Wafer Processing Method

Abstract

To provide a method of processing a wafer, the method being less likely to have a resist film swell on an outer circumferential edge portion of the wafer.SOLUTION: A method in use of processing a wafer having a first surface and a second surface opposite to the first surface is provided. The method includes the steps of: holding the second surface side of the wafer such that the first surface side thereof is exposed; processing an exposed first surface side of an outer circumferential edge portion of the wafer with a processing tool including a grinding stone made of abrasive grains bound together by a bonding material, thereby forming on the outer circumferential edge portion a slanted surface that is inclined to the first surface so as to be progressively closer to the second surface in a direction from a central area side of the wafer toward an outer circumferential edge side thereof; and coating the first surface side of the wafer with a liquid material according to a spin coating process, thereby forming a resist film on the first surface side of the wafer.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present invention relates to a wafer processing method. [Background technology]

[0002] Device chips equipped with devices such as electronic circuits are essential components of electronic devices such as mobile phones and personal computers. Device chips are obtained, for example, by dividing the front surface of a wafer made of a semiconductor such as silicon into a plurality of regions along division lines (streets), providing devices in each region, and then dividing the wafer along the division lines.

[0003] The above-mentioned devices are generally formed by stacking metal films, insulating films, etc. in the thickness direction of the wafer and processing them into a predetermined pattern corresponding to the device. For processing the metal films, insulating films, etc., etching is applied in which a target is processed with a highly reactive gas or chemical liquid using a resist film obtained by applying a liquid material by spin coating as a mask (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 8-44064 Summary of the Invention [Problem to be solved by the invention]

[0005] However, when a resist film is formed by spin coating, the resist film is likely to rise in a convex (or granular) shape on the outer periphery of the wafer, reducing the flatness of the resist film. In such a thick part of the resist film that rises up, the solvent is not sufficiently removed by the subsequent pre-baking, and when contact exposure is employed in which a photomask is brought into contact with the resist film to perform exposure, the material of the resist film may adhere to the photomask.

[0006] In addition, gas may be trapped in the thick raised portion of the resist film, and in such a case, the gas may expand during a subsequent heat treatment (e.g., a heat treatment performed when bonding a wafer on which a resist film has been formed to another wafer), causing the thick raised portion of the resist film to burst, potentially polluting the environment.

[0007] The present invention has been made in consideration of such problems, and an object of the present invention is to provide a wafer processing method capable of reducing the possibility of a resist film swelling on the outer periphery of the wafer. [Means for solving the problem]

[0008] According to one aspect of the present invention, there is provided a wafer processing method for processing a wafer having a first surface, a second surface opposite to the first surface, and an outer peripheral surface that is shaped into a curved surface by chamfering and connects the first surface and the second surface to each other, the method comprising: holding the second surface of the wafer so that the first surface of the wafer is exposed; and, after holding the second surface of the wafer, processing the outer peripheral portion of the exposed first surface of the wafer with a processing tool including a grinding wheel obtained by bonding abrasive grains with a bonding material, thereby forming a surface that is inclined with respect to the first surface so as to approach the second surface from the center of the wafer toward the outer peripheral edge. and an outer periphery located outside the inner end of the outer periphery and inside the outer periphery edge. A method for processing a wafer is provided in which an inclined surface is formed on the outer periphery, and after the inclined surface is formed, a liquid material is applied to the first surface of the wafer by spin coating, thereby forming a resist film on the first surface side of the wafer.

[0009] In one embodiment of the present invention, the tool is a truncated cone-shaped cutting blade having a first side with a circular outer peripheral edge, a second side having a circular outer peripheral edge with a larger diameter than the first side and positioned opposite the first side, and an outer peripheral surface connecting the outer peripheral edge of the first side and the outer peripheral edge of the second side and formed by the grinding stone, the outer peripheral surface being inclined with respect to the first side and the second side, and when forming the inclined surface, the cutting blade may be caused to cut into the outer periphery of the wafer with the second side of the cutting blade positioned on the outer peripheral edge side of the wafer.

[0010] In one embodiment of the present invention, the tool is a disk-shaped cutting blade having a first side with a circular outer peripheral edge, a second side with a circular outer peripheral edge located opposite the first side, and an outer peripheral surface connecting the outer peripheral edge of the first side and the outer peripheral edge of the second side and formed by the grinding wheel, and when forming the inclined surface, the cutting blade may be cut into the outer periphery of the wafer with an axis of rotation that rotates the cutting blade tilted with respect to the first side.

[0011] In one embodiment of the present invention, the tool may be a grinding wheel having the grindstone. Furthermore, in one embodiment of the present invention, the inclined surface may be formed so that the angle between the inclined surface and the first surface is 10° or more and 25° or less. Effect of the Invention

[0012] In a wafer processing method according to one aspect of the present invention, an inclined surface is formed on the outer periphery of the first surface side, inclined relative to the first surface so as to approach the second surface as it moves from the center side to the outer periphery side of the wafer, so that when a liquid material to be a resist film is applied to the first surface of the wafer by spin coating, the liquid material flowing from the center side to the outer periphery side of the wafer is easily discharged to the outside of the wafer along the inclined surface. In other words, the liquid material is less likely to accumulate on the outer periphery of the wafer, so the possibility of the resist film swelling on the outer periphery of the wafer is reduced. [Brief description of the drawings]

