JP2017064899A - Polishing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a polishing device that has an endpoint detecting sensor capable of measuring a narrow range and is improved in film thickness detection accuracy.SOLUTION: A polishing device 10 comprises: a polishing pad 101 having a polishing surface 101a for polishing a semiconductor wafer WF; a polishing table 100 which can be mounted with a backside 101b at the opposite side of the polishing surface 101a of the polishing pad 101; a top ring 1 that can hold the semiconductor wafer WF opposing the wafer to the polishing surface 101a; and an overcurrent sensor 50, arranged in the polishing table 100, which detects a polishing endpoint. The polishing table 100 has at a mounting surface 104 a protruding member 12 protruding from the mounting surface 104 on which is mounted the polishing pad 101. The backside 101b of the polishing pad 101 has a recessed part at a part opposing to the protruding member 12, and a part of the overcurrent sensor 50 is arranged inside the protruding member 12.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a polishing apparatus, and more particularly to a polishing apparatus that includes an end point detection sensor that detects an end point of polishing and is used to polish a conductive film formed on a substrate such as a semiconductor wafer.

  In recent years, as semiconductor devices are highly integrated, circuit wiring is becoming finer and the distance between wirings is becoming narrower. Therefore, it is necessary to flatten the surface of the semiconductor wafer, which is an object to be polished, and polishing (polishing) is performed by a polishing apparatus as one means of this flattening method.

  The polishing apparatus includes a polishing table for holding a polishing pad for polishing a polishing object, and a top ring for holding the polishing object and pressing it against the polishing pad. Each of the polishing table and the top ring is rotationally driven by a drive unit (for example, a motor). The polishing object is polished by flowing a liquid (slurry) containing an abrasive onto the polishing pad and pressing the polishing object held on the top ring.

  In the polishing equipment, if the polishing target is not polished sufficiently, the circuit cannot be insulated, and there is a risk of short-circuiting. In the case of overpolishing, the resistance value due to the reduced cross-sectional area of the wiring Or the wiring itself is completely removed and the circuit itself is not formed. For this reason, the polishing apparatus is required to detect an optimum polishing end point.

  As such a technique, there is an eddy current type end point detection sensor (hereinafter referred to as “eddy current sensor”) described in JP-A-2012-135865. In this eddy current sensor, a solenoid type or spiral type coil is used.

JP 2012-135865 A

  In recent years, in order to reduce the defective product rate near the edge of the semiconductor wafer, there is a demand to measure the film thickness closer to the edge of the semiconductor wafer and to control the film thickness by in-situ closed loop control.

  In addition, there is an airbag head type top ring using pneumatic pressure or the like. The airbag head has a plurality of concentric airbags. In order to improve the resolution of unevenness on the surface of a semiconductor wafer by an eddy current sensor and control the film thickness with a narrow-width airbag, there is a demand for measuring a film thickness in a narrower range.

However, with a solenoid type or spiral type coil, it is difficult to reduce the magnetic flux, and there is a limit to measurement in a narrow range.
The area of the eddy current formed on the polished surface of the semiconductor wafer by the conventional general eddy current sensor (that is, the spot diameter of the eddy current sensor) is about 20 mm or more, and the detection monitor area per point is generally Only a film thickness that was wide and averaged over a wide range could be obtained. For this reason, there is a limit to the accuracy of detecting the presence or absence of the remaining film and the accuracy of profile control, and in particular, it has not been possible to cope with film thickness variations at the edge portion of the substrate after polishing. This is because when the conductive film such as a copper film formed on the substrate is polished, the edge portion of the substrate becomes a boundary region, and the film thickness of the film formed here is formed elsewhere. This is because it is more likely to change than the film thickness of the film. In addition, it is generally difficult to detect a remaining film of 6 mm or less remaining on a part of the substrate, and the film to be originally polished depends on the film formation state on the substrate or the fluctuation of the film polishing conditions. There were times when it was left in part.

  One of the reasons why the spot diameter of the eddy current sensor is wide is that the sensor coil diameter is large. In order to solve this, it is conceivable to reduce the sensor coil diameter of the eddy current sensor and reduce the film thickness detection monitor region. However, the distance from the eddy current sensor to which the film thickness can be detected by the eddy current sensor has a correlation with the sensor coil diameter, and the distance decreases as the sensor coil diameter decreases. Since there is a polishing pad between the eddy current sensor and the substrate, the distance between the eddy current sensor and the substrate cannot be less than the thickness of the polishing pad. When the sensor coil diameter is reduced, the distance from the eddy current sensor to the film that can detect the film thickness by the eddy current sensor is reduced, and it becomes difficult to form the eddy current on the substrate due to the thickness of the polishing pad, It becomes difficult to detect the film thickness.

