheel 72 described later to enter and exit the processing chamber. More specifically, the opening 28a is so formed that its center overlaps with a center of the grinding wheel 72 in plan view and its diameter is greater than an outer diameter of the grinding wheel 72.

An upper end of the front side plate 30 is fixed to a lower side of the front end of the top plate 28. Moreover, the front side plate 30 has a rectangular opening 30a formed therein. The opening 30a enables the chuck table 8 that holds the workpiece 11 thereon to enter and exit the processing chamber. In other words, the front side plate 30 has a bridge-type shape, i.e., such a shape that a lower side of a portion thereof overlapping with the recess 4a is cut out.

A lower portion of a rear end, a lower portion of a left end, and a lower portion of a right end of the top plate 28 have an upper end of a rear side plate 32, an upper end of a left side plate 34, and an upper end of a right side plate 36 respectively fixed thereto. Note that the rear side plate 32, the left side plate 34, and the right side plate 36 each have a rectangular shape. In addition, a lower end of each of the front side plate 30, the rear side plate 32, the left side plate 34, and the right side plate 36 is fixed to the upper surface of the base 4.

Further, the processing chamber cover 26 includes a partition wall 38 that partitions the processing chamber into a space (grinding space) S1 in which grinding of the workpiece 11 is performed and a space (capturing space) S2 in which capturing of the ground workpiece 11 is performed.

Note that the partition wall 38 extends along the Y-axis direction and has a length substantially equal to those of the front side plate 30 and the rear side plate 32. Also, an upper end, a left end, and a right end of the partition wall 38 are fixed to the underneath of a portion of the top plate 28 that is slightly closer to the frontward than the opening 28a, the inner side of the upper portion of the left side plate 34, and the inner side of the upper portion of the right side plate 36, respectively.

In the capturing space S2, a capturing unit 40 that captures the one surface 11a side of the workpiece 11 held on the holding surface of the chuck table 8 is provided. The capturing unit 40 has a rectangular top plate 40a which is positioned closer to the frontward as viewed from the center of the holding surface of the chuck table 8 positioned at the grinding position and which overlaps with the front side of the holding surface in plan view.

The top plate 40a of the capturing unit 40 is supported by the processing chamber cover 26 via four support tools 42 provided in such a manner as to extend downward from the top plate 28 of the processing chamber cover 26. Also, there is provided a camera 40b an objective lens of which is directed downward, in the center of the top plate 40a of the capturing unit 40.

In addition, respective light sources 40c are provided on lower sides of four end portions of the top plate 40a. Note that each of the light sources 40c can emit light (for example, visible light) in an oblique downward direction so as to illuminate a location overlapping with the top plate 40a in plan view.

Moreover, in a direction opposite to the rotational direction (direction of the arrow A1 illustrated in FIG. 3) of the chuck table 8 as viewed from the camera 40b of the capturing unit 40, an air curtain (fluid jetting unit) 44 is provided. The air curtain 44 is supported by the processing chamber cover 26 via a plurality of support tools 46 each of which is so provided as to project forward from the partition wall 38.

Further, the air curtain 44 extends, in plan view, along a radial direction of the holding surface of the chuck table 8 positioned at the grinding position and is allowed to jet air to a portion directly therebelow. More specifically, the air curtain 44 can jet air toward a region of the holding surface of the chuck table 8 which enters the capturing space S2 from the grinding space S1.

As illustrated in FIG. 1, in a region positioned on the rear side of the recess 4a on the upper surface of the base 4, a support structure 48 shaped as a quadrangular prism is provided. In front of the support structure 48, a grinding unit 50 is provided. The grinding unit 50 has a Z-axis direction moving mechanism 52 provided on the front surface of the support structure 48.

The Z-axis direction moving mechanism 52 includes a pair of guide rails 54 each of which extends along the Z-axis direction. Moreover, in front of each of the pair of guide rails 54, there is provided a slider (not illustrated) in such a manner as to be slidable along the Z-axis direction. In addition, the front end of the slider is fixed to the rear surface side of the Z-axis moving plate 56 having a rectangular parallelepiped shape.

Further, between the pair of guide rails 54, there is provided a screw shaft 58 that extends along the Z-axis direction. Moreover, to an upper end of the screw shaft 58, a motor 60 for rotating the screw shaft 58 is connected. In addition, on a circumferential surface formed with a screw thread of the screw shaft 58, a nut (not illustrated) for accommodating a ball that circulates according to the rotation of the screw shaft 58 is provided, to constitute a ball screw.

In addition, the nut is fixed to a rear surface of the Z-axis moving plate 56. Thus, when the screw shaft 58 is rotated by the motor 60, the Z-axis moving plate 56 moves along the Z-axis direction together with the nut. To the front side of the Z-axis moving plate 56, a cylindrical supporting member 62 is fixed.

