Polishing apparatus and polishing method

Abstract

To provide a polishing device and a polishing method which can uniformly polish a plane part of a substrate without giving an influence on a pressing force of a polishing head by a dynamic frictional force generated between the polishing head and a polishing tape.SOLUTION: A polishing device 100 includes a substrate holding part for holding a substrate W and rotating the substrate W, a polishing tape supply mechanism 141 for feeding a polishing tape 3 in its longitudinal direction, and at least one polishing head 10 arranged in close contact with the plane part of the substrate W, wherein the polishing head 10 has a fluid pressing part for pressing the polishing tape 3 against the plane part of the substrate by fluid, and the fluid pressing part has a fluid supply port arranged opposite to the rear face of the polishing tape 3.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a polishing apparatus and a polishing method for polishing a planar portion of a substrate such as a wafer.

Background Art

[0002] In recent years, devices such as memory circuits, logic circuits, and image sensors (e.g., CMOS sensors) have been becoming more highly integrated. In the process of forming these devices on a substrate such as a wafer, foreign substances such as fine particles, dust, and unnecessary films may adhere to the substrate. The foreign substances adhering to the substrate cause problems such as defective formation or breakage of the device. Therefore, in order to improve the reliability of the device, it is necessary to remove the foreign substances on the substrate.

[0003] There is a polishing apparatus that polishes a substrate using an abrasive tool in order to remove foreign substances on the substrate such as a wafer. As such a polishing apparatus, there is a polishing apparatus that polishes a substrate by bringing an abrasive tool into sliding contact with the substrate. The polishing apparatus polishes the substrate by pressing the abrasive tool against the substrate with a polishing head.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Patent Document 3

Patent Document 4

Patent Document 5

Summary of the Invention

Problems to be Solved by the Invention

[0005] As an example of a polishing apparatus, there is a polishing apparatus that polishes a substrate by rotating the substrate and pressing a polishing tool such as a polishing tape against the substrate with a polishing head while feeding the polishing tool in one direction. FIG. 21 is a diagram for explaining the problems of a conventional polishing head. The polishing head 310 presses the polishing tape 303 against the wafer W with the polishing blade 340 to polish the wafer W. At this time, the polishing tape 303 is fed in the direction indicated by the arrow, and a dynamic frictional force is generated between the polishing blade 340 and the polishing tape 303. Due to this dynamic frictional force, the tension applied to the polishing tape 303 is greater on the downstream side T1 than on the upstream side T2 in the feeding direction of the polishing tape 303. The polishing head 310 has a universal joint (not shown), and the polishing blade 340 is tilted by the tension of the polishing tape 303. Therefore, at the downstream pressing point P1 in the feeding direction of the polishing tape 303, the pressing force on the polishing tape 303 is smaller than that at the upstream pressing point P2, and the wafer W cannot be polished uniformly.

[0006] As a countermeasure against the above problems, it is possible to change the material of the polishing blade 340 to reduce the friction coefficient, but it is not possible to make the dynamic frictional force zero. Also, there is a method of adjusting the inclination of the polishing blade 340 to equalize the pressing forces at the pressing point P1 and the pressing point P2 without applying a universal joint to the polishing head 310, but it is difficult to adjust the inclination of the polishing head 310 as the tension applied to the polishing tape 303 changes.

[0007] Therefore, an object of the present invention is to provide a polishing apparatus and a polishing method capable of uniformly polishing a flat portion of a substrate without being affected by the pressing force of the polishing head due to the dynamic frictional force generated between the polishing head and the polishing tape.

Means for Solving the Problems

[0008] In one aspect, a polishing apparatus for polishing a planar portion of a substrate, comprising: a substrate holding unit that holds the substrate and rotates the substrate; a polishing tape supply mechanism that feeds a polishing tape in its longitudinal direction; and at least one polishing head disposed close to the planar portion of the substrate, wherein the polishing head has a fluid pressing unit that presses the polishing tape against the planar portion of the substrate with a mixed fluid of gas and liquid, and the fluid pressing unit is A slit nozzle having a slit-shaped fluid supply port, said fluid supply port disposed opposite to the back surface of the polishing tape wherein, when viewing the polishing head from above, and is inclined obliquely with respect to the advancing direction of the polishing tape ing , a polishing apparatus is provided. 。 one In an aspect, A polishing apparatus for polishing a planar portion of a substrate, comprising a substrate holding portion for holding the substrate and rotating the substrate, a polishing tape supply mechanism for feeding a polishing tape in its longitudinal direction, and at least one polishing head disposed close to the planar portion of the substrate, said polishing head having a fluid pressing portion for pressing the polishing tape against the planar portion of the substrate with a mixed fluid of gas and liquid, the fluid pressing unit is an area pad having a pressing surface with a depression formed in the center and a fluid supply port in the depression flowing , and said fluid supply port is disposed to face the back surface of the polishing tape, the depression wherein, when viewing the polishing head from above, is inclined obliquely with respect to the advancing direction of the polishing tape a polishing apparatus is provided .

[0009] In one aspect, the ratio of the gas in the mixed fluid is greater than the ratio of the liquid. In one aspect, A polishing apparatus for polishing a planar portion of a substrate, comprising a substrate holding portion for holding the substrate and rotating the substrate, a polishing tape supply mechanism for feeding a polishing tape in its longitudinal direction, and at least one polishing head disposed close to the planar portion of the substrate, said polishing head having a fluid pressing portion for pressing the polishing tape against the planar portion of the substrate with a mixed fluid of gas and liquid, said fluid pressing portion having a fluid supply port disposed to face the back surface of the polishing tape, the planar portion of the substrate is an edge portion located at the peripheral edge of the substrate, and the fluid pressing unit has an arc shape having substantially the same curvature as the outer peripheral shape of the substrate a polishing apparatus is provided .

[0010] In one aspect, a polishing method for polishing a planar portion of a substrate, comprising: holding the substrate by a substrate holding unit, rotating the substrate, feeding a polishing tape in its longitudinal direction by a polishing tape supply mechanism, and supplying a mixed fluid of gas and liquid from a fluid supply port provided in a fluid pressing unit of a polishing head toward the back surface of the polishing tape, thereby pressing the polishing tape against the planar portion of the substrate with the mixed fluid for polishing, wherein the fluid pressing unit A slit nozzle having a slit-shaped fluid supply port, said fluid supply port is disposed to face the back surface of the polishing tape, said fluid supply port is wherein, when viewing the polishing head from above, inclined obliquely with respect to the advancing direction of the polishing tape ing , a polishing method is provided. 。 one In an aspect,A polishing method for polishing a planar portion of a substrate, comprising holding the substrate by a substrate holding portion, rotating the substrate, feeding a polishing tape in its longitudinal direction by a polishing tape supply mechanism, and supplying a mixed fluid of gas and liquid from a fluid supply port provided in a fluid pressing portion of a polishing head toward the back surface of the polishing tape, thereby pressing the polishing tape against the planar portion of the substrate with the mixed fluid and polishing, The fluid pressing part is an area pad having a pressing surface with a depression formed in the center and a body supply port, flowing and said fluid supply port is disposed to face the back surface of the polishing tape, the depression wherein, when viewing the polishing head from above, is inclined obliquely with respect to the advancing direction of the polishing tape. a polishing method is provided .

[0011] In one aspect, the ratio of the gas in the mixed fluid is larger than the ratio of the liquid. In one aspect, A polishing method for polishing a planar portion of a substrate, comprising holding the substrate by a substrate holding portion, rotating the substrate, feeding a polishing tape in its longitudinal direction by a polishing tape supply mechanism, and supplying a mixed fluid of gas and liquid from a fluid supply port provided in a fluid pressing portion of a polishing head toward the back surface of the polishing tape, thereby pressing the polishing tape against the planar portion of the substrate with the mixed fluid and polishing, the flat part of the substrate is an edge part located at the peripheral part of the substrate, and the fluid pressing part has an arc shape having substantially the same curvature as the outer peripheral shape of the substrate. , a grinding method is provided .

