JP5597033B2 - Polishing apparatus and method - Google Patents

Description

  The present invention relates to a polishing apparatus and method, and more particularly to a polishing apparatus and method for polishing and planarizing a polishing object (substrate) such as a semiconductor wafer.

  In recent years, with higher integration and higher density of semiconductor devices, circuit wiring has become increasingly finer and the number of layers of multilayer wiring has increased. When trying to realize multilayer wiring while miniaturizing the circuit, the step becomes larger while following the surface unevenness of the lower layer, so as the number of wiring layers increases, the film coverage to the step shape in thin film formation (Step coverage) deteriorates. Therefore, in order to carry out multilayer wiring, it is necessary to improve the step coverage and perform a flattening process in an appropriate process. Further, since the depth of focus becomes shallower as the optical lithography becomes finer, it is necessary to planarize the surface of the semiconductor device so that the uneven steps on the surface of the semiconductor device are kept below the depth of focus.

Accordingly, in the semiconductor device manufacturing process, a planarization technique for the surface of the semiconductor device is becoming increasingly important. Among the planarization techniques, the most important technique is chemical mechanical polishing (CMP). This chemical mechanical polishing uses a polishing apparatus to slide a substrate such as a semiconductor wafer onto the polishing surface while supplying a polishing solution containing abrasive grains such as silica (SiO ₂ ) onto the polishing surface such as a polishing pad. Polishing in contact.

  This type of polishing apparatus includes a polishing table having a polishing surface made of a polishing pad, and a substrate holding device called a top ring or a polishing head for holding a semiconductor wafer. When polishing a semiconductor wafer using such a polishing apparatus, the semiconductor wafer is pressed against the polishing surface with a predetermined pressure while the semiconductor wafer is held by the substrate holding apparatus. At this time, the semiconductor wafer is brought into sliding contact with the polishing surface by moving the polishing table and the substrate holding device relative to each other, so that the surface of the semiconductor wafer is polished to a flat and mirror surface.

  In such a polishing apparatus, when the relative pressing force between the semiconductor wafer being polished and the polishing surface of the polishing pad is not uniform over the entire surface of the semiconductor wafer, the pressing force applied to each part of the semiconductor wafer. Depending on the pressure, insufficient polishing or overpolishing occurs. In order to equalize the pressing force on the semiconductor wafer, a pressure chamber formed of an elastic film is provided in the lower part of the substrate holding device, and a fluid such as air is supplied to the pressure chamber by the fluid pressure through the elastic film. Polishing is performed by pressing a semiconductor wafer against a polishing surface of a polishing pad.

  In this case, since the polishing pad has elasticity, the pressing force applied to the outer peripheral edge portion of the semiconductor wafer being polished becomes non-uniform, so that only the outer peripheral edge portion of the semiconductor wafer is polished. It may happen. In order to prevent such sag, a polishing pad located on the outer peripheral side of the semiconductor wafer by allowing the retainer ring that holds the outer peripheral edge of the semiconductor wafer to move up and down relative to the top ring main body (or carrier head main body). The polishing surface is pressed.

  In the polishing apparatus having the above-described configuration, after the polishing process on the polishing surface of the polishing pad is completed, the polished wafer is vacuum-sucked to the top ring which is the substrate holding device, the top ring is raised, and the substrate delivery device (pusher) ) To remove the wafer. In order to easily remove the wafer from the top ring, as disclosed in Patent Documents 1 to 3, a release nozzle is provided in the substrate transfer device. The release nozzle is a mechanism that assists the release (detachment) of the wafer by injecting a pressurized fluid between the back surface of the wafer and the membrane. In the technique disclosed in Patent Document 1 and Patent Document 2, At the time of release, the membrane is pressurized and swelled, the peripheral edge of the wafer is peeled off from the membrane, and pressurized fluid is sprayed onto the peeled portion. In this case, when the membrane is pressurized and inflated, local stress is applied to the wafer, and fine wiring formed on the wafer is broken, or in the worst case, the wafer is damaged. is there.

  On the other hand, in the technique disclosed in Patent Document 3, by pressing the bottom surface of the retainer ring when the pusher is lifted, the bottom surface of the retainer ring is pushed up above the bottom surface of the membrane, It is possible to spray a release shower from the release nozzle between the wafer and the membrane in an open state without pressurizing the membrane, that is, without applying stress to the wafer. Is possible.

JP 2005-123485 A US Patent No. 7,044,832 JP 2010-46756 A

  The above-described polishing apparatus was continuously operated to polish the wafer, and the wafer processing step was repeated in which the polished wafer was separated by a substrate transfer device (pusher). As a result, it has been found that there is a variation in the release time, which is the time from when the release operation for ejecting the pressurized fluid from the release nozzle in the substrate transfer apparatus to the time when the wafer is detached from the top ring. That is, when the release times of several hundred wafers were analyzed, the release was most often performed in a short time, but there were a considerable number of cases where the release time was twice or more.

