JP6974117B2 - Polishing device and pressing pad for pressing the polishing tool - Google Patents

Description

The present invention relates to a polishing device for polishing a substrate such as a wafer, and more particularly to a polishing device for polishing a peripheral portion of a substrate using a polishing tool such as a polishing tape. Further, the present invention relates to a pressing pad that presses the polishing tool against the peripheral edge of the substrate.

From the viewpoint of improving the yield in the manufacture of semiconductor devices, the management of the surface state of the peripheral portion of the substrate has been attracting attention in recent years. In the process of manufacturing a semiconductor device, various materials are formed on a silicon wafer to form a multilayer structure. Therefore, an unnecessary film or surface roughness is formed on the peripheral edge of the substrate. In recent years, a method of transporting a substrate by holding only the peripheral portion of the substrate with an arm has become common. Under such a background, the unnecessary film remaining on the peripheral edge is peeled off during various steps and adheres to the device formed on the substrate, which reduces the yield. Therefore, in order to remove an unnecessary film formed on the peripheral edge of the substrate, the peripheral edge of the substrate is polished using a polishing device. Here, in the present specification, the peripheral edge portion of the substrate is defined as a region including a bevel portion located on the outermost periphery of the substrate and a top edge portion and a bottom edge portion located radially inside the bevel portion.

23 (a) and 23 (b) are enlarged cross-sectional views showing a peripheral portion of a wafer as an example of a substrate. More specifically, FIG. 23 (a) is a cross-sectional view of a so-called straight type wafer, and FIG. 23 (b) is a cross-sectional view of a so-called round type wafer. In the wafer W of FIG. 23A, the bevel portion is a wafer W composed of an upper inclined portion (upper bevel portion) P, a lower inclined portion (lower bevel portion) Q, and a side portion (apex) R. The outermost peripheral surface (indicated by reference numeral B). In the wafer W of FIG. 23B, the bevel portion is a portion (indicated by reference numeral B) having a curved cross section constituting the outermost peripheral surface of the wafer W. The top edge portion is a flat portion E1 located radially inside the bevel portion B. The bottom edge portion is a flat portion E2 located on the opposite side of the top edge portion and radially inside the bevel portion B. The top edge portion may include the area where the device is formed.

As a device for removing the film formed on the peripheral edge of the wafer W, a polishing device using a polishing tool such as a polishing tape is known (see, for example, Patent Document 1). This type of polishing device includes a substrate holding portion for holding and rotating the wafer W, and a polishing head for bringing a polishing tape (polishing tool) into contact with the peripheral portion of the wafer W. It has a pressing pad that presses the polishing tape against the peripheral edge of the wafer W. The pressing pad arranged on the back surface side of the polishing tape presses the polished surface of the polishing tape against the peripheral edge portion of the wafer W to polish the peripheral edge portion. As the polishing tool, a strip-shaped polishing cloth may be used instead of the polishing tape.

FIG. 24 is a perspective view showing an example of a conventional pressing pad. As shown in FIG. 24, the pressing pad 150 includes an elastic member 155 having a rectangular pressing surface 155a, and a pad body 154 to which the elastic member 155 is fixed. The elastic member 155 is fixed to the pad body 154 in a state where the entire back surface opposite to the pressing surface 155a is in contact with the pad body 154. The pressing pad 150 is arranged on the back surface side of the polishing tape, and the front surface (polishing surface) of the polishing tape is pressed against the bevel portion B of the wafer W by the pressing surface 155a of the elastic member 155. The elastic member 155 of the pressing pad 150 is formed of a material such as rubber or sponge. For example, urethane rubber, silicone sponge, or the like having a hardness suitable for polishing a substrate (for example, 20 to 40 degrees) is selected as a material for the elastic member 155.

FIG. 25 is a schematic view showing a state in which the bevel portion B of the wafer W is polished by the polishing head 130 having the pressing pad 150 shown in FIG. 24. As shown in FIG. 25, the polishing head 130 includes a pressing pad 150 that presses the polishing tape 123 against the peripheral edge of the wafer W, and an air cylinder (drive mechanism) 152 that moves the pressing pad 150 toward the peripheral edge of the wafer W. And a tape feeding mechanism 142 for feeding the polishing tape 123 in a predetermined direction. By controlling the air pressure supplied to the air cylinder 152, the force for pressing the polishing tape 123 against the wafer W is adjusted. During polishing of the bevel portion B of the wafer W, the polishing head 130 (that is, the pressing pad 150) is tilted with respect to the wafer W by a tilt mechanism (not shown). While the polishing head 130 is tilted with respect to the wafer W, the pressing surface 155a of the elastic member 155 of the pressing pad 150 presses the polishing tape 123 against the bevel portion B of the wafer W, so that the entire bevel portion B is polished by the polishing tape 123. can do.

Japanese Patent No. 5254575

When the polishing head 130 (that is, the pressing pad 150) is tilted with respect to the wafer W in order to polish the entire bevel portion B, the width of the polishing tape 123 in contact with the bevel portion B of the wafer W changes. FIG. 26 shows contact with the bevel portion B of the wafer W via the polishing tape 123 when the pressing surface 155a of the elastic member 155 of the pressing pad 150 shown in FIG. 24 is perpendicular to the flat surface of the wafer W. It is a schematic diagram which shows the width of the pressing surface 155a of the elastic member 155. 27 shows contact with the bevel portion B of the wafer W via the polishing tape 123 when the pressing surface 155a of the elastic member 155 of the pressing pad 150 shown in FIG. 24 is inclined with respect to the flat surface of the wafer W. It is a schematic diagram which shows the width of the pressing surface 155a of the elastic member 155. In FIGS. 26 and 27, the polishing tape 123 is not drawn for the sake of brevity, but the width of the polishing tape 123 that comes into contact with the bevel portion B of the wafer W during polishing is the width of the polishing tape 123 via the polishing tape 123. It corresponds to the width of the pressing surface 155a of the elastic member 155 that comes into contact with the bevel portion B of W.

As shown in FIGS. 26 and 27, when the pressing surface 155a is perpendicular to the flat surface of the wafer W, the width Wa of the polishing tape in contact with the bevel portion B of the wafer W is such that the pressing surface 155a is the wafer W. It is smaller than the width Wb of the polishing tape in contact with the bevel portion B of the wafer W when it is inclined with respect to the flat surface. As the inclination angle of the pressing surface 155a with respect to the flat surface of the wafer W increases, the width of the polishing tape in contact with the bevel portion B of the wafer W increases.

FIG. 28 is a photograph showing polishing marks on the polishing tape 123 when the polishing tape 123 is pressed against the bevel portion B of the wafer W by the conventional pressing pad 150 and the bevel B is polished. FIG. 28 shows a plurality of polishing marks when the bevel portion B of the wafer W is polished by changing the inclination angle θ of the pressing surface 155a with respect to the flat surface of the wafer W every 10 °. 29 (a), (b), and (c) are schematic views showing an inclination angle θ of the pressing surface 155a with respect to the flat surface of the wafer W. In FIGS. 29 (a), 29 (b), and (c), the polishing tape 123 is shown as a vertical cross section along the center of the pressing surface 155a. As shown in FIG. 29A, this inclination angle θ is 0 degrees when the pressing surface 155a of the elastic member 155 of the pressing pad 150 is perpendicular to the flat surface of the wafer W. As shown in FIG. 29 (b), this inclination angle θ becomes a positive value when the pressing surface 155a is inclined in a direction in which the upper end of the pressing surface 155a approaches the flat surface of the wafer W, and is shown in FIG. 29 (c). As shown, a negative value is obtained when the pressing surface 155a is tilted in a direction in which the upper end of the pressing surface 155a is away from the flat surface of the wafer W.

As can be seen from the photograph shown in FIG. 28, the length of the polishing mark increases as the absolute value of the inclination angle θ increases. For example, the length La of the polishing mark when the inclination angle θ is 0 ° is smaller than the length Lb of the polishing mark when the inclination angle θ is 70 °. This difference in the length of the polishing marks corresponds to the difference in the width of the polishing tape 123 in contact with the bevel portion B of the wafer W. When the width of the polishing tape 123 in contact with the bevel portion B of the wafer W becomes smaller, the amount of the polishing tape 123 that contributes to the polishing of the bevel portion B decreases. As a result, the polishing rate when the absolute value of the inclination angle θ of the pressing surface 155a is small is lower than the polishing rate when the absolute value of the inclination angle θ of the pressing surface 155a is large.

