JP6981773B2 - Wafer processing method - Google Patents

Description

The present invention relates to a method for processing a wafer that forms a convex lens shape on the wafer.

For the convex lens for an infrared camera, for example, a material such as germanium, sapphire, or silicon is used. In particular, silicon has the property of transmitting in a wide infrared region of 1.2 to 6 μm and not transmitting wavelengths of 1.2 μm or less, so that it is effective as an infrared transmission filter that blocks visible light and transmits only infrared rays. Can also be obtained. In the past, in order to obtain a convex lens from a material such as silicon, it was polished one by one. Therefore, Patent Document 1 below proposes a manufacturing method capable of manufacturing a plurality of convex lenses at the same time without polishing one by one.

Japanese Patent No. 3049323

However, since the above-mentioned manufacturing method requires many processes and devices such as resist coating, exposure, and etching, there is a problem that the production efficiency of the convex lens shape is poor and the manufacturing cost is high.

The present invention has been made in view of the above circumstances, and an object of the present invention is to make it possible to easily form a convex lens shape.

The present invention forms a convex lens shape on a wafer using a holding table for holding the wafer, a grinding means for grinding the wafer held on the holding table, and a grinding device having an air source connected to the holding table. A support substrate preparation method for processing a wafer, which comprises a recess corresponding to the convex lens shape on a contact surface in contact with the wafer and a suction tube for communicating the bottom surface of the recess and the air source. step a, the holding and retaining steps of the wafer through the support substrate held by the holding table, through write no grinding load and the suction tube press wafer the recess pressing the the grinding means to the ground surface of the wafer The grinding step of grinding the wafer to a specified thickness while pushing the wafer into the recess by the suction force that sucks the wafer on the table, the grinding load that pushes the wafer into the recess and the suction force are eliminated, and the recess is eliminated in the grinding step. It is provided with a convex lens shape appearance step in which the pushed portion pushed into the wafer appears as a convex lens shape on the ground surface of the wafer.

The present invention is further provided with a convex lens shape cutting step of cutting out along the peripheral edge of the convex lens shape formed on the wafer and cutting out the convex lens shape.

The method for processing a wafer according to the present invention uses a holding table for holding the wafer, a grinding means for grinding the wafer held on the holding table, and a grinding device having an air source connected to the holding table. A method for processing a wafer that forms a convex lens shape, which includes a support substrate preparation step for preparing a support substrate having a recess corresponding to the convex lens shape on a contact surface in contact with the wafer, and holding the wafer on a holding table via the support substrate. The holding step, the grinding step in which the grinding means is pressed against the grinding surface of the wafer and the wafer W is pushed into the recess to grind to a specified thickness, and the grinding load in which the wafer W is pushed into the recess is eliminated, and the wafer W is pushed into the recess in the grinding step. Since it is equipped with a convex lens shape appearance step that makes the pushed-in part appear as a convex lens shape on the grinding surface of the wafer, it is only necessary to grind while pushing the wafer into the concave portion and remove the grinding load on the wafer when the specified thickness is reached. It is possible to form a desired convex lens shape on the ground surface of a wafer, eliminating the need for many processing steps (for example, resist coating, exposure, etching, etc.) and many processing devices, and easily forming a convex lens shape. Can be done. Therefore, the production efficiency of the convex lens shape can be improved and the manufacturing cost can be reduced.

The support substrate further includes a suction tube for communicating the bottom surface of the recess and the air source, and in the grinding step, a grinding load for pushing the wafer into the recess and a suction force for sucking the wafer on the holding table through the suction tube. by, for grinding while pushing the wafer in the recess, by the synergistic effect of the grinding load and the suction force, can thinned to a specified thickness while reliably pushing the wafer in the recess, it can be easily formed the desired convex shape Will be.

The present invention further includes a convex lens shape cutting step for cutting out a convex lens shape by cutting along the peripheral edge of the convex lens shape formed on the wafer by using a processing device including at least a holding table and a dividing means. Therefore, the convex lens from the wafer is further provided. It is possible to acquire the shape with high accuracy.