  The present inventors conducted various experiments and analyzed the experimental results in order to elucidate the cause of the variation in the wafer release time, and as a result, the results show that there is a difference between the rotation phase of the top ring and the wafer release time. Have been found to have a correlation (described later). In order to find out the cause of this correlation, the relationship between the top ring structure and the release nozzle was investigated. As a result, the membrane has a plurality of holes to hold and hold the wafer. If the rotational phase of the membrane hole and the pressurized fluid ejected from the release nozzle match, the pressurized fluid will enter the membrane through the membrane hole, causing the membrane to expand significantly, and if the membrane expands significantly, the release nozzle It has been found that the pressurized fluid from is not applied at an appropriate position between the wafer and the membrane, and that it takes a long time to release the wafer.

  The present invention has been made on the basis of the above knowledge, reduces deformation of a substrate such as a semiconductor wafer and stress applied to the substrate, prevents defects in the substrate and breakage of the substrate, and removes the substrate from the top ring ( It is an object of the present invention to provide a polishing apparatus and method capable of performing (release) safely and efficiently.

The polishing apparatus of the present invention has a polishing table having a polishing surface, and a substrate holding surface at least partially made of an elastic film, holds the substrate by the substrate holding surface, and retains the outer peripheral edge of the substrate. provided a substrate holding apparatus for pressing said polishing surface and retaining ring, and a substrate transfer device for transferring the substrate from the substrate holding device at the substrate delivery position from the substrate holding device, together with the substrate transfer device Or a substrate peeling acceleration mechanism that ejects pressurized fluid from the outer peripheral side of the substrate holding surface and peels the substrate from the substrate holding surface, a rotation drive mechanism that rotates the substrate holding device, and a detection mechanism for detecting the rotational angular position of the substrate holding apparatus, a polishing apparatus and a control unit for controlling the rotational angular position of the substrate holding device, the substrate transfer device Before receiving the substrate from the substrate holding device, the bottom surface of the retainer ring is pushed up above the substrate holding surface, and before the substrate is transferred from the substrate holding device to the substrate delivery device, the substrate holding device The rotation angle position is controlled to a specific position .
According to the present invention, before the substrate after polishing is transferred from the substrate holding device to the substrate transport mechanism, the rotational angle position of the substrate holding device is controlled to a desired position, and then the substrate after polishing by the substrate peeling promotion mechanism. Can be peeled off from the substrate holding surface, and the substrate can be transferred from the substrate holding device to the substrate transport mechanism. Therefore, before the substrate is delivered, the pressurized fluid can be ejected in a state where the positional relationship between the substrate holding device and the substrate peeling promoting mechanism is in an optimum positional relationship. It is possible to accurately hit between the surface and the substrate and to peel the substrate safely and efficiently from the substrate holding surface.

In a preferred aspect of the present invention, the elastic film of the substrate holding surface has a hole, and the control unit prevents the pressurized fluid sprayed from the substrate peeling promotion mechanism from being sprayed toward the hole. The rotation angle position of the holding device is controlled.
According to the present invention, since the injected pressurized fluid does not enter the inside of the elastic film from the hole, the elastic film does not swell, and the substrate can be safely separated from the substrate holding surface in a short time. it can.

The polishing apparatus of the present invention has a polishing table having a polishing surface, and a substrate holding surface at least partially made of an elastic film, holds the substrate by the substrate holding surface, and retains the outer peripheral edge of the substrate. A substrate holding device that is held by a ring and pressed against the polishing surface, a substrate transfer device that transfers a substrate from the substrate holding device at a substrate transfer position from the substrate holding device, and the substrate transfer device are provided integrally. or separately provided, and a substrate peeling promotion mechanism for peeling the substrate from the substrate holding surface, wherein the substrate holding surface is provided multiple holes, diameter of said hole is 2mm or more than 6mm polishing apparatus a is, the substrate transfer apparatus, especially that pushes up the substrate prior to receiving from said substrate holding apparatus, the bottom surface of the retainer ring upward from the substrate holding surface To.
According to the present invention, even when the pressurized fluid is ejected when the substrate is peeled from the substrate holding surface, since the hole diameter of the hole of the elastic membrane is 6 mm or less, the ejected pressurized fluid is the elastic membrane. It is very difficult to enter the inside of the substrate, the elastic film does not swell, and the substrate can be safely and efficiently peeled from the substrate holding surface. Moreover, since the hole diameter of the hole of the elastic membrane is 2 mm or more, the substrate can be safely adsorbed and held.

In a preferred aspect of the present invention, the substrate peeling promotion mechanism is characterized in that a pressurized fluid is ejected from an outer peripheral side of the substrate holding surface to peel the substrate from the substrate holding surface .
According to the present invention, since it is difficult for the injected pressurized fluid to enter the elastic film, the positional relationship between the substrate holding surface and the mechanism for injecting the pressurized fluid can be set to an optimal positional relationship. In addition, the injected pressurized fluid can accurately hit between the substrate holding surface and the substrate, and the substrate can be safely and efficiently separated from the substrate holding surface.