Further, as can be seen from the photograph shown in FIG. 28, when the absolute value of the inclination angle θ is small, the color brightness in the central region of the polishing mark is higher than the color brightness in the outer region of the polishing mark. As shown in FIG. 30, the difference in the brightness of the polishing marks is that the central pressing force Fa in the contact region between the polishing tape 123 and the bevel portion B of the wafer W is the difference between the polishing tape 123 and the bevel portion B of the wafer W. It means that it is larger than the outer pressing force Fb in the contact region. In this case, the polishing tape 123 is likely to be clogged at the center of the contact area of the polishing tape, and the polishing rate is lowered.

Therefore, the present invention is a polishing apparatus capable of maintaining a constant width of the polishing tool in contact with the peripheral edge portion when the peripheral edge portion of the substrate is polished with the polishing tool while tilting the polishing tool with respect to the substrate. The purpose is to provide. Furthermore, it is an object of the present invention to provide a pressing pad for pressing a polishing tool used in such a polishing apparatus.

According to one aspect of the present invention, the pressing pad comprises a substrate holding portion for holding and rotating the substrate, and a pressing pad for pressing the polishing tool on the peripheral edge portion of the substrate held by the substrate holding portion. An elastic member having a pressing surface for pressing the peripheral edge of the substrate via the polishing tool, a support member for supporting the elastic member, and fixing means for fixing both ends of the elastic member to the support member, respectively. , And a recess into which the elastic member can enter is formed on the front surface of the support member, and the elastic member has fixing protrusions protruding from both side surfaces of the elastic member. Each fixing means is provided with a polishing device including a fixing block having a stepped portion into which the fixing protrusion is fitted.

In one embodiment, the bottom surface of the recess is curved.
According to one aspect of the present invention, the pressing pad comprises a substrate holding portion for holding and rotating the substrate, and a pressing pad for pressing the polishing tool on the peripheral edge portion of the substrate held by the substrate holding portion. It has an elastic member having a pressing surface for pressing the peripheral edge portion of the substrate via the polishing tool, and a support member for supporting the elastic member, and the elastic member is on the front surface of the support member. A polishing apparatus is provided in which a recess is formed so that the elastic member can enter, and a sheet is attached to the back surface of the elastic member on the opposite side of the pressing surface.

In one embodiment, the polishing tool comprises a polishing tape.
In one embodiment, the pressing surface of the elastic member is formed with a groove extending toward the back surface opposite to the pressing surface, and the elastic member has a block body divided by the groove.
In one embodiment, the polishing tool is a grindstone attached to the front surface of the block body.

According to one aspect of the present invention, it is a pressing pad that presses a polishing tool for polishing the peripheral edge portion of the substrate against the peripheral edge portion, and has a pressing surface that presses the peripheral edge portion of the substrate via the polishing tool. It has an elastic member, a support member that supports the elastic member, and fixing means for fixing both ends of the elastic member to the support member, respectively, and the elastic member can enter the front surface of the support member. The elastic member has a fixing protrusion protruding from both side surfaces of the elastic member, and each fixing means includes a fixing block having a step portion into which the fixing protrusion is fitted. A pressing pad characterized by this is provided.

In one embodiment, the bottom surface of the recess is curved.
According to one aspect of the present invention, it is a pressing pad that presses a polishing tool for polishing the peripheral edge portion of the substrate against the peripheral edge portion, and has a pressing surface that presses the peripheral edge portion of the substrate via the polishing tool. It has an elastic member and a support member that supports the elastic member, and a recess into which the elastic member can enter is formed on the front surface of the support member, and is opposite to the pressing surface of the elastic member. A pressing pad is provided, characterized in that a sheet is attached to the back surface of the surface.

In one embodiment, the polishing tool comprises a polishing tape.
In one embodiment, the pressing surface of the elastic member is formed with a groove extending toward the back surface opposite to the pressing surface, and the elastic member has a block body divided by the groove.
In one embodiment, a grindstone used as the polishing tool is attached to the front surface of the block body.

According to the present invention, when the polishing tool is pressed against the peripheral edge of the rotating substrate of the pressing pad, the elastic member of the pressing pad enters the recess of the support member, and the elastic member has a shape along the peripheral edge of the substrate. Transforms into. As a result, when the peripheral portion of the substrate is polished with the polishing tool while tilting the polishing tool with respect to the substrate, the width of the polishing tool in contact with the substrate can be kept constant.

It is a top view which shows the polishing apparatus which concerns on one Embodiment. It is a vertical sectional view of the polishing apparatus shown in FIG. It is an enlarged view of a polishing head. It is a perspective view which showed schematicly about the pressing pad which concerns on one Embodiment. It is a schematic front view of the pressing pad shown in FIG. It is a schematic side view of the pressing pad shown in FIG. FIG. 5 is a cross-sectional view taken along the line AA of FIG. 8 (a) is a schematic perspective view of the silicone sponge shown in FIG. 4, and FIG. 8 (b) is a schematic front view of the silicone sponge shown in FIG. 8 (a). 9 (a) is a front view of the support member shown in FIG. 4, and FIG. 9 (b) is a sectional view taken along line BB of FIG. 9 (a). FIG. 7 is a cross-sectional view taken along the line CC of FIG. It is a figure which shows the state which the polishing head is polishing the bevel part of a wafer. It is a figure which shows the state that the polishing head is polishing the top edge portion of a wafer. It is a figure which shows the state that the polishing head is polishing the bottom edge portion of a wafer. It is a schematic diagram which shows the state which the elastic member has entered into the concave part of the support member. FIG. 15A is a schematic view showing an elastic member deformed by being pushed back to the bevel portion of the wafer when the pressing surface of the elastic member of the pressing pad is perpendicular to the flat surface of the wafer. FIG. 15B is a schematic view showing the pressing force in the contact region between the polishing tape pressed by the pressing pad shown in FIG. 15A and the bevel portion of the wafer. FIG. 16A is a schematic view showing an elastic member deformed by being pushed back to the bevel portion of the wafer when the pressing surface of the elastic member of the pressing pad is inclined with respect to the flat surface of the wafer. 16 (b) is a schematic view showing the pressing force in the contact region between the polishing tape pressed by the pressing pad shown in FIG. 16 (a) and the bevel portion of the wafer. It is a photograph which showed the polishing mark which is attached to the polishing tape when the polishing tape is pressed against the bevel part of a wafer by a pressing pad, and the bevel is polished. It is a graph which shows the result of another experiment. It is sectional drawing which shows the pressing pad which concerns on another embodiment. It is sectional drawing of the pressing pad which concerns on still another Embodiment. It is sectional drawing of the pressing pad which concerns on still another Embodiment. It is sectional drawing of the pressing pad which concerns on still another Embodiment. 23 (a) and 23 (b) are enlarged cross-sectional views showing the peripheral edge of the substrate. It is a perspective view which shows an example of the conventional pressing pad. It is a schematic diagram which shows the state which the bevel portion of a wafer is polished by the polishing head which has the pressing pad shown in FIG. 24. FIG. 24 is a schematic view showing the width of the pressing surface of the elastic member that comes into contact with the bevel portion of the wafer via the polishing tape when the pressing surface of the elastic member of the pressing pad shown in FIG. 24 is perpendicular to the flat surface of the wafer. Is. A schematic showing the width of the pressing surface of the elastic member that comes into contact with the bevel portion of the wafer via the polishing tape when the pressing surface of the elastic member of the pressing pad shown in FIG. 24 is inclined with respect to the flat surface of the wafer. It is a figure. FIG. 24 is a photograph showing polishing marks on the polishing tape when the polishing tape is pressed against the bevel portion of the wafer by the pressing pad shown in FIG. 24 and the bevel portion is polished. 29 (a), (b), and (c) are schematic views showing the inclination angle of the pressing surface with respect to the flat surface of the wafer. It is a schematic diagram which showed the pressing force in the contact area between the polishing tape pressed by the pressing pad shown in FIG. 24, and the bevel portion of a wafer.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a plan view showing a polishing apparatus according to an embodiment, and FIG. 2 is a vertical sectional view of the polishing apparatus shown in FIG. As shown in FIGS. 1 and 2, this polishing apparatus is provided with a rotation holding mechanism (board holding portion) 3 for horizontally holding and rotating a wafer W, which is an example of a substrate, in a central portion thereof. FIG. 1 shows a state in which the rotation holding mechanism 3 holds the wafer W. The rotation holding mechanism 3 includes a dish-shaped holding stage 4 that holds the back surface of the wafer W by vacuum suction, a hollow shaft 5 connected to the central portion of the holding stage 4, and a motor M1 that rotates the hollow shaft 5. I have. The wafer W is placed on the holding stage 4 by a hand (not shown) of the transport mechanism so that the center of the wafer W coincides with the axis of the hollow shaft 5.