Moreover, inside the supporting member 62, a cylindrical spindle housing 64 that extends along the Z-axis direction is provided. In addition, inside the spindle housing 64, there is provided a spindle 68 which is supported by the spindle housing 64 in a rotatable manner and an upper end of which is connected to a motor 66 (see FIG. 2 and FIG. 3).

A lower end of the spindle 68 is exposed from the spindle housing 64 and fixed to a circular plate-shaped wheel mount 70. Also, a ring-shaped grinding wheel 72 having an outer diameter substantially equal to a diameter of the wheel mount 70 is attached to a lower surface of the wheel mount 70 through a fixing member (not illustrated) such as a bolt.

The grinding wheel 72 has a plurality of grinding stones 72a and a wheel base 72b having a lower surface on which the plurality of grinding stones 72a are disposed in a ring shape at predetermined intervals. When the motor 66 is operated, with the line extending along the Z-axis direction as the rotational axis, for example, the wheel mount 70 and the grinding wheel 72 are rotated in a clockwise direction (along a direction of an arrow A2 illustrated in FIG. 3), in plan view.

Note that the plurality of grinding stones 72a have abrasive grains, such as diamond or cubic boron nitride (cBN), which are dispersed in a binder such as a vitrified bond or a resin bond. In addition, the wheel base 72b is made of, for example, a metal material such as stainless steel or aluminum.

Further, at the periphery of the grinding wheel 72, a grinding liquid supplying unit 74 is provided. The grinding liquid supplying unit 74 has a pipe 76 which is inserted into a through hole formed in the rear side plate 32 of the processing chamber cover 26. Further, a proximal end portion (one end portion) of the pipe 76 is connected to a grinding liquid supplying source (not illustrated).

In addition, a nozzle 78 is provided at a distal end portion (the other end portion) of the pipe 76. Further, when the grinding liquid supplying unit 74 is operated, a grinding liquid (for example, water) is supplied from the grinding liquid supplying source through the pipe 76 and the nozzle 78, toward the rear side of the holding surface of the chuck table 8 positioned at the grinding position.

The grinding apparatus 2 incorporates a controller that controls the holding unit 6, the grinding unit 50, the capturing unit 40, and the like. FIG. 4A is a block diagram schematically illustrating the controller. A controller 80 illustrated in FIG. 4A includes a processor 80a and a memory 80b.

The processor 80a includes, for example, a central processing unit (CPU) and the like. The memory 80b includes, for example, a volatile memory such as a dynamic random access memory (DRAM) or a static random access memory (SRAM) and a nonvolatile memory such as a solid state drive (SSD) also known as a Not-AND (NAND)-type flash memory or a hard disk drive (HDD) also known as a magnetic storage device.

In addition, the processor 80a reads out a program for grinding the one surface 11a side of the workpiece 11 from the memory 80b to allow the program to be performed. In addition, the memory 80b is able to store not only the program but also data to be used when the program is executed by the processor 80a.

For example, the memory 80b stores information regarding modified layers to be used for a determination as to whether grinding of the one surface 11a side of the workpiece 11 is to be terminated. Such information includes, for example, a threshold for a proportion of the modified layers present on the one surface 11a side of the workpiece 11, a threshold for a period in which presence of the modified layers has not been confirmed in a capturing region of the one surface 11a side of the workpiece 11, or other types of parameters.

In addition, the memory 80b may store information regarding modified layers to be used for a determination as to whether a grinding condition used when the one surface 11a side of the workpiece 11 is ground is to be changed. Such information includes, for example, a table obtained by associating a plurality of numeral ranges which are different from each other for the proportion or the period mentioned above and a plurality of grinding conditions with each other, and the like.

Note that, in the table, a large one among the plurality of numerical ranges for the proportion described above or a small one among the plurality of numerical ranges for the period described above and such a grinding condition that a load becomes large (for example, in a grinding condition in which a lowering speed of the grinding wheel 72 (grinding feed speed) is high) are associated with each other. In other words, in this table, a small one among the plurality of numerical ranges for the proportion described above or a large one among the plurality of numerical ranges for the period described above and such a grinding condition that a load becomes small (for example, a grinding condition in which the grinding feed speed is low) are associated with each other.

In addition, the memory 80b may store information to be used for identification of the modified layer present on the one surface 11a side of the captured workpiece 11. Such information includes, for example, a direction in which the modified layer extends, or the like.

FIG. 4B is a block diagram schematically illustrating functional sections implemented by the controller 80, when the one surface 11a side of the workpiece 11 is ground. More specifically, in grinding, an information acquisition section 80c and a grinding instruction section 80d are implemented by the controller 80.

The information acquisition section 80c acquires information regarding the modified layers on the one surface 11a side of the workpiece 11. More specifically, the information acquisition section 80c first controls the capturing unit 40 such that the one surface 11a side of the workpiece 11 is captured in a state in which grinding of the one surface 11a side of the workpiece 11 is performed in parallel or is suspended.