In the polishing method of the present invention, a substrate is held by a substrate holding device having a substrate holding surface at least partially made of an elastic film, and the outer peripheral edge of the substrate is held by a retainer ring and pressed against the polishing surface. The substrate is polished while relatively moving the polishing surface and the polishing surface, the polished substrate is sucked and held by the substrate holding device, and the substrate holding device holding the polished substrate is rotated to hold the substrate The rotation angle position of the apparatus is controlled to a specific position, the pressurized fluid is ejected from the outer peripheral side of the substrate holding apparatus controlled to the specific position, the substrate is peeled off from the substrate holding surface, and the substrate is delivered. a receiving pass to Migaku Ken method in the apparatus, before receiving and transferring the substrates from the substrate holding device to the substrate transfer apparatus, and controls the rotational angular position of the substrate holding device in a particular position, the substrate holding device Or Before receiving and transferring the substrates to the substrate transfer apparatus, and wherein the pushing up the bottom surface of the retainer ring by the substrate transfer device upward from the substrate holding surface.
According to the present invention, before the substrate after polishing is transferred from the substrate holding device to the substrate transport mechanism, the rotational angle position of the substrate holding device is controlled to a specific position, and then the substrate after polishing by the substrate peeling promotion mechanism. Can be peeled off from the substrate holding surface, and the substrate can be transferred from the substrate holding device to the substrate transport mechanism. Therefore, before the substrate is delivered, the positional relationship between the substrate holding device and the substrate peeling promoting mechanism can be set to an optimum positional relationship, and the substrate can be peeled off safely and efficiently from the substrate holding surface.

The present invention has the following effects.
(1) When the substrate is peeled from the substrate holding device that holds the polished substrate and delivered to the substrate transport mechanism, the substrate is not deformed, and no local stress is applied to the substrate. Therefore, breakage and breakage of fine wirings and elements formed on the substrate can be prevented, and breakage of the substrate can also be prevented.
(2) When the substrate is peeled off from the substrate holding device holding the polished substrate and delivered to the substrate transport mechanism, the substrate can be quickly and safely peeled off from the substrate holding surface and delivered to the substrate transport mechanism. In addition, the throughput of the polishing apparatus can be improved while sufficiently protecting circuit elements and wirings on the substrate.

FIG. 1 is a schematic diagram showing the overall configuration of a polishing apparatus according to the present invention. FIG. 2 is a schematic cross-sectional view of a top ring that constitutes a substrate holding device that holds a semiconductor wafer as an object to be polished and presses it against a polishing surface on a polishing table. FIG. 3 is a schematic diagram showing a top ring and a substrate delivery device (pusher), and is a schematic diagram showing a state in which the pusher is raised in order to deliver the wafer from the top ring to the pusher. FIG. 4 is a schematic view showing the detailed structure of the pusher. FIG. 5 is a schematic view showing a state at the time of wafer release in which the wafer is detached from the membrane. FIG. 6 is a graph showing the result of measuring the rotation phase of the top ring with respect to the pusher at the time of wafer release and the wafer release time at that time. FIG. 7 is a schematic diagram showing the positional relationship between the release shower and the membrane hole in the case of the phase of 50 degrees in FIG. FIG. 8 is a schematic diagram showing the positional relationship between the release shower and the membrane hole in the case of the phase of 60 degrees in FIG. FIG. 9 is a schematic diagram showing the positional relationship between the release shower and the membrane hole in the case of a phase of 10 degrees in FIG. FIG. 10 is a schematic diagram showing the positional relationship between the release shower and the membrane hole in the case of the phase of 40 degrees in FIG. FIG. 11 is a schematic diagram showing the behavior of the release shower when the membrane hole and the release shower are in phase. FIG. 12 is a schematic diagram showing the behavior of the membrane when the phases of the membrane hole and the release shower coincide. FIG. 13 is a schematic diagram showing the positional relationship between the release shower and the membrane hole when the hole diameter is 6 mm and the phase is 60 degrees. FIG. 14 is a graph showing the results of measuring the rotational phase of the top ring with respect to the pusher at the time of wafer release with a hole diameter of 6 mm and the wafer release time at that time.

  Hereinafter, embodiments of a polishing apparatus according to the present invention will be described in detail with reference to FIGS. 1 to 14, the same or corresponding components are denoted by the same reference numerals, and redundant description is omitted.

FIG. 1 is a schematic diagram showing the overall configuration of a polishing apparatus according to the present invention. As shown in FIG. 1, the polishing apparatus includes a polishing table 100 and a top ring 1 that holds a substrate such as a semiconductor wafer that is an object to be polished and presses the substrate against a polishing surface on the polishing table.
The polishing table 100 is connected to a motor (not shown) disposed below the table via a table shaft 100a, and is rotatable around the table shaft 100a. A polishing pad 101 is affixed to the upper surface of the polishing table 100, and the surface 101 a of the polishing pad 101 constitutes a polishing surface for polishing the semiconductor wafer W. A polishing liquid supply nozzle 102 is installed above the polishing table 100, and the polishing liquid Q is supplied onto the polishing pad 101 on the polishing table 100 by the polishing liquid supply nozzle 102.