Advantages of the Invention

[0012] According to the present invention, by pressing the polishing head against the polishing tape with a fluid, a dynamic frictional force does not occur between the polishing head and the polishing tape, and the flat part of the substrate can be polished uniformly.

[0013] Also, according to the present invention, the frictional heat generated between the substrate and the polishing tape during polishing can be cooled by a fluid, and the polishing rate can be improved.

[0014] Furthermore, by allowing the fluid to reach the polishing point of the substrate, the polishing debris can be removed from the surface of the substrate.

Brief Description of the Drawings

[0015]

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Embodiments for Carrying Out the Invention

[0016] Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a schematic diagram showing an embodiment of a polishing apparatus. The polishing apparatus 100 shown in FIG. 1 holds a wafer W which is an example of a substrate, and rotates it about its axis. A polishing head 10 presses a polishing tape 3 as a polishing tool against a first surface 1 of the wafer W held by the substrate holding unit 110 with a fluid to polish the first surface 1 of the wafer W, and includes a polishing tape supply mechanism 141 that supplies the polishing tape 3 to the polishing head 10.

[0017] The substrate holding unit 110 includes a plurality of rollers 111 that can contact the peripheral edge of the wafer W, and a roller rotation mechanism (not shown) that rotates each of the plurality of rollers 111 about its axis. The polishing head 10 is disposed below the wafer W held by the substrate holding unit 110. In FIG. 1, part of the substrate holding unit 110 is not shown. The substrate holding unit 110 of the present embodiment includes four rollers 111 (two of which are not shown).

[0018] In the present embodiment, the first surface 1 of the wafer W is the back surface of the wafer W on which no device is formed or on which no device is planned to be formed, that is, the non-device surface. The second surface 2 of the wafer W on the opposite side of the first surface 1 is the surface on which a device is formed or on which a device is planned to be formed, that is, the device surface. In the present embodiment, the wafer W is horizontally held by the substrate holding unit 110 with its first surface 1 facing downward.

[0019] The roller rotation mechanism is configured to rotate the four rollers 111 in the same direction at the same speed. During polishing of the first surface 1 of the wafer W, the peripheral edge of the wafer W is gripped by the rollers 111. The wafer W is held horizontally, and the wafer W is rotated about its axis by the rotation of the rollers 111. During polishing of the first surface 1 of the wafer W, the four rollers 111 rotate about their respective axes, but the positions of the rollers 111 themselves are stationary.

[0020] As shown in FIG. 1, below the wafer W held by the substrate holding unit 110, a rinse liquid supply nozzle 127 for supplying a rinse liquid (e.g., pure water or an alkaline chemical solution) to the first surface 1 of the wafer W is disposed. This rinse liquid supply nozzle 127 is connected to a rinse liquid supply source (not shown). The rinse liquid supply nozzle 127 is disposed facing the processing point on the first surface 1 of the wafer W. In FIG. 1, one rinse liquid supply nozzle 127 is disposed, but in one embodiment, a plurality of rinse liquid supply nozzles 127 may be disposed facing the processing point and / or an area other than the processing point on the first surface 1 of the wafer W. The rinse liquid supplied from the rinse liquid supply nozzle 127 to the processing point on the first surface 1 of the wafer W can remove abrasive debris from the first surface 1 of the wafer W. At this time, the rinse liquid may be supplied to the upstream side of the polishing head 10 in the direction in which the wafer W rotates. Also, the rinse liquid supplied to areas other than the processing point can prevent the wafer W from drying.

[0021] Above the wafer W held by the substrate holding unit 110, a protective liquid supply nozzle 128 for supplying a protective liquid (e.g., pure water) to the second surface 2 of the wafer W is disposed. The protective liquid supply nozzle 128 is connected to a protective liquid supply source (not shown). The protective liquid supply nozzle 128 is disposed facing the center of the second surface 2 of the wafer W. The protective liquid is supplied from the protective liquid supply nozzle 128 to the center of the second surface 2 of the wafer W, and the protective liquid spreads over the second surface 2 of the wafer W by centrifugal force. The protective liquid prevents the rinse liquid containing abrasive debris and foreign matter generated during polishing of the wafer W from flowing onto the second surface 2 of the wafer W and adhering to the second surface of the wafer W. As a result, the second surface 2 of the wafer W can be kept clean.

[0022] The polishing head 10 is supported by a support member 131, and the support member 131 is fixed to the movable plate 120. Therefore, the entire polishing head 10 can move integrally with the movable plate 120. The support member 131 has a through hole (not shown), and the polishing tape 3 extends through this through hole.

[0023] The polishing head 10 is configured to press the polishing tape 3 against the first surface 1 of the wafer W by means of a fluid. The polishing head 10 is connected to a fluid supply line 30 and fluid is supplied from a fluid supply source (not shown). Details of the polishing head 10 will be described later.

[0024] The polishing tape supply mechanism 141 includes a tape unwinding reel 143 that supplies the polishing tape 3 and a tape winding reel 144 that winds up the polishing tape 3. The tape unwinding reel 143 and the tape winding reel 144 are respectively connected to tension motors 143a and 144a. The tension motors 143a and 144a are fixed to a reel base 142. The reel base 142 is fixed to a movable plate 120, and the entire polishing tape supply mechanism 141 can move integrally with the movable plate 120.

[0025] By rotating the tape winding reel 144 in the direction indicated by the arrow, the polishing tape 3 is sent from the tape unwinding reel 143 through the polishing head 10 in the direction indicated by the arrow of the tape winding reel 144. The polishing tape 3 is supplied above the polishing head 10 such that the polishing surface 3a of the polishing tape 3 faces the first surface 1 of the wafer W. The tension motor 143a can apply tension to the polishing tape 3 by applying a predetermined torque to the tape unwinding reel 143. The tension motor 144a is controlled to feed the polishing tape 3 at a constant speed. The speed at which the polishing tape 3 is fed can be changed by changing the rotational speed of the tape winding reel 144. In one embodiment, the direction in which the polishing tape 3 is fed may be the reverse direction of the direction indicated by the arrow in FIG. 1 (the arrangements of the tape unwinding reel 143 and the tape winding reel 144 may be interchanged). Separately from the tape winding reel 144, a tape feeding device may be provided. In this case, the tension motor 144a connected to the tape winding reel 144 can apply tension to the polishing tape 3 by applying a predetermined torque to the tape winding reel 144.

[0026] The polishing apparatus 100 further includes a plurality of guide rollers 153a, 153b, 153c, 153d that support the polishing tape 3. The polishing tape 3 is guided by these guide rollers 153a, 153b, 153c, 153d so as to surround the polishing head 10. The polishing head 10 polishes the first surface 1 of the wafer W by pressing the polishing tape 3 against the first surface 1 of the wafer W from its back side with a fluid. The guide rollers 153b, 153c disposed above the polishing head 10 guide the polishing tape 3 so that the polishing tape 3 advances in a direction parallel to the first surface 1 of the wafer W. The guide rollers 153a, 153b, 153c, 153d are fixed to a holding member (not shown), and this holding member is fixed to the movable plate 120.

[0027] In order to bring the polishing tape 3 into contact with the wafer W from the center O1 to the outermost part of the first surface 1 of the wafer W, the polishing apparatus 100 of the present embodiment includes a polishing head moving mechanism 191 that relatively translates the polishing head 10 with respect to the substrate holding unit 110. The polishing head moving mechanism 191 is configured to move the polishing head 10 between the center O1 of the first surface 1 of the wafer W and the outermost part of the first surface 1.

[0028] A plurality of linear guides 195 are fixed to the lower surface of the movable plate 120, and the movable plate 120 is supported by the plurality of linear guides 195. The plurality of linear guides 195 are disposed on the installation surface 197. The movable plate 120 is moved by the polishing head moving mechanism 191, and the linear guides 195 limit the movement of the movable plate 120 to a linear motion in the radial direction of the wafer W.