[0013] [Figure 1] FIG. 1 is a perspective view of a wafer. [Diagram 2] FIG. 2 is a cross-sectional view showing a state in which a wafer is held in the wafer processing method according to the first embodiment. [Diagram 3] FIG. 3 is a cross-sectional view showing how an inclined surface is formed on a wafer by the wafer processing method according to the first embodiment. [Figure 4] FIG. 4 is an enlarged cross-sectional view of a portion of a wafer on which an inclined surface is formed. [Diagram 5] FIG. 5 is a cross-sectional view showing a state in which a resist film is formed on a wafer by the wafer processing method according to the first embodiment. [Figure 6] FIG. 6 is an enlarged cross-sectional view of a part of a wafer on which an inclined surface is formed and a part of a resist film formed on this wafer. [Figure 7] FIG. 7 is an enlarged cross-sectional view of a part of a wafer on which no inclined surface is formed and a part of a resist film formed on this wafer. [Figure 8] FIG. 8 is a cross-sectional view showing how an inclined surface is formed on a wafer by the wafer processing method according to the second embodiment. [Figure 9] FIG. 9 is a cross-sectional view showing how an inclined surface is formed on a wafer by the wafer processing method according to the third embodiment. [Figure 10] FIG. 10 is a cross-sectional view showing how an inclined surface is formed on a wafer by the wafer processing method according to the fourth embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0014] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described with reference to the accompanying drawings.

[0015] (First embodiment) Fig. 1 is a perspective view of a wafer 11 processed by the wafer processing method according to the present embodiment. As shown in Fig. 1, the wafer 11 is formed in a disk shape using a semiconductor such as silicon, and has a first surface 11a and a second surface 11b on the opposite side (back side) to the first surface 11a. The first surface 11a and the second surface 11b are both formed in a roughly flat circular shape. The first surface 11a and the second surface 11b are connected to each other by an outer peripheral surface 11c that is shaped into a curved surface by chamfering.

[0016] It should be noted that no devices such as electronic circuits are formed on this wafer 11. However, in the wafer processing method according to this embodiment, it is also possible to process a wafer on which devices are formed. There are no limitations on the material, structure, size, etc. of the wafer 11. For example, it is also possible to process a wafer formed using materials such as other semiconductors, ceramics, resins, metals, etc. Furthermore, the wafer 11 may be bonded to another wafer, substrate, etc. in a later process.

[0017] In the wafer processing method according to the present embodiment, first, the second surface 11b side of the wafer 11 is held so that the first surface 11a side of the wafer 11 is exposed (holding step). Fig. 2 is a cross-sectional view showing the state in which the wafer 11 is held. In Fig. 2, some components are represented by symbols, functional blocks, etc.

[0018] The wafer 11 is held, for example, by using a processing device 2 shown in Fig. 2. The processing device 2 is equipped with a chuck table (holding table) 4 configured to be able to hold the wafer 11. The chuck table 4 includes a cylindrical frame 6 formed, for example, by using a metal such as stainless steel and having a recess on the upper surface side. Inside the frame 6, a flow path 6a is provided for transmitting a negative pressure used to suck the wafer 11.

[0019] A porous plate 8 formed in a porous shape using ceramics or the like is fixed in the recess of the frame 6. A wafer 11 is held by an upper surface (holding surface) 8a of this porous plate 8. A suction source 12 such as a vacuum pump is connected to the flow path 6a of the frame 6 via a valve 10 or the like. Therefore, if the valve 10 is opened while the suction source 12 is operating, the negative pressure generated by the suction source 12 can be applied to the upper surface 8a of the porous plate 8.

[0020] A rotation drive source (not shown) such as a motor is connected to the frame 6 of the chuck table 4, and the chuck table 4 rotates around a rotation axis that is approximately perpendicular to the upper surface 8a of the porous plate 8 by power transmitted from the rotation drive source. In addition, the frame 6 of the chuck table 4 is supported by a table movement mechanism (not shown), and moves in a first direction (first horizontal direction) that is approximately parallel to the upper surface 8a of the porous plate 8 by this table movement mechanism.

[0021] When holding the wafer 11, for example, as shown in Fig. 2, the second surface 11b of the wafer 11 is brought into contact with the upper surface 8a of the porous plate 8. Then, with the suction source 12 in operation, the valve 10 is opened to apply negative pressure to the upper surface 8a of the porous plate 8. This causes the second surface 11b of the wafer 11 to be adsorbed onto the upper surface 8a of the porous plate 8. That is, the second surface 11b side of the wafer 11 is held by the chuck table 4 with the first surface 11a side exposed upward.

[0022] In this embodiment, the second surface 11b of the wafer 11 is brought into direct contact with the upper surface 8a of the porous plate 8, but a protective member such as tape may be attached to the second surface 11b of the wafer 11 in advance. In this case, the second surface 11b side of the wafer 11 is held by the chuck table 4 via the protective member, so that damage to the second surface 11b of the wafer 11 due to contact with the porous plate 8 or the like can be prevented.

[0023] After the second surface 11b side of the wafer 11 is held, the outer periphery of the first surface 11a side of the wafer 11 is processed to form an inclined surface (processing step). Fig. 3 is a cross-sectional view showing how the inclined surface 11d is formed on the wafer 11. In Fig. 3, some of the components are represented by symbols, functional blocks, etc.