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

The top ring 1 is connected to a top ring shaft 111, and 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 rotation 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 rotation motor 114 via a timing belt 115. Accordingly, when the top ring rotary motor 114 is driven to rotate, 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 rotary motor 114 includes an encoder 140. The encoder 140 has a function of detecting the rotational angle position of the top ring 1 and a function of integrating the rotational speed of the top ring 1. A sensor for detecting the rotation angle “reference position (0 degree)” of the top ring 1 may be provided separately. The top ring head 110 is supported by a top ring head shaft 117 that is rotatably supported by a frame (not shown). The polishing apparatus includes a control unit 50 that controls each device in the apparatus including the top ring rotation motor 114, the servo motor 138, and the encoder 140.

  In the polishing apparatus configured as shown in FIG. 1, the top ring 1 can hold a substrate such as a semiconductor wafer W on its lower surface. The top ring head 110 is configured to be pivotable about a top ring shaft 117, and the top ring 1 holding the semiconductor wafer W on the lower surface thereof is rotated from the receiving position of the semiconductor wafer W by the rotation of the top ring head 110. Is moved above. Then, the top ring 1 is lowered to press the semiconductor wafer W 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 W is polished by bringing the semiconductor wafer W into sliding contact with the polishing surface 101a of the polishing pad 101.

Next, the top ring (polishing head) in the polishing apparatus of the present invention will be described. FIG. 2 is a schematic cross-sectional view of the top ring 1 that constitutes a substrate holding device that holds a semiconductor wafer as an object to be polished and presses it against a polishing surface on a polishing table. In FIG. 2, only main components constituting the top ring 1 are illustrated.
As shown in FIG. 2, the top ring 1 basically includes a top ring body (also referred to as a carrier) 2 that presses the semiconductor wafer W against the polishing surface 101a and a retainer ring 3 that directly presses the polishing surface 101a. It is configured. The top ring body (carrier) 2 is formed of a substantially disk-shaped member, and the retainer ring 3 is attached to the outer peripheral portion of the top ring body 2. The top ring body 2 is formed of a resin such as engineering plastic (for example, PEEK). An elastic film (membrane) 4 that is in contact with the back surface of the semiconductor wafer is attached to the lower surface of the top ring body 2. The elastic membrane (membrane) 4 is formed of a rubber material having excellent strength and durability, such as ethylene propylene rubber (EPDM), polyurethane rubber, silicon rubber and the like.

  The elastic membrane (membrane) 4 has a plurality of concentric partition walls 4a. By these partition walls 4a, a circular center chamber 5 and an annular ripple are formed between the upper surface of the elastic film 4 and the lower surface of the top ring body 2. A chamber 6, an annular outer chamber 7, and an annular edge chamber 8 are formed. That is, a center chamber 5 is formed at the center of the top ring main body 2, and a ripple chamber 6, an outer chamber 7, and an edge chamber 8 are sequentially formed concentrically from the center toward the outer peripheral direction. The elastic membrane (membrane) 4 has a plurality of holes 4h penetrating in the ripple area (ripple chamber 6) in the thickness direction of the elastic membrane for wafer adsorption. In this embodiment, the hole 4h is provided in the ripple area, but it may be provided in a place other than the ripple area. In the top ring body 2, a flow path 11 communicating with the center chamber 5, a flow path 12 communicating with the ripple chamber 6, a flow path 13 communicating with the outer chamber 7, and a flow path 14 communicating with the edge chamber 8 are formed. Has been. The flow path 11 communicating with the center chamber 5, the flow path 13 communicating with the outer chamber 7, and the flow path 14 communicating with the edge chamber 8 are connected to the flow paths 21, 23, and 24 via the rotary joint 25, respectively. ing. The flow paths 21, 23, 24 are connected to the pressure adjusting unit 30 via valves V1-1, V3-1, V4-1 and pressure regulators R1, R3, R4, respectively. The flow paths 21, 23, and 24 are connected to the vacuum source 31 via valves V1-2, V3-2, and V4-2, respectively, and via valves V1-3, V3-3, and V4-3. Can communicate with the atmosphere.

  On the other hand, the flow path 12 communicating with the ripple chamber 6 is connected to the flow path 22 via the rotary joint 25. And the flow path 22 is connected to the pressure adjustment part 30 via the steam-water separation tank 35, valve | bulb V2-1, and pressure regulator R2. The flow path 22 is connected to the vacuum source 131 via the steam-water separation tank 35 and the valve V2-2, and can communicate with the atmosphere via the valve V2-3.

  A retainer ring pressurizing chamber 9 made of an elastic film is also formed immediately above the retainer ring 3, and the retainer ring pressurizing chamber 9 includes a flow path 15 formed in the top ring body (carrier) 2 and a rotary. It is connected to the flow path 26 via the joint 25. The flow path 26 is connected to the pressure adjusting unit 30 via the valve V5-1 and the pressure regulator R5. The flow path 26 is connected to the vacuum source 31 via a valve V5-2 and can communicate with the atmosphere via a valve V5-3. The pressure regulators R1, R2, R3, R4, and R5 adjust the pressure of the pressure fluid supplied from the pressure adjusting unit 30 to the center chamber 5, the ripple chamber 6, the outer chamber 7, the edge chamber 8, and the retainer ring pressurizing chamber 9, respectively. It has a pressure adjustment function. Pressure regulators R1, R2, R3, R4, R5 and valves V1-1 to V1-3, V2-1 to V2-3, V3-1 to V3-3, V4-1 to V4-3, V5-1 V5-3 is connected to the control part 50 (refer FIG. 1), and those operations are controlled. Further, pressure sensors P1, P2, P3, P4, P5 and flow sensors F1, F2, F3, F4, F5 are installed in the flow paths 21, 22, 23, 24, 26, respectively.