When the one surface 11a side of the workpiece 11 is captured, the information acquisition section 80c identifies that an element on the one surface 11a side of the workpiece 11 linearly extending along a direction stored in advance is the modified layer, for example. Note that the direction may be corrected according to the rotational angle of the chuck table 8 detected by the encoder 20. More specifically, the information acquisition section 80c may identify that an element extending linearly along the direction being changed according to the rotational angle of the chuck table 8 is the modified layer.

When the modified layer present on the one surface 11a side of the workpiece 11 is identified, the information acquisition section 80c calculates the proportion of the modified layers present on the one surface 11a side of the workpiece 11, for example. In addition, in a case in which capturing of the one surface 11a side of the workpiece 11 is performed in parallel with grinding of the one surface 11a side of the workpiece 11, the information acquisition section 80c may measure the period in which the presence of the modified layers has not been confirmed in the capturing region on the one surface 11a side of the workpiece 11.

The grinding instruction section 80d controls the grinding unit 50 such that, with reference to information regarding the modified layers that is acquired by the information acquisition section 80c (more specifically, the proportion calculated or the period measured by the information acquisition section 80c, or the like), the one surface 11a side of the workpiece 11 is suitably ground. More specifically, the grinding instruction section 80d includes a change section 80e that determines whether the grinding condition used when the one surface 11a side of the workpiece 11 is ground is to be changed and a termination section 80f that determines whether this grounding process is to be terminated.

For example, in a case in which a value of the proportion calculated or a value of the period measured by the information acquisition section 80c is not included in the numerical range associated with the current grinding condition in the table stored in advance, the change section 80e controls the grinding unit 50 such that the one surface 11a side of the workpiece 11 is ground under a grinding condition associated with the numerical range including this value.

For example, in a case in which the value of the proportion calculated by the information acquisition section 80c is smaller than the threshold stored in advance for the proportion of the modified layers, or in a case in which the value of the period measured by the information acquisition section 80c is larger than the threshold stored in advance for the period in which presence of the modified layers has not been confirmed, the termination section 80f controls the grinding unit 50 such that grinding of the one surface 11a side of the workpiece 11 is terminated.

FIG. 5 is a flowchart schematically indicating one example of a method of grinding the one surface 11a side of the workpiece 11 in the grinding apparatus 2. In this method, first, the workpiece 11 is held such that the one surface 11a side is exposed (holding step S10). FIG. 6A is a partial cross sectional side view schematically illustrating the manner of performing the holding step S10 indicated in FIG. 5.

In the holding step S10, first, the chuck table 8 is positioned at the loading/unloading position. Next, the workpiece 11 is disposed on the holding surface of the chuck table 8 in such a manner that the one surface 11a is oriented upward and the workpiece 11 covers the porous plate 12.

Subsequently, the suction source 16a is operated, and the valve 14a is opened. In this case, a suction force is applied to the workpiece 11 from the chuck table 8. As a result, in a state in which the one surface 11a side is exposed, the workpiece 11 is held on the holding surface of the chuck table 8.

Subsequently, the chuck table 8 is positioned at the grinding position. The holding step S10 is thus completed. After the holding step S10, the one surface 11a side of the workpiece 11 is ground (grinding step S20). FIG. 6B is a partial cross sectional side view schematically illustrating the manner of performing the grinding step S20 indicated in FIG. 5.

In the grinding step S20, while both the chuck table 8 and the grinding wheel 72 are rotated, the grinding wheel 72 is lowered in such a manner that the plurality of grinding stones 72a are brought into contact with the one surface 11a of the workpiece 11. In addition, immediately before the grinding process, supply of a grinding liquid L from the nozzle 78 of the grinding liquid supplying unit 74, jetting of air from the air curtain 44, and capturing by the camera 40b in a state in which light is emitted from each light source 40c of the capturing unit 40 are started.

Accordingly, grinding of the one surface 11a side of the workpiece 11 in a state in which the grinding liquid L is supplied to a contact interface (processing point) between the plurality of grinding stones 72a and the one surface 11a of the workpiece 11 is performed in parallel with capturing of the one surface 11a side of the workpiece 11 in a state in which the grinding liquid L is prevented from entering a portion between the camera 40b and the one surface 11a of the workpiece 11.

Moreover, in the grinding step S20, a determination as to whether the grinding condition used when the one surface 11a side of the workpiece 11 is ground is to be changed and a determination as to whether this grinding process is to be terminated are repeatedly made by the controller 80, according to capturing of the one surface 11a side of the workpiece 11. FIG. 7 is a flowchart schematically indicating one example of processes to be performed by the controller 80 in order to make these determinations.

More specifically, the controller 80 first acquires the information regarding the modified layers (acquiring step S21). In the acquiring step S21, immediately before the acquiring step S21 is performed, the one surface 11a side of the workpiece 11 is captured by the camera 40b, and an image thus formed is referenced.