The hollow shaft 5 is supported by a ball spline bearing (linear motion bearing) 6 so as to be vertically movable. A groove 4a is formed on the upper surface of the holding stage 4, and the groove 4a communicates with a communication passage 7 extending through the hollow shaft 5. In one embodiment, a sheet having a groove 4a communicating with the communication passage 7 extending through the hollow shaft 5 may be attached to the upper surface of the holding stage 4. The groove 4a is formed, for example, by punching a sheet. The communication passage 7 is connected to the vacuum line 9 via a rotary joint 8 attached to the lower end of the hollow shaft 5. The communication passage 7 is also connected to a nitrogen gas supply line 10 for separating the processed wafer W from the holding stage 4. By switching between these vacuum lines 9 and the nitrogen gas supply line 10, the wafer W is vacuum-adsorbed to the upper surface of the holding stage 4 and detached.

The hollow shaft 5 is rotated by the motor M1 via a pulley p1 connected to the hollow shaft 5, a pulley p2 attached to the rotation shaft of the motor M1, and a belt b1 hung on the pulleys p1 and p2. .. The rotation shaft of the motor M1 extends parallel to the hollow shaft 5. With such a configuration, the wafer W held on the upper surface of the holding stage 4 is rotated by the motor M1.

The ball spline bearing 6 is a bearing that allows the hollow shaft 5 to freely move in the longitudinal direction thereof. The ball spline bearing 6 is fixed to the cylindrical casing 12. Therefore, in the present embodiment, the hollow shaft 5 is configured to be able to operate linearly up and down with respect to the casing 12, and the hollow shaft 5 and the casing 12 rotate integrally. The hollow shaft 5 is connected to an air cylinder (elevating mechanism) 15, and the hollow shaft 5 and the holding stage 4 can be raised and lowered by the air cylinder 15.

A radial bearing 18 is interposed between the casing 12 and the cylindrical casing 14 arranged concentrically on the outer side of the casing 12, and the casing 12 is rotatably supported by the bearing 18. With such a configuration, the rotation holding mechanism 3 can rotate the wafer W around its central axis Cr and raise and lower the wafer W along the central axis Cr.

As shown in FIG. 1, four polishing head assemblies (polishing portions) 1A, 1B, 1C, and 1D are arranged around the wafer W held by the rotation holding mechanism 3. Polishing tape supply mechanisms 2A, 2B, 2C, and 2D are provided on the radial outer sides of the polishing head assembly 1A, 1B, 1C, and 1D, respectively. The polishing head assembly 1A, 1B, 1C, 1D and the polishing tape supply mechanism 2A, 2B, 2C, 2D are separated from each other by a partition wall 20. The internal space of the partition wall 20 constitutes the polishing chamber 21, and the four polishing head assemblies 1A, 1B, 1C, 1D and the holding stage 4 are arranged in the polishing chamber 21. On the other hand, the polishing tape supply mechanisms 2A, 2B, 2C, and 2D are arranged outside the partition wall 20 (that is, outside the polishing chamber 21). The polishing head assemblies 1A, 1B, 1C, and 1D have the same configuration as each other, and the polishing tape supply mechanisms 2A, 2B, 2C, and 2D also have the same configuration as each other. Hereinafter, the polishing head assembly 1A and the polishing tape supply mechanism 2A will be described.

The polishing tape supply mechanism 2A includes a supply reel 24 for supplying the polishing tape 23, which is an example of a polishing tool, to the polishing head assembly 1A, and a recovery reel 25 for collecting the polishing tape 23 used for polishing the wafer W. ing. The supply reel 24 is arranged above the recovery reel 25. A motor M2 is connected to the supply reel 24 and the recovery reel 25 via a coupling 27, respectively (FIG. 1 shows only the coupling 27 and the motor M2 connected to the supply reel 24). Each motor M2 can apply a constant torque in a predetermined rotation direction to apply a predetermined tension to the polishing tape 23.

The polishing tape 23 is a long strip-shaped polishing tool, and one side thereof constitutes a polishing surface. The polishing tape 23 has a base material tape made of a PET sheet or the like, and a polishing layer formed on the base material tape. The polishing layer is composed of a binder (for example, resin) that covers one surface of the base tape and abrasive grains held by the binder, and the surface of the polishing layer constitutes the polishing surface. As the polishing tool, a strip-shaped polishing cloth may be used instead of the polishing tape 23.

The polishing tape 23 is set in the polishing tape supply mechanism 2A in a state of being wound around the supply reel 24. The side surface of the polishing tape 23 is supported by a reel plate so that the winding collapse does not occur. One end of the polishing tape 23 is attached to the recovery reel 25, and the recovery reel 25 winds up the polishing tape 23 supplied to the polishing head assembly 1A to collect the polishing tape 23. The polishing head assembly 1A includes a polishing head 30 for bringing the polishing tape 23 supplied from the polishing tape supply mechanism 2A into contact with the peripheral edge portion of the wafer W. The polishing tape 23 is supplied to the polishing head 30 so that the polishing surface (front surface) of the polishing tape 23 faces the wafer W.

The polishing tape supply mechanism 2A has a plurality of guide rollers 31, 32, 33, 34, and the polishing tape 23 supplied to the polishing head assembly 1A and collected from the polishing head assembly 1A is the guide rollers 31. , 32, 33, 34. The polishing tape 23 is supplied from the supply reel 24 to the polishing head 30 through the opening 20a provided in the partition wall 20, and the used polishing tape 23 is collected by the recovery reel 25 through the opening 20a.

As shown in FIG. 2, an upper supply nozzle 36 is arranged above the wafer W, and the polishing liquid is supplied toward the center of the upper surface of the wafer W held by the rotation holding mechanism 3. Further, a lower supply nozzle 37 for supplying the polishing liquid toward the boundary portion between the back surface of the wafer W and the holding stage 4 of the rotation holding mechanism 3 (the outer peripheral portion of the holding stage 4) is provided. Pure water is usually used as the polishing liquid, but ammonia can also be used when silica is used as the abrasive grains of the polishing tape 23. Further, the polishing apparatus includes a cleaning nozzle 38 for cleaning the polishing head 30 after the polishing process, and after the wafer W is raised by the rotation holding mechanism 3 after the polishing process, cleaning water is sprayed toward the polishing head 30. The polishing head 30 after the polishing process can be cleaned.

As shown in FIG. 2, in order to isolate the mechanism such as the ball spline bearing 6 and the radial bearing 18 from the polishing chamber 21 when the hollow shaft 5 moves up and down with respect to the casing 12, the hollow shaft 5 and the upper end of the casing 12 are separated from each other. It is connected by a bellows 19 that can be expanded and contracted up and down. FIG. 2 shows a state in which the hollow shaft 5 is lowered, and shows that the holding stage 4 is in the polishing position. After the polishing process, the wafer W is raised to the transfer position together with the holding stage 4 and the hollow shaft 5 by the air cylinder 15, and the wafer W is separated from the holding stage 4 at this transfer position.