  In the top ring 1 configured as shown in FIG. 2, as described above, the center chamber 5 is formed at the center of the top ring main body 2, and the ripples are sequentially concentrically from the center toward the outer peripheral direction. The chamber 6, the outer chamber 7, and the edge chamber 8 are formed, and the pressure of the fluid supplied to the center chamber 5, the ripple chamber 6, the outer chamber 7, the edge chamber 8 and the retainer ring pressurizing chamber 9 is adjusted by the pressure adjusting unit 30 and the pressure. Each of the regulators R1, R2, R3, R4, and R5 can be adjusted independently. With such a structure, the pressing force for pressing the semiconductor wafer W against the polishing pad 101 can be adjusted for each region of the semiconductor wafer, and the pressing force for the retainer ring 3 to press the polishing pad 101 can be adjusted.

Next, a series of polishing processing steps by the polishing apparatus configured as shown in FIGS. 1 and 2 will be described.
The top ring 1 receives the semiconductor wafer W from the substrate transfer device and holds it by vacuum suction. The elastic film (membrane) 4 is provided with a plurality of holes 4 h for vacuum-sucking the semiconductor wafer W, and these holes 4 h communicate with a vacuum source 131. The top ring 1 holding the semiconductor wafer W by vacuum suction is lowered to a preset setting position for polishing the top ring. At this polishing setting position, the retainer ring 3 is in contact with the surface (polishing surface) 101a of the polishing pad 101. However, before the polishing, the top ring 1 holds the semiconductor wafer W by suction. There is a slight gap (for example, about 1 mm) between the lower surface (surface to be polished) and the surface (polishing surface) 101a of the polishing pad 101. At this time, both the polishing table 100 and the top ring 1 are rotationally driven. In this state, the elastic film (membrane) 4 on the back side of the semiconductor wafer is expanded, the lower surface (surface to be polished) of the semiconductor wafer is brought into contact with the surface (polishing surface) of the polishing pad 101, and the polishing table 100 and the top ring The surface of the semiconductor wafer (surface to be polished) is polished until it reaches a predetermined state (for example, a predetermined film thickness).

After the wafer processing step on the polishing pad 101 is completed, the wafer W is attracted to the top ring 1, the top ring 1 is lifted, and moved to a substrate delivery device (pusher) that constitutes a substrate transport mechanism. Release (release).
FIG. 3 is a schematic view showing the top ring 1 and the substrate delivery device (pusher) 150, and is a schematic view showing a state in which the pusher is raised in order to deliver the wafer from the top ring 1 to the pusher 150. As shown in FIG. 3, the pusher 150 includes a top ring guide 151 that can be fitted to the outer peripheral surface of the top ring 1 for centering with the top ring 1, and between the top ring 1 and the pusher 150. In order to move the pusher stage 152 up and down, the pusher stage 152 for supporting the wafer, an air cylinder (not shown) for moving the pusher stage 152 up and down, and the pusher stage 152 and the top ring guide 151 up and down. Air cylinder (not shown).

In the following, an operation for transferring the wafer W from the top ring 1 to the pusher 150 will be described.
After the wafer processing process on the polishing pad 101 is completed, the top ring 1 attracts the wafer W. The adsorption of the wafer is performed by communicating the hole 4h of the membrane 4 with the vacuum source 131. After the wafer is adsorbed, the top ring 1 is raised and moved to the pusher 150, and the wafer W is released (released). After moving to the pusher 150, the cleaning operation may be performed by rotating the top ring 1 while supplying pure water or chemicals to the wafer W adsorbed and held on the top ring 1.

  In the present invention, the rotational phase of the top ring is positioned at a specific phase before the wafer is detached. When the cleaning operation is not performed, the rotational phase of the top ring 1 is adjusted during movement to the pusher 150, etc., and “the rotational phase of the top ring is positioned at a specific phase”. When performing the cleaning operation with the rotation of the top ring 1, the rotation of the top ring 1 is stopped so as to “position the rotation phase of the top ring at a specific phase” at the end of the cleaning operation. In this case, in order to “position the rotation phase of the top ring at a specific phase”, the encoder 140 detects the rotation angle position from the reference position (0 degree) of the top ring 1 and the control unit 50 rotates the top ring. By controlling the motor 114, the top ring 1 is stopped at a predetermined rotational angle position. Thereafter, the pusher stage 152 and the top ring guide 151 of the pusher 150 are raised, and the top ring guide 151 is fitted to the outer peripheral surface of the top ring 1 to center the top ring 1 and the pusher 150. At this time, the top ring guide 151 pushes up the retainer ring 3, but at the same time, the retainer ring pressurizing chamber 9 is evacuated to quickly raise the retainer ring 3. When the pusher has been lifted, the bottom surface of the retainer ring 3 is pressed against the top surface of the top ring guide 151 and pushed up above the bottom surface of the membrane 4, so that the space between the wafer and the membrane is exposed. It has become. In the example shown in FIG. 3, the bottom surface of the retainer ring 3 is located 1 mm above the lower surface of the membrane. Thereafter, vacuum suction of the wafer W by the top ring 1 is stopped, and a wafer release operation is performed. In addition, you may move to a desired positional relationship by a top ring falling instead of a pusher raising.