Note that the controller 80 may perform various types of processes on this image, prior to the acquiring step S21. This process includes, for example, rotation according to the rotational angle of the chuck table 8 detected by the encoder 20, extraction executed with use of Fourier transform or the like of a pattern corresponding to the modified layers formed at a predetermined cycle, or the like.

FIG. 8A is a plan view schematically illustrating the one surface 11a side of the workpiece 11 that has not undergone the grinding process. The one surface 11a side of the workpiece 11 has a plurality of modified layers 13 provided at substantially equal intervals in plan view, each of which extends along a direction orthogonal to the orientation flat 11c, for example.

In addition, an image I1 formed by capturing the one surface 11a side of the workpiece 11 also has a plurality of the modified layers 13 as well. Hence, the controller 80, by referencing the image I1, is capable of obtaining information regarding the modified layers 13 (for example, a value of the proportion of the modified layers 13 present on the one surface 11a side of the workpiece 11 and/or a value for the period in which presence of the modified layers 13 has not been confirmed in a capturing region on the one surface 11a side of the workpiece 11).

Moreover, if the grinding condition (for example, grinding feed speed) is determined not to be appropriate in reference to the information regarding the modified layers 13 obtained by referencing the image I1 (for example, if a value of the proportion and/or a value for the period obtained is/are not included in the numerical range associated with the current grinding condition in the table stored in advance) (change determination step S22: NO), the controller 80 changes the grinding condition to an appropriate one (for example, changes the grinding condition to another grinding condition associated with the numerical range including these values) (changing step S23), and then performs the acquiring step S21 again.

FIG. 8B is a plan view schematically illustrating the one surface 11a side of the workpiece 11 having some of the modified layers 13 removed by grinding. On the one surface 11a side of the workpiece 11, for example, the number of the modified layers 13 is reduced, and grinding kerfs (saw marks) may be newly formed. More specifically, periodic ruggedness due to grinding may be formed. In addition, in an image 12 formed by capturing the one surface 11a side of the workpiece 11, the number of the modified layers 13 is reduced, and grinding kerfs newly appear.

Note that the controller 80 identifies, with use of information (for example, the direction in which the modified layer 13 extends) which is used for identifying the modified layer 13 and which is stored in advance, that the grinding kerfs that newly appear in the image I2 are not the modified layers 13. Hence, by referencing the image I2 with use of the information which is used for identifying the modified layer 13, the controller 80 can newly obtain the information regarding the modified layers 13 accurately, more specifically, can update this information accurately.

Further, if the grinding condition is determined not to be appropriate in reference to the information regarding the modified layers 13 obtained with reference to the image I2 (change determination step S22: NO), the controller 80 performs the change step S23 and the acquiring step S21 again. In addition, even if the grinding condition is determined to be appropriate in reference to this information (change determination step S22: YES), if grinding of the one surface 11a side of the workpiece 11 is necessary as a result of referencing this information (for example, if the value obtained is larger than the threshold stored in advance for the proportion of the modified layers 13, or, if the period obtained is smaller than the threshold stored in advance for the period in which presence of the modified layers 13 has not been confirmed) (termination determination step S24: YES), the controller 80 performs the acquiring step S21 again.

FIG. 8C is a plan view schematically illustrating the one surface 11a side of the workpiece 11 having most of the modified layer 13 removed by grinding. On the one surface 11a side of the workpiece 11, for example, the number of the modified layers 13 is further reduced, and each of the modified layers 13 is divided into small parts. In addition, in an image 13 formed by capturing the one surface 11a side of the workpiece 11 as well, the number of the modified layers 13 is further reduced, and each of the modified layers 13 is divided into small parts.

Then, if the grinding condition is determined not to be appropriate in reference to the information regarding the modified layers 13 obtained with reference to the image 13 (change determination step S22: NO), the controller 80 performs the change step S23 and the acquiring step S21 again. In addition, even if the grinding condition is determined to be appropriate in reference to the information (change determination step S22: YES), if grinding of the one surface 11a side of the workpiece 11 is necessary as a result of referencing this information (termination determination step S24: YES), the controller 80 performs the acquiring step S21 again.

Note that, in a case in which it is assumed that the one surface 11a side of the workpiece 11 is polished after the grinding step S20 is performed or the like, all of the modified layers 13 may not be removed in the grinding step S20. In this case, the threshold for the proportion of the modified layers 13 may be set to be relatively great. Alternatively, the threshold for the period in which presence of the modified layers 13 has not been confirmed may be set to be relatively small.

Also, even if the information regarding the modified layers 13 is obtained with reference to the image 13, if grinding of the one surface 11a side of the workpiece 11 is determined not to be necessary as a result of referencing this information (for example, if the value of the proportion obtained is smaller than the threshold stored in advance for the proportion of the modified layers 13, or, if the period obtained is larger than the threshold stored in advance for the period in which presence of the modified layers 13 has not been confirmed) (termination determination step S24: NO), the controller 80 terminates the grinding step S20 (termination step S25).