It is a perspective view which shows the structure of an example of a grinding apparatus. It is a perspective view which shows the 1st example of a support substrate preparation step. It is sectional drawing which shows the 1st example of the holding step. It is sectional drawing which shows the 1st example of a grinding step. It is sectional drawing which shows the 1st example of the convex lens shape appearance step. It is a perspective view which shows the 1st example of the convex lens shape appearance step. (A) is a cross-sectional view showing a first example of a convex lens shape cutting step. (B) is a perspective view showing a convex lens shape in a state of being cut out by carrying out the first example of the convex lens shape cutting step. It is a perspective view which shows the 2nd example of a support substrate preparation step. It is sectional drawing which shows the 2nd example of a holding step. It is sectional drawing which shows the 2nd example of a grinding step. It is sectional drawing which shows the 2nd example of the convex lens shape appearance step. It is a perspective view which shows the 2nd example of the convex lens shape appearance step. (A) is a cross-sectional view showing a second example of a convex lens shape cutting step. (B) is a perspective view showing a convex lens shape in a state of being cut out by carrying out the second example of the convex lens shape cutting step.

1 First Embodiment The grinding device 10 shown in FIG. 1 is an example of a grinding device that grinds a wafer W as a workpiece. The grinding device 10 is arranged on the device base 11 extending in the Y-axis direction, the column 12 erected on the rear side in the Y-axis direction of the device base 11, and the wafer W, and holds the wafer W. The table 13, the grinding means 14 for grinding the wafer W held on the holding table 13, and the grinding feeding means for grinding and feeding the grinding means 14 in the grinding feed direction (Z-axis direction) approaching and separating from the holding table 13. It has 15 and an air source 16 connected to the holding table 13.

The upper surface of the holding table 13 is a holding surface 13a that sucks and holds the wafer W. An air source 16 is connected to the holding table 13, and the suction force of the air source 16 can be applied to the holding surface 13a. Below the holding table 13, although not shown, a rotating means for rotating the holding table 13 and a moving means for moving the holding table 13 in the Y-axis direction are connected.

The grinding means 14 is supported by the grinding feed means 15 in front of the column 12 so as to be able to move up and down. The grinding means 14 includes a spindle 140 having an axial center in the Z-axis direction, a spindle housing 141 surrounding the outer periphery of the spindle 140, a motor 142 attached to one end of the spindle 140, and a holder 143 for holding the spindle housing 141. , A grinding wheel 145 mounted at the lower end of the spindle 140 via a mount 144, and a grinding wheel 146 fixed in an annular shape to the lower portion of the grinding wheel 145. By rotating the spindle 140 by the motor 142, the grinding wheel 145 can be rotated at a predetermined rotation speed.

The grinding feed means 15 includes a ball screw 150 extending in the Z-axis direction, a motor 151 connected to one end of the ball screw 150, a pair of guide rails 152 extending in parallel with the ball screw 150, and a grinding means on one surface. It is provided with an elevating plate 153 to which 14 is connected. In the pair of guide rails 152, the other surface of the elevating plate 153 is in sliding contact with each other, and the ballnet 150 is screwed into the nut formed on the other surface side of the elevating plate 153. When the ball screw 150 is rotated by the motor 151, the grinding feed means 15 can raise and lower the grinding means 14 in the Z-axis direction by moving the elevating plate 153 in the Z-axis direction along the pair of guide rails 152. ..

Next, a first example of a wafer processing method for forming a convex lens shape on the wafer W using the grinding device 10 will be described. The wafer W is an example of a workpiece, and has a circular plate-shaped substrate, and the upper surface thereof is a grinding surface Wa grounded by a grinding wheel 146. On the other hand, the surface opposite to the grinding surface Wa is the lower surface Wb held by the holding table 13. The material of the substrate constituting the wafer W is, for example, silicon, germanium, sapphire, or the like. The thickness of the wafer W before grinding is not particularly limited, and is formed to be several hundred μm (for example, 300 μm to 800 μm).

(1) Support substrate preparation step As shown in FIG. 2, a circular plate-shaped support substrate 1 is prepared. The support substrate 1 of the first example is a support member that supports the wafer W shown in FIG. 1 from below, and the first protective tape 1a and the second protective tape 1b having a similar shape to the wafer W are bonded to each other. It has a two-layer structure. The upper surface of the first protective tape 1a is a contact surface 2a that comes into contact with the lower surface Wb of the wafer W, and the contact surface 2a has a plurality of recesses 3 corresponding to the convex lens shape. The shape and number of the concave portions 3 are not particularly limited, and can be appropriately changed according to the thickness and outer diameter of the desired convex lens shape to be manufactured. On the other hand, nothing is particularly formed on the second protective tape 1b, and the lower surface 2b side thereof is held by the holding table 13. The material of the first protective tape 1a and the second protective tape 1b is not particularly limited, and may be formed of resin using, for example, a three-dimensional molding machine.