[0029] The polishing head moving mechanism 191 includes a ball screw mechanism 193 and a motor 194 that drives the ball screw mechanism 193. A servo motor can be used as the motor 194. The movable plate 120 is connected to the screw shaft 193a of the ball screw mechanism 193. When the polishing head moving mechanism 191 is actuated, the polishing head 10, the polishing tape supply mechanism 141, and the guide rollers 153a, 153b, 153c, 153d move relative to the substrate holding portion 110 in the radial direction of the wafer W.

[0030] During the polishing of the wafer W, the polishing head moving mechanism 191 moves the polishing head 10 between the center O1 of the first surface 1 of the wafer W and the outermost part of the first surface 1. The polishing apparatus 100 further includes an operation control unit 180 that controls the operations of the respective components of the polishing apparatus 100. The polishing head moving mechanism 191 is electrically connected to the operation control unit 180, and the operation of the polishing head moving mechanism 191 is controlled by the operation control unit 180. When the polishing head moving mechanism 191 operates, the polishing head 10, the polishing tape supply mechanism 141, and the guide rollers 153a, 153b, 153c, 153d move integrally.

[0031] During the polishing of the first surface 1 of the wafer W, the position of the roller 111 itself is stationary, and the roller 111 is disposed at a position where it does not contact even when the polishing head 10 moves from the center side to the outside of the wafer W. Therefore, the polishing tape 3 can polish the entire first surface 1 of the wafer W including the outermost part.

[0032] FIG. 2 is a schematic diagram showing an embodiment of the polishing head 10. FIG. 3 is a top view of the polishing head 10 shown in FIG. 2. FIG. 2 shows a state in which the polishing tape 3 is pressed against the first surface 1 of the wafer W by the fluid supplied from the polishing head 10. The polishing tape 3 is being fed at a predetermined speed in the direction indicated by the arrow. The polishing head 10 is disposed below the polishing tape 3, and the polishing tape 3 and the polishing head 10 are separated from each other.

[0033] The polishing head 10 is connected to a fluid supply line 30, and fluid is supplied from a fluid supply source (not shown). More specifically, the fluid supply line 30 has a liquid supply line 31 through which liquid (e.g., pure water, carbonated water, alkaline chemical solution, etc.) is supplied from a liquid supply source (not shown), and a gas supply line 32 through which gas (e.g., dry air, inert gas, etc.) is supplied from a gas supply source (not shown). In one embodiment, the fluid supply line 30 may have only one of the liquid supply line 31 or the gas supply line 32.

[0034] The polishing head 10 has a fluid pressing portion 12, a flow path 14, and a fluid mixing chamber 15. In the polishing head 10 of the present embodiment, the fluid pressing portion 12 is constituted by a slit nozzle. The fluid pressing portion 12 is provided at the upper part of the polishing head 10. As shown in FIG. 3, a slit-shaped fluid supply port 13 extending linearly in the longitudinal direction of the fluid pressing portion 12 is formed in the fluid pressing portion 12. The fluid pressing portion 12 and the fluid supply port 13 are inclined obliquely with respect to the polishing head 10 when viewed from above the polishing head 10.

[0035] The flow path 14 communicates with the fluid supply port 13 and the fluid mixing chamber 15. The fluid mixing chamber 15 is connected to the fluid supply line 30, that is, the liquid supply line 31 and the gas supply line 32. The liquid flowing through the liquid supply line 31 and the gas flowing through the gas supply line 32 are mixed in the fluid mixing chamber 15 to generate a mixed fluid. This mixed fluid flows through the flow path 14 and is supplied as a two-fluid jet from the fluid supply port 13 toward the back surface of the polishing tape 3. The fluid supply port 13 is disposed facing the back surface of the polishing tape 3, and the polishing tape 3 can be pressed against the first surface 1 of the wafer W by the mixed fluid (two-fluid jet) supplied from the fluid supply port 13.

[0036] The liquid supply line 31 is provided with a liquid supply valve 33 for opening and closing the flow path of the liquid supply line 31, a flow rate control device 35 for adjusting the flow rate of the liquid flowing through the liquid supply line 31, and a flow meter 37 for measuring the flow rate of the liquid flowing through the liquid supply line 31. The liquid supply valve 33 is arranged upstream of the flow rate control device 35 and the flow meter 37 in the liquid flow direction. Examples of the flow rate control device 35 include a flow rate control valve or a mass flow controller. A pressure sensor (not shown) may be provided between the flow meter 37 and the fluid mixing chamber 15.

[0037] The gas supply line 32 is provided with a gas supply valve 34 for opening and closing the flow path of the gas supply line 32, a flow rate control device 36 for adjusting the flow rate of the gas flowing through the gas supply line 32, and a flow meter 38 for measuring the flow rate of the gas flowing through the gas supply line 32. The gas supply valve 34 is arranged upstream of the flow rate control device 36 and the flow meter 38 in the gas flow direction. Examples of the flow rate control device 36 include a flow rate control valve or a mass flow controller. Instead of the flow rate control device 36, a pressure control device for adjusting the pressure of the gas flowing through the gas supply line 32 may be provided. Examples of the pressure control device include a pneumatic regulator. Instead of the flow meter 38, a pressure gauge for measuring the pressure of the gas flowing through the gas supply line 32 may be provided. Also, a flow meter and a pressure gauge may be provided together between the flow rate control device 36 (or the pressure control device) and the fluid mixing chamber 15.

[0038] In one embodiment, the proportion of gas in the mixed fluid is larger than the proportion of liquid in the mixed fluid. Generally, for the same amount of liquid (e.g., pure water, carbonated water, chemical solution, etc.) and gas (e.g., dry air, inert gas, etc.), the gas is of lower cost. Therefore, by making the proportion of gas in the mixed fluid larger than the proportion of liquid, the cost can be reduced. The proportion of gas and liquid in the mixed fluid can be adjusted by the flow rate control device 35 and the flow rate control device 36 (or the pressure control device).

[0039] In this embodiment, a mixed fluid was generated by mixing a liquid and a gas in the fluid mixing chamber 15 provided in the polishing head 10. However, in one embodiment, a fluid supply line 30 through which the pre-mixed mixed fluid flows may communicate with the flow path 14 without passing through the fluid mixing chamber 15, and the mixed fluid may be directly supplied to the fluid pressing portion 12. Further, in one embodiment, either one of the liquid supply line 31 or the gas supply line 32 may communicate with the flow path 14 without passing through the fluid mixing chamber 15, and only either the liquid or the gas may be supplied to the fluid pressing portion 12. In any case, the polishing head 10 can supply the fluid from the fluid supply port 13 toward the back surface of the polishing tape 3.

[0040] FIG. 4 is a plan view showing the arrangement of the polishing head 10 shown in FIG. 2. The fluid pressing portion 12 and the fluid supply port 13 of the polishing head 10 are arranged obliquely with respect to the advancing direction of the polishing tape 3 (indicated by the arrow E). Thereby, since the polishing tape 3 can be brought into contact with the polishing point on the wafer W a plurality of times, the wafer W can be polished efficiently.

[0041] The angles of the fluid pressing portion 12 and the fluid supply port 13 of the present invention with respect to the advancing direction of the polishing tape 3 are not limited to the embodiment shown in FIG. 4. For example, they may be arranged perpendicular to the advancing direction of the polishing tape 3. By making the fluid pressing portion 12 and the fluid supply port 13 perpendicular to the advancing direction of the polishing tape 3, the width of the polishing head 10 in the advancing direction of the polishing tape 3 can be reduced. Further, the shapes of the fluid pressing portion 12 and the fluid supply port 13 of the present invention are not limited to the embodiment shown in FIG. 4. For example, the fluid supply port 13 may have a shape extending outside the width of the polishing tape 3.