The partition wall 20 is provided with a transport port 20b for loading and unloading the wafer W into and out of the polishing chamber 21. The transport port 20b is formed as a notch extending horizontally. Therefore, the wafer W gripped by the transport mechanism can cross the inside of the polishing chamber 21 through the transport port 20b while maintaining a horizontal state. An opening 20c and a louver 40 are provided on the upper surface of the partition wall 20, and an exhaust port (not shown) is provided on the lower surface. During the polishing process, the transport port 20b is closed by a shutter (not shown). Therefore, a downflow of clean air is formed inside the polishing chamber 21 by exhausting air from the exhaust port by a fan mechanism (not shown). Since the polishing treatment is performed in this state, the polishing liquid is prevented from scattering upward, and the polishing treatment can be performed while keeping the upper space of the polishing chamber 21 clean.

As shown in FIG. 1, the polishing head 30 is fixed to one end of the arm 60, and the arm 60 is rotatably configured around a rotation axis Ct parallel to the tangential direction of the wafer W. The other end of the arm 60 is connected to the motor M4 via pulleys p3 and p4 and a belt b2. When the motor M4 rotates clockwise and counterclockwise by a predetermined angle, the arm 60 rotates about the axis Ct by a predetermined angle. In the present embodiment, a tilt mechanism that tilts the polishing head 30 with respect to the surface of the wafer W is configured by the motor M4, the arm 60, the pulleys p3 and p4, and the belt b2.

The tilt mechanism is mounted on the moving table 61. The moving table 61 is movably connected to the base plate 65 via the guide 62 and the rail 63. The rail 63 extends linearly along the radial direction of the wafer W held by the rotation holding mechanism 3, and the moving table 61 can move linearly along the radial direction of the wafer W. A connecting plate 66 penetrating the base plate 65 is attached to the moving table 61, and a linear actuator 67 is connected to the connecting plate 66 via a joint 68. The linear actuator 67 is directly or indirectly fixed to the base plate 65.

As the linear actuator 67, a combination of an air cylinder or a positioning motor and a ball screw can be adopted. The linear actuator 67, the rail 63, and the guide 62 constitute a moving mechanism for linearly moving the polishing head 30 in the radial direction of the wafer W. That is, the moving mechanism operates so as to move the polishing head 30 closer to and further from the wafer W along the rail 63. On the other hand, the polishing tape supply mechanism 2A is fixed to the base plate 65.

FIG. 3 is an enlarged view of the polishing head 30. As shown in FIG. 3, the polishing head 30 includes a pressing mechanism 41 that presses the polished surface of the polishing tape 23 against the wafer W with a predetermined force. Further, the polishing head 30 is provided with a tape feeding mechanism 42 for feeding the polishing tape 23 from the supply reel 24 to the recovery reel 25. The polishing head 30 has a plurality of guide rollers 43, 44, 45, 46, 47, 48, 49, and these guide rollers allow the polishing tape 23 to advance in a direction orthogonal to the tangential direction of the wafer W. Guide the polishing tape 23.

The tape feeding mechanism 42 provided in the polishing head 30 includes a tape feeding roller 42a, a tape gripping roller 42b, and a motor M3 for rotating the tape feeding roller 42a. The motor M3 is provided on the side surface of the polishing head 30, and a tape feed roller 42a is attached to the rotating shaft of the motor M3. The tape gripping roller 42b is arranged adjacent to the tape feed roller 42a. The tape gripping roller 42b is supported by a mechanism (not shown) so as to generate a force in the direction indicated by the arrow NF in FIG. 3 (direction toward the tape feed roller 42a), and is configured to press the tape feed roller 42a. ing.

When the motor M3 rotates in the direction of the arrow shown in FIG. 3, the tape feed roller 42a rotates and the polishing tape 23 can be fed from the supply reel 24 to the recovery reel 25 via the polishing head 30. The tape gripping roller 42b is configured to rotate about its own axis and rotates as the polishing tape 23 is fed.

The pressing mechanism 41 includes a pressing pad 50 arranged on the back surface side of the polishing tape 23, and an air cylinder (driving mechanism) 52 that moves the pressing pad 50 toward the peripheral edge of the wafer W. The air cylinder 52 is a so-called single rod cylinder. By controlling the air pressure supplied to the air cylinder 52, the force for pressing the polishing tape 23 against the wafer W is adjusted. The tilt mechanism, pressing mechanism 41, tape feeding mechanism 42, and moving mechanism for moving each polishing head assembly of the four polishing head assemblies 1A, 1B, 1C, and 1D arranged around the wafer W are independent of each other. It is configured to be operational.

4 is a perspective view schematically showing the pressing pad 50 according to the embodiment, FIG. 5 is a schematic front view of the pressing pad 50 shown in FIG. 4, and FIG. 6 is shown in FIG. It is a schematic side view of the pressing pad 50.

As shown in FIGS. 4 to 6, the pressing pad 50 has an elastic member 55 having a flat pressing surface 55a that directly presses the polishing tape 23 against the peripheral edge of the wafer W, and a plate-shaped support for supporting the elastic member 55. It includes a member 56. The detailed configuration of the elastic member 55 and the support member 56 will be described later. In the present embodiment, the pressing pad 50 further has a pad body 54, and the support member 56 is sandwiched between the elastic member 55 and the pad body 54.

The elastic member 55 is formed of a material such as sponge or rubber. For example, a silicone sponge having a hardness suitable for polishing the wafer W (for example, 20 to 40 degrees) is selected as the material of the elastic member 55. The elastic member 55 may be formed of rubber (for example, urethane rubber) having a hardness (for example, 20 to 40 degrees) suitable for polishing the wafer W. The support member 56 is made of a material that is harder than the elastic member 55. In the embodiments described below, the elastic member 55 is formed of a silicone sponge, and the elastic member 55 is referred to as a silicone sponge 55.

The pressing surface 55a of the silicone sponge 55 that directly presses the back surface of the polishing tape 23 (that is, the surface opposite to the polishing surface) has a rectangular shape, and the width of the pressing surface 55a (dimensions along the circumferential direction of the wafer W) D1. Is formed to be larger than the height (dimension along the direction perpendicular to the surface of the wafer W) D2.

In the present embodiment, the pressing pad 50 has two protrusions 54a and 54b formed on the front surface of the pad body 54. These protrusions 54a and 54b have a rail-like shape and are arranged in parallel. The protrusions 54a and 54b are curved along the circumferential direction of the wafer W. More specifically, the protrusions 54a and 54b have an arc shape having substantially the same curvature as the curvature of the wafer W.

The two protrusions 54a and 54b are arranged symmetrically with respect to the rotation axis Ct (see FIG. 1), and as shown in FIG. 5, the protrusions 54a and 54b are the rotation axes when viewed from the front of the pressing pad 50. It curves inward toward Ct. The polishing head 30 is installed so that the center line (that is, the axis of rotation Ct) between the tips of the protrusions 54a and 54b coincides with the center in the thickness direction of the wafer W. The protrusions 54a and 54b are arranged closer to the wafer W than the guide rollers 46 and 47 (see FIG. 3) arranged on the front surface of the polishing head 30, and the polishing tape 23 is arranged on the back surface by the protrusions 54a and 54b. Is supported by. The pad body 54 including the protrusions 54a and 54b is formed of a resin such as PEEK (polyetheretherketone).

As shown in FIGS. 4 and 5, the silicone sponge 55 is arranged between the two protrusions 54a, 54b. The height of the silicone sponge 55 is slightly lower than the height of the protrusions 54a and 54b. When the pressing pad 50 is moved toward the wafer W by the air cylinder 52 while the polishing head 30 is maintained horizontally, the silicone sponge 55 applies the polishing tape 23 from the back surface side to the bevel portion B of the wafer W. Press.

7 is a sectional view taken along the line AA of FIG. 5, FIG. 8A is a schematic perspective view of the silicone sponge 55 shown in FIG. 4, and FIG. 8B is FIG. 8A. It is a schematic front view of the silicone sponge 55 shown in. 9 (a) is a front view of the support member 56 shown in FIG. 4, and FIG. 9 (b) is a sectional view taken along line BB of FIG. 9 (a). In FIG. 9B, the silicone sponge 55 supported by the support member 56 is drawn by a virtual line (dotted line). FIG. 10 is a cross-sectional view taken along the line CC of FIG.

As shown in FIG. 7, both end portions 55c and 55d of the silicone sponge 55 are supported by the support member 56, and both end portions 55c and 55d of the silicone sponge 55 are fixed to the support member 56 by the fixing means 70 described later.