(2) Holding step As shown in FIG. 3, the lower surface Wb of the wafer W is attached to the contact surface 2a of the support substrate 1 and placed on the holding surface 13a of the holding table 13 from the lower surface 2b side of the support substrate 1. At this time, each recess 3 of the support substrate 1 is sealed by the lower surface Wb of the wafer W and becomes hollow. Then, by applying the suction force of the air source 16 shown in FIG. 1 to the holding surface 13a of the holding table 13, the wafer W is sucked and held by the holding surface 13a of the holding table 13 via the support substrate 1.

(3) Grinding step The holding table 13 holding the wafer W is moved below the grinding means 14 shown in FIG. Next, the holding table 13 is rotated, and the grinding wheel 145 is lowered in a direction approaching the holding surface 13a of the holding table 13 by the grinding feed means 15 while rotating the grinding wheel 145 in a predetermined direction. The grinding wheel 146, which descends while rotating, presses the grinding surface Wa of the wafer W to grind to a specified thickness. The designated thickness is set to, for example, a finish thickness of 200 μm or less.

In the grinding step, as shown in FIG. 4, a grinding load is applied to the grinding surface Wa of the wafer W, and the wafer W is pushed into the recess 3 of the support substrate 1. That is, since the grinding load on the wafer W is applied downward by the grinding operation, the lower surface Wb side of the wafer W is pushed into each of the sealed and hollow recesses 3, and for example, a hemispherical pushing portion 4 is formed. ..

(4) Convex lens shape appearance step As shown in FIG. 5, when the wafer W is thinned to a specified thickness, it is pushed into the recess 3 in the grinding step by eliminating the grinding load of the wafer W pushing into the recess 3 of the support substrate 1. The pushed-in portion 4 that has been pushed up is raised to the side of the grinding surface Wa of the wafer W to appear as a convex lens shape 5. That is, when the grinding means 14 is raised in the direction away from the holding table 13 by the grinding feed means 15 shown in FIG. 1 to remove the grinding load applied to the grinding surface Wa of the wafer W, the wafer is formed in each recess 3. W is no longer pushed in, the lower surface Wb becomes flat due to the elasticity of the wafer W, and as shown in FIG. 6, a plurality of convex lens shapes 5 appear on the ground surface Wa of the wafer W. When the desired convex lens shape 5 appears on the entire surface of the grinding surface Wa of the wafer W in this way, the convex lens shape appearance step is completed. Since there is a concern that a load for forming a convex portion exceeding 100 μm may cause cracks or damage to the wafer W, the upper limit of the height of the convex lens shape 5 is, for example, 100 μm. Further, the outer diameter of the convex lens shape 5 is set in the range of, for example, φ6 to φ25 mm.

(5) Convex lens shape cutting step After performing the convex lens shape appearance step, for example, using the processing device 20 shown in FIG. 7A, cutting out along the peripheral edge 5c of the convex lens shape 5 formed on the wafer W and individually. The convex lens shape 5 of is cut out. The processing apparatus 20 is a laser processing apparatus and includes at least a laser processing head 21 as a dividing means for cutting out the convex lens shape 5, and a holding table 23 for holding the wafer W. The upper surface of the holding table 23 is a holding surface 23a that sucks and holds the wafer W by receiving a suction action from a suction source (not shown).

The laser processing head 21 is connected to an oscillator that oscillates a laser beam 22 having a wavelength that is absorbent to the wafer W. Inside the laser processing head 21, a condenser lens for condensing the laser beam 22 oscillated from the oscillator is built. The laser processing head 21 is movable in the vertical direction, and the focusing position of the laser beam 22 can be adjusted.

When cutting out the convex lens shape 5 from the wafer W using the processing device 20, the lower surface Wb side of the wafer W is placed on the holding surface 23a of the holding table 23, and the wafer W is sucked and held by the holding surface 23a to suck and hold the wafer W. The Wa side of the grinding surface of W is exposed upward. The position of the laser processing head 21 is aligned with the position where the laser beam 22 is to be irradiated, and the laser processing head 21 is lowered in a direction approaching the wafer W to position the focusing point of the laser beam 22 at a desired position.