[0042] Next, the operation of the polishing apparatus 100 of the present embodiment will be described. The operation of the polishing apparatus 100 described below is controlled by the operation control unit 180 shown in FIG. 1. The operation control unit 180 is electrically connected to the liquid supply valve 33, the gas supply valve 34, the flow rate control device 35, the flow rate control device 36 (or pressure control device), the substrate holding unit 110, the polishing tape supply mechanism 141, and the polishing head moving mechanism 191. The operations of the liquid supply valve 33, the gas supply valve 34, the flow rate control device 35, the flow rate control device 36 (or pressure control device), the substrate holding unit 110, the rinse liquid supply nozzle 127, the protective liquid supply nozzle 128, the polishing tape supply mechanism 141, and the polishing head moving mechanism 191 are controlled by the operation control unit 180.

[0043] The operation control unit 180 is composed of at least one computer. The operation control unit 180 includes a storage device 180a and an arithmetic device 180b. The arithmetic device 180b includes a CPU (Central Processing Unit) or a GPU (Graphics Processing Unit) that performs calculations according to instructions included in a program stored in the storage device 180a. The storage device 180a includes a main storage device (e.g., random access memory) accessible by the arithmetic device 180b and an auxiliary storage device (e.g., hard disk drive or solid state drive) that stores data and programs.

[0044] The wafer W to be polished is held by the roller 111 of the substrate holding unit 110 with the first surface 1 facing downward, and is further rotated about the axis of the wafer W. Specifically, the substrate holding unit 110 rotates the wafer W by rotating a plurality of rollers 111 about their respective axes while bringing the plurality of rollers 111 into contact with the peripheral edge of the wafer W with the first surface 1 of the wafer W facing downward. Next, a rinse liquid is supplied from the rinse liquid supply nozzle 127 to the first surface 1 of the wafer W, and a protective liquid is supplied from the protective liquid supply nozzle 128 to the second surface 2 of the wafer W. The rinse liquid is supplied to prevent the cleaning of the processing points on the first surface 1 of the wafer W and / or the drying of areas other than the processing points, and the protective liquid spreads over the entire second surface 2 of the wafer W by centrifugal force.

[0045] The polishing head moving mechanism 191 moves the polishing head 10 below the center O1 of the first surface 1 of the wafer W. The operation control unit 180 drives the polishing tape supply mechanism 141 to advance the polishing tape 3 in its longitudinal direction at a predetermined speed while applying a predetermined tension. Next, the operation control unit 180 opens the liquid supply valve 33 and the gas supply valve 34 to supply fluid to the polishing head 10. The polishing head 10 brings the polishing surface 3a of the polishing tape 3 into contact with the first surface 1 of the wafer W by the fluid and starts polishing the first surface 1 of the wafer W in the presence of the rinse liquid. Further, while pressing the polishing tape 3 against the first surface 1 of the wafer W by the fluid supplied from the polishing head 10, the polishing head moving mechanism 191 moves the polishing head 10, the polishing tape supply mechanism 141, and the guide rollers 153a, 153b, 153c, 153d outward in the radial direction of the wafer W. The operation control unit 180 can adjust the pressing force of the fluid against the polishing tape 3 by controlling the flow rate supplied to the polishing head 10 by the flow rate control device 35 and the flow rate control device (pressure control device) 36. During the polishing of the wafer W, the rinse liquid supply nozzle 127 and the protective liquid supply nozzle 128 continuously supply the rinse liquid and the protective liquid to the wafer W.

[0046] When the polishing head 10 reaches the outermost part of the first surface 1 of the wafer W, the operation control unit 180 ends the polishing of the wafer W. Specifically, the liquid supply valve 33 and the gas supply valve 34 are closed, the supply of fluid to the polishing head 10 is stopped, and the polishing tape 3 is separated from the first surface 1 of the wafer W. Thereafter, the operation control unit 180 stops the operations of the substrate holding unit 110, the rinse liquid supply nozzle 127, the protective liquid supply nozzle 128, and the polishing tape supply mechanism 141, and ends the polishing of the wafer W. In one embodiment, the polishing head moving mechanism 191 may reciprocate the polishing head 10 between the outermost part and the center O1 of the first surface 1 of the wafer W.

[0047] According to the above-described embodiments, since the polishing head 10 does not contact the back surface of the polishing tape 3 and the polishing tape 3 is pressed by a fluid, even when the wafer W is polished while feeding the polishing tape 3, no kinetic friction force is generated between the polishing tape 3 and the polishing head 10. Therefore, by adjusting the pressure of the fluid supplied from the fluid pressing portion 12 of the polishing head 10 to make the pressing force uniform, the back surface of the polishing tape 3 can be uniformly pressed against the flat portion of the wafer W, and as a result, the flat portion of the wafer W can be uniformly polished.

[0048] In particular, in the present embodiment, a mixed fluid of a liquid and a gas is used as the fluid for pressing the polishing tape 3. This mixed fluid is jetted from the polishing head 10 to the back surface of the polishing tape 3 as a two-fluid jet. The mixed fluid can press the polishing tape 3 against the wafer W with a larger pressing force than the liquid alone.

[0049] Also, the friction heat generated between the wafer W and the polishing tape 3 when the wafer W is polished can be cooled by the fluid supplied from the polishing head 10 to the back surface of the polishing tape 3. Generally, it is known that the polishing performance of the polishing tape 3 deteriorates and the polishing rate decreases due to the friction heat generated at the polishing point of the wafer W. Therefore, the polishing rate can be improved by cooling the friction heat with a fluid.

[0050] Furthermore, since the fluid supplied from the polishing head 10 wraps around to the polishing point of the wafer W on the back surface of the polishing tape 3, the polishing debris can be removed from the first surface 1 of the wafer W.

[0051] FIG. 5 is a schematic diagram showing another embodiment of the polishing head 10. FIG. 6 is a top view of the polishing head 10 shown in FIG. 5. FIG. 5 shows a state in which the polishing tape 3 is pressed against the first surface 1 of the wafer W by the fluid supplied from the polishing head 10. Details of the present embodiment not specifically described are the same as those of the above-described embodiments described with reference to FIGS. 1 to 4, and thus the overlapping description is omitted.

[0052] The polishing head 10 has a fluid pressing portion 12, a flow path 14, and a fluid mixing chamber 15. In the polishing head 10 of the present embodiment, the fluid pressing portion 12 is constituted by an area pad. The fluid pressing portion 12 is provided at the upper part of the polishing head 10 and has a rectangular shape when the polishing head 10 is viewed from above as shown in FIG. 6. A rectangular depression 17 is formed at the center of the pressing surface 16 which is the upper surface of the fluid pressing portion 12, and a fluid supply port 18 is formed at the center of the depression 17. Two or more fluid supply ports 18 may be formed. The flow path 14 communicates with the fluid supply port 18 and the fluid mixing chamber 15.

[0053] The mixed fluid generated in the fluid mixing chamber 15 is supplied into the depression 17 from the fluid supply port 18 through the flow path 14 to fill the depression 17, and further flows out toward the outside of the fluid pressing portion 12. The fluid supply port 18 and the depression 17 are arranged to face the back surface of the polishing tape 3. When the gap between the pressing surface 16 of the fluid pressing portion 12 and the back surface of the polishing tape 3 is filled with the fluid, the entire pressing surface 16 including the depression 17 can press the polishing tape 3 against the first surface 1 of the wafer W.

[0054] FIG. 7 is a top view showing another embodiment of the fluid pressing portion 12. Details of this embodiment not specifically described are the same as those of the above-described embodiment described with reference to FIGS. 5 and 6, and thus the overlapping description thereof is omitted. As shown in FIG. 7, the fluid pressing portion 12 may have a parallelogram shape when the polishing head 10 is viewed from above. A parallelogram-shaped depression 17 is formed at the center of the pressing surface 16 which is the upper surface of the fluid pressing portion 12, and a fluid supply port 18 is formed at the center of the depression 17. Two or more fluid supply ports 18 may be formed. The flow path 14 communicates with the fluid supply port 18 and the fluid mixing chamber 15.