[0024] The inclined surface 11d is subsequently formed by using the processing device 2. As shown in Fig. 3, a cutting unit (processing unit) 14 is disposed above the chuck table 4. The cutting unit 14 includes, for example, a spindle 16 having an axis that is generally parallel to the upper surface 8a of the porous plate 8 and generally perpendicular to the first direction. A cutting blade (processing tool) 18 including a grinding wheel obtained by bonding abrasive grains with a bonding material is attached to one end of the spindle 16.

[0025] A rotary drive source (not shown) such as a motor is connected to the other end of the spindle 16, and the cutting blade 18 attached to one end of the spindle 16 rotates by power transmitted from this rotary drive source. The cutting unit 14 is supported by, for example, a cutting unit moving mechanism (not shown), and is moved by this cutting unit moving mechanism in a second direction (second horizontal direction) that is approximately parallel to the upper surface 8a of the porous plate 8 and approximately perpendicular to the first direction, and a third direction (vertical direction) that is approximately perpendicular to the first direction and the second direction.

[0026] The cutting blade 18 is formed in a truncated cone shape including, for example, a first side surface 18a having a circular outer peripheral edge, and a second side surface 18b having a circular outer peripheral edge with a larger diameter than the first side surface 18a and located on the opposite side (back side) of the first side surface 18a. That is, the outer peripheral edge of the first side surface 18a and the outer peripheral edge of the second side surface 18b are connected to each other by an outer peripheral surface 18c that is inclined with respect to both the first side surface 18a and the second side surface 18b. In addition, at least the outer peripheral surface 18c is made of a grindstone in which abrasive grains such as diamond are bonded with a bonding material such as resin.

[0027] The cutting blade 18 is attached to one end of the spindle 16 so that the first side surface 18a and the second side surface 18b are approximately perpendicular to the axis of the spindle 16. In other words, the first side surface 18a and the second side surface 18b of the cutting blade 18 are approximately perpendicular to the second direction.

[0028] The width of the cutting blade 18 (the distance between the first side surface 18a and the second side surface 18b) is set arbitrarily according to the desired width of the inclined surface 11d. For example, by using a cutting blade 18 having a width of 0.5 mm to 3.0 mm, typically 1 mm, an inclined surface 11d having a sufficient width can be easily formed.

[0029] When forming the inclined surface 11d on the wafer 11, as shown in Fig. 3, the cutting blade 18 is rotated while cutting into the outer periphery including the boundary between the first surface 11a and the outer periphery surface 11c of the wafer 11. At this time, the cutting blade 18 is caused to cut into the outer periphery of the wafer 11 so that the first side surface 18a of the cutting blade 18 is positioned toward the center of the wafer 11 and the second side surface 18b of the cutting blade 18 is positioned toward the outer periphery of the wafer 11. Then, in this state, the chuck table 4 is rotated once.

[0030] The height of the cutting unit 14 when the cutting blade 18 cuts into the wafer 11 is adjusted within a range in which only the outer peripheral surface 18c of the cutting blade 18 contacts the wafer 11. Specifically, for example, the height of the cutting unit 14 is adjusted so that the height of the lower end of the first side surface 18a of the cutting blade 18 is equal to or greater than the height of the first surface 11a of the wafer 11, and the height of the lower end of the second side surface 18b is less than the height of the first surface 11a.

[0031] In this way, the cutting blade 18 cuts into the outer periphery on the first surface 11a side of the wafer 11, forming an inclined surface 11d that is connected to the first surface 11a without any difference in height. The inclined surface 11d thus formed is inclined with respect to the first surface 11a so as to approach the second surface 11b from the center side of the wafer 11 toward the outer periphery side.

[0032] That is, the height of the inclined surface 11d is lower on the outer peripheral surface 11c side (outer side of the wafer 11) than on the first surface 11a side (inner side of the wafer 11). Also, the thickness of the wafer 11 at the outer periphery where the inclined surface 11d is formed is thinner on the outer peripheral surface 11c side than on the first surface 11a side.

[0033] 4 is an enlarged cross-sectional view of a portion of the wafer 11 on which the inclined surface 11d is formed. The angle θ between the first surface 11a and the inclined surface 11d is desirably adjusted to, for example, a range of 10° to 25°. This sufficiently reduces the possibility that the resist film formed on the first surface 11a side of the wafer 11 will swell. Meanwhile, the width W of the inclined surface 11d (the length of the inclined surface 11d along the radial direction of the wafer 11) is adjusted to, for example, a range of 0.5 mm to 3.0 mm. However, there is no particular limit to this width W.

[0034] After forming the inclined surface 11d on the wafer 11, a liquid material is applied to the first surface 11a of the wafer 11 by spin coating, thereby forming a resist film on the first surface 11a side of the wafer 11 (resist film forming step). Fig. 5 is a cross-sectional view showing the state in which a resist film is formed on the wafer 11. The resist film is formed by using, for example, a spin coater 22 shown in Fig. 5.

[0035] The spin coater 22 includes a cylindrical storage section 24 in which the wafer 11 and the like are stored. An inner space 24a of this storage section 24 serves as a processing chamber when a resist film is formed on the wafer 11. A disk-shaped spinner table 26 having a smaller diameter than the wafer 11 is disposed near the center of the space 24a. The wafer 11 is held by an upper surface (holding surface) 26a of this spinner table 26.