The laser processing head 21 irradiates the laser beam 22 circularly along the peripheral edge 5c of the convex lens shape 5 from the grinding surface Wa side of the wafer W in one or a plurality of times, so that the lower surface from the grinding surface Wa of the wafer W is irradiated. It is completely cut over Wb to cut out the convex lens shape 5 shown in FIG. 7 (b). Then, the same laser processing as described above is repeatedly performed along the peripheral edges 5c of all the convex lens shapes 5 on the ground surface Wa of the wafer W, and a plurality of convex lens shapes 5 are cut out. As described above, according to the present invention, it is possible to accurately acquire the convex lens shape 5 from the wafer W. In the convex lens shape cutting step of the first example, the case where a plurality of convex lens shapes 5 are cut out by laser processing has been described, but a plurality of convex lens shapes 5 may be cut out by cutting the wafer W described later.

As described above, in the first example of the wafer processing method according to the present invention, when the grinding step is performed and the grinding means 14 is pressed against the grinding surface Wa of the wafer W to grind and reach a specified thickness, a convex lens shape appears. By performing the step, the grinding load on the wafer W is removed, and the pushed portion 4 of the wafer W pushed into the concave portion 3 is raised to the grinding surface Wa side so as to appear as a convex lens shape 5 on the grinding surface Wa. This eliminates the need for many processing steps (for example, resist coating, exposure, etching, etc.) and many processing devices, and makes it possible to easily form a desired convex lens shape 5. Therefore, the production efficiency of the convex lens shape 5 can be improved and the manufacturing cost can be reduced.

2 Second Embodiment Next, a second example of a wafer processing method for forming a convex lens shape on a wafer W1 will be described using the grinding device 10 shown in FIG. 1. Since the wafer W1 has the same configuration as the wafer W, it has a common reference numeral.

(1) Support substrate preparation step As shown in FIG. 8, a circular plate-shaped support substrate 6 is prepared. The support substrate 6 is a support member having a similar shape to the wafer W1 that supports the wafer W1 from below, and has a one-layer structure. The support substrate 6 has a plurality of recesses 8 corresponding to the convex lens shape on the contact surface 7a in contact with the wafer W1. The concave portion 8 is formed in a hemispherical shape in advance according to a desired convex lens shape. The shape and number of the recesses 8 are not particularly limited, and can be appropriately changed according to the thickness and outer diameter of the desired convex lens shape to be manufactured.

The support substrate 6 includes a suction pipe 9 that allows the bottom surface 80 of the recess 8 and the air source 16 to communicate with each other. The suction tube 9 is formed so as to penetrate from the bottom surface 80 of the recess 8 to the bottom surface 7b of the support substrate 6. The suction pipe 9 is configured to communicate with the air source 16 through the inside of the holding table 13 shown in FIG. Although not shown, a valve is arranged between the air source 16 and the suction pipe 9. Then, by opening the valve, the bottom surface 80 of the recess 8 and the air source 16 can be communicated with each other, and the bottom surface 80 can exert a suction action through the suction pipe 9. The support substrate 6 may be formed of resin using, for example, a three-dimensional molding machine.

(2) Holding step As shown in FIG. 9, the lower surface Wb of the wafer W1 is attached to the contact surface 7a of the support substrate 6 and placed on the holding surface 13a of the holding table 13 from the lower surface 7b side of the support substrate 6. At this time, each recess 7 of the support substrate 6 becomes a hemispherical space sealed by the lower surface Wb of the wafer W1. Subsequently, by opening the valve, the bottom surface 80 of the recess 8 and the air source 16 are communicated with each other, and the bottom surface 80 of the recess 8 exerts a suction action through the suction pipe 9, so that the holding table 13 is interposed via the support substrate 6. The wafer W1 is sucked and held by the holding surface 13a of the above.