FIG. 8D is a plan view schematically illustrating the one surface 11a side of the workpiece 11 having all of the modified layers 13 removed by grinding. On the one surface 11a side of the workpiece 11, for example, the grinding kerfs 15 alone remain. In addition, also in an image 14 formed by capturing the one surface 11a side of the workpiece 11, the grinding kerfs 15 alone remain.

Note that, at the end of the grinding step S20, in a case in which it is assumed that removal of the grinding kerfs 15, i.e., planarization of the one surface 11a side of the workpiece 11 so as to eliminate the periodic ruggedness arising from grinding, is performed or the like, the grinding condition may be changed after all of the modified layers 13 is removed by grinding. In this case, the threshold for the period in which presence of the modified layers 13 has not been confirmed and which is set to be relatively large is used for the determination as to whether grinding of the one surface 11a side of the workpiece 11 is to be terminated, for example.

Also, even in a case in which the information regarding the modified layers 13 is obtained with reference to the image 14, if the grinding condition is determined not to be appropriate in reference to this information (change determination step S22: NO), the controller 80 performs the change step S23 and the acquiring step S21 again and then performs the termination step S25.

In the grinding apparatus 2, as described above, with reference to the information regarding the modified layers 13 obtained by capturing of the one surface 11a side of the workpiece 11 which is performed in parallel with grinding of the one surface 11a side of the workpiece 11, whether grinding of the one surface 11a side of the workpiece 11 is to be terminated is determined. In this case, it is possible to remove the one surface 11a of the workpiece 11 by an appropriate thickness in just the right amount.

More specifically, in this case, for example, at a time point at which it is determined that all of the modified layers 13 has been removed without excessively grinding the one surface 11a side of the workpiece 11, it is possible to terminate grinding of the one surface 11a side of the workpiece 11. Hence, in the grinding apparatus 2, it is possible to prevent reduction in productivity of the semiconductor devices that are manufactured with use of the workpiece 11 and prevent reduction of the throughput thereof.

Note that the description described above is one mode of the present invention and the present invention is not limited to the description described above. For example, according to the present invention, with the grinding of the one surface 11a side of the workpiece 11 being suspended instead of being performed in parallel, a determination as to whether the grinding condition in grinding the one surface 11a side of the workpiece 11 is to be changed (change determination step S22) and a determination as to whether this grinding process is to be terminated (termination determination step S24) may be made.

In addition, according to the present invention, with the grinding of the one surface 11a side of the workpiece 11 being performed in parallel or being suspended, a determination as to whether the grinding condition in grinding the one surface 11a side of the workpiece 11 is to be changed (change determination step S22) may not be made, and a determination as to whether this grinding process is to be terminated (termination determination step S24) may be made.

In addition, according to the present invention, a capturing unit having a structure different from that of the capturing unit 40 may be provided. FIG. 9 is a partial cross sectional side view schematically illustrating an example of a grinding apparatus including a capturing unit with a structure different from that of the capturing unit 40 illustrated in FIG. 2 and FIG. 3.

A grinding apparatus 82 illustrated in FIG. 9 has the same structure as that of the grinding apparatus 2, except that the capturing unit 40 is replaced with a capturing unit 84. In addition, the capturing unit 84 has a top plate 84a and a camera 84b having the same structures as those of the top plate 40a and the camera 40b of the capturing unit 40.

Moreover, the capturing unit 84 has a ring-shaped light source 84c that is provided on a lower surface of the top plate 84a so as to surround a lower surface of the camera 84b and that is capable of emitting light going downward and mirrors 84d that are provided below four end portions of the top plate 84a. Note that each of the mirrors 84d is thinner than each of the light sources 40c included in the capturing unit 40, in general.

The grinding apparatus 82 is preferable in terms of being able to allow a capturing field of view of the camera 84b to be made wider than that of the grinding apparatus 2. In contrast, the grinding apparatus 2 is preferable, compared to the grinding apparatus 82, in such respects that the shape of the one surface 11a side of the workpiece 11 (for example, periodic ruggedness caused by grinding) is more likely to appear in the image formed by capturing by the camera 40b.

In addition, according to the present invention, the one surface 11a side of the workpiece 11 may be captured in a state in which the capturing space S2 is filled with liquid. Each of FIG. 10A and FIG. 11A is a partial cross sectional side view schematically illustrating an example of a grinding apparatus which can capture the one surface 11a side of the workpiece 11 in this manner.

A grinding apparatus 86 illustrated in FIG. 10A has the same structure as that of the grinding apparatus 2, except that the capturing unit 40 is replaced with a capturing unit 88 and the air curtain 44 is not provided. In addition, the capturing unit 88 has a top plate 88a, a camera 88b, and light sources 88c which have the same structures as those of the top plate 40a, the camera 40b, and the light sources 40c of the capturing unit 40, respectively.