  FIG. 4 is a schematic diagram showing the detailed structure of the pusher 150. As shown in FIG. 4, the pusher 150 includes a top ring guide 151, a pusher stage 152, and a release nozzle 153 that is formed in the top ring guide 151 and ejects pressure fluid. A plurality of release nozzles 153 are provided at predetermined intervals in the circumferential direction of the top ring guide 151 so as to eject a mixed fluid of pressurized nitrogen and pure water inward in the radial direction of the top ring guide 151. It has become. Thereby, a release shower made of a mixed fluid of pressurized nitrogen and pure water is sprayed between the wafer W and the membrane 4 to perform wafer release for releasing the wafer from the membrane. The release nozzle 153 constitutes a substrate peeling promotion mechanism.

  FIG. 5 is a schematic view showing a state at the time of wafer release in which the wafer is detached from the membrane. As shown in FIG. 5, the pusher is lifted and the bottom surface of the retainer ring 3 is pressed against the upper surface of the top ring guide 151 and pushed up above the lower surface of the membrane 4, and the gap between the wafer W and the membrane 4 is exposed. The release shower is sprayed between the wafer W and the membrane 4 from the release nozzle 153 in an open state without pressurizing the membrane 4, that is, without applying stress to the wafer W. Is possible. From the release nozzle 153, a mixed fluid of pressurized nitrogen and pure water is ejected, but only pressurized gas or pressurized liquid may be ejected, or other combinations of pressurized fluid may be ejected. Anyway. Depending on the state of the back surface of the wafer, the adhesion between the membrane and the back surface of the wafer is strong, and the wafer may be difficult to peel off from the membrane. In such a case, the ripple area (ripple chamber 6) may be pressurized at a low pressure of 0.1 MPa or less to assist the wafer removal. Further, when pressurizing the ripple area, in order to prevent the membrane from continuing to expand while the wafer is in close contact with the membrane, the area other than the ripple area may be in a vacuum state to suppress the expansion of the membrane. .

Next, the above-mentioned “positioning the rotational phase of the top ring at a specific phase” will be described with reference to FIGS.
FIG. 6 is a graph showing the result of measuring the rotation phase of the top ring with respect to the pusher at the time of wafer release and the wafer release time at that time. In FIG. 6, the vertical axis represents the wafer release time, and the horizontal axis represents the rotation angle of the top ring from 0 degrees to 360 degrees. The top ring was calibrated in the rotation direction, and the rotation phase of the top ring with respect to the pusher during wafer release and the wafer release time at that time were measured for 300 wafers. It can be clearly seen from FIG. 6 that the wafer release time becomes longer every 60 degrees of the rotation phase of the top ring. In this experiment, since a membrane having six equally spaced holes is used, the hole position of the membrane with respect to the pusher is the same even if the top ring rotates 60 degrees. That is, it can be seen that the wafer release time is long when the hole of the membrane is positioned in a specific phase with respect to the pusher. In this measurement result, the wafer release time is long when the phase is 50 to 60 degrees and when the phase is rotated every 60 degrees from this phase.

FIG. 7 is a schematic diagram showing the positional relationship between the release shower and the membrane hole in the case of the phase of 50 degrees in FIG. The same positional relationship is obtained when the phase is 110 degrees, 170 degrees, and the like. As shown in FIG. 7, two release nozzles 153 are provided in each of the top ring guides 151 installed in the circumferential direction, so that eight locations are provided between the wafer W and the membrane 4 when the wafer is released. It is possible to spray the release shower SH. The membrane 4 of the top ring 1 has six equally spaced membrane holes 4h. Therefore, even if the top ring rotates 60 degrees, the hole position of the membrane with respect to the pusher is the same.
FIG. 8 is a schematic diagram showing the positional relationship between the release shower and the membrane hole in the case of the phase of 60 degrees in FIG. The same positional relationship is obtained when the phase is 0 degrees, 120 degrees, and the like.
7 and 8, it can be seen that when the phase is 50 degrees and the phase is 60 degrees, the phases of the two membrane holes 4h and the release shower SH are the same. The membrane hole 4h and the release shower SH that are in phase are surrounded by a dotted circle.