(3) Grinding step A direction in which the grinding wheel 145 is brought closer to the holding surface 13a of the holding table 13 by the grinding feed means 15 while rotating the holding table 13 holding the wafer W1 and rotating the grinding wheel 145 in a predetermined direction. To lower to. In the grinding step of the second example, the wafer W1 is pushed into the recess 8 by the grinding load for pushing the wafer W1 by the grinding means 14 and the suction force for sucking the wafer W1 on the holding table 13 through the suction pipe 9 shown in FIG. Grind to the specified thickness. That is, as shown in FIG. 10, the grinding load is applied downward to the wafer W1 by the grinding operation, and the lower surface Wb side of the wafer W1 directly above the recess 8 is sucked downward through the suction pipe 9, so that the grinding load and the suction force are applied. Since they act in the same direction (downward), the lower surface Wb side of the wafer W1 is surely pushed into the recess 8 to form a hemispherical pushed portion 4A. As the designated thickness, as in the first example, the finish thickness is set to, for example, 200 μm or less.

(4) Convex lens shape appearance step As shown in FIG. 11, when the wafer W1 is thinned to a specified thickness, it is pushed into the recess 8 in the grinding step by eliminating the grinding load of the wafer W1 with respect to the recess 8 of the support substrate 6. The pushed-in portion 4A that has been pushed up is raised to the side of the grinding surface Wa of the wafer W1 to appear as a convex lens shape 5A. That is, the grinding means 14 is raised in the direction away from the holding table 13 by the grinding feed means 15 shown in FIG. 1, and the valve is closed to cut off the communication between the bottom surface 80 of the recess 8 and the air source 16. The grinding load applied to the grinding surface Wa of the wafer W1 is removed, and the suction force for sucking the lower surface Wb of the wafer W1 disappears. As a result, the wafer W1 is not pushed into each recess 8, the lower surface Wb becomes flat due to the elasticity of the wafer W1, and as shown in FIG. 12, a plurality of convex lens shapes 5A appear on the grinding surface Wa of the wafer W1. .. When the desired convex lens shape 5A appears on the entire surface of the grinding surface Wa of the wafer W1 in this way, the convex lens shape appearance step is completed. The upper limit of the height and the outer diameter of the convex lens shape 5 are the same as in the first example.

In the second example, even if there is no grinding load, the wafer W1 can be pushed into the recess 8 only by the suction force of the air source 16 to form the hemispherical pushed portion 4A. In this case, in the grinding device 10 shown in FIG. 1, by controlling the grinding feed means 15, the rotating grinding wheel 145 is brought closer to the holding surface 13a of the holding table 13 to a position where the finish thickness of the wafer W1 is reached. After lowering, it is preferable to perform creep feed grinding in which the grinding wheel 146 is cut from the side surface side of the wafer W1 and ground by relatively moving the grinding wheel 146 and the holding table 13. After that, the desired convex lens shape 5A can be formed by carrying out the convex lens shape appearance step.

(5) Convex lens shape cutting step After performing the convex lens shape appearance step, for example, the processing device 30 shown in FIG. 13A is used to cut out individual convex lens shapes 5A from the wafer W1. The processing apparatus 30 is a cutting apparatus and includes at least a cutting means 31 as a dividing means for cutting out the convex lens shape 5A, and a holding table 33 for holding the wafer W1.

The cutting means 31 includes at least a cutting blade 32 mounted on the tip of a spindle having an axis in a direction parallel to the grinding surface Wa of the waha W1, and the cutting blade 32 also rotates as the spindle rotates. It is configured to do. An elevating means (not shown) is connected to the cutting means 31, and the cutting means 31 can be moved up and down in the vertical direction. In the second example, it is assumed that the convex lens shape 5A is cut out by the cutting means 31, for example, along the grid-shaped planned division region S shown in FIG.

The upper surface of the holding table 33 is a holding surface 33a that sucks and holds the wafer W1 by receiving a suction action from a suction source (not shown). It is preferable to form a relief groove 34 on the holding surface 33a at a position corresponding to the planned division region S shown in FIG. 12 for allowing the cutting edge of the cutting blade 32 to escape.

As shown in FIG. 13A, the lower surface Wb side of the wafer W1 is placed on the holding surface 33a of the holding table 33, the wafer W1 is sucked and held by the holding surface 33a, and the grinding surface Wa side of the wafer W1 faces upward. To expose to. While relatively moving the holding table 33 and the cutting means 31, the cutting means 31 rotates the cutting blade 32 in the direction of arrow A, for example, about the axis in the direction parallel to the grinding surface Wa of the wafer W1. However, the cutting blade 32 is cut from the grinding surface Wa side of the wafer W1 by lowering the cutting blade 32 in a direction approaching the grinding surface Wa of the wafer W1.