  Another reason why the spot diameter of the eddy current sensor is wide is that the magnetic flux spreads because the distance between the semiconductor wafer and the eddy current sensor is large. When the same coil is used, as the distance between the semiconductor wafer and the eddy current sensor increases, the magnetic flux spreads and the spot diameter of the eddy current sensor increases. As the magnetic flux spreads, the magnetic flux becomes weaker and the eddy current formed in the semiconductor wafer becomes weaker. As a result, the sensor output becomes smaller. In order to accurately control the film thickness of a semiconductor wafer, an eddy current sensor capable of measuring a narrow range is desired.

  The present invention has been made in view of the above circumstances, and an object thereof is to provide a polishing apparatus having an end point detection sensor capable of measuring a narrow range and having improved film thickness detection accuracy.

  According to the first aspect of the polishing apparatus of the present invention, a polishing pad having a polishing surface for polishing an object to be polished, and a polishing table to which a back surface of the polishing pad opposite to the polishing surface is attached, In the polishing apparatus, comprising: a holding portion that can hold the polishing object facing the polishing surface of the polishing pad; and an end point detection sensor that is disposed in the polishing table and detects the polishing end point. The table has a projecting member projecting from a mounting surface to which the polishing pad is mounted on the mounting surface, the back surface of the polishing pad has a recess in a portion facing the projecting member, and the end point detection A polishing apparatus is provided in which at least a part of the sensor is disposed inside the protruding member.

  According to the above embodiment, the end point detection sensor is arranged inside the protruding member protruding from the mounting surface to which the polishing pad is attached, and the back surface of the polishing pad has the concave portion in the portion facing the protruding member. And the sensor distance can be reduced. The film thickness in a smaller range can be measured with higher sensitivity than before.

  Also, when mounting a polishing pad with a different shape on the polishing table for the first time, or when replacing the polishing pad with a new one when the shape is the same and the polishing pad is worn out, do not use the protruding member of this embodiment. When the end point detection sensor is exposed to the outside from the mounting surface of the polishing table toward the polishing pad, there are the following problems. That is, it is necessary to adjust the height of the end point detection sensor from the mounting surface every time the polishing pad is newly mounted or replaced so that the exposed end point detection sensor does not come into contact with the polishing pad.

In the present embodiment, since the end point detection sensor is disposed inside the protruding member, the end point detection sensor does not come into contact with the polishing pad. Therefore, in this embodiment, when mounting a polishing pad with a different shape on the polishing table for the first time, and when replacing with a new polishing pad with the same shape, the height of the end point detection sensor from the mounting surface is increased. There is no need to adjust. That is, before and after mounting a polishing pad with a different shape on the polishing table for the first time, or before and after replacing with a new polishing pad, the height from the mounting surface of the end point detection sensor is always at the same position inside the protruding member. Can be maintained. Furthermore, since the height of the end point detection sensor from the mounting surface is always the same position, there is an advantage that the sensitivity of the end point detection sensor is stabilized.

The shape of the protruding member can be any shape, for example, a cylinder, a prism, a truncated cone, a truncated pyramid, or the like.
According to the second aspect of the present invention, the protruding member is integral with the polishing table. According to the third aspect of the present invention, the protruding member is a component independent of the polishing table. When the protruding member is a component independent of the polishing table, the protruding member can be easily detached from the polishing table. At this time, the projecting member and the end point detection sensor may be assembled in advance, and the assembly may be attached to the polishing table.

  According to a fourth aspect of the present invention, the polishing pad includes a polishing layer having the polishing surface and a backing layer having the back surface, and at least one of the polishing layer and the backing layer in the recess. Is thinner than at least one of the polishing layer and the backing layer other than the recesses. According to a fifth aspect of the present invention, the polishing pad includes a polishing layer having the polishing surface and a backing layer having the back surface, and in the recess, at least of the polishing layer and the backing layer. One is recessed on the polishing surface side.

  In the fourth and fifth embodiments of the present invention, the recess on the back surface of the polishing pad may be formed by removing a part of the backing layer, may be formed without removing, or not removed, An existing polishing pad made of urethane foam or the like can be easily deformed by heat to make a recess.

  According to the sixth aspect of the present invention, the protruding member is in contact with the back surface of the polishing pad. According to the seventh aspect of the present invention, the protruding member is not in contact with the back surface of the polishing pad.

  According to the eighth aspect of the present invention, the entire end point detection sensor is arranged inside the polishing table. That is, as shown in the first embodiment of the present invention, at least a part of the end point detection sensor is disposed inside the projecting member, and the other part of the end point detection sensor not disposed inside the projecting member is the projecting member. Arranged inside the polishing table other than the members.

  According to the ninth aspect of the present invention, the end point detection sensor does not protrude from the protruding member to the outside of the polishing table. According to the eighth and ninth aspects of the present invention, the end point detection sensor can be prevented from coming into contact with the outside of the polishing table. In particular, it is possible to prevent the polishing pad around the protruding member and the end point detection sensor from contacting each other.