[0036] A suction source (not shown) such as a vacuum pump is connected to the top surface 26a of the spinner table 26 via a flow path (not shown) and a valve (not shown) formed inside the spinner table 26. Therefore, if the valve is opened while the suction source is operating, the negative pressure generated by the suction source can be applied to the top surface 26a of the spinner table 26. A rotation drive source 30 such as a motor is connected to the lower part of the spinner table 26 via a spindle 28, and the spinner table 26 rotates by the power transmitted from the rotation drive source 30.

[0037] A nozzle 32 that drips liquid material 13 from its tip is disposed above spinner table 26. A rotary drive source 34 such as a motor is connected to the base end of nozzle 32, and the tip of nozzle 32 moves in an arc-shaped trajectory in the area above spinner table 26 by power transmitted from rotary drive source 34. When dripping liquid material 13, the tip of nozzle 32 is moved from a retreat area at the end of space 24a to a drip area directly above spinner table 26.

[0038] When forming a resist film on the first surface 11a of the wafer 11, for example, as shown in Fig. 5, the second surface 11b of the wafer 11 is brought into contact with the upper surface 26a of the spinner table 26. Then, with the suction source in operation, a valve is opened to apply negative pressure to the upper surface 26a of the spinner table 26. This causes the second surface 11b of the wafer 11 to be attracted to the upper surface 26a of the spinner table 26. That is, with the first surface 11a exposed upward, the second surface 11b of the wafer 11 is held by the spinner table 26.

[0039] Next, the tip of nozzle 32 is moved to a dripping area directly above spinner table 26, and liquid material 13 is dripped from this tip onto first surface 11a of wafer 11 held on spinner table 26. More specifically, the tip of nozzle 32 is positioned above the center of wafer 11, and liquid material 13 is dripped.

[0040] Thereafter, the spinner table 26 is rotated. The rotation speed of the spinner table 26 is, for example, 1000 rpm to 3000 rpm, and the time for which the spinner table 26 is rotated is, for example, 10 seconds to 60 seconds. However, there are no particular limitations on the conditions for the rotation of the spinner table 26.

[0041] For example, rotation of the spinner table 26 at 1000 rpm to 3000 rpm (high rotation speed) and rotation of the spinner table 26 at 10 rpm to 300 rpm (low rotation speed) can be combined. This rotation of the spinner table 26 causes the liquid material 13 to spread over the entire first surface 11a side of the wafer 11. That is, the liquid material 13 is applied over the entire first surface 11a side of the wafer 11.

[0042] In this embodiment, an epoxy resin such as SU-8, which is suitable for forming a resist film, is used as the liquid material 13. However, there is no particular limitation on this liquid material 13. The liquid material 13 can be changed depending on the properties required for the resist film.

[0043] After the liquid material 13 is spread over the entire first surface 11a side of the wafer 11, the liquid material 13 is dried to evaporate the solvent and water contained in the liquid material 13. For example, the wafer 11 is placed on a hot plate heated to 80°C to 120°C for about 60 seconds to dry the liquid material 13 together with the wafer 11. This forms a resist film 15 (see FIG. 6) that covers the entire first surface 11a of the wafer 11. However, there are no particular limitations on the conditions for drying the liquid material 13.

[0044] For example, the liquid material 13 applied to the first surface 11a of the wafer 11 can be dried by continuing to rotate the spinner table 26 while stopping the supply of the liquid material 13. Also, instead of using a hot plate, the liquid material 13 may be heated and dried using an oven (drying furnace), heater, lamp, or the like. For example, the liquid material 13 can be dried by placing the wafer 11 in an oven set at 80° C. to 120° C. The heating time in this case may be, for example, about 10 minutes to 20 minutes.

[0045] Fig. 6 is an enlarged cross-sectional view of a part of the wafer 11 on which the inclined surface 11d is formed, and a part of the resist film 15 formed on the wafer 11. As shown in Fig. 6, in this embodiment, the inclined surface 11d is formed on the outer periphery of the first surface 11a side of the wafer 11, so that when the liquid material 13 that becomes the resist film 15 is applied to the first surface 11a of the wafer 11 by spin coating, the liquid material 13 that flows from the center side of the wafer 11 toward the outer periphery side is easily discharged to the outside of the wafer 11 along the inclined surface 11d.

[0046] That is, the liquid material 13 is less likely to accumulate on the outer periphery of the wafer 11, which reduces the possibility of the resist film 15 swelling up on the outer periphery of the wafer 11. Fig. 7 is an enlarged cross-sectional view of a part of a wafer 21 on which no inclined surface is formed, and a part of a resist film 25 formed on the wafer 21.

[0047] The wafer 21 is the same as the wafer 11, except that no inclined surface is formed. That is, the wafer 21 is formed in a disk shape having a first surface 21a and a second surface 21b on the opposite side (back side) to the first surface 21a. The first surface 21a and the second surface 21b are connected to each other by an outer peripheral surface 21c that is shaped into a curved surface by chamfering.

[0048] When a resist film 25 is formed on the first surface 21a side of such a wafer 21 by spin coating, as shown in Fig. 7, there is a high possibility that a raised convex portion 25a of the resist film 25 will be formed on the outer periphery of the wafer 21. In a wafer 21 without an inclined surface, the liquid material 13 is likely to accumulate on the outer periphery of the wafer 21, and it is presumed that the liquid material 13 accumulated on the outer periphery is locally dried due to the influence of the air current (turbulent air current) generated on the outer periphery of the wafer 21 when the spinner table 26 is rotated, forming the convex portion 25a.