FIG. 9 is a schematic diagram showing the positional relationship between the release shower and the membrane hole in the case of a phase of 10 degrees in FIG. FIG. 10 is a schematic diagram showing the positional relationship between the release shower and the membrane hole in the case of the phase of 40 degrees in FIG. In the case of FIG. 9 and FIG. 10, the phase matching between the membrane hole 4h and the release shower SH is not observed. Note that the membrane hole diameter in the case of FIGS. 7 to 10 is φ15 mm.
6 to 10, the phase of the release shower coincides with the phase of the membrane hole when the rotation phase of the top ring is 50 to 60 degrees and the phase rotated every 60 degrees from this phase. At that time, the wafer is released. You can see that the time is getting longer.

Next, the influence on the membrane when the phase of the membrane hole coincides with the release shower will be described with reference to FIGS. 11 and 12. FIG.
FIG. 11 is a schematic diagram showing the behavior of the release shower when the membrane hole and the release shower are in phase. FIG. 12 is a schematic diagram showing the behavior of the membrane when the phases of the membrane hole and the release shower coincide. When the phases of the membrane hole and the release shower coincide with each other, as shown in FIG. 11, the pressurized fluid of the release shower enters the membrane from the membrane hole. Here, a mixed fluid of 0.35 MPa N ₂ gas and 0.1 MPa DIW (pure water) is used as the pressurized fluid of the release shower, but only a pressurized gas of 0.25 MPa or more may be used. Only a pressurized liquid of 0.05 MPa or more or a mixed fluid thereof may be used. As shown in FIG. 12, the release shower pressurized fluid that has entered the membrane acts to swell the membrane in the ripple area (ripple chamber 6) downward. When the membrane swells, the position of the release shower sprayed between the membrane and the back surface of the wafer shifts from the optimum position, resulting in a long wafer release time as shown in the experimental results. Further, when the membrane swells, local stress is applied to the wafer, and fine wiring formed on the wafer may be broken, or in the worst case, the wafer may be damaged.

  In the present invention, in order to avoid such a situation, the rotational phase of the top ring is controlled so that the positional relationship shown in FIGS. 9 and 10 is obtained before the wafer is released. That is, the rotation angle position of the top ring 1 is detected by the encoder 140, and the top ring rotation motor 114 is controlled by the control unit 50, whereby the top ring 1 is stopped at a predetermined rotation angle position. By doing so, even when the release shower is ejected at the time of wafer release, the pressurized fluid of the release shower does not enter the membrane from the membrane hole, and the wafer can be released stably. Instead of controlling the rotation phase of the top ring, the release shower may be rotated in accordance with the phase of the top ring by making the top ring guide 151 rotatable.

Next, another embodiment of the present invention will be described with reference to FIGS.
FIG. 13 is a schematic diagram showing a positional relationship between a release shower and a membrane hole in the case of a phase of 60 degrees when a membrane having a hole diameter of 6 mm is used. FIG. 14 is a graph showing experimental results similar to those of FIG. 6 in the case of using a membrane having a hole diameter of 6 mm, and measuring the rotational phase of the top ring with respect to the pusher at the time of wafer release and the wafer release time at that time. In FIG. 6, a membrane with a hole diameter of 15 mm was used, whereas in FIG. 14, a membrane with a hole diameter of 6 mm was used. The vertical range in FIG. 14 is the same as the vertical range in FIG. As shown in FIG. 14, when a membrane having a hole diameter of 6 mm is used, it is apparent that the wafer release time is long and is greatly reduced and improved. This is because, as shown in FIG. 13, it is very difficult for the release shower SH to enter the inside of the membrane hole 4h by reducing the pore diameter of the membrane, and the situation shown in FIGS. 11 and 12 may occur. This is because has become extremely small.

The above-mentioned effect can be obtained when the hole diameter of the membrane hole is 6 mm or less, but there are some problems when the hole diameter is too small.
The first problem is that assembly is difficult. Usually, the holes of the membrane are attached in alignment with the holes of the carrier body (top ring body) to which the membrane is attached. This is because the wafer is sucked and held through the membrane hole when the wafer is sucked. However, for example, when the hole diameter is 1 mm, the membrane hole and the carrier hole must be aligned with an accuracy of 1 mm or less, which makes assembly very difficult.
The second problem is the problem of wafer adsorption. As the hole diameter is reduced, the area that is in a vacuum state on the backside of the wafer during wafer adsorption decreases. For example, in a membrane in which six holes are arranged with a hole diameter of 1 mm, the total area of the holes is about 4.7 mm ² . When a wafer is adsorbed at a vacuum pressure of −80 kPa, which is normally used, the adsorbing force is about 0.38 N. For example, the adsorbing force is smaller than about 1.3 N of the weight of a silicon wafer having a diameter of 12 inches. As a result, it cannot be held by suction. It is possible to increase the adsorption power by increasing the number of holes, but there are problems such as the pressurized fluid leaking from the holes during polishing and the match between the release shower and the holes is likely to occur. In practice, it is difficult to adopt. Therefore, it is desirable to use a membrane having a hole diameter of 2 mm or more.