  According to a tenth aspect of the present invention, the polishing pad includes a first member and a second member that is independent from the first member, and the recess is formed in the second member. Is provided. According to the tenth aspect of the present invention, since the first member and the second member are independent of each other, a recess is formed solely in the second member and incorporated into the first member. Can do. Manufacturing and assembly operations are facilitated.

According to an eleventh aspect of the present invention, the first member includes a polishing layer having the polishing surface and a backing layer having the back surface, and at least the backing of the polishing layer and the backing layer. The layer has a hole, and the second member is disposed in the hole.

  According to a twelfth aspect of the present invention, the first member has a hole penetrating the polishing surface and the back surface of the polishing pad, and the second member is disposed in the hole penetrating. The

  According to a thirteenth aspect of the present invention, the polishing pad has a third member on the polishing surface side of the second member.

FIG. 1 is a schematic diagram illustrating the overall configuration of a polishing apparatus according to the present embodiment. FIG. 2 is a plan view showing the relationship among the polishing table, the eddy current sensor, and the semiconductor wafer. FIG. 3 is a diagram showing the configuration of the eddy current sensor, FIG. 3 (a) is a block diagram showing the configuration of the eddy current sensor, and FIG. 3 (b) is an equivalent circuit diagram of the eddy current sensor. FIG. 4 shows an enlarged view of the vicinity of the eddy current sensor 50 of FIG. FIG. 5 is a cross-sectional view showing a protruding member that is a part independent of the polishing table. FIG. 6 is a diagram showing the recess 30 provided on the back surface 101 b of the polishing pad 101. FIG. 7 is a view showing the recess 30 provided on the back surface 101 b of the polishing pad 101. FIG. 8 is a view showing the recess 30 provided on the back surface 101 b of the polishing pad 101. FIG. 9 is a diagram showing the recess 30 provided on the back surface 101 b of the polishing pad 101. FIG. 10 is a diagram illustrating an example in which the polishing pad includes a first member and a second member that is independent of the first member. FIG. 11 is a view showing an embodiment having holes in the backing layer 28. FIG. 12 is a view showing an embodiment having holes in both the polishing layer 26 and the backing layer 28. FIG. 13 is a diagram illustrating an example in which a third member 212 is provided on the polishing surface 101 a side of the second member 202. FIG. 14 is a diagram illustrating an example in which an adhesive 214 is provided on the second member 202. FIG. 15 is a diagram illustrating an example in which the protruding member 16 includes a flat portion and an inclined portion that are in contact with the backing layer 28 of the polishing pad 101.

  Embodiments of a polishing apparatus according to an embodiment of the present invention will be described below in detail with reference to the accompanying drawings. In the accompanying drawings, the same or corresponding components are denoted by the same reference numerals, and redundant description is omitted.

  FIG. 1 is a schematic diagram showing an overall configuration of a polishing apparatus 10 according to an embodiment of the present invention. As shown in FIG. 1, a polishing apparatus 10 includes a polishing table 100, a top ring (holding unit) 1 that holds a substrate such as a semiconductor wafer WF that is an object to be polished and presses the polishing table 100 on a polishing surface. It has.

The polishing table 100 is connected via a table shaft 100a to a motor (not shown) which is a driving unit disposed below the table shaft 100a, and is rotatable around the table shaft 100a. A polishing pad 101 is affixed to the upper surface (mounting surface) 104 of the polishing table 100. A surface 101a of the polishing pad 101 constitutes a polishing surface for polishing the semiconductor wafer WF. A back surface 101 b of the polishing pad 101 opposite to the polishing surface 101 a is attached to the mounting surface 104 of the polishing table 100. The top ring 1 can hold the semiconductor wafer WF while facing the polishing surface 101 a of the polishing pad 101.

  A polishing liquid supply nozzle 102 is installed above the polishing table 100. The polishing liquid supply nozzle 102 supplies the polishing liquid Q1 onto the polishing pad 101 on the polishing table 100. As shown in FIG. 1, an eddy current sensor (end point detection sensor) 50 for detecting the end point of polishing is embedded in the polishing table 100.

  The top ring 1 includes a top ring body 2 that presses the semiconductor wafer WF against the polishing surface 101a, and a retainer ring 3 that holds the outer peripheral edge of the semiconductor wafer WF so that the semiconductor wafer WF does not jump out of the top ring. It basically consists of

  The top ring 1 is connected to the top ring shaft 111. The top ring shaft 111 moves up and down with respect to the top ring head 110 by a vertical movement mechanism 124. By moving the top ring shaft 111 up and down, the entire top ring 1 is moved up and down with respect to the top ring head 110 for positioning. A rotary joint 125 is attached to the upper end of the top ring shaft 111.