[0049] As described above, in the wafer processing method according to the present embodiment, an inclined surface 11d is formed on the outer periphery of the first surface 11a, inclined relative to the first surface 11a so as to approach the second surface 11b as it moves from the center of the wafer 11 toward the outer periphery. Therefore, when liquid material 13 that will become the resist film 15 is applied to the first surface 11a of the wafer 11 by spin coating, the liquid material 13 flowing from the center of the wafer 11 toward the outer periphery is easily discharged to the outside of the wafer 11 along the inclined surface 11d.

[0050] In other words, since the liquid material 13 is less likely to accumulate on the outer periphery of the wafer 11, even in a situation in which the liquid material 13 applied to the wafer 11 is likely to dry locally due to the influence of air currents (turbulent air currents) generated around the wafer 11 as the wafer 11 rotates, the possibility of the resist film 15 swelling up on the outer periphery of the wafer 11 is reduced.

[0051] Second embodiment In this embodiment, a wafer processing method for forming an inclined surface 11d on the wafer 11 using a method different from that of the above-mentioned embodiment will be described. Note that the process is the same as the wafer processing method according to the above-mentioned embodiment except for the method (processing step) for forming the inclined surface 11d on the wafer 11. Therefore, the following mainly describes the differences.

[0052] Fig. 8 is a cross-sectional view showing how an inclined surface 11d is formed on a wafer 11 by the wafer processing method according to the present embodiment. Note that in Fig. 8, some components are represented by symbols, functional blocks, or the like.

[0053] In the wafer processing method according to the present embodiment, a processing device 42 shown in Fig. 8 is used. Specifically, the second surface 11b side of the wafer 11 is held by the chuck table 4 of the processing device 42 (holding step), and then the processing device 42 forms an inclined surface 11d on the wafer 11 (processing step). Note that some of the components of the processing device 42 are the same as some of the components of the processing device 2 described above. Therefore, the same components as those of the processing device 2 are denoted by the same reference numerals, and detailed description thereof will be omitted.

[0054] 8, a cutting unit (processing unit) 54 is disposed above the chuck table 4. The cutting unit 54 includes, for example, a spindle 56 configured so that the angle of its axis can be changed with respect to the upper surface 8a of the porous plate 8. A cutting blade (processing tool) 58 including a grindstone obtained by bonding abrasive grains with a bonding material is attached to one end of the spindle 56.

[0055] A rotary drive source (not shown) such as a motor is connected to the other end of the spindle 56, and the cutting blade 58 attached to one end of the spindle 56 rotates by power transmitted from this rotary drive source. The cutting unit 54 is supported by, for example, a cutting unit moving mechanism (not shown), and is moved by this cutting unit moving mechanism in a second direction that is approximately parallel to the upper surface 8a of the porous plate 8 and approximately perpendicular to the first direction in which the chuck table 4 moves, and in a third direction that is approximately perpendicular to the first and second directions.

[0056] The cutting blade 58 is formed in a disk shape including, for example, a first side surface 58a having a circular outer peripheral edge, and a second side surface 58b having a circular outer peripheral edge of the same diameter as the first side surface 58a and located on the opposite side (back side) to the first side surface 58a. The outer peripheral edge of the first side surface 58a and the outer peripheral edge of the second side surface 58b are connected to each other by an outer peripheral surface 58c. In addition, at least the outer peripheral surface 58c is formed of a grindstone in which abrasive grains such as diamond are bonded with a bonding material such as resin.

[0057] The cutting blade 58 is attached to one end of the spindle 56 so that the first side surface 58a and the second side surface 58b are approximately perpendicular to the axis of the spindle 56. The width of the cutting blade 58 (the distance between the first side surface 58a and the second side surface 58b) is set arbitrarily according to the desired width of the inclined surface 11d. For example, by using a cutting blade 58 having a width of 0.5 mm or more and 3.0 mm or less, typically 1 mm, an inclined surface 11d having a sufficient width can be easily formed.

[0058] When forming the inclined surface 11d on the wafer 11, as shown in Fig. 8, the spindle 56 serving as the rotation axis is inclined with respect to the upper surface 8a of the porous plate 8. That is, the spindle 56 is inclined with respect to the first surface 11a and the second surface 11b of the wafer 11. Thereafter, while rotating the cutting blade 58, the cutting blade 58 is caused to cut into the outer periphery including the boundary between the first surface 11a and the outer periphery surface 11c of the wafer 11. Then, in this state, the chuck table 4 is rotated once.

[0059] In this case, the first side surface 58a is disposed on the outer peripheral edge side of the wafer 11, the second side surface 58b is disposed on the central side of the wafer 11, and the spindle 56 is tilted so that the height of the bottom end of the first side surface 58a is lower than the height of the bottom end of the second side surface 58b. However, when the second side surface 58b is disposed on the outer peripheral edge side of the wafer 11 and the first side surface 58a is disposed on the central side of the wafer 11, the spindle 56 is tilted so that the height of the bottom end of the second side surface 58b is lower than the height of the bottom end of the first side surface 58a.

[0060] Furthermore, the height of the cutting unit 54 when the cutting blade 58 cuts into the wafer 11 is adjusted within a range in which only the outer peripheral surface 58c of the cutting blade 58 contacts the wafer 11. Specifically, for example, the height of the cutting unit 54 is adjusted so that the height of the lower end of the first side surface 58a of the cutting blade 58 is less than the height of the first surface 11a of the wafer 11 and the height of the lower end of the second side surface 58b is equal to or greater than the height of the first surface 11a.

