JP2015150648A - Substrate holding device and polishing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a substrate holding device which prevents water droplets from intruding in a liquid level detection line of an air-water separation tank in vacuum-sucking a substrate, in pressurizing the substrate, or in discharging a liquid accumulated in the air-water separation tank to an external.SOLUTION: An air-water separation tank 35 includes a chamber 35CH as a space for accumulating a liquid inside, a liquid level detection line L4 which is arranged outside the chamber and detects a liquid level of the liquid accumulated in the chamber by communicating with an inside of the chamber, and a sensor S which detects a full state of the chamber by detecting a liquid level in the liquid level detection line L4. A vacuum suction line L1 for connecting a pressure chamber 6 and a vacuum source 31 and a pressurization line L2 for connecting the pressure chamber 6 and a pressure regulation part 30 are arranged so as to pass through the chamber 35CH of the air-water separation tank. An upper end of the liquid level detection line L4 is connected to a line which is a part of the pressurization line L2 and connects the pressure regulation part 30 and the chamber 35CH.

Description

  The present invention relates to a substrate holding device used in a polishing apparatus that polishes a substrate such as a wafer, and more particularly to a substrate holding device that holds a substrate and presses it against a polishing surface. The present invention also relates to a polishing apparatus provided with such a substrate holding device.

  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.

Therefore, in the semiconductor device manufacturing process, planarization of the surface of the semiconductor device has become increasingly important. The most important technique for planarizing the surface is chemical mechanical polishing (CMP). In this chemical mechanical polishing, polishing is performed by bringing a wafer into sliding contact with the polishing surface while supplying a polishing liquid containing abrasive grains such as silica (SiO ₂ ) onto the polishing surface of the polishing pad.

  A polishing apparatus for performing CMP includes a polishing table that supports a polishing pad, and a substrate holding apparatus called a top ring or a polishing head for holding a substrate such as a wafer. When polishing a substrate using such a polishing apparatus, the substrate is pressed against the polishing surface of the polishing pad with a predetermined pressure while the substrate is held by the substrate holding apparatus. At this time, the substrate is brought into sliding contact with the polishing surface by moving the polishing table and the substrate holding device relative to each other, and the surface of the substrate is polished.

  When the relative pressing force between the substrate being polished and the polishing surface of the polishing pad is not uniform over the entire surface of the substrate, insufficient polishing or overpolishing may occur depending on the pressing force applied to each part of the substrate. It will occur. Therefore, in order to equalize the pressing force on the substrate, a pressure chamber formed of a membrane (elastic film) is provided in the lower part of the substrate holding device, and a pressure fluid such as compressed air is supplied to the pressure chamber to The substrate is pressurized with a fluid pressure. Therefore, the pressure chamber is connected to the pressure adjusting unit via the pressurizing line, and the pressure fluid is supplied from the pressure adjusting unit.

  In addition, the pressure chamber of the substrate holding device is connected to a vacuum source via a vacuum suction line, and a plurality of through holes are formed in the membrane. By forming a negative pressure in the through hole of the membrane, the substrate is made by the membrane. The substrate is held by vacuum suction.

JP 2010-46756 A

  As described above, the substrate holding device is provided with a vacuum suction line for vacuum suction of the substrate. However, when vacuum suctioning the substrate, the vacuum suction line is connected to the atmosphere and the substrate from the through hole for vacuum suction. In order for the washing water remaining on the top to be sucked, it is necessary to separate these waters in a steam-water separation tank. Therefore, a steam / water separation tank is connected to the vacuum adsorption line. If these water | moisture content is isolate | separated in a steam-water separation tank, since a water | moisture content will accumulate in the tank of a steam-water separation tank, it is necessary to drain. A drainage line is provided to drain the liquid (water) in the tank from the steam / water separation tank. When draining the liquid (water) in the tank from the steam-water separation tank, it is necessary to open the drain valve and pressurize the tank. Therefore, a pressurization line provided for pressurizing the substrate is connected to the steam / water separation tank.