Moreover, the capturing unit 88 has a rectangular light transmitting member 88d that is made of, for example, a material through which light emitted from each of the light sources 88c passes (for example, glass). The light transmitting member 88d is positioned slightly below the light sources 88c, and one end thereof is fixed to a lower end of the partition wall 38 of the processing chamber cover 26. FIG. 10B is a partial cross sectional side view schematically illustrating the manner of the grinding step S20 indicated in FIG. 5 that is performed in the grinding apparatus 86 illustrated in FIG. 10A.

In the grinding step S20, while both the chuck table 8 and the grinding wheel 72 are rotated, the grinding wheel 72 is lowered in such a manner that the plurality of grinding stones 72a are brought into contact with the one surface 11a of the workpiece 11. In addition, immediately before this grinding process, supply of the grinding liquid L from the nozzle 78 of the grinding liquid supplying unit 74 and capturing by the camera 88b in a state in which light is emitted from each of the light sources 88c of the capturing unit 88 are started.

Hence, grinding of the one surface 11a side of the workpiece 11 in a state in which the grinding liquid L is supplied at a processing point and capturing of the one surface 11a side of the workpiece 11 in a state in which the grinding liquid L enters a portion between the light transmitting member 88d and the one surface 11a of the workpiece 11, more specifically, in a state in which the capturing space S2 is filled with the grinding liquid L, are performed in parallel with each other.

Compared to the grinding apparatus 2, the grinding apparatus 86 does not include the air curtain 44 and thus realizes simplification of its structure and low cost. In addition, mist droplets caused by air jetting to the grinding liquid L are not generated. Hence, it is possible to eliminate the possibility that these mist droplets enter the capturing space S2 to reduce the accuracy of an image formed by capturing with the camera 84b, which is preferable. In contrast, compared to the grinding apparatus 82 in FIG. 9, the grinding apparatus 2 is not required to fill the capturing space S2 with the grinding liquid L. Accordingly, a flexibility for the grinding condition in grinding the one surface 11a side of the workpiece 11 (especially, a supplying condition of the grinding liquid L) becomes higher, which is preferable.

A grinding apparatus 90 illustrated in FIG. 11A has the same structure as that of the grinding apparatus 2, except that the capturing unit 40 is replaced with a capturing unit 92 and the support tool 42 provided in such a manner to extend downward from the top plate 28 is replaced with a support tool 94 longer than the support tool 42. In addition, the capturing unit 92 has a top plate 92a, a camera 92b, and light sources 92c which have the same structures as those of the top plate 40a, the camera 40b, and the light sources 40c of the capturing unit 40, respectively.

However, the top plate 92a has a through hole formed therein, and an upper surface of the top plate 92a has a distal end portion of a pipe 92d connected thereto so as to communicate with the through hole. In addition, the pipe 92d is inserted into a through hole formed in the top plate 28 of the processing chamber cover 26, and further, a proximal end portion of the pipe 92d is connected to a water supplying source (not illustrated). FIG. 11B is a partial cross sectional side view schematically illustrating the manner of the grinding step S20 indicated in FIG. 5 that is performed in the grinding apparatus 90 illustrated in FIG. 11A.

In the grinding step S20, while both the chuck table 8 and the grinding wheel 72 are rotated, the grinding wheel 72 is lowered such that the plurality of grinding stones 72a are brought into contact with the one surface 11a of the workpiece 11. In addition, immediately before the grinding process, supply of the grinding liquid L from the nozzle 78 of the grinding liquid supplying unit 74, jetting of air from the air curtain 44, capturing by the camera 92b in a state in which light is emitted from each of the light sources 92c of the capturing unit 92, and supply of water W from the water supply source through the pipe 92d are started.

Accordingly, grinding of the one surface 11a side of the workpiece 11 in a state in which the grinding liquid L is supplied to a contact interface (processing point) between the plurality of grinding stones 72a and the one surface 11a of the workpiece 11 and capturing of the one surface 11a side of the workpiece 11 in a state in which the grinding liquid L is prevented from entering a portion between the camera 92b and the one surface 11a of the workpiece 11 and the water W is supplied, more specifically, a state in which the capturing space S2 is filled with the water W, are performed in parallel with each other.

Compared to the grinding apparatus 2, the grinding apparatus 90 can reduce the probability that mist droplets caused by air jetting to the grinding liquid L and grinding swarf or the like generated by grinding the one surface 11a side of the workpiece 11 enter the capturing space S2. Hence, the grinding apparatus 90 is preferable in such respects that reduction in the accuracy of an image formed by capturing with the camera 92b is prevented. In contrast, compared to the grinding apparatus 90, the grinding apparatus 2 does not include the pipe 92d and the water supply source. Hence, the grinding apparatus 2 is preferable in terms of having a simplified structure and being inexpensive.

In addition, according to the present invention, a fluid jetting unit having a structure different from that of the air curtain 44 may be provided. For example, the fluid jetting unit of the present invention may include, in place of the air curtain 44, a nozzle that is capable of jetting fluid (for example, air or water) toward the holding surface of the chuck table 8.