[0061] As a result, the cutting blade 58 cuts into the outer periphery on the first surface 11a side of the wafer 11, forming an inclined surface 11d that is connected to the first surface 11a without any difference in height. The inclined surface 11d thus formed is inclined with respect to the first surface 11a so as to approach the second surface 11b from the center side of the wafer 11 toward the outer periphery side.

[0062] That is, the height of the inclined surface 11d is lower on the outer peripheral surface 11c side (outer side of the wafer 11) than on the first surface 11a side (inner side of the wafer 11). Also, the thickness of the wafer 11 at the outer periphery where the inclined surface 11d is formed is thinner on the outer peripheral surface 11c side than on the first surface 11a side.

[0063] The angle θ between the first surface 11a and the inclined surface 11d and the width W of the inclined surface 11d (the length of the inclined surface 11d along the radial direction of the wafer 11) may be the same as in the above-described embodiment. After the inclined surface 11d is formed on the wafer 11, a liquid material 13 is applied to the first surface 11a of the wafer 11 by spin coating to form a resist film 15 on the first surface 11a side of the wafer 11 (resist film forming step).

[0064] In the wafer processing method according to the present embodiment, an inclined surface 11d is also formed on the outer periphery of the wafer 11, so that when the liquid material 13 that becomes the resist film 15 is applied to the first surface 11a of the wafer 11 by spin coating, the liquid material 13 flowing from the center of the wafer 11 toward the outer periphery is easily discharged to the outside of the wafer 11 along the inclined surface 11d.

[0065] In other words, since the liquid material 13 is less likely to accumulate on the outer periphery of the wafer 11, even in a situation in which the liquid material 13 applied to the wafer 11 is likely to dry locally due to the influence of air currents (turbulent air currents) generated around the wafer 11 as the wafer 11 rotates, the possibility of the resist film 15 swelling up on the outer periphery of the wafer 11 is reduced.

[0066] Third embodiment In this embodiment, a wafer processing method for forming an inclined surface 11d on the wafer 11 using a method different from that of the above-mentioned embodiment will be described. Note that the process is the same as the wafer processing method according to the above-mentioned embodiment except for the method (processing step) for forming the inclined surface 11d on the wafer 11. Therefore, the following mainly describes the differences.

[0067] Fig. 9 is a cross-sectional view showing how an inclined surface 11d is formed on a wafer 11 by the wafer processing method according to the present embodiment. Note that in Fig. 9, some components are represented by symbols, functional blocks, or the like.

[0068] In the wafer processing method according to this embodiment, a processing device 62 shown in Fig. 9 is used. Specifically, the second surface 11b side of the wafer 11 is held by the chuck table 4 of the processing device 62 (holding step), and then the processing device 62 forms an inclined surface 11d on the wafer 11 (processing step). Some of the components of the processing device 62 are the same as some of the components of the processing device 2 and the like described above. Therefore, the same reference numerals are used for the same components as the processing device 2 and the like, and detailed description thereof will be omitted.

[0069] 9, a grinding unit (processing unit) 64 is disposed above the chuck table 4. The grinding unit 64 includes, for example, a spindle 66 having an axis that is approximately perpendicular to the upper surface 8a of the porous plate 8. A disk-shaped mounter 68 is fixed to the lower end of the spindle 66.

[0070] An annular grinding wheel (machining tool) 70 having roughly the same diameter as the mounter 68 is attached to the underside of the mounter 68. The grinding wheel 70 is equipped with an annular wheel base 72 made of a material such as stainless steel or aluminum. A plurality of grinding stones 74 obtained by bonding abrasive grains such as diamonds with a bonding material such as resin are fixed to the underside of the wheel base 72.

[0071] A rotation drive source (not shown) such as a motor is connected to the upper end of the spindle 66, and the grinding wheel 70 attached to the lower end of the spindle 66 via a mounter 68 rotates by power transmitted from this rotation drive source. The grinding unit 64 is supported by, for example, a lifting mechanism (not shown), and is moved in a direction approximately perpendicular to the upper surface 8a of the porous plate 8 by this lifting mechanism.

[0072] When forming the inclined surface 11d on the wafer 11, first, the chuck table 4 and the grinding unit 64 are moved relative to each other to position the end of the grinding wheel 70 above the outer periphery including the boundary between the first surface 11a and the outer periphery 11c of the wafer 11 held on the chuck table 4.

[0073] 9, the grinding unit 64 is lowered while rotating the chuck table 4 and the grinding wheel 70. After at least the grindstone 74 of the grinding wheel 70 comes into contact with the wafer 11, the chuck table 4 is moved in a direction away from the grinding unit 64. In other words, the grinding wheel 70 is moved relative to the wafer 11 in the direction indicated by the arrow in FIG. 9 (direction from the center side to the outer periphery side of the wafer 11).

[0074] As a result, the outer periphery on the first surface 11a side of the wafer 11 can be ground with the grindstone 74 of the grinding wheel 70 to form an inclined surface 11d that is connected to the first surface 11a without any difference in height. The inclined surface 11d thus formed is inclined with respect to the first surface 11a so as to approach the second surface 11b from the center side of the wafer 11 toward the outer periphery side.