  The vertical movement mechanism 124 that moves the top ring shaft 111 and the top ring 1 up and down includes a bridge 128 that rotatably supports the top ring shaft 111 via a bearing 126, a ball screw 132 attached to the bridge 128, and a column 130. A support base 129 supported by the above-mentioned structure, and an AC servo motor 138 provided on the support base 129. A support base 129 that supports the servo motor 138 is fixed to the top ring head 110 via a support 130.

  The ball screw 132 includes a screw shaft 132a connected to the servo motor 138 and a nut 132b into which the screw shaft 132a is screwed. The top ring shaft 111 moves up and down integrally with the bridge 128. Therefore, when the servo motor 138 is driven, the bridge 128 moves up and down via the ball screw 132, and thereby the top ring shaft 111 and the top ring 1 move up and down.

  The top ring shaft 111 is connected to the rotary cylinder 112 via a key (not shown). The rotating cylinder 112 includes a timing pulley 113 on the outer periphery thereof. A top ring motor 114 is fixed to the top ring head 110, and the timing pulley 113 is connected to a timing pulley 116 provided on the top ring motor 114 via a timing belt 115. Accordingly, when the top ring motor 114 is rotationally driven, the rotary cylinder 112 and the top ring shaft 111 rotate together via the timing pulley 116, the timing belt 115, and the timing pulley 113, and the top ring 1 rotates. The top ring head 110 is supported by a top ring head shaft 117 that is rotatably supported by a frame (not shown).

In the polishing apparatus configured as shown in FIG. 1, the top ring 1 can hold a substrate such as a semiconductor wafer WF on its lower surface. The top ring head 110 is configured to be pivotable about the top ring shaft 117, and the top ring 1 holding the semiconductor wafer WF on the lower surface thereof is rotated from the receiving position of the semiconductor wafer WF by the rotation of the top ring head 110. Is moved above. Then, the top ring 1 is lowered to press the semiconductor wafer WF against the surface (polishing surface) 101 a of the polishing pad 101. At this time, the top ring 1 and the polishing table 100 are rotated, and the polishing liquid is supplied onto the polishing pad 101 from the polishing liquid supply nozzle 102 provided above the polishing table 100. Thus, the surface of the semiconductor wafer WF is polished by bringing the semiconductor wafer WF into sliding contact with the polishing surface 101a of the polishing pad 101.

FIG. 2 is a plan view showing the relationship among the polishing table 100, the eddy current sensor 50, and the semiconductor wafer WF. As shown in FIG. 2, the eddy current sensor 50 is installed at a position passing through the center Cw of the semiconductor wafer WF being held held by the top ring 1. Reference symbol _CT denotes the rotation center of the polishing table 100. For example, the eddy current sensor 50 can detect a metal film (conductive film) such as a Cu layer of the semiconductor wafer WF continuously on a passing locus (scanning line) while passing under the semiconductor wafer WF. It has become.

Next, the eddy current sensor 50 provided in the polishing apparatus according to an embodiment of the present invention will be described in more detail with reference to the accompanying drawings.
FIG. 3 is a diagram illustrating the configuration of the eddy current sensor 50, FIG. 3A is a block diagram illustrating the configuration of the eddy current sensor 50, and FIG. 3B is an equivalent circuit diagram of the eddy current sensor 50. is there.

  As shown in FIG. 3A, the eddy current sensor 50 is disposed in the vicinity of the metal film (or conductive film) mf to be detected. A specific arrangement of the eddy current sensor 50 will be described later. An AC signal source 52 is connected to the coil. Here, the metal film (or conductive film) mf to be detected is a thin film such as Cu, Al, Au, or W formed on the semiconductor wafer WF, for example. The eddy current sensor 50 is disposed, for example, in the vicinity of about 1.0 to 4.0 mm with respect to the metal film (or conductive film) to be detected.

In the eddy current sensor, an eddy current is generated in the metal film (or conductive film) mf, so that the oscillation frequency changes, and the frequency at which the change in the thickness of the metal film (or conductive film) is detected from this frequency change. There is an impedance type in which the impedance changes and the change in the thickness of the metal film (or conductive film) is detected from this impedance change. That is, in the frequency type, in the equivalent circuit shown in FIG. 3 (b), by eddy current I ₂ is changed, the impedance Z1 changes, the oscillation frequency of the signal source (variable-frequency oscillator) 52 is changed, the detection circuit The change of the oscillation frequency can be detected at 54, and the change of the metal film (or conductive film) can be detected. The impedance type, in the equivalent circuit shown in FIG. 3 (b), by eddy current I ₂ is changed, the impedance Z1 changes, the impedance Z1 changes seen from the signal source (fixed frequency oscillator) 52, a detection circuit The change of the impedance Z1 can be detected at 54, and the change of the metal film (or conductive film) can be detected.