As shown in FIGS. 8 (a) and 8 (b), the silicone sponge 55 has fixed protrusions 55e and 55f protruding from both side surfaces of the silicone sponge 55, respectively. The fixing protrusions 55e and 55f extend along the longitudinal direction of the silicone sponge 55. The fixing protrusion 55e constitutes a part of one end 55c of the silicone sponge 55, and the fixing protrusion 55f constitutes a part of the other end 55d of the silicone sponge 55.

As shown in FIGS. 9A and 9B, a recess 57 is formed in the front surface 56a of the support member 56. The recess 57 is formed at a position sandwiched between both ends 58 and 59 of the support member 56. That is, the support member 56 includes a recess region in which the recess 57 is formed, and two end regions located outside the recess region and constituting both end portions 58 and 59 of the support member 56, respectively. One end 55c of the silicone sponge 55 is a part of the silicone sponge 55 to which one end 58 (ie, one end region) of the support member 56 faces. In the present embodiment, the end portion 55c of the silicone sponge 55 including the fixing protrusion 55e is in contact with the end portion 58 of the support member. One end region of the support member 56 is composed of a fixed region facing the fixed protrusion 55e and a support region facing the end 55c of the silicone sponge 55 other than the fixed protrusion 55e. Similarly, the other end 55d of the silicone sponge 55 is a portion of the silicone sponge 55 to which the other end 59 (ie, the other end region) of the support member 56 faces. In the present embodiment, the end portion 55d of the silicone sponge 55 including the fixing protrusion 55f is in contact with the end portion 59 of the support member. The other end region of the support member 56 is composed of a fixed region facing the fixed protrusion 55f and a support region facing the end 55d of the silicone sponge 55 other than the fixed protrusion 55f. The support region is a region formed on the support member 56 in order to reliably support the silicone sponge 55, and the fixing region fixes both ends 55c and 55d of the silicone sponge 55 to the support member 56 by the fixing means 70 described later. It is a region formed to do.

By forming the recess 57 in the support member 56, the front surface 56a of the support member 56 is divided into a bottom surface 57a of the recess 57, a front surface 58a of the end portion 58, and a front surface 59a of the end portion 59. That is, the front surface 58a of the end portion 58 corresponds to the front surface of the support member 56 in one end region, and the front surface 59a of the end portion 59 corresponds to the front surface of the support member 56 in the other end region. In the present embodiment, the bottom surface 57a of the recess 57 is connected to the front surface 58a of one end 58 of the support member 56 via one side surface 57b of the recess 57, and the support member via the other side surface 57c of the recess 57. It is connected to the front surface 59a of the other end 59 of 56.

As shown in FIG. 7, the front surfaces 58a and 59a of both end portions 58 and 59 of the support member 56 are in contact with the back surface 55b on the opposite side of the pressing surface 55a of the silicone sponge 55. More specifically, the front surfaces 58a and 59a of both ends 58 and 59 of the support member 56 are the back surface of the end portion 55c of the silicone sponge 55 including the fixing protrusion 55e and the end portion 55d of the silicone sponge 55 including the fixing protrusion 55f. It is in contact with the back surface of each. The back surface of the support member 56 (that is, the surface of the support member 56 opposite to the front surface 56a) 56b is in contact with the pad body 54.

Next, the fixing means 70 for fixing both ends 55c and 55d of the silicone sponge 55 to the support member 56 will be described with reference to FIGS. 7 and 10. The fixing means 70 is provided at both ends of the pressing pad 50, and has a fixing block 71 and a screw 72 screwed into the fixing block 71. As shown in FIG. 10, the fixing block 71 of the fixing means 70 has a stepped portion 71a and has an L-shaped cross-sectional shape. The stepped portion 71a has a shape corresponding to the fixed protrusion 55e (or 55f) of the silicone sponge 55 shown in FIGS. 8 (a) and 8 (b), and the fixed protrusion 55e (or the stepped portion 71a) is formed on the stepped portion 71a. 55f) is fitted. The fixing block 71 is formed with a screw hole 71b into which the screw 72 is screwed, and the screw 72 is inserted into the fixing region (see FIG. 9B) of each end region of the support member 56. The hole 56c is formed. The through hole 56c is formed at a position corresponding to the screw hole 71b. Through holes 54c into which the screws 72 are inserted are also formed at both ends of the pad body 54, and these through holes 54c are formed at positions corresponding to the screw holes 71b.

With both ends 55c and 55d of the silicone sponge 55 supported by both ends 58 and 59 of the support member 56, the stepped portions 71a of the fixing block 71 are fitted into the fixing protrusions 55e and 55f of the silicone sponge 55, respectively. In this state, the screw 72 is inserted into the through hole 54c of the pad main body 54 and the through hole 56c of the support member 56, and further screwed into the screw hole 71b of the fixing block 71. By this fixing operation, both ends 55c and 55d of the silicone sponge 55 can be fixed to the support member 56, and further, the support member 56 to which the silicone sponge 55 is fixed can be fixed to the pad body 54.

The fixing means for fixing the silicone sponge 55 and the support member 56 to the pad body 54 is not limited to the above-described embodiment including the fixing block 71 and the screw 72. For example, the silicone sponge 55 is fixed to the support member 56 with clips sandwiching both ends 55c, 55d, the support member 56, and the pad body 54 of the silicone sponge 55, and at the same time, the silicone sponge 55 and the support member 56 are fixed to the pad body 54. It may be fixed to. Alternatively, both ends 55c and 55d of the silicone sponge 55 are adhered (that is, fixed) to both ends 58 and 59 of the support member 56 with an adhesive, and the support member 56 to which the silicone sponge 55 is fixed is padded with an adhesive or a screw. It may be fixed to the main body 54.

FIG. 11 is a diagram showing a state in which the polishing head 30 is polishing the bevel portion B of the wafer W. When polishing the bevel portion of the wafer W, as shown in FIG. 11, the polishing tape 23 is applied to the wafer by the pressing pad 50 while intermittently or continuously changing the tilt angle of the polishing head 30 by the above-mentioned tilt mechanism. Press against the bevel part of W. During polishing, the polishing tape 23 may be fed at a predetermined speed by the tape feeding mechanism 42.

Further, the polishing head 30 having the pressing pad 50 of the present embodiment can polish the top edge portion and the bottom edge portion of the wafer W. That is, as shown in FIG. 12, the polishing head 30 is tilted upward by the above-mentioned tilt mechanism, and the polishing tape 23 is pressed against the top edge portion of the wafer W by the protrusion 54a to polish the top edge portion. can. Further, as shown in FIG. 13, the polishing head 30 can be tilted downward and the polishing tape 23 can be pressed against the bottom edge portion of the wafer W by the protrusion 54b to polish the bottom edge portion.

As described above, the polishing head 30 of the present embodiment can polish the entire peripheral edge portion of the wafer W including the top edge portion E1, the bevel portion B, and the bottom edge portion E2. The polishing head assemblies 1A to 1D (see FIG. 1) each have the polishing head 30. Therefore, in order to improve the throughput of the polishing apparatus, all the polishing head assemblies 1A to 1D may polish the entire peripheral edge portion of the wafer W including the top edge portion E1, the bevel portion B, and the bottom edge portion E2. .. Alternatively, the polishing head assembly 1A may be used to polish the top edge portion E1, the polishing head assembly 1B may be used to polish the bevel portion B, and the polishing head assembly 1C may be used to polish the bottom edge portion E2.

In order to polish the bevel portion B of the wafer W, the silicone sponge 55 of the pressing pad 50 is pressed against the bevel portion B of the wafer W by the air cylinder 52 with a predetermined force via the polishing tape 23, and the silicone sponge 55 presses the wafer. It is pushed back by the bevel portion B of W and deformed. At this time, a recess 57 is formed in the front surface 56a of the support member 56, and the silicone sponge 55 is supported by the support member 56 at both ends 55c and 55d, so that the silicone sponge 55 is the support member 56. It can easily enter the recess 57.