  Depending on the layout of the release nozzle, the phases may coincide at the four locations of the release shower and the membrane hole. Even in such a case, it has been confirmed that the release shower enters the inside of the membrane hole, inflates the membrane and takes a long release time. Therefore, the layout of the release shower may be selected so that the four phases do not coincide with each other so that this situation does not occur.

  Although the embodiment of the present invention has been described so far, the present invention is not limited to the above-described embodiment, and it is needless to say that the present invention may be implemented in various different forms within the scope of the technical idea.

1 Top ring 2 Top ring body 3 Retainer ring 4 Elastic membrane (membrane)
4a Partition 4h Hole 5 Center chamber 6 Ripple chamber 7 Outer chamber 8 Edge chamber 9 Retainer ring pressurizing chamber 11, 12, 13, 14, 15, 21, 22, 23, 24, 26 Flow path 25 Rotary joint 30 Pressure adjusting section 31 Vacuum source 35 Air-water separation tank 50 Control unit 100 Polishing table 100a Table shaft 101 Polishing pad 101a Surface 102 Polishing liquid supply nozzle 111 Top ring shaft 112 Rotating cylinder 113 Timing pulley 114 Top ring rotation motor 115 Timing belt 116 Timing pulley 117 Top ring head shaft 124 Vertical movement mechanism 125 Rotary joint 126 Bearing 128 Bridge 129 Support stand 130 Post 131 Vacuum source 132 Ball screw 132a Screw shaft 132b Nut 138 AC servo motor 1 0 encoder 150 substrate transfer apparatus (pusher)
151 Top ring guide 152 Pusher stage 153 Release nozzle F1 to F5 Flow rate sensor R1 to R5 Pressure regulator P1 to P5 Pressure sensor SH Release shower V1-1 to V1-3, V2-1 to V2-3, V3-1 to V3- 3, V4-1 to V4-3, V5-1 to V5-3 Valve

Claims (5)

A polishing table having a polishing surface;
A substrate holding device having at least a part of a substrate holding surface made of an elastic film, holding the substrate by the substrate holding surface and holding the outer peripheral edge of the substrate by a retainer ring, and pressing the polishing surface;
A substrate transfer device for transferring the substrate from the substrate holding device at the substrate delivery position from the substrate holding device,
A substrate peeling promotion mechanism that is provided integrally with the substrate delivery device or provided separately, and ejects pressurized fluid from the outer peripheral side of the substrate holding surface to peel the substrate from the substrate holding surface;
A rotational drive mechanism for rotationally driving the substrate holding device;
A detection mechanism for detecting a rotation angle position of the substrate holding device;
A polishing apparatus comprising: a control unit that controls a rotation angle position of the substrate holding device ;
The substrate delivery device pushes up the bottom surface of the retainer ring above the substrate holding surface before receiving the substrate from the substrate holding device,
A polishing apparatus , wherein a rotation angle position of the substrate holding device is controlled to a specific position before the substrate is transferred from the substrate holding device to the substrate delivery device. The elastic film of the substrate holding surface has a hole, and the control unit controls the rotation angle position of the substrate holding device so that the pressurized fluid injected from the substrate peeling promotion mechanism is not injected toward the hole. The polishing apparatus according to claim 1 , wherein the polishing apparatus is controlled. A polishing table having a polishing surface;
A substrate holding device having at least a part of a substrate holding surface made of an elastic film, holding the substrate by the substrate holding surface and holding the outer peripheral edge of the substrate by a retainer ring, and pressing the polishing surface;
A substrate delivery device for delivering a substrate from the substrate holding device at a substrate delivery position from the substrate holding device;
A substrate peeling acceleration mechanism that is provided integrally with the substrate delivery device or provided separately, and peels the substrate from the substrate holding surface;
Wherein the substrate holding surface is provided multiple holes, diameter of said hole is a polishing apparatus is 2mm or more than 6mm,
The polishing apparatus, wherein the substrate delivery device pushes up the bottom surface of the retainer ring above the substrate holding surface before receiving the substrate from the substrate holding device . The polishing apparatus according to claim 3, wherein the substrate peeling promotion mechanism ejects a pressurized fluid from an outer peripheral side of the substrate holding surface to peel the substrate from the substrate holding surface . The substrate is held by a substrate holding device having a substrate holding surface at least partially made of an elastic film, and the outer peripheral edge of the substrate is held by a retainer ring and pressed against the polishing surface, so that the substrate and the polishing surface are relatively Polish the substrate while moving it,
The substrate after polishing is sucked and held by the substrate holding device,
Rotating the substrate holding device holding the polished substrate, and controlling the rotation angle position of the substrate holding device to a specific position,
The injected pressurized fluid from the outer peripheral side of a particular of the substrate holding device which is controlled in position, the substrate is peeled off the substrate from the substrate holding surface a receiving pass to Migaku Ken method in the substrate transfer device,
Before transferring the substrate from the substrate holding device to the substrate delivery device, the rotational angle position of the substrate holding device is controlled to a specific position,
A polishing method , wherein before the substrate is transferred from the substrate holding device to the substrate transfer device, the bottom surface of the retainer ring is pushed upward from the substrate holding surface by the substrate transfer device .

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