In an impedance type eddy current sensor, a resistance component (R1), a reactance component (X1), an amplitude output ((R1 ² + X1 ² ) ^1/2 ) and a phase output (tan ⁻¹ R1 / X1) accompanying a change in film thickness Can be taken out. From the frequency or amplitude output ((R1 ² + X1 ² ) ^1/2 ) or the like, measurement information relating to changes in the film thickness of the metal film (or conductive film) Cu, Al, Au, W can be obtained. As shown in FIG. 1, the eddy current sensor 50 can be built in a position near the inner surface of the polishing table 100, and is positioned so as to face a semiconductor wafer to be polished via a polishing pad. A change in the metal film (or conductive film) can be detected from eddy current flowing in the metal film (or conductive film) on the wafer.

  As the frequency of the eddy current sensor, a single radio wave, a mixed radio wave, an AM modulated radio wave, an FM modulated radio wave, a function generator sweep output, or a plurality of oscillation frequency sources can be used. It is preferable to select an oscillation frequency or modulation method with good sensitivity in accordance with the film type of the metal film.

The impedance type eddy current sensor will be specifically described below. The AC signal source 52 is an oscillator having a fixed frequency of about 2 to 30 MHz. For example, a crystal oscillator is used. The current I ₁ flows through the eddy current sensor 50 due to the AC voltage supplied from the AC signal source 52. When a current flows through the eddy current sensor 50 arranged in the vicinity of the metal film (or conductive film) mf, this magnetic flux is linked to the metal film (or conductive film) mf, so that a mutual inductance M1 is generated therebetween. The eddy current I ₂ flows through the metal film (or conductive film) mf. Where R1 is the equivalent resistance of the primary side including the eddy current sensor, L ₁ is self inductance of the primary side including the eddy current sensor as well. A metal film (or conductive film) mf side, R2 is equivalent resistance corresponding to eddy current loss, L ₂ is its self-inductance. The impedance Z1 when the eddy current sensor side is viewed from the terminals a1 and b1 of the AC signal source 52 varies depending on the magnitude of the eddy current loss formed in the metal film (or conductive film) mf.

  FIG. 4 shows an enlarged cross-sectional view of the vicinity of the eddy current sensor 50 of FIG. The polishing table 100 has projecting members 12, 14, and 16 projecting from a flat mounting surface 104 to which the polishing pad 101 is mounted on the mounting surface 104. Various shapes of the protrusion can be considered. FIG. 4 shows an example of various shapes of the projecting members 12, 14, and 16. FIGS. 4 (a) and 4 (b) show the cylindrical projecting member 12, and FIG. 4 (c) shows a truncated cone. A protruding member 16 having a shape is shown. The difference in shape between the protruding member 12 in FIG. 4A and the protruding member 14 in FIG. 4B is in the corner 18 of the protruding member. The corner 18a of the protruding member 12 in FIG. 4A is not rounded, and the corner 18b of the protruding member 14 in FIG. 4B is rounded.

  The back surface 101 b of the polishing pad 101 has a recess in a portion facing the protruding members 12, 14, and 16. Details of the recess will be described later. At least a part of the eddy current sensor 50 is disposed inside the protruding members 12, 14, 16. The other part of the eddy current sensor 50 is disposed inside the polishing table 100 below the mounting surface 104. Therefore, the entire eddy current sensor 50 is disposed inside the polishing table 100. The eddy current sensor 50 is fixed to the projecting members 12, 14, 16 or the polishing table 100 by means such as adhesion or screwing.

  The eddy current sensor 50 protrudes from the protruding members 12, 14, 16 toward the inside of the polishing table 100, but does not protrude from the protruding members 12, 14, 16 toward the outside of the polishing table 100. When the eddy current sensor 50 protrudes from the protruding members 12, 14, 16 toward the outside of the polishing table 100, the eddy current sensor 50 may interfere with the polishing pad 101 around the protruding members 12, 14, 16. is there.

  The heights S1, S2, and S3 of the upper surface 50a of the eddy current sensor 50 from the mounting surface 104 are as shown in FIG. 4 from the mounting surfaces 104 of the uppermost portions 12a, 14a, and 16a of the protruding members 12, 14, and 16. The heights H1, H2 and H3 are preferably the same. By being the same, the distance between the eddy current sensor 50 and the wafer WF can be minimized while preventing the eddy current sensor 50 from interfering with the polishing pad 101.