[0055] FIG. 8 is a plan view showing the arrangement of the polishing head 10 shown in FIG. 7. The fluid pressing portion 12 is arranged to be a parallelogram having two sides parallel to the advancing direction of the polishing tape 3 (indicated by the arrow E) when the polishing head 10 is viewed from above. Thereby, since the polishing tape 3 can be brought into contact with the polishing point on the wafer W a plurality of times, the wafer W can be polished efficiently. The shape of the fluid pressing portion 12 of the present invention is not limited to the embodiment shown in FIG. 8, and for example, it may have a shape extending outside the width of the polishing tape 3.

[0056] In the embodiments shown in FIGS. 5 to 8, instead of the mixed fluid of liquid and gas, a liquid may be used as the fluid for pressing the polishing tape 3 against the wafer W.

[0057] FIG. 9 is a schematic view showing another embodiment of the polishing apparatus. The details of this embodiment not particularly described are the same as those of the above-described embodiment described with reference to FIGS. 1 to 8, and thus the overlapping description thereof is omitted. In FIG. 9, the illustration of the rinse liquid supply nozzle 127 is omitted. The polishing apparatus 100 of this embodiment includes polishing head assemblies 11A and 11B, and polishing tape supply mechanisms 141A and 141B for supplying the polishing tape 3 to the polishing head assemblies 11A and 11B, respectively. The polishing head assembly 11A includes polishing heads 10A and 10B. Similarly, the polishing head assembly 11B includes polishing heads 10A and 10B. The polishing head assembly 11A is supported by a support member 131A, and the polishing head assembly 11B is supported by a support member 131B.

[0058] The polishing tape 3 supplied to the polishing head assembly 11A is supported by guide rollers 163a, 163b, 163c, 163d, and the polishing tape 3 supplied to the polishing head assembly 11B is supported by guide rollers 173a, 173b, 173c, 173d. The configurations of the polishing tape supply mechanisms 141A, 141B, the support members 131A, 131B, the guide rollers 163a, 163b, 163c, 163d, and the guide rollers 173a, 173b, 173c, 173d are the same as those of the polishing tape supply mechanism 141, the support member 131, and the guide rollers 153a, 153b, 153c, 153d described with reference to FIG. 1. The polishing apparatus 100 of the present embodiment does not include a polishing head moving mechanism 191. Therefore, during polishing, the positions of the polishing head assemblies 11A and 11B are fixed.

[0059] The polishing head 10A corresponds to the polishing head 10 in which the fluid pressing portion 12 described with reference to FIGS. 2 to 4 is a slit nozzle. FIG. 10 is a top view showing the polishing head 10B in which the fluid pressing portions 12A and 12B are two slit nozzles. Since the details of the fluid pressing portions 12A and 12B of the present embodiment that are not particularly described are the same as those of the fluid pressing portion 12 described with reference to FIGS. 2 to 4, the overlapping description thereof is omitted. The polishing head 10B has two fluid pressing portions 12A and 12B, and fluid supply ports 13A and 13B are formed therein, respectively. The two fluid pressing portions 12A and 12B are provided above the polishing head 10B and are arranged symmetrically with respect to the center line L1 of the polishing head 10B extending in the traveling direction of the polishing tape 3 (not shown in FIG. 10). In one embodiment, the two fluid pressing portions 12A and 12B may not be arranged symmetrically with respect to the center line L1 as long as they are inclined obliquely with respect to the traveling direction of the polishing tape 3.

[0060] FIG. 11 is a plan view showing the arrangement of the polishing heads 10A and 10B shown in FIG. 9. The plurality of polishing heads 10A and 10B are arranged at different distances from the axis CP of the substrate holding portion 110 (the center O1 of the first surface 1 of the wafer W). The distance d1 from the axis CP of the substrate holding portion 110 to the outermost end of the fluid pressing portion is longer than the radius d2 of the wafer W.

[0061] During polishing, the polishing tape supply mechanism 141A feeds the polishing tape 3 in the direction indicated by the arrow F in FIGS. 9 and 11, and the polishing tape supply mechanism 141B feeds the polishing tape 3 in the direction indicated by the arrow G in FIGS. 9 and 11. That is, each polishing tape 3 is fed from the central portion of the wafer W toward the outer peripheral portion. Thereby, the polishing debris generated during the polishing of the wafer W can be efficiently discharged from the central portion of the wafer W to the outside of the wafer W.

[0062] The plurality of polishing heads 10A and 10B are configured to be operable independently of each other. The polishing heads 10A and 10B of the polishing head assembly 11A are arranged with a gap along the traveling direction F (the longitudinal direction of the polishing tape 3) of the polishing tape 3, and the polishing heads 10A and 10B of the polishing head assembly 11B are arranged with a gap along the traveling direction G (the longitudinal direction of the polishing tape 3) of the polishing tape 3. Each of the plurality of fluid pressing portions 12, 12A, and 12B of the present embodiment extends obliquely with respect to the traveling directions F and G of the polishing tape 3. When viewed from the traveling direction F or the traveling direction G of the polishing tape 3, the plurality of fluid pressing portions 12, 12A, and 12B are continuously arranged along a direction perpendicular to the traveling directions F and G of the polishing tape 3. Further, when viewed from the traveling direction F or the traveling direction G of the polishing tape 3, the plurality of fluid pressing portions 12, 12A, and 12B are continuously arranged without a gap.

[0063] The plurality of fluid pressing portions 12, 12A, and 12B are not aligned in a straight line, but are located at different distances from the axis CP of the substrate holding portion 110. Therefore, when the wafer W is rotating, each region of the first surface 1 of the wafer W passes through one of the plurality of fluid pressing portions 12, 12A, and 12B. Accordingly, the polishing tape 3 can be pressed against the entire surface of the first surface 1 of the wafer W by the fluid supplied from the plurality of fluid pressing portions 12, 12A, and 12B.

[0064] The angles of the fluid pressing portions 12, 12A, 12B and the fluid supply ports 13, 13A, 13B with respect to the advancing direction of the polishing tape 3 are not limited to the embodiment shown in FIG. 11, and for example, they may be arranged perpendicular to the advancing direction of the polishing tape 3. By making the fluid pressing portions 12, 12A, 12B and the fluid supply ports 13, 13A, 13B perpendicular to the advancing direction of the polishing tape 3, the width of the polishing head 10 in the advancing direction of the polishing tape 3 can be reduced.

[0065] FIG. 12 is a top view of the polishing head 10 in which the fluid pressing portions 12A, 12B are two area pads. Since the fluid pressing portions 12A, 12B of this embodiment not particularly described are the same as the fluid pressing portion 12 described with reference to FIGS. 7 and 8, the overlapping description thereof is omitted. The polishing head 10B has two fluid pressing portions 12A, 12B having a rectangular shape when viewed from above. On the pressing surface 16A which is the upper surface of the fluid pressing portion 12A, a rectangular depression 17A is formed at the center thereof, and a fluid supply port 18A is formed at the center of the depression 17A. Similarly, in the fluid pressing portion 12B, a depression 17B is formed in the pressing surface 16B which is the upper surface of the fluid pressing portion 12B, and a fluid supply port 18B is formed in the depression 17B. The two fluid pressing portions 12A, 12B are provided at the upper part of the polishing head 10B, and the fluid pressing portion 12A and the fluid pressing portion 12B are symmetrically arranged with respect to the center line L1 of the polishing head 10B extending in the advancing direction of the polishing tape 3 (not shown in FIG. 12). In one embodiment, if the two fluid pressing portions 12A, 12B are inclined obliquely with respect to the advancing direction of the polishing tape 3, they may not be symmetrically arranged with respect to the center line L1.

[0066] In one embodiment, instead of the polishing head 10 having the fluid pressing portion 12 described with reference to FIGS. 3 and 4, the polishing head 10 having the fluid pressing portion 12 described with reference to FIGS. 7 and 8 may be applied to the polishing head 10A. Instead of the two fluid pressing portions 12A, 12B described in FIGS. 10 and 11, the polishing head 10B having the two fluid pressing portions 12A, 12B described with reference to FIG. 12 may be applied to the polishing head 10B.