  However, in the substrate holding device, when the substrate is vacuum-sucked to the membrane via the vacuum suction line, or when the substrate is pressurized and pressed against the polishing pad via the pressure line, or the air / water separation is performed via the drain line. When the liquid stored in the tank is discharged (drained) to the outside, water droplets may enter the tube from the upper connector or the lower connector of the liquid level gauge equipped with the liquid level measuring tube. When water drops enter the tube, the liquid level in the gas / water separation tank rises only to the vicinity of the lower connector, but the water drops that have entered the tube actuate the full-water sensor. There is a problem of misdetection.

  The present invention has been made in view of the above-described circumstances. When the substrate is vacuum-adsorbed, when the substrate is pressurized and pressed against the polishing pad, or when the liquid stored in the steam separator is discharged to the outside, It is an object of the present invention to provide a substrate holding device and a polishing device in which water droplets do not enter the liquid level detection line of the water separation tank.

  In order to solve the above-described problems, a first aspect of the present invention includes an elastic film that forms a pressure chamber to which a fluid is supplied, and vacuum-adsorbs the substrate by communicating the pressure chamber with a vacuum source. A gas is provided in a vacuum suction line that connects the pressure chamber and the vacuum source, and a top ring that presses the substrate against the polishing surface by connecting the pressure chamber to a pressure adjusting unit that supplies the pressure fluid. A substrate holding apparatus including a water separation tank, wherein the gas / water separation tank is provided in a space that stores a liquid therein, and is provided outside the chamber and extends upward from a lower portion of the chamber. And a liquid level detection line for detecting the liquid level of the liquid stored in the chamber in communication with the chamber and detecting the liquid level in the liquid level detection line to detect that the chamber is full. A vacuum suction line that connects the pressure chamber and the vacuum source, and a pressurization line that connects the pressure chamber and the pressure adjustment unit so as to pass through the chamber of the steam separation tank. The upper end of the liquid level detection line is connected to a line that is a part of the pressurization line and connects the pressure adjusting unit and the chamber.

In a preferred aspect of the present invention, the line connecting the pressure adjusting unit and the chamber includes an opening / closing valve, and an upper end of the liquid level detection line is connected to a downstream side of the opening / closing valve. Features.
In a preferred aspect of the present invention, the liquid level detection line includes a tube, and the sensor includes a light projecting and receiving unit provided so as to sandwich the tube.

In a preferred aspect of the present invention, the vacuum adsorption line is connected to the chamber via a connector provided in the line and a flow path formed in the steam separator, and the pressure line is It is directly connected to the chamber through a connector provided in the line.
According to a second aspect of the present invention, there is provided a polishing apparatus comprising the substrate holding apparatus and a polishing table that supports a polishing pad having a polishing surface.

  According to the present invention, when the substrate is vacuum-adsorbed, when the substrate is pressurized and pressed against the polishing pad, or when the liquid stored in the steam-water separation tank is discharged to the outside, the liquid level detection line of the steam-water separation tank Water droplets do not enter inside. That is, since no liquid is sucked up in the liquid level detection line, erroneous detection of full water by the full water sensor can be prevented.