As shown in FIG. 4, in this embodiment, a part of the eddy current sensor 50 is not projected from the polishing table 100 toward the polishing pad 101, but the shape of the polishing table 100 is changed, that is, the polishing table 100. Protruding members 12, 14, and 16 are provided as part of the eddy current sensor 50 so that the eddy current sensor 50 is kept inside the polishing table 100 ("platen"). Advantages of the method of FIG. -Since the eddy current sensor is not in contact with the polishing pad, the eddy current sensor is mechanically (physically) protected from the polishing pad. In FIGS. 6 and 8, which will be described later, when the heights S1, S2, and S3 are the same as the heights H1, H2, and H3, the eddy current sensor may come into contact with the polishing pad. The heights S1, S2, and S3 are slightly lower than the heights H1, H2, and H3, respectively. -When the end point detection sensor is exposed to the polishing pad from the mounting surface of the polishing table without using the protruding member of this embodiment, it is replaced with a polishing pad with a different shape, or a new polishing with the same shape is used. When changing to a pad,
The problem described above occurs. In this embodiment, the height of the eddy current sensor from the mounting surface 104, that is, from the polishing table 100, is always constant before and after newly mounting a polishing pad having a different shape or before and after replacement with a new polishing pad. They are at the same position (same height) and do not require position adjustment (height adjustment). Therefore, it is possible to set the distance between the object to be polished and the eddy current sensor so that the distance is always the same before and after the polishing pad is replaced at the start of polishing. The protruding member exerts a force on the object to be polished via the polishing pad, so that the shape of the protruding member may affect the polishing state. In that case, by changing only the shape of the protruding member, the influence on polishing can be reduced without changing the electrical characteristics and shape of the eddy current sensor.

  Although it is not preferable to project the eddy current sensor 50 outward from the projecting members 12, 14, 16 toward the polishing pad 101 (that is, upward), the eddy current sensor 50 is outward from the lower surface 106 of the polishing table 100, that is, downward. You may make it protrude toward.

  The protruding members 12, 14, and 16 in FIG. 4 are integral with the polishing table 100, but the protruding members may not be integral with the polishing table 100. FIG. 5 shows an attachment-type protruding member 20 which is a part independent of the polishing table. The protruding member 20 has an upper part 20a and a lower part 20b, and the upper part 20a is inserted into a hole 100c provided in the polishing table 100a. The protruding member 20 is attached to the polishing table 100a as follows. First, the lower part 20 b is attached to the polishing table 100 a with a plurality of screws 22. Next, the upper part 20 a is attached to the lower part 20 b with a plurality of screws 24.

  The eddy current sensor 50 is attached to the polishing table 100a after assembling with the upper part 20a in advance, or attached to the upper part 20a after attaching the protruding member 20 to the polishing table 100a. Although the screws 22 and 24 are used in FIG. 5, the fastening method is not limited to screws. The fastening method may be adhesion or welding.

  Next, the recess 30 provided on the back surface 101b of the polishing pad 101 will be described with reference to FIGS. The recess 30 is provided in a portion facing the protruding members 12, 14, and 16. The polishing pad 101 has a polishing layer 26 having a polishing surface 101a and a backing layer 28 having a back surface 101b. The polishing layer 26 is made of a foamed polyurethane sheet or the like. The backing layer 28 is made of polyurethane or nonwoven fabric. The polishing layer 26 has a foamed structure or a non-foamed structure. In the case of a non-foamed structure, the polishing surface 101a is roughened by a dressing process on polyurethane or the like, and a process for increasing the retention of the abrasive is performed.

  FIGS. 6 to 9 show how the recesses 30 are formed in the case of the eddy current sensor 501 having a large height and the eddy current sensor 502 having a small height. FIGS. 6A, 7A, 8A, and 9A show the recess 30 in the case of the eddy current sensor 501 having a small height. FIGS. 6B, 7B, 8B, and 9B show the recess 30 in the case of the eddy current sensor 502 having a large height. In the case of the eddy current sensor 501 having a large height, as shown in FIG. 6B, a part of the eddy current sensor 50 is indented into the polishing layer 26, and in the case of the eddy current sensor 502 having a small height, the polishing layer. Suppose that the eddy current sensor 50 does not intrude into H.26.

  6 to 9 show a case where the distance between the object to be polished and the eddy current sensor 50 is long (FIG. 6A, FIG. 7A, FIG. 8A, FIG. 9A) and a case where the distance is close ( 6 (b), FIG. 7 (b), FIG. 8 (b), and FIG. 9 (b)) may be considered to show how the recesses 30 are formed, respectively.

As a method for forming the recess 30, there is a method in which the thickness of at least one of the polishing layer 26 and the backing layer 28 in the recess 30 is made thinner than the thickness of at least one of the polishing layer 26 and the backing layer 28 other than the recess 30. is there. In this case, the polishing layer 26 is formed in the recess 30.
At least one of the backing layer 28 is recessed toward the polishing surface. Below, these are demonstrated concretely.

  In FIG. 6A, a recess 30 is formed by providing a depression only in the backing layer 28 (without changing the thickness of the polishing layer 26 and by thinning only a part of the backing layer 28). In FIG. 6B, a recess 30 is formed by forming a recess in the polishing layer 26 and the backing layer 28 by thinning a part of the polishing layer 26 and completely removing a part of the backing layer 28. .