FIG. 14 is a schematic view showing a state in which the silicone sponge 55 has entered the recess 57 of the support member 56. FIG. 15A shows the silicone sponge 55 deformed by being pushed back to the bevel portion B of the wafer W when the pressing surface 55a of the silicone sponge 55 of the pressing pad 50 is perpendicular to the flat surface of the wafer W. 15 (b) is a schematic diagram showing the pressing force in the contact region between the polishing tape 23 pressed by the pressing pad 50 shown in FIG. 15 (a) and the bevel portion B of the wafer W. It is a figure. FIG. 16A shows a silicone sponge deformed by being pushed back to the bevel portion B of the wafer W when the pressing surface 55a of the silicone sponge 55 of the pressing pad 50 is inclined with respect to the flat surface of the wafer W. FIG. 16 (b) is a schematic view showing 55, and FIG. 16 (b) shows the pressing force in the contact region between the polishing tape 23 pressed by the pressing pad 50 shown in FIG. 16 (a) and the bevel portion B of the wafer W. It is a schematic diagram.

In FIGS. 14 to 16 (b), a schematic pressing pad 50 is drawn to aid in understanding the invention. More specifically, only the silicone sponge 55, the support member 56, the pad body 54, and the fixing block 71 of the fixing means 70 are schematically drawn. Further, in FIGS. 15 (a), 15 (b), 16 (a), and 16 (b), the polishing tape 23 is not drawn for the sake of brevity, but the bevel portion of the wafer W is not drawn. During the polishing of B, as shown in FIG. 14, the pressing pad 50 presses the polishing tape 23 against the bevel portion B of the wafer W. More specifically, the pressing surface 55a of the silicone sponge 55 of the pressing pad 50 directly contacts the back surface of the polishing tape 23, and in this state, the pressing pad 50 has the front surface (polishing surface) of the polishing tape 23 on the wafer W. Press against the bevel portion B. The width of the polishing tape 23 that comes into contact with the bevel portion B of the wafer W during polishing corresponds to the width of the pressing surface 55a of the silicone sponge 55 that comes into contact with the bevel portion B of the wafer W via the polishing tape 23.

As shown in FIG. 14, when the silicone sponge 55 of the pressing pad 50 is pressed against the bevel portion B of the wafer W via the polishing tape 23 by the air cylinder 52, the silicone sponge 55 is recessed in the support member 56. It transforms to enter 57. The back surface 55b of the silicone sponge 55 that has entered the recess 57 of the support member 56 contacts the bottom surface 57a of the recess 57, and the silicone sponge 55 is the wafer W as shown in FIGS. 15 (a) and 16 (a). It is deformed into a shape along the bevel portion B of. By forming the recess 57 into which the silicone sponge 55 can enter in the support member 56 in this way, the silicone sponge 55 can be deformed into a shape along the bevel portion B of the wafer W. As a result, even if the pressing surface 55a of the silicone sponge 55 is tilted with respect to the wafer W, the width of the polishing tape 23 in contact with the bevel portion B of the wafer W can be maintained constant. That is, when the pressing surface 55a is perpendicular to the flat surface of the wafer W, the width W1 of the polishing tape 23 in contact with the bevel portion B of the wafer W (see FIG. 15A) is such that the pressing surface 55a is the wafer W. It is the same as the width W2 of the polishing tape 23 (see FIG. 16A) that comes into contact with the bevel portion B of the wafer W when it is inclined with respect to the flat surface of the wafer W.

The silicone sponge 55 is a foam containing a plurality of minute voids inside. The silicone sponge 55 is formed, for example, by foaming silicone in a mold. The surface of the silicone sponge 55 immediately after being taken out from the mold is a smooth flat surface without unevenness. However, cutting this flat surface exposes the voids in the silicone sponge 55. That is, unevenness appears on the surface of the cut silicone sponge 55. For example, when the pressing surface 55a and / or the back surface 55b of the silicone sponge 55 is cut to adjust the height of the silicone sponge 55, unevenness appears on the cut pressing surface 55a and / or the back surface 55b.

When the silicone sponge 55 having irregularities on the pressing surface 55a and / or the back surface 55b is pressed against the bevel portion B of the wafer W, the irregularities on the pressing surface 55a and / or the back surface 55b are crushed, and the silicone sponge 55 becomes the bevel portion B of the wafer W. It may not be possible to deform to the desired shape along the line. Therefore, it is preferable that the pressing surface 55a and / or the back surface 55b of the silicone sponge 55 is not subjected to processing such as cutting, and the pressing surface 55a and / or the back surface 55b is configured as a smooth flat surface.

FIG. 17 is a photograph showing polishing marks on the polishing tape 23 when the polishing tape 23 is pressed against the bevel portion B of the wafer W by the pressing pad 50 according to the present embodiment and the bevel B is polished. FIG. 17 shows a plurality of polishing marks when the bevel portion B of the wafer W is polished by changing the inclination angle θ of the pressing surface 55a with respect to the flat surface of the wafer W every 10 °. This inclination angle θ is 0 degrees when the pressing surface 55a of the silicone sponge 55 of the pressing pad 50 is perpendicular to the flat surface of the wafer W. This inclination angle θ becomes a positive value when the upper end of the pressing surface 55a is inclined toward the flat surface of the wafer W, and the upper end of the pressing surface 55a is pressed away from the flat surface of the wafer W. It becomes a negative value when the surface 55a is inclined.

As can be seen from the photograph of FIG. 17, the lengths of the polishing marks are almost the same at all inclination angles. For example, the length L1 of the polishing mark when the inclination angle θ is 0 ° is substantially the same as the length L2 of the polishing mark when the inclination angle θ is 70 °. As described above, by using the pressing pad 50 according to the present embodiment, when the polishing tape 23 is tilted with respect to the wafer W and the bevel portion B of the wafer W is polished with the polishing tape 23, the polishing tape 23 comes into contact with the wafer W. The width of the polishing tape 23 can be kept constant. As a result, even if the inclination angle θ of the pressing surface 55a is changed, the polishing rate does not change. Therefore, as compared with the case where the bevel portion B of the wafer W is polished using the conventional pressing pad 150 (see FIG. 24), The throughput of the polishing device can be improved.

Further, as can be seen from the photograph of FIG. 17, the color brightness in the central region of the polishing mark is substantially the same as the color brightness in the outer region of the polishing mark at all the inclination angles θ. This is because, as shown in FIGS. 15 (b) and 16 (b), the central pressing force F1 in the contact region between the polishing tape 23 and the bevel portion B of the wafer W is the bevel portion of the polishing tape 23 and the wafer W. It means that it is almost the same as the outer pressing force F2 in the contact region with B. Therefore, as compared with the case where the bevel portion B of the wafer W is polished using the conventional pressing pad 150 (see FIG. 24), clogging of the polishing tape 23 is less likely to occur in the central region of the polishing tape 23. As a result, the polishing rate of the bevel portion B of the wafer W does not decrease, so that the throughput of the polishing apparatus can be improved.

The silicone sponge (elastic member) 55 according to the present embodiment has a plurality of minute voids inside thereof, but has a solid structure in which the pressing surface 55a and the back surface 55b of the silicone sponge 55 are integrally deformed. That is, the silicone sponge 55 does not have an internal space that allows deformation of only the pressing surface 55a of the silicone sponge 55. Even when the silicone sponge 55 has a hollow structure in which such an internal space is formed, when the pressing pad 50 is pressed against the bevel portion B of the wafer W, the pressing surface 55a of the silicone sponge 55 is moved in the circumferential direction of the wafer W. Can be curved along. However, in this case, it is difficult to control the amount of deformation of the pressing surface 55a of the silicone sponge 55. If the pressing surface 55a of the silicone sponge 55 is significantly deformed, the polishing tape 23 may come into contact with the top edge portion E1 and / or the bottom edge portion E2 of the wafer W and damage the wafer W. Further, the central pressing force in the contact region between the polishing tape 23 and the bevel portion B of the wafer W becomes larger than the outer pressing pressure in the contact region between the polishing tape 23 and the bevel portion B of the wafer W, and the polishing tape The polishing tape 23 is likely to be clogged in the central region.