[0067] According to the above-described embodiment, since the polishing heads 10A and 10B press the polishing tape 3 by fluid without contacting the back surface of the polishing tape 3, even when the wafer W is polished while feeding the polishing tape 3, no kinetic friction force is generated between the polishing tape 3 and the polishing heads 10A and 10B. Therefore, by adjusting the pressure of the fluid supplied from the fluid pressing portions 12 of the polishing heads 10A and 10B to make the pressing force uniform, the back surface of the polishing tape 3 can be uniformly pressed against the flat portion of the wafer W, and as a result, the flat portion of the wafer W can be uniformly polished.

[0068] In addition, the friction heat generated between the wafer W and the polishing tape 3 when the wafer W is polished can be cooled by the fluid supplied from the polishing heads 10A and 10B to the back surface of the polishing tape 3. Generally, it is known that the polishing performance of the polishing tape 3 deteriorates and the polishing rate decreases due to the friction heat generated at the polishing point of the wafer W. Therefore, the polishing rate can be improved by cooling the friction heat with the fluid.

[0069] Furthermore, since the fluid supplied from the polishing heads 10A and 10B to the back surface of the polishing tape 3 reaches the polishing point of the wafer W, the polishing debris can be removed from the first surface 1 of the wafer W.

[0070] FIG. 13 is a schematic diagram showing still another embodiment of the polishing apparatus. The polishing apparatus 200 shown in FIG. 13 is suitably used for a polishing apparatus that polishes the peripheral portion of a substrate (for example, a wafer). In this specification, the peripheral portion of the substrate is defined as a region including a bevel portion located at the outermost periphery of the substrate and an edge portion that is a flat portion located radially inward of the bevel portion. More specifically, the edge portion is a top edge portion and a bottom edge portion.

[0071] Figs. 14(a) and 14(b) are enlarged cross-sectional views showing the peripheral portion of the substrate. Fig. 14(a) is a cross-sectional view of a so-called straight-type substrate, and Fig. 14(b) is a cross-sectional view of a so-called round-type substrate. In the substrate W of Fig. 14(a), the bevel portion is the outermost peripheral surface (indicated by reference sign B) of the substrate 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. In the substrate W of Fig. 14(b), the bevel portion is a portion (indicated by reference sign B) having a curved cross-section that constitutes the outermost peripheral surface of the substrate W. The top edge portion is an annular flat portion E1 located radially inward of the bevel portion B and is a region located within the device surface of the substrate W. The bottom edge portion is located on the side opposite to the top edge portion and is an annular flat portion E2 located radially inward of the bevel portion B. The top edge portion E1 may include a region where a device is formed.

[0072] Returning to Fig. 13, the polishing apparatus 200 includes a substrate holding unit 210 that holds and rotates a wafer W, which is an example of a substrate, a polishing head 10 for polishing the peripheral portion of the wafer W held by the substrate holding unit 210, a lower supply nozzle 222 that supplies a liquid to the lower surface of the wafer W, and an upper supply nozzle 230 that supplies a liquid to the upper surface of the wafer W. As an example of the liquid supplied to the wafer W, pure water can be mentioned. During the polishing of the wafer W, a liquid is supplied from the lower supply nozzle 222 to the lower surface of the wafer, and a liquid is supplied from the upper supply nozzle 230 to the upper surface of the wafer W.

[0073] Fig. 13 shows a state in which the substrate holding unit 210 holds the wafer W. The polishing head 10 faces the peripheral portion of the wafer W when the wafer W is held by the substrate holding unit 210. The substrate holding unit 210 includes a holding stage 204 that holds the wafer W by vacuum suction, a shaft 205 connected to the central portion of the holding stage 204, and a holding stage drive mechanism 207 that rotates and moves the holding stage 204 up and down. The holding stage drive mechanism 207 is configured to be able to rotate the holding stage 204 about its axis Cr and move it in the vertical direction along the axis Cr.

[0074] The polishing head 10, the holding stage 204, the lower supply nozzle 222, and the upper supply nozzle 230 are disposed inside the partition wall 260. The inside of the partition wall 260 constitutes a polishing chamber where the wafer W is polished. The partition wall 260 is disposed on the base plate 265. The shaft 205 extends through the base plate 265.

[0075] The holding stage drive mechanism 207 includes a motor 214 as a stage rotating device that rotates the holding stage 204, and an air cylinder 217 for moving the holding stage 204 up and down. The motor 214 is fixed to the lower surface of the base plate 265. The holding stage 204 is rotated by the motor 214 via the shaft 205, a pulley 211a connected to the shaft 205, a pulley 211b attached to the rotating shaft of the motor 214, and a belt 212 wound around these pulleys 211a and 211b. The rotating shaft of the motor 214 extends parallel to the shaft 205. With such a configuration, the wafer W held on the upper surface of the holding stage 204 is rotated by the motor 214. The shaft 205 is connected to the air cylinder 217 via a rotary joint 216 attached to the lower end of the shaft 205, and the air cylinder 217 enables the shaft 205 and the holding stage 204 to move up and down.

[0076] The wafer W is placed on the upper surface of the holding stage 204 by a transfer mechanism (not shown) such that the center O1 of the wafer W is on the axis Cr of the holding stage 204. The wafer W is held on the upper surface of the holding stage 204 with the device surface facing upward. With such a configuration, the substrate holding unit 210 can rotate the wafer W about the axis Cr of the holding stage 204 (i.e., the axis of the wafer W) and move the wafer W up and down along the axis Cr of the holding stage 204.

[0077] The polishing head 10 is configured to press the polishing tape 3 against the edge portion of the wafer W by a fluid. The polishing head 10 is connected to a fluid supply line 30 and fluid is supplied from a fluid supply source (not shown). Details of the polishing head 10 will be described later.

[0078] The polishing apparatus 200 further includes a polishing tape supply mechanism 242 that supplies the polishing tape 3 to the polishing head 10 and recovers it from the polishing head 10. The polishing tape supply mechanism 242 is disposed outside the partition wall 260. The polishing tape supply mechanism 242 includes a tape unwinding reel 243 that supplies the polishing tape 3 to the polishing head 10 and a tape winding reel 244 that recovers the polishing tape 3 used for polishing the wafer W. By rotating the tape winding reel 244 in the direction indicated by the arrow, the polishing tape 3 is sent from the tape unwinding reel 243 through the fluid pressing portion 12 of the polishing head 10 in the direction indicated by the arrow of the tape winding reel 244.

[0079] Tension motors (not shown) are respectively connected to the tape unwinding reel 243 and the tape winding reel 244. The tension motor connected to the tape unwinding reel 243 can apply a predetermined torque to the tape unwinding reel 243 and apply tension to the polishing tape 3. The tension motor connected to the tape winding reel 244 is controlled to send the polishing tape 3 at a constant speed. The speed at which the polishing tape 3 is sent can be changed by changing the rotational speed of the tape winding reel 244. In one embodiment, the direction in which the polishing tape 3 is sent may be the reverse of the direction indicated by the arrow in FIG. 13 (the arrangements of the tape unwinding reel 243 and the tape winding reel 244 may be interchanged). Separately from the tape winding reel 244, a tape feeding device may be provided. In this case, the tension motor connected to the tape winding reel 244 can apply tension to the polishing tape 3 by applying a predetermined torque to the tape winding reel 244.

[0080] The polishing tape 3 is supplied to the polishing head 10 such that the polishing surface of the polishing tape 3 faces the peripheral portion of the wafer W. The polishing tape 3 is supplied from the tape unwinding reel 243 to the polishing head 10 through the opening 260a provided in the partition wall 260, and the used polishing tape 3 is collected by the tape winding reel 244 through the opening 260a. The polishing tape supply mechanism 242 further includes a plurality of guide rollers 245, 246, 247, 248 for supporting the polishing tape 3. The advancing direction of the polishing tape 3 is guided by the guide rollers 245, 246, 247, 248.