[0075] That is, the height of this inclined surface 11d is lower on the outer circumferential surface 11c side (outer side of the wafer 11) than on the first surface 11a side (inner side of the wafer 11). Also, the thickness of the wafer 11 in the outer circumferential portion where this inclined surface 11d is formed is thinner on the outer circumferential surface 11c side than on the first surface 11a side.

[0076] The angle θ between the first surface 11a and the inclined surface 11d and the width W of the inclined surface 11d (the length of the inclined surface 11d along the radial direction of the wafer 11) may be the same as in the above-described embodiment. After the inclined surface 11d is formed on the wafer 11, a liquid material 13 is applied to the first surface 11a of the wafer 11 by spin coating to form a resist film on the first surface 11a side of the wafer 11 (resist film forming step).

[0077] In the wafer processing method according to the present embodiment, an inclined surface 11d is also formed on the outer periphery of the wafer 11, so that when the liquid material 13 that becomes the resist film 15 is applied to the first surface 11a of the wafer 11 by spin coating, the liquid material 13 flowing from the center of the wafer 11 toward the outer periphery is easily discharged to the outside of the wafer 11 along the inclined surface 11d.

[0078] In other words, since the liquid material 13 is less likely to accumulate on the outer periphery of the wafer 11, even in a situation in which the liquid material 13 applied to the wafer 11 is likely to dry locally due to the influence of air currents (turbulent air currents) generated around the wafer 11 as the wafer 11 rotates, the possibility of the resist film 15 swelling up on the outer periphery of the wafer 11 is reduced.

[0079] (Fourth embodiment) In this embodiment, a wafer processing method for forming an inclined surface 11d on the wafer 11 using a method different from that of the above-mentioned embodiment will be described. Note that the process is the same as the wafer processing method according to the above-mentioned embodiment except for the method (processing step) for forming the inclined surface 11d on the wafer 11. Therefore, the following mainly describes the differences.

[0080] Fig. 10 is a cross-sectional view showing how an inclined surface 11d is formed on a wafer 11 by the wafer processing method according to the present embodiment. Note that in Fig. 10, some components are represented by symbols, functional blocks, or the like.

[0081] In the wafer processing method according to the present embodiment, a processing device 82 shown in Fig. 10 is used. Specifically, the second surface 11b side of the wafer 11 is held by the chuck table 4 of the processing device 82 (holding step), and then the processing device 82 forms an inclined surface 11d on the wafer 11 (processing step). Some of the components of the processing device 82 are the same as some of the components of the processing device 2 and the like described above. Therefore, the same components as those of the processing device 2 and the like are denoted by the same reference numerals, and detailed description thereof will be omitted.

[0082] 10, a grinding unit (processing unit) 84 is disposed above the chuck table 4. The grinding unit 84 includes, for example, a spindle 86 configured so that the angle of the axis of the spindle 84 can be changed with respect to the upper surface 8a of the porous plate 8. A disk-shaped mounter 88 is fixed to the lower end of the spindle 86.

[0083] An annular grinding wheel (machining tool) 90 having roughly the same diameter as the mounter 88 is attached to the underside of the mounter 88. The grinding wheel 90 is equipped with an annular wheel base 92 made of a material such as stainless steel or aluminum. A plurality of grinding stones 94 obtained by bonding abrasive grains such as diamonds with a bonding material such as resin are fixed to the underside of the wheel base 92.

[0084] A rotation drive source (not shown) such as a motor is connected to the upper end of the spindle 86, and the grinding wheel 90 attached to the lower end of the spindle 86 via a mounter 88 rotates by power transmitted from this rotation drive source. The grinding unit 84 is supported by, for example, a lifting mechanism (not shown), and is moved in a direction approximately perpendicular to the upper surface 8a of the porous plate 8 by this lifting mechanism.

[0085] 10, when forming the inclined surface 11d on the wafer 11, first, the spindle 86 serving as the rotation axis is tilted with respect to the upper surface 8a of the porous plate 8. That is, the spindle 86 is tilted with respect to the first surface 11a and the second surface 11b of the wafer 11. Thereafter, the chuck table 4 and the grinding unit 84 are moved relatively to each other, and the grinding wheel 90 is positioned above the outer periphery including the boundary between the first surface 11a and the outer periphery surface 11c of the wafer 11 held on the chuck table 4.

[0086] 10, while rotating the chuck table 4 and the grinding wheel 90, the grinding unit 84 is lowered to bring the grinding wheel 94 of the grinding wheel 90 into contact with the outer periphery of the wafer 11. Note that the spindle 56 is tilted so that the height of the lower surface of the grinding wheel 94 that contacts the wafer 11 is lower on the outer periphery side than on the center side of the wafer 11.

[0087] As a result, the outer periphery on the first surface 11a side of the wafer 11 can be ground with the grindstone 94 of the grinding wheel 90 to form an inclined surface 11d that is connected to the first surface 11a without any difference in height. The inclined surface 11d thus formed is inclined with respect to the first surface 11a so as to approach the second surface 11b from the center side of the wafer 11 toward the outer periphery side.

[0088] That is, the height of this inclined surface 11d is lower on the outer circumferential surface 11c side (outer side of the wafer 11) than on the first surface 11a side (inner side of the wafer 11). Also, the thickness of the wafer 11 in the outer circumferential portion where this inclined surface 11d is formed is thinner on the outer circumferential surface 11c side than on the first surface 11a side.