In addition, the present invention may be a method of manufacturing a substrate having a thickness less than a predetermined thickness from an ingot having the predetermined thickness. Note that the thickness of the ingot is not limited to any particular value. For example, the thickness of the ingot may be submillimeters (for example, 0.3 mm), several millimeters (for example, 3 mm), several centimeters (for example, 3 cm), or several tens of centimeters (for example, 30 cm). FIG. 12 is a flowchart schematically indicating an example of a method of manufacturing a substrate. In this method, first, modified layers are formed in the ingot (modified layer forming step S30).

FIG. 13 is a perspective view schematically illustrating the manner of a modified layer forming step S30 indicated in FIG. 12. Note that a U-axis direction and a V-axis direction indicated in FIG. 13 are directions orthogonal to each other on the horizontal plane. In addition, a W-axis direction is a direction (vertical direction) orthogonal to the U-axis direction and the V-axis direction.

The modified layer forming step S30 is performed by a laser processing apparatus 96. The laser processing apparatus 96 includes a chuck table 98 having a circular holding surface that is substantially in parallel with the horizonal plane and capable of holding an ingot 17 on the holding surface.

The chuck table 98 is connected to a suction mechanism (not illustrated). The suction mechanism has, for example, an ejector and the like. When the suction mechanism is operated, a suction force is applied to a space in the vicinity of the holding surface of the chuck table 98. As such, when the suction mechanism is operated in a state in which the ingot 17 is placed on the holding surface, the ingot 17 is held under suction on the holding surface of the chuck table 98.

In addition, the chuck table 98 is connected to a rotational mechanism (not illustrated). The rotational mechanism has, for example, a pulley, a motor, and the like. When the rotational mechanism is operated, with a straight line passing through the center of the holding surface along the W-axis direction as a rotational axis, the chuck table 98 is rotated. For example, the rotational mechanism rotates the chuck table 98 such that an orientation flat 17a of the ingot 17 held on the holding surface of the chuck table 98 is in parallel with the V-axis direction.

In addition, the chuck table 98 is connected to a moving mechanism (not illustrated). The moving mechanism has, for example, a ball screw, a motor, and the like. When the moving mechanism is operated, the chuck table 98 moves along the U-axis direction, the V-axis direction, and/or the W-axis direction.

Above the chuck table 98, there is provided a head 102 of a laser beam applying unit 100. The head 102 is provided at a distal end portion of a cylindrical housing 104 extending along the V-axis direction. Note that the head 102 accommodates an optical system such as a focusing lens and a mirror, and the housing 104 accommodates an optical system such as a mirror and/or a lens.

In addition, the laser beam applying unit 100 has, for example, a laser oscillator (not illustrated) including neodymium-doped yttrium aluminum garnet (Nd:YAG) or the like as a laser medium. The laser oscillator generates a pulsed laser beam LB of a wavelength (for example, 1030 nm or 1064 nm) passing through a material of the ingot 17 (for example, a single crystal made of Si, SiC, GaN, LT, LN, or the like). Moreover, output (power) of the laser beam LB is adjusted at an attenuator (not illustrated) and is then applied to a portion immediately below from the head 102 through the optical systems accommodated in the housing 104 and the head 102.

Further, beside the housing 104, there is provided the capturing unit 106 which is capable of capturing a region immediately below the capturing unit 106. The capturing unit 106 has, for example, a light source such as a light emitting diode (LED), an objective lens, and an imaging element such as a charge coupled device (CCD) image sensor or a complementary metal oxide semiconductor (CMOS) image sensor.

In the laser processing apparatus 96, when the modified layer forming step S30 is performed, the ingot 17 is placed on the holding surface of the chuck table 98. Subsequently, the suction mechanism is operated such that the ingot 17 is held under suction on the holding surface of the chuck table 98. Then, the capturing unit 106 is so operated as to form an image of a front surface of the ingot 17.

Subsequently, with reference to the formed image, for example, the rotational mechanism rotates the chuck table 98 such that the orientation flat 17a is in parallel with the V-axis direction. Then, in such a manner that a region of the ingot 17 in the vicinity of one end of the V-axis direction is positioned in the U-axis direction as viewed from the head 102, in plan view, the moving mechanism moves the chuck table 98 along the U-axis direction and/or the V-axis direction.

Subsequently, in such a manner that a focused spot on which the laser beam LB emitted from the head 102 is focused is positioned to a predetermined depth corresponding to a thickness of the substrate manufactured from the ingot 17 from the front surface of the ingot 17, the moving mechanism moves the chuck table 98 along the W-axis direction. Then, while the laser beam LB is emitted from the head 102, the moving mechanism moves the chuck table 98 along the U-axis direction such that the focused spot on which the laser beam LB is focused passes from the one end of the ingot 17 in the U-axis direction to the other end thereof.