In the present embodiment, both ends 55c and 55d of the silicone sponge 55 having a solid structure are supported by both ends 58 and 59 of the support member 56 having the recess 57. With such a configuration, when the pressing pad 50 is pressed against the bevel portion B of the wafer W, the pressing surface 55a and the back surface 55b of the silicone sponge 55 are integrally deformed, and the silicone sponge 55 easily penetrates into the recess 57. be able to. The silicone sponge 55 that has entered the recess 57 is deformed along the shape of the bevel portion B of the wafer W with its back surface 55b supported by the bottom surface 57a of the recess 57. Therefore, the shape of the recess 57 (for example, the width of the recess 57, the depth Dp, etc.) is based on the shape of the bevel portion of the wafer W, the width of the polishing tape 23, the force for pressing the polishing tape 23 against the wafer W, and the like. By optimizing the width Wd of the support region in the support member 56 (see FIG. 9B), the amount of deformation of the silicone sponge 55 can be controlled to a desired value. Further, as shown in FIGS. 15 (b) and 16 (b), the central pressing force F1 in the contact region between the polishing tape 23 and the bevel portion B of the wafer W, and the bevel portion of the polishing tape 23 and the wafer W. The pressing force F2 on the outside in the contact region with B can be made substantially the same.

An experiment was conducted in which the bevel portion B of the bare silicon wafer was polished using the polishing head 30 having the above-mentioned pressing pad 50. In the experiment, when the tilt angle of the polishing head 30 (that is, the tilt angle θ of the pressing surface 55a of the silicone sponge 55) is 0 °, 70 °, and −70 °, the polishing tape 23 is attached to the bare silicon wafer by the pressing pad 50. ^{The polishing area (μm 2} ) when pressed against the bevel portion B of the above for a predetermined time was measured. Further, a plurality of experiments were performed in which the width Wd of the support region of the support member 56 and the depth Dp of the recess 57 (see FIG. 9B) were changed. ^{Further, as a comparative example, the polishing area (μm 2} ) when the polishing tape 23 was pressed against the bevel portion B of the bare silicon wafer with the conventional pressing pad 150 (see FIG. 24) under the same conditions was measured. Table 1 shows the experimental results when the tilt angle of the polishing head 30 is 0 °, Table 2 shows the experimental results when the tilt angle of the polishing head 30 is 70 °, and Table 3 shows the experimental results of the polishing head 30. The experimental result when the inclination angle is -70 ° is shown.

As can be seen from Tables 1 to 3, the polishing area of the bare silicon wafer polished by using the above-mentioned pressing pad 50 is larger than the polishing area of the bare silicon wafer polished by using the conventional pressing pad 150. Therefore, by using the pressing pad 50 according to the present embodiment, the bare silicon wafer W can be efficiently polished. Further, it can be seen that the polishing area is greatly increased when the width Wd of the support region in the support member 56 is 3 mm or 5 mm and the depth Dp of the recess 57 is 0.5 mm.

Further, another experiment was conducted in which the entire bevel portion of the wafer in which the silicon nitride film was laminated on the bare silicon wafer was polished by using the polishing head 30 having the above-mentioned pressing pad 50. For convenience of explanation, a wafer W in which a silicon nitride film is laminated on a bare silicon wafer is referred to as a SiN wafer. In another experiment, the polishing head 30 having the pressing pad 50 was intermittently tilted to measure the time required to polish the silicon nitride film of the SiN wafer by 200 nm at each angle. Further, another experiment was performed a plurality of times by changing the width Wd of the support region in the support member 56 and the depth Dp of the recess 57 (see FIG. 9B). Further, as a comparative example, the polishing head 30 having the conventional pressing pad 150 (see FIG. 24) is intermittently tilted, and the time required to polish the silicon nitride film of the SiN wafer by 200 nm is measured at each angle. bottom.

The results of another experiment are shown in the graph of FIG. In the graph shown in FIG. 18, the vertical axis represents the time required to polish the silicon nitride film by 200 nm, and the horizontal axis represents the tilt angle of the polishing head 30. In the graph shown in FIG. 18, the result of the polishing head 30 having the conventional pressing pad 150 as a comparative example is drawn by a thick solid line.

As can be seen from the graph shown in FIG. 18, the polishing time of the silicon nitride film by the polishing head 30 having the pressing pad 50 according to the present embodiment is the polishing time of the silicon nitride film by the polishing head 30 having the conventional pressing pad 150. Shorter than. In particular, when the pressing pad 50 having a depth Dp of 0.5 mm in the recess 57 of the support member 56 is used, the polishing time of the silicon nitride film can be greatly reduced. More specifically, when the polishing head 30 having the conventional pressing pad 150 is used, the polishing time of the silicon nitride film in the entire bevel portion of the SiN wafer is 69 seconds. On the other hand, when a polishing head 30 having a pressing pad 50 having a depth Dp of 0.5 mm in the recess 57 of the support member 56 is used, the polishing time of the silicon nitride film in the entire bevel portion of the SiN wafer is 52 seconds. be. Therefore, the polishing time when polishing the silicon nitride film with the polishing head 30 having the pressing pad 50 described above is about 25% of the polishing time when polishing the silicon nitride film with the polishing head 130 having the conventional polishing pad 150. It gets shorter.

FIG. 19 is a cross-sectional view showing a pressing pad 50 according to another embodiment. Since the configuration of the present embodiment, which is not particularly described, is the same as that of the embodiments described with reference to FIGS. 4 to 10, the overlapping description thereof will be omitted. The recess 57 of the pressing pad 50 shown in FIG. 19 has a curved bottom surface 57a. More specifically, the bottom surface 57a of the recess 57 has a shape curved in an arc shape. In the present embodiment, the bottom surface 57a of the recess 57 is directly connected to the front surfaces 58a, 59a of both ends 58, 59 of the support member 56. That is, the recess 57 of the present embodiment does not have the side surfaces 57b and 57c of the recess 57 shown in FIGS. 9A and 9B. In one embodiment, the curved bottom surface 58a may be connected to the front surfaces 58a, 59a of both ends 58, 59 of the support member 56 via the side surfaces 58b, 58c of the recess 57.

The silicone sponge 55 can also enter the recess 57 having the curved bottom surface 58a. The back surface 55b of the silicone sponge 55 that has entered the recess 57 of the support member 56 comes into contact with the curved bottom surface 57a of the recess 57, and the silicone sponge 55 is deformed into a shape along the bevel portion B of the wafer W. Therefore, when the bevel portion B of the wafer W is polished with the polishing tape 23 while tilting the polishing tape 23 with respect to the wafer W, the width of the polishing tape 23 in contact with the wafer W can be kept constant. Further, the pressing force in the contact region between the polishing tape 23 and the bevel portion B of the wafer W can be made uniform. The bottom surface 57a of the recess 57 preferably has an arc shape having substantially the same radius of curvature as the radius of curvature of the bevel portion of the wafer W. In this case, when the back surface 55b of the silicone sponge 55 that has entered the recess 57 of the support member 56 comes into contact with the curved bottom surface 57a of the recess 57, the silicone sponge 55 is the same as the bevel portion B along the circumferential direction of the wafer W. It can be transformed into a shape.

FIG. 20 is a cross-sectional view of the pressing pad 50 according to still another embodiment. Since the configuration of the present embodiment, which is not particularly described, is the same as that of the embodiments described with reference to FIGS. 4 to 10, the overlapping description thereof will be omitted. The pressing pad 50 shown in FIG. 20 has a sheet 73 attached to the pressing surface 55a of the silicone sponge 55 in order to reduce friction with the back surface of the polishing tape 23. The sheet 73 has a surface that has been subjected to a treatment such as Teflon (registered trademark) processing to reduce the coefficient of friction, and this surface comes into contact with the back surface of the polishing tape 23. Further, in the present embodiment, the sheet 74 having the same structure as the sheet 73 is attached to the back surface 55b of the silicone sponge 55.