  The recess 30 can be thinned by partially removing a part of the polishing layer 26 and the backing layer 28 to form a recess. As a method for forming the recess, the polishing layer 26 and the backing layer 28 can be used. It is also possible to make the film thinner without removing it. For example, the existing polishing layer 26 or the backing layer 28 (foamed polyurethane or non-foamed polyurethane) is deformed by heat without removing a part of the existing (ie, already completed) polishing layer 26 or backing layer 28. There is a way to make a dent. In the case of thermal deformation, there is an advantage that a recess can be easily made in an arbitrary polishing layer 26 or backing layer 28. In this specification, when the polishing layer 26 and the backing layer 28 are thinned, it means both the removal of the polishing layer 26 and the backing layer 28 to make them thin and the thinning by thermal deformation without removing them. In addition, you may make thin using both a heat deformation process and a removal process.

  In FIG. 7A, the backing layer 28 is partially removed to form the recess 30. In FIG. 7B, the backing layer 28 is completely removed in part, and a part of the polishing layer 26 is thinned to form the recess 30. Region 32 is where the backing layer 28 has been completely removed. On the other hand, in FIGS. 8 and 9, the recess 30 is formed by partially thinning the polishing layer 26 and the backing layer 28 without completely removing the backing layer 28.

  8 and 9, unlike FIG. 7, the backing layer 28 is not completely removed in the recess 30. 8A, 8B, and 9B, the backing layer 28 and the polishing layer 26 are partially thinned to form the recess 30. In FIG. 9A, only a part of the backing layer 28 is thinned to form the recess 30.

  6 to 9, in FIGS. 6 and 8, the protruding member 16 is in contact with the back surface 101 b of the polishing pad 101. On the other hand, in FIGS. 7 and 9, the protruding member 16 is not in contact with the back surface 101 b of the polishing pad 101. In the present specification, the back surface 101b of the polishing pad 101 means the lower surface of the backing layer 28 when the backing layer 28 is present, and the lower surface of the polishing layer 26 when the backing layer 28 is absent.

  When the protruding member 16 and the back surface 101b of the polishing pad 101 are in contact with each other, when the wafer is pressed against the polishing layer 26 from above, the portion where the protruding member 16 is present, that is, the portion where the eddy current sensor 50 is present is the polishing layer 26. May be convex upward. On the other hand, when the protruding member 16 and the back surface 101b of the polishing pad 101 are not in contact, that is, when there is a space between the protruding member 16 and the polishing pad 101, the polishing layer 26 may be concave downward. . When the polishing layer 26 is convex or concave, the polishing flatness of the wafer is affected.

  As a countermeasure against this, when the backing layer 28 is not completely removed, at least one of the backing layer 28 and the polishing layer 26 is appropriately processed or molded, or the backing layer 28 and the polishing layer 26 are formed. Select at least one of the materials appropriately. Accordingly, it is possible to cope with the pressure applied to the polishing layer 26 from above by designing the polishing layer 26 to be deformed to the same extent in a portion where the protruding member is present and a portion where the protruding member is not present.

Further, when the backing layer 28 is completely removed, another member may be formed in the removed portion so that the polishing layer 26 is deformed to the same extent in the portion where the protruding member is present and the portion where the protruding member is not present. . When forming another member or without forming another member, the shape of the polishing layer 26 may be appropriately processed and formed, or the material of the polishing layer 26 may be appropriately selected.

  Next, an example in which the polishing pad 101 includes a first member 200 and a second member 202 that is independent from the first member 200, and the concave portion 30 is provided in the second member 202. explain. FIG. 10 shows an example in which the first member 200 has a polishing layer 26 having a polishing surface 101a and a backing layer 28 having a back surface 101b.

  The first member 200 has a through hole 204 that penetrates the polishing surface 101 a and the back surface 101 b of the polishing pad 101. The second member 202 is disposed in the through hole 204. The second member 202 may be a flexible material such as a sponge-like material, and is not limited to a specific material. The second member 202 is, for example, a urethane sponge.

  FIG. 11 shows an example in which at least the backing layer 28 has holes in the polishing layer 26 and the backing layer 28. In particular, in FIG. 11, only the backing layer 28 has a hole 206, and the polishing layer 26 has no hole. The second member 202 is disposed in the hole 206. The second member 202 is, for example, a sponge material.

  FIG. 12 shows an embodiment having holes in both the polishing layer 26 and the backing layer 28. In FIG. 12, the backing layer 28 has a through hole 208, and the polishing layer 26 has a hole 210 in a part thereof. The second member 202 is disposed in the through hole 208 and the hole 210. The second member 202 is, for example, a sponge material.