At this time, the rotating cutting blade 32 is cut to the relief groove 34 formed in the holding surface 33a and cut along the planned division region S shown in FIG. 12, and the lower surface from the grinding surface Wa of the wafer W1 is cut. The convex lens shape 5A shown in FIG. 13B is cut out by completely cutting over Wb. Then, cutting is performed along all the planned division regions S, and a plurality of convex lens shapes 5A are cut out. The case where the convex lens shape cutting step of the second example is carried out by holding the lower surface Wb of the wafer W1 on the holding surface 33a of the holding table 33 and exposing the grinding surface Wa side is described, but the present invention is not limited to this case. For example, a protective tape is attached to the grinding surface Wa of the wafer W1, the protective tape side is held by the holding surface 33a, cutting is performed from the lower surface Wb side with the cutting blade 32, and a plurality of convex lens shapes 5A are cut out. May be good. Further, a protective tape is attached to the lower surface Wb of the wafer W1, the protective tape side is held by the holding surface 33a to expose the grinding surface Wa side, and cutting is performed from the grinding surface Wa side with the cutting blade 32. The convex lens shape 5A may be cut out. In this case, since the cutting blade 32 is cut into the protective tape attached to the lower surface Wb, a holding table without the relief groove 34 may be used. In the convex lens shape cutting step of the second example, the case where a plurality of convex lens shapes 5A are cut out by cutting has been described. However, the wafer W1 is laser-machined by using the processing device 20 of the first example to obtain a plurality of convex lens shapes 5A. You may cut it out.

In the second example of the wafer processing method according to the present invention, the bottom surface 80 of the recess 8 of the support substrate 6 is provided with a suction pipe 9 for communicating the air source 16 and the bottom surface 80, and when the grinding step is performed, the recess 8 is provided with a suction pipe 9. Since the wafer W1 is ground while being pushed into the recess 8 by the grinding load for pushing the wafer W1 and the suction force for sucking the wafer W1 on the holding table 13 through the suction pipe 9, the recess 8 is produced by the synergistic effect of the grinding load and the suction force. The wafer W1 can be thinned to a specified thickness while being reliably pushed in, and a desired convex lens shape 5A can be easily formed.

1: Support substrate 1a: First protective tape 1b: Second protective tape 3: Concave 4, 4A: Push-in portion 5, 5A: Convex lens shape 6: Support substrate 8: Concave 80: Bottom surface 9: Suction tube 10: Grinding Equipment 11: Equipment base 12: Column 13: Holding table 14: Grinding means 140: Spindle 141: Spindle housing 142: Motor 143: Holder 144: Mount 145: Grinding wheel 146: Grinding wheel 15: Grinding feed means 150: Ball screw 151: Motor 152: Guide rail 153: Elevating plate 16: Air source 20: Processing equipment 21: Laser processing head 22: Laser beam 23: Holding table 30: Processing equipment 31: Cutting means 32: Cutting blade 34: Holding table 34: Relief groove

Claims (2)

Machining of a wafer to form a convex lens shape on a wafer using a grinding device having a holding table for holding the wafer, a grinding means for grinding the wafer held on the holding table, and an air source connected to the holding table. It ’s a method,
A support substrate preparation step for preparing a support substrate having a recess corresponding to the convex lens shape on the contact surface in contact with the wafer and having a suction tube communicating the bottom surface of the recess and the air source.
A holding step of holding the wafer on the holding table via the support substrate, and
The grinding means is pressed against the grinding surface of the wafer to push the wafer into the recess, and the suction force that sucks the wafer at the holding table through the suction tube pushes the wafer into the recess and grinds to a specified thickness. Grinding steps and
A wafer having a convex lens shape appearance step that eliminates the grinding load and the suction force for pushing the wafer into the recess and causes the pushed portion pushed into the recess to appear as a convex lens shape on the grinding surface of the wafer in the grinding step. Processing method. The method for processing a wafer according to claim 1, further comprising a convex lens shape cutting step for cutting out the convex lens shape along the peripheral edge of the convex lens shape formed on the wafer.

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