Since the sheets 73 and 74 having the same configuration are attached to the pressing surface 55a and the back surface 55b of the silicone sponge 55, the pressing surface 55a of the silicone sponge 55 presses the bevel portion B of the wafer W to press the silicone sponge 55. Can be deformed according to the deformation of the pressing surface 55a of the silicone sponge 55 on the back surface 55b of the silicone sponge 55. That is, the silicone sponge 55 can appropriately enter the recess 57, and the silicone sponge 55 can be deformed into a shape along the bevel portion B of the wafer W. As a result, even if the sheet 73 is attached to the pressing surface 55a of the silicone sponge 55, when the bevel portion B of the wafer W is polished with the polishing tape 23 while the polishing tape 23 is tilted with respect to the wafer W, The width of the polishing tape 23 in contact with the wafer W can be kept constant. Further, the pressing force in the contact region between the polishing tape 23 and the bevel portion B of the wafer W can be made uniform.

FIG. 21 is a cross-sectional view of the pressing pad 50 according to still another embodiment. Since the configuration of the present embodiment, which is not particularly described, is the same as that of the embodiments described with reference to FIGS. 4 to 10, the overlapping description thereof will be omitted. The pressing surface 55a of the silicone sponge 55 of the pressing pad 50 shown in FIG. 21 is formed with a plurality of (two in FIG. 21) grooves 78 extending from the pressing surface 55a toward the back surface 55b. These grooves 78 are arranged in parallel with each other at equal intervals. By forming the plurality of grooves 78 on the pressing surface 55a of the silicone sponge 55, a plurality of (three in FIG. 21) block bodies 80 are formed on the silicone sponge 55. In the present embodiment, the pressing surface 55a of the silicone sponge 55 is composed of the front surfaces of the plurality of block bodies 80.

When the silicone sponge 55 on which the plurality of block bodies 80 are formed is used, the silicone sponge 55 is easily deformed into a shape along the bevel portion B of the wafer W. As a result, when the bevel portion B of the wafer W is polished with the polishing tape 23 while tilting the polishing tape 23 with respect to the wafer W, the width of the polishing tape 23 in contact with the wafer W can be kept constant. .. Further, the pressing force in the contact region between the polishing tape 23 and the bevel portion B of the wafer W can be made uniform.

FIG. 22 is a cross-sectional view of the pressing pad 50 according to still another embodiment. Since the configuration of the present embodiment, which is not particularly described, is the same as that of the embodiment described with reference to FIG. 21, the duplicated description thereof will be omitted. The silicone sponge 55 of the pressing pad 50 shown in FIG. 22 also has a plurality of grooves 78 extending from the pressing surface 55a toward the back surface 55b. Therefore, a plurality of block bodies 80 are formed on the silicone sponge 55 of the pressing pad 50 shown in FIG. 22.

A grindstone 82 is attached to the front surface of the plurality of block bodies 80 of the silicone sponge 55 shown in FIG. 22. The grindstone 82 is a polishing tool for polishing the bevel portion B of the wafer W. That is, in this embodiment, the grindstone 82 is used as a polishing tool instead of the polishing tape 23. Therefore, when the pressing pad 50 shown in FIG. 22 is used, the polishing tape supply mechanisms 2A to 2D described above are not required, so that the polishing apparatus can be manufactured compactly and inexpensively.

Even when the bevel portion B of the wafer W is polished by using the polishing head 30 having the pressing pad 50 of the present embodiment, the silicone sponge 55 is deformed into a shape along the bevel portion B of the wafer W. As a result, when the bevel portion B of the wafer W is polished with the grindstone 82 while tilting the grindstone 82 with respect to the wafer W, the width of the grindstone 82 in contact with the wafer W can be kept constant. Further, the pressing force in the contact region between the grindstone 82 and the bevel portion B of the wafer W can be made uniform.

The present invention is not limited to the embodiments described above. For example, in the embodiment shown in FIGS. 20 to 22, the bottom surface 57a of the recess 57 may have the curved shape shown in FIG. Further, the grindstone 82 shown in FIG. 22 may be attached to the pressing surface 55a of the silicone sponge 55 shown in FIG. 7 or 19. In this case, the grindstone 82 may be attached to the entire pressing surface 55a, or the grindstone 82 may be attached only to a part of the pressing surface 55a. For example, the grindstone 82 is attached only to a part of the pressing surface 55a that is deformed when the pressing pad 50 is pressed against the bevel portion B of the substrate.

The above-described embodiments have been described for the purpose of allowing a person having ordinary knowledge in the technical field to which the present invention belongs to carry out the present invention. Various modifications of the above embodiment can be naturally made by those skilled in the art, and the technical idea of the present invention can be applied to other embodiments. Accordingly, the invention is not limited to the described embodiments, but is to be construed in the broadest range in accordance with the technical ideas defined by the claims.

1A-1D polishing head assembly (polishing part)
2A-2D Polishing tape supply mechanism 3 Rotation holding mechanism (board holding part)
4 Holding stage 5 Hollow shaft 6 Ball spline bearing 7 Continuous passage 9 Vacuum line 10 Nitrogen gas supply line 15 Air cylinder 20 Partition 24 Supply reel 25 Recovery reel 30 Polishing head 41 Pressing mechanism 42 Tape feeding mechanism 43 to 49 Guide roller 50 Pressing pad 52 Air cylinder (drive mechanism)
54 Pad body 55 Elastic member (silicone sponge)
56 Support member 57 Recess 67 Linear actuator 70 Fixing means 71 Fixing block 72 Screw 80 Block body 82 Whetstone

Claims (12)

A board holding part that holds and rotates the board,
A pressing pad for pressing the polishing tool is provided on the peripheral edge of the substrate held by the substrate holding portion.
The pressing pad is
An elastic member having a pressing surface that presses the peripheral edge of the substrate via the polishing tool, and
A support member that supports the elastic member and
It has fixing means for fixing both ends of the elastic member to the support member, respectively.
A recess into which the elastic member can enter is formed on the front surface of the support member .
The elastic member has fixed protrusions protruding from both side surfaces of the elastic member.
Each fixing means is a polishing apparatus including a fixing block having a stepped portion into which the fixing protrusion is fitted. The polishing apparatus according to claim 1, wherein the bottom surface of the recess is curved. A board holding part that holds and rotates the board,
A pressing pad for pressing the polishing tool is provided on the peripheral edge of the substrate held by the substrate holding portion.
The pressing pad is
An elastic member having a pressing surface that presses the peripheral edge of the substrate via the polishing tool, and
It has a support member that supports the elastic member, and has.
A recess into which the elastic member can enter is formed on the front surface of the support member.
Said resilient said pressing surface opposite to the to that Migaku Ken apparatus wherein a sheet is attached on the rear surface of the member. The polishing apparatus according to any one of claims 1 to 3 , wherein the polishing tool is made of a polishing tape. A groove extending toward the back surface on the opposite side of the pressing surface is formed on the pressing surface of the elastic member.
The polishing apparatus according to claim 1 or 2 , wherein the elastic member has a block body divided by the groove. The polishing apparatus according to claim 5 , wherein the polishing tool is a grindstone attached to the front surface of the block body. A pressing pad that presses a polishing tool for polishing the peripheral edge of a substrate against the peripheral edge.
An elastic member having a pressing surface that presses the peripheral edge of the substrate via the polishing tool, and
A support member that supports the elastic member and
It has fixing means for fixing both ends of the elastic member to the support member, respectively.
A recess into which the elastic member can enter is formed on the front surface of the support member .
The elastic member has fixed protrusions protruding from both side surfaces of the elastic member.
Each fixing means is a pressing pad comprising a fixing block having a stepped portion into which the fixing protrusion is fitted. The pressing pad according to claim 7 , wherein the bottom surface of the recess is curved. A pressing pad that presses a polishing tool for polishing the peripheral edge of a substrate against the peripheral edge.
An elastic member having a pressing surface that presses the peripheral edge of the substrate via the polishing tool, and
It has a support member that supports the elastic member, and has.
A recess into which the elastic member can enter is formed on the front surface of the support member.
The pressing pad on the back of the opposite side of the pressing surface of the elastic member characterized in that the sheet is attached. The pressing pad according to any one of claims 7 to 9 , wherein the polishing tool is made of a polishing tape. A groove extending toward the back surface on the opposite side of the pressing surface is formed on the pressing surface of the elastic member.
The pressing pad according to claim 7 , wherein the elastic member has a block body divided by the groove. The pressing pad according to claim 11 , wherein a grindstone used as the polishing tool is attached to the front surface of the block body.

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