Specifically, with a direction orthogonal to the orientation flat 17a as a scanning direction of the laser beam LB, the laser beam LB is applied to the ingot 17. As a result, with the focused spot on which the laser beam LB is focused as the center, the modified layer 19 with a disordered crystal structure of a material thereof is formed in the ingot 17.

Subsequently, in plan view, in such a manner that the head 102 is positioned in the U-axis direction as viewed from a region slightly closer to the inner side of the ingot 17 than a region of the ingot 17 to which the laser beam LB has been applied, the moving mechanism moves the chuck table 98 along the V-axis direction. Then, with a direction opposite to the U-axis direction as a scanning direction of the laser beam LB, application of the laser beam LB to the ingot 17 is performed as described above.

Further, the operation described above is repeated until application of the laser beam LB to a region in the vicinity of the other end of the ingot 17 in the V-axis direction has been completed. In other words, a relative movement between the ingot 17 and the position at which the focused spot on which the laser beam LB is focused is formed (more specifically, movement of the chuck table 98) along the V-axis direction and application of the laser beam LB to the ingot 17 with the U-axis direction or the direction opposite thereto set as the scanning direction of the laser beam LB are alternately repeated.

Accordingly, a plurality of columns of the modified layers 19 each of which is orthogonal to the orientation flat 17a are formed in the ingot 17. In this manner, the modified layer forming step S30 is completed.

After the modified layer forming step S30, with the modified layers 19 as an initiating point, by separating the ingot 17, the substrate is manufactured (substrate manufacturing step S40). FIG. 14A and FIG. 14B are each a side view schematically illustrating the manner of the substrate manufacturing step S40 indicated in FIG. 12.

The substrate manufacturing step S40 is performed in a separating apparatus 108. The separating apparatus 108 includes a chuck table 110 having the same structure as that of the chuck table 98 illustrated in FIG. 13.

The chuck table 110 is connected to a table-side suction mechanism (not illustrated). The table-side suction mechanism has, for example, a vacuum pump and the like. When the table-side suction mechanism is operated, a suction force is applied to a space in the vicinity of a holding surface of the chuck table 110. As a result, when the table-side suction mechanism is operated in a state in which the ingot 17 is placed on the holding surface, the ingot 17 is held under suction on the holding surface of the chuck table 110.

Above the chuck table 110, there is provided a separating unit 112. The separating unit 112 has a suction plate 114 formed with a plurality of suction ports on a lower surface thereof. Each of the suction ports communicates with a separating unit-side suction mechanism (not illustrated) such as a vacuum pump through a suction path formed in the suction plate 114. When the separating unit-side suction mechanism is operated, a suction force is applied to a space in the vicinity of the lower surface of the suction plate 114.

In addition, a vertical direction moving mechanism 116 is connected to an upper surface of the suction plate 114. The vertical direction moving mechanism 116 has, for example, a ball screw, a motor, and the like. Also, when the vertical direction moving mechanism 116 is operated, the suction plate 114 moves along the vertical direction.

When the substrate manufacturing step S40 is performed in the separating apparatus 108, first, in a state in which the chuck table 110 and the suction plate 114 are sufficiently spaced apart from each other, the ingot 17 is placed on the holding surface of the chuck table 110 in such a manner that the front surface of the ingot 17 formed with the modified layers 19 therein faces upward. Subsequently, the table-side suction mechanism is operated such that the ingot 17 is held under suction on the holding surface of the chuck table 110.

Next, in such a manner that the lower surface of the suction plate 114 is brought into contact with the front surface of the ingot 17, the vertical direction moving mechanism 116 lowers the suction plate 114 (see FIG. 14A). Subsequently, in such a manner that the front surface of the ingot 17 is sucked in an upward direction, the separating unit-side suction mechanism is operated. Then, in such a manner that the suction plate 114 is spaced apart from the chuck table 110, the vertical direction moving mechanism 116 lifts the suction plate 114 (see FIG. 14B).

Consequently, such an external force that the front surface side and the back surface side of the ingot 17 are separated from each other is applied to the ingot 17. As a result, cracks extend and develop from the modified layers 19, so that the ingot 17 is separated. More specifically, with the modified layers 19 as an initiating point, the ingot 17 is separated, and a substrate 21 having the modified layers 19 remaining on one surface 21a thereof is manufactured. In this manner, the substrate manufacturing step S40 is completed.

After the substrate manufacturing step S40, the one surface 21a side of the substrate 21 is ground (grinding step S50). The grinding step S50 is performed similarly to the grinding step S20 described above, and description thereof will be omitted.

Other structures, methods, and the like according to the abovementioned embodiments can be implemented by appropriately being modified within a scope not departing from the object of the present invention.

The present invention is not limited to the details of the above described preferred embodiments. The scope of the invention is defined by the appended claims and all changes and modifications as fall within the equivalence of the scope of the claims are therefore to be embraced by the invention.

GRINDING APPARATUS, METHOD OF GRINDING WORKPIECE, AND METHOD OF MANUFACTURING SUBSTRATE

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CPC

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Priority Claims (1)