[0089] The angle θ between the first surface 11a and the inclined surface 11d and the width W of the inclined surface 11d (the length of the inclined surface 11d along the radial direction of the wafer 11) may be the same as in the above-described embodiment. After the inclined surface 11d is formed on the wafer 11, a liquid material 13 is applied to the first surface 11a of the wafer 11 by spin coating to form a resist film on the first surface 11a side of the wafer 11 (resist film forming step).

[0090] In the wafer processing method according to the present embodiment, an inclined surface 11d is also formed on the outer periphery of the wafer 11, so that when the liquid material 13 that becomes the resist film 15 is applied to the first surface 11a of the wafer 11 by spin coating, the liquid material 13 flowing from the center of the wafer 11 toward the outer periphery is easily discharged to the outside of the wafer 11 along the inclined surface 11d.

[0091] In other words, since the liquid material 13 is less likely to accumulate on the outer periphery of the wafer 11, even in a situation in which the liquid material 13 applied to the wafer 11 is likely to dry locally due to the influence of air currents (turbulent air currents) generated around the wafer 11 as the wafer 11 rotates, the possibility of the resist film 15 swelling up on the outer periphery of the wafer 11 is reduced.

[0092] The present invention is not limited to the above-described embodiments and can be modified in various ways. For example, the wafer processing method according to each of the above-described embodiments uses two types of devices (processing device 2 and spin coater 22), but the wafer processing method according to the present invention may use one composite device that combines the functions of processing device 2 and spin coater 22.

[0093] In addition, the structures, methods, and the like according to the above-described embodiments and modifications can be implemented without departing from the scope of the present invention. [Explanation of symbols]

[0094] 11: Wafer 11a: 1st page 11b: 2nd side 11c: Outer surface 11d: Inclined surface 13: Liquid materials 15: Resist film 21: Wafer 21a: 1st page 21b: 2nd side 21c: Outer surface 25: Resist film 25a: Convex part 2: Processing equipment 4: Chuck table (holding table) 6: Frame 6a: Flow path 8: Porous plate 8a:Top surface (holding surface) 10: Valve 12: Suction source 14: Cutting unit (processing unit) 16: Spindle 18: Cutting blade (machining tool) 18a: 1st side 18b: 2nd side 18c: Outer surface 22: Spin coater 24: Storage unit 24a: Space 26: Spinner table 26a:Top surface (holding surface) 28: Spindle 30: Rotation drive source 32: Nozzle 34: Rotation drive source 42: Processing equipment 54: Cutting unit (processing unit) 56: Spindle 58: Cutting blade (machining tool) 58a: 1st side 58b: 2nd side 58c: Outer surface 62: Processing equipment 64: Grinding unit (processing unit) 66: Spindle 68: Mounter 70: Grinding wheel (machining tool) 72: Wheel base 74: Grindstone 82: Processing equipment 84: Grinding unit (processing unit) 86: Spindle 88: Mounter 90: Grinding wheel (machining tool) 92: Wheel base 94: Grindstone

Claims

1. A wafer processing method used when processing a wafer having a first surface, a second surface opposite to the first surface, and an outer peripheral surface that is shaped into a curved surface by chamfering and connects the first surface and the second surface to each other, comprising: holding the second surface side of the wafer such that the first surface side of the wafer is exposed; After holding the second surface side of the wafer, an outer periphery of the exposed first surface side of the wafer is processed with a processing tool including a grindstone obtained by bonding abrasive grains with a bond material, thereby forming an inclined surface on the outer periphery, the inclined surface being inclined with respect to the first surface so as to approach the second surface from the center side of the wafer toward the outer periphery edge side, and including an inner periphery located on the inside of the inner end of the outer periphery surface and an outer periphery located on the outside of the inner end of the outer periphery surface and on the inside of the outer periphery edge, After forming the inclined surface, a liquid material is applied to the first surface of the wafer by spin coating, thereby forming a resist film on the first surface side of the wafer.

2. The tool is a truncated cone-shaped cutting blade having a first side surface with a circular outer circumferential edge, a second side surface having a circular outer circumferential edge with a larger diameter than the first side surface and positioned on the opposite side to the first side surface, and an outer circumferential surface connecting the outer circumferential edge of the first side surface and the outer circumferential edge of the second side surface and formed by the grindstone, the outer circumferential surface being inclined with respect to the first side surface and the second side surface, A method for processing a wafer as described in claim 1, wherein when forming the inclined surface, the cutting blade is caused to cut into the outer periphery of the wafer with the second side of the cutting blade positioned on the outer periphery side of the wafer.

3. The tool is a disk-shaped cutting blade having a first side surface having a circular outer periphery, a second side surface having a circular outer periphery and positioned opposite the first side surface, and an outer periphery surface connecting the outer periphery of the first side surface and the outer periphery of the second side surface and formed by the grindstone, 2. The method for processing a wafer according to claim 1, wherein when forming the inclined surface, the cutting blade is caused to cut into the outer periphery of the wafer while the axis of rotation for rotating the cutting blade is tilted with respect to the first surface.

4. 2. The method for processing a wafer according to claim 1, wherein the tool is a grinding wheel having the grindstone.

5. 5. The wafer processing method according to claim 1, wherein the inclined surface is formed so that the angle between the inclined surface and the first surface is 10 degrees or more and 25 degrees or less.

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