  In FIG. 13, the polishing pad 101 has a third member 212 on the polishing surface 101 a side of the second member 202. The first member 200 has a through hole 204 that penetrates the polishing surface 101 a and the back surface 101 b of the polishing pad 101. A third member 212 having water resistance and chemical resistance is attached to the upper part of the second member 202 that is a sponge-like material. The third member 212 is a sponge material cover, and the material is not particularly limited as long as the material is nonmagnetic and nonconductive. The third member 212 is, for example, a urethane resin.

  In the embodiment of FIG. 14, an adhesive 216 for attaching the polishing pad 101 to the polishing table 100 is provided on the backing layer 28 of the polishing pad 101. An adhesive 214 for attaching the second member 202 to the protruding member 16 may also be provided on the second member 202 that is a sponge-like material.

  10 to 14, the first member 200 includes the polishing layer 26 and the backing layer 28. However, in FIGS. 10 to 14, the first member 200 may include only the polishing layer 26.

  In the embodiment of FIG. 15, the protruding member 16 includes a flat portion 218 and an inclined portion 220 that contact the backing layer 28 of the polishing pad 101 or the second member 202. The flat portion 218 is provided on the top of the protruding member 16. The inclined portion 220 is provided on the side surface of the protruding member 16. The protruding member 16 is disposed in a through hole 222 provided in the polishing table 100. The height L1 of the protruding member 16 and the height L1 of the polishing table 100 are the same. An eddy current sensor 501 is disposed in internal spaces 224 and 226 provided inside the protruding member 16.

In the embodiment of FIG. 15, since the protruding member 16 and the polishing table 100 are separate members, only the protruding member 16 can be manufactured independently and incorporated into the polishing table 100. Prior to incorporating the protruding member 16 into the polishing table 100, the eddy current sensor 501 can be incorporated into the protruding member 16. Since the protruding member 16 and the polishing table 100 can be manufactured independently, the manufacturing operation and the assembling operation are facilitated as compared with the case where the whole is manufactured integrally.

  Since the protruding member 16 and the polishing table 100 can be manufactured independently, the protruding member 16 and the polishing table 100 can be made of different materials that are optimum for each. The material of the protruding member 16 is, for example, silicon carbide (SIC) or stainless steel (SUS). The material of the polishing table 100 is, for example, SIC or SUS.

DESCRIPTION OF SYMBOLS 1 Top ring 10 Polishing apparatus 12, 14, 16 Protruding member 26 Polishing layer 28 Backing layer 30 Recessed part 50 Eddy current sensor 100 Polishing table 101 Polishing pad

Claims (13)

A polishing pad having a polishing surface for polishing a polishing object;
A polishing table to which a back surface opposite to the polishing surface of the polishing pad is attached;
A holding part capable of holding the object to be polished while facing the polishing surface of the polishing pad;
In a polishing apparatus that is disposed in the polishing table and has an end point detection sensor that detects an end point of the polishing,
The polishing table has a protruding member protruding from an attachment surface to which the polishing pad is attached on the attachment surface,
The back surface of the polishing pad has a recess in a portion facing the protruding member,
At least a part of the end point detection sensor is disposed inside the protruding member.   The polishing apparatus according to claim 1, wherein the protruding member is integral with the polishing table.   The polishing apparatus according to claim 1, wherein the protruding member is a component independent of the polishing table.   The polishing pad includes a polishing layer having the polishing surface and a backing layer having the back surface, and the thickness of at least one of the polishing layer and the backing layer in the recess is the polishing in the portion other than the recess. The polishing apparatus according to claim 1, wherein the polishing apparatus is thinner than at least one of the layer and the backing layer.   The polishing pad includes a polishing layer having the polishing surface and a backing layer having the back surface, and in the recess, at least one of the polishing layer and the backing layer is recessed toward the polishing surface side. The polishing apparatus according to any one of claims 1 to 3, wherein:   The polishing apparatus according to claim 1, wherein the protruding member is in contact with the back surface of the polishing pad.   The polishing apparatus according to claim 1, wherein the protruding member is not in contact with the back surface of the polishing pad.   The polishing apparatus according to any one of claims 1 to 7, wherein the entire end point detection sensor is disposed inside the polishing table.   The polishing apparatus according to any one of claims 1 to 8, wherein the end point detection sensor does not protrude from the protruding member to the outside of the polishing table.   The polishing pad includes a first member and a second member that is independent of the first member, and the concave portion is provided in the second member. 4. The polishing apparatus according to any one of items 1 to 3.   The first member has a polishing layer having the polishing surface and a backing layer having the back surface, and at least the backing layer of the polishing layer and the backing layer has a hole, and the second member The polishing apparatus according to claim 10, wherein the member is disposed in the hole.   The first member has a hole penetrating the polishing surface and the back surface of the polishing pad, and the second member is disposed in the hole penetrating. Polishing equipment.   The polishing apparatus according to claim 12, wherein the polishing pad has a third member on the polishing surface side of the second member.

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