[0081] FIG. 15 is a schematic view showing the polishing head 10 of the polishing apparatus 200 shown in FIG. 13. FIG. 16 is a top view of the polishing head 10 shown in FIG. 15. The polishing head 10 includes two fluid pressing portions 12A and 12B that press the polishing surface 3a of the polishing tape 3 against the edge portion of the wafer W by fluid. The details of the fluid pressing portions 12A and 12B of this embodiment that are not particularly described are the same as those of the fluid pressing portion 12 of the embodiment described with reference to FIGS. 2 and 3, so the overlapping description thereof is omitted. In FIG. 15, the illustration of the liquid supply valve 33, the gas supply valve 34, the flow rate control device 35, the flow rate control device (pressure control device) 36, the flow meter 37, and the flow meter (pressure gauge) 38 is omitted.

[0082] The polishing head 10 has a plurality of guide rollers 253, 254, 255, 256, 257, 258, 259 that guide the polishing tape 3 from the tape unwinding reel 243 (see FIG. 13) to the tape winding reel 244 (see FIG. 13) via the fluid pressing portions 12A and 12B of the polishing head 10, and these guide rollers guide the polishing tape 3 such that the polishing tape 3 advances in a direction perpendicular to the tangential direction of the wafer W.

[0083] The polishing head 10 has fluid pressing parts 12A and 12B which are two slit nozzles, a flow path 14, and a fluid mixing chamber 15. The fluid pressing part 12A and the fluid pressing part 12B are arranged in parallel and symmetrically with respect to the center line Ct. Slit-shaped fluid supply ports 13A and 13B are respectively formed in the two fluid pressing parts 12A and 12B. The two fluid pressing parts 12A and 12B and the fluid supply ports 13A and 13B are curved inward toward the center line Ct. More specifically, the fluid pressing parts 12A and 12B and the fluid supply ports 13A and 13B have an arc shape having substantially the same curvature as the outer peripheral shape of a wafer W (not shown in FIG. 16) which is an object to be polished.

[0084] The flow path 14 communicates with the fluid supply ports 13A and 13B and the fluid mixing chamber 15, and the mixed fluid mixed in the fluid mixing chamber 15 is supplied from the fluid supply ports 13A and 13B through the flow path 14 toward the back surface of the polishing tape 3. The fluid supply ports 13A and 13B are arranged to face the back surface of the polishing tape 3, and the polishing tape 3 can be pressed against the edge portion of the wafer W by the fluid supplied from the fluid supply ports 13A and 13B.

[0085] In the present embodiment, a liquid and a gas are mixed in the fluid mixing chamber 15 provided in the polishing head 10 to form a mixed fluid. However, in one embodiment, a fluid supply line 30 through which a pre-mixed mixed fluid flows communicates with the flow path 14 without passing through the fluid mixing chamber 15, and the mixed fluid may be directly supplied to the fluid pressing parts 12A and 12B. Further, in one embodiment, either one of a liquid supply line 31 or a gas supply line 32 communicates with the flow path 14 without passing through the fluid mixing chamber 15, and only either liquid or gas may be supplied to the fluid pressing parts 12A and 12B.

[0086] The polishing head 10 may further have a pressing pad (bevel pad) 270 disposed between the fluid pressing portion 12A and the fluid pressing portion 12B. The pressing pad 270 is made of an independent foam material having elasticity such as silicone rubber. When the polishing head 10 is moved toward the wafer W by a pressing mechanism (not shown), the pressing pad 270 presses the polishing tape 3 against the bevel portion of the wafer W from its back side, and the polishing head 10 polishes the bevel portion of the wafer W. In order to reduce the friction with the back surface of the polishing tape 3, a sheet whose surface is covered with a fluororesin may be attached to the front surface (pressing surface) of the pressing pad 270. The pressing pad 270 is detachable by bolts or the like.

[0087] The polishing apparatus 200 further includes a tilt mechanism (not shown). The polishing apparatus 200 can polish the peripheral portion of the wafer W while changing the tilt angle of the polishing head 10 by the tilt mechanism. FIG. 17 is a view showing the polishing head 10 tilted upward by a tilt mechanism (not shown), and FIG. 18 is a view showing the polishing head 10 tilted downward by the tilt mechanism.

[0088] As shown in FIG. 17, when the polishing head 10 is tilted upward, the fluid pressing portion 12A is located above the peripheral portion of the wafer W and faces the top edge portion. As shown in FIG. 18, when the polishing head 10 is tilted downward, the fluid pressing portion 12B is located below the peripheral portion of the wafer W and faces the bottom edge portion. When polishing the top edge portion, with the polishing head 10 tilted upward, the fluid pressing portion 12A presses the polishing surface 3a of the polishing tape 3 against the top edge portion of the wafer W. When polishing the bottom edge portion, with the polishing head 10 tilted downward, the fluid pressing portion 12B presses the polishing surface 3a of the polishing tape 3 against the bottom edge portion of the wafer W. In one embodiment, the polishing head 10 may be provided with only one of the fluid pressing portion 12A or the fluid pressing portion 12B. For example, when polishing only the top edge portion, the polishing head 10 is provided with only the fluid pressing portion 12A, and when polishing only the bottom edge portion, the polishing head 10 is provided with only the fluid pressing portion 12B.

[0089] The polishing apparatus 200 includes an operation control unit 280 that controls the operations of the respective components of the polishing apparatus 200. The polishing head 10, the liquid supply valve 33, the gas supply valve 34, the flow rate control device 35, the flow rate control device (pressure control device) 36, the substrate holding unit 210, the lower supply nozzle 222, the upper supply nozzle 230, the polishing tape supply mechanism 242, and the tilt mechanism are electrically connected to the operation control unit 280. The operations of the polishing head 10, the liquid supply valve 33, the gas supply valve 34, the flow rate control device 35, the flow rate control device (pressure control device) 36, the substrate holding unit 210, the lower supply nozzle 222, the upper supply nozzle 230, the polishing tape supply mechanism 242, and the tilt mechanism are controlled by the operation control unit 280. During polishing, the operation control unit 280 operates the polishing tape supply mechanism 242 to advance the polishing tape 3 at a predetermined speed in its longitudinal direction while applying a predetermined tension to the polishing tape 3.

[0090] The operation control unit 280 is composed of at least one computer. The operation control unit 280 includes a storage device 280a and an arithmetic unit 280b. The arithmetic unit 280b includes a CPU (Central Processing Unit) or a GPU (Graphics Processing Unit) that performs calculations according to instructions included in a program stored in the storage device 280a. The storage device 280a includes a main storage device (e.g., random access memory) accessible by the arithmetic unit 280b and an auxiliary storage device (e.g., hard disk drive or solid state drive) that stores data and programs.

[0091] FIG. 19 is a schematic diagram showing a state when the top edge portion of the wafer W is being polished. The polishing head 10 moves at a constant speed in the direction indicated by the arrow in FIG. 19 (the outer radial direction of the wafer W) by a moving mechanism composed of a linear actuator (not shown) while pressing the polishing tape 3 against the wafer W with a fluid. The operation of the moving mechanism is controlled by the operation control unit 280. In the present embodiment, since the fluid pressing portions 12A and 12B of the polishing head 10 are curved along the peripheral edge portion of the wafer W, the time during which the polishing tape 3 is in contact with the wafer W becomes uniform over the entire top edge portion. Therefore, the entire top edge portion can be polished uniformly. The two fluid pressing portions 12A and 12B and the fluid supply ports 13A and 13B are curved inward toward the center line Ct (see FIG. 16).

[0092] Since the fluid pressing portion 12A and the fluid pressing portion 12B are symmetrically arranged with respect to the center line Ct (see FIG. 16), when the polishing head 10 is tilted downward until the fluid pressing portion 12B faces the bottom edge portion as shown in FIG. 18, the fluid pressing portion 12B extends along the bottom edge portion of the wafer W. Therefore, similar to the top edge portion, the bottom edge portion can be polished accurately and uniformly by the fluid pressing portion 12B.

[0093] FIG. 20 is a view showing a state when the polishing head 10 is polishing the bevel portion of the wafer W. When polishing the peripheral edge portion of the wafer W, the pressing mechanism (not shown) presses the polishing tape 3 against the peripheral edge portion (for example, the bevel portion) of the wafer W while continuously changing the tilt angle of the polishing head 10 by a tilt mechanism (not shown).

[0094] In one embodiment, the fluid pressing portions 12A and 12B of the polishing head 10 may be provided with the area pads described with reference to FIGS. 5 to 8 instead of the slit nozzles.

[0095] In yet another embodiment, when the polishing head 10 polishes either one of the top edge portion and the bottom edge portion, the polishing head 10 may include only one of the two fluid pressing portions 12A and 12B. In yet another embodiment, the polishing apparatus 200 may include a plurality of polishing heads 10 arranged in the circumferential direction of the holding stage 204.

[0096] The above-described embodiments are described for the purpose of enabling those with ordinary knowledge in the technical field to which the present invention pertains to implement the present invention. Various modifications of the above embodiments can be naturally made by those skilled in the art, and the technical idea of the present invention can also be applied to other embodiments. Therefore, the present invention is not limited to the described embodiments, but is to be construed in the broadest scope in accordance with the technical idea defined by the claims.

Explanation of Reference Numerals

[0097] 1 First surface 2 Second surface 3 Polishing tape 10, 10A, 10B Polishing head 11A, 11B Polishing head assembly 12, 12A, 12B Fluid pressing portion 13, 13A, 13B Fluid supply port 14 Flow path 15 Fluid mixing chamber 16, 16A, 16B Pressing surface 17, 17A, 17B Depression 18, 18A, 18B Fluid supply port 30 Fluid supply line 31 Liquid supply line 32 Gas supply line 33 Liquid supply valve 34 Gas supply valve 35 Flow rate control device 36 Flow rate control device (pressure control device) 37 Flow meter 38 Flow meter (pressure gauge) 100 Polishing apparatus 110 Substrate holding portion 111 Roller 120 Movable Plate 127 Rinse Liquid Supply Nozzle 128 Protecting Liquid Supply Nozzle 131, 131A, 131B Support Member 141, 141A, 141B Polishing Tape Feeding Mechanism 142 Reel Base 143 Tape Pay - out Reel 143a Tension Motor 144 Tape Take - up Reel 144a Tension Motor 153a, 153b, 153c, 153d, 163a, 163b, 163c, 163d, 173a, 173b, 173c, 173d Guide Roller 180 Operation Control Unit 180a Memory Device 180b Arithmetic Unit 191 Polishing Head Moving Mechanism 193 Ball Screw Mechanism 193a Screw Shaft 194 Motor 195 Linear Guide 197 Installation Surface 200 Polishing Device 204 Holding Stage 205 Shaft 207 Holding Stage Driving Mechanism 210 Substrate Holding Part 214 Motor 217 Air Cylinder 222 Lower Supply Nozzle 230 Upper Supply Nozzle 242 Polishing Tape Feeding Mechanism 243 Tape Pay - out Reel 244 Tape Take - up Reel 245, 246, 247, 248 Guide Roller 253, 254, 255, 256, 257, 258, 259 Guide Roller 260 Partition Wall 265 Base Plate 270 Pressing Pad 280 Operation Control Unit

Claims

1. A polishing apparatus for polishing a flat surface of a substrate, comprising: a substrate holding unit that holds the substrate and rotates the substrate; a polishing tape supply mechanism that feeds a polishing tape in its longitudinal direction; at least one polishing head disposed close to the flat surface of the substrate, wherein the polishing head has a fluid pressing unit that presses the polishing tape against the flat surface of the substrate with a mixed fluid of gas and liquid; the fluid pressing unit is a slit nozzle having a slit-shaped fluid supply port; the fluid supply port is disposed to face the back surface of the polishing tape; the fluid supply port is inclined obliquely with respect to the advancing direction of the polishing tape when the polishing head is viewed from above, the polishing apparatus.

2. A polishing apparatus for polishing a flat surface of a substrate, comprising: a substrate holding unit that holds the substrate and rotates the substrate; a polishing tape supply mechanism that feeds a polishing tape in its longitudinal direction; at least one polishing head disposed close to the flat surface of the substrate, wherein the polishing head has a fluid pressing unit that presses the polishing tape against the flat surface of the substrate with a mixed fluid of gas and liquid; the fluid pressing unit is an area pad having a pressing surface with a depression formed at the center and a fluid supply port in the depression; the fluid supply port is disposed to face the back surface of the polishing tape; the depression is inclined obliquely with respect to the advancing direction of the polishing tape when the polishing head is viewed from above, the polishing apparatus.

3. The polishing apparatus according to claim 1 or 2, wherein a ratio of the gas in the mixed fluid is larger than a ratio of the liquid.

4. A polishing apparatus for polishing a flat surface of a substrate, comprising: a substrate holding unit that holds the substrate and rotates the substrate; a polishing tape supply mechanism that feeds a polishing tape in its longitudinal direction; at least one polishing head disposed close to the flat surface of the substrate, wherein the polishing head has a fluid pressing unit that presses the polishing tape against the flat surface of the substrate with a mixed fluid of gas and liquid; the fluid pressing unit has a fluid supply port disposed to face the back surface of the polishing tape; the flat surface of the substrate is an edge portion located at a peripheral edge of the substrate; the fluid pressing unit has an arc shape having a curvature substantially the same as an outer peripheral shape of the substrate, the polishing apparatus.

5. A polishing method for polishing a flat surface of a substrate, comprising: holding the substrate by a substrate holding unit and rotating the substrate; While feeding the polishing tape in its longitudinal direction by a polishing tape supply mechanism, including supplying a mixed fluid of gas and liquid from a fluid supply port provided in a fluid pressing portion of a polishing head toward the back surface of the polishing tape, and pressing and polishing the polishing tape against a flat portion of the substrate by the mixed fluid, wherein the fluid pressing portion is a slit nozzle having a slit-shaped fluid supply port, the fluid supply port is disposed to face the back surface of the polishing tape, the fluid supply port is inclined obliquely with respect to the advancing direction of the polishing tape when the polishing head is viewed from above, a polishing method. **Claim 6**: A polishing method for polishing a flat portion of a substrate, holding the substrate by a substrate holding portion and rotating the substrate, while feeding the polishing tape in its longitudinal direction by a polishing tape supply mechanism, including supplying a mixed fluid of gas and liquid from a fluid supply port provided in a fluid pressing portion of a polishing head toward the back surface of the polishing tape, and pressing and polishing the polishing tape against a flat portion of the substrate by the mixed fluid, wherein the fluid pressing portion is an area pad having a pressing surface with a depression formed in the center and a fluid supply port in the depression, the fluid supply port is disposed to face the back surface of the polishing tape, the depression is inclined obliquely with respect to the advancing direction of the polishing tape when the polishing head is viewed from above, a polishing method. **Claim 7** The polishing method according to claim 5 or 6, wherein the ratio of the gas in the mixed fluid is larger than the ratio of the liquid. **Claim 8** A polishing method for polishing a flat portion of a substrate, holding the substrate by a substrate holding portion and rotating the substrate, while feeding the polishing tape in its longitudinal direction by a polishing tape supply mechanism, including supplying a mixed fluid of gas and liquid from a fluid supply port provided in a fluid pressing portion of a polishing head toward the back surface of the polishing tape, and pressing and polishing the polishing tape against a flat portion of the substrate by the mixed fluid, wherein the flat portion of the substrate is an edge portion located at a peripheral edge of the substrate, the fluid pressing portion has an arc shape having a curvature substantially the same as the outer peripheral shape of the substrate, a polishing method.

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