FIG. 1 is a schematic diagram showing an overall configuration of a polishing apparatus provided with a substrate holding device according to an embodiment of the present invention. FIG. 2 is a schematic cross-sectional view of a top ring constituting a substrate holding device that holds a substrate W as an object to be polished and presses it against a polishing surface on a polishing table. FIG. 3 is a schematic diagram showing the steam-water separation tank and the lines connected to the steam-water separation tank shown in FIG. FIG. 4 is a diagram showing a state when the full water sensor detects the full water in the steam / water separation tank in the steam / water separation tank configured as shown in FIG. 3. FIG. 5 is a schematic view showing the operating state of the steam-water separation tank configured as shown in FIGS. 3 and 4. FIG. 6 is a schematic diagram showing an improvement measure for preventing erroneous detection of full water caused by water droplets entering the tube. Fig.7 (a) is the schematic which shows the state at the time of the operation | movement of the steam-water separation tank comprised as shown in FIG. FIG.7 (b) is typical sectional drawing which shows the flow path in the steam-water separation tank shown to Fig.7 (a). FIG. 8 is a schematic diagram showing a configuration for preventing erroneous detection of full water caused by the liquid in the steam / water separation tank being sucked up by the liquid level detection line. FIG. 9 is a side view of the steam / water separation tank shown in FIG. 8 and shows each connector for connecting the vacuum adsorption line, the pressurization line, and the liquid level detection line to the steam / water separation tank.

Hereinafter, embodiments of a substrate holding apparatus and a polishing apparatus according to the present invention will be described in detail with reference to FIGS. 1 to 9. In FIG. 1 to FIG. 9, 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 provided with a substrate holding device according to an embodiment of the present invention. As shown in FIG. 1, the polishing apparatus includes a polishing table 100 that supports a polishing pad 101 and a top ring 1 as a substrate holding device that holds a substrate W such as a wafer to be polished and presses it against the polishing pad 101. And.

  The polishing table 100 is connected to a motor (not shown) disposed below the table via a table shaft 100a, and is rotatable about the table shaft 100a. The polishing pad 101 is affixed to the upper surface of the polishing table 100, and the upper surface 101 a of the polishing pad 101 constitutes a polishing surface for polishing the substrate W. A polishing liquid supply mechanism 105 is installed above the polishing table 100, and the polishing liquid is supplied onto the polishing pad 101 by the polishing liquid supply mechanism 105.

  The top ring 1 is connected to a top ring shaft 16, and the top ring shaft 16 is moved up and down by a vertical movement mechanism (not shown) installed on the top ring head 18. By moving the top ring shaft 16 up and down, the entire top ring 1 is moved up and down as shown by arrows with respect to the top ring head 18 for positioning. Further, the top ring shaft 16 is rotated by a rotation mechanism (not shown) installed in the top ring head 18. Accordingly, the top ring 1 rotates about its own axis as indicated by the arrow as the top ring shaft 16 rotates.

  The top ring 1 and the polishing table 100 rotate as indicated by arrows, and in this state, the top ring 1 presses the substrate W against the polishing surface 101 a of the polishing pad 101. The polishing liquid is supplied onto the polishing pad 101 from the polishing liquid supply mechanism 105, and the substrate W is polished by sliding contact with the polishing pad 101 in a state where the polishing liquid exists between the polishing pad 101 and the substrate W. .

Next, the top ring constituting the substrate holding device will be described. FIG. 2 is a schematic cross-sectional view of the top ring 1 that constitutes the substrate holding device that holds the substrate W as an object to be polished and presses the substrate W against the polishing surface on the 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 substrate W against the polishing pad 101, and a retainer ring 3 that directly presses the polishing surface 101a. Has been. 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 pressure chambers including a ripple chamber 6, an outer chamber 7, and an edge chamber 8 are formed sequentially and concentrically from the center toward the outer circumferential direction. ing. 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, R5 are respectively supplied with pressure fluid (compressed air or the like) 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. ) To adjust the pressure. 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 a control unit (not shown), and their operation is 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 substrate W against the polishing pad 101 can be adjusted for each region of the substrate W, and the pressing force for the retainer ring 3 to press the polishing pad 101 can be adjusted.

Next, the structure of the steam separation tank 35 shown in FIG. 2 will be described with reference to FIG.
FIG. 3 is a schematic diagram showing the steam-water separation tank 35 and the lines connected to the steam-water separation tank 35 shown in FIG. As shown in FIG. 3, a vacuum adsorption line L1 (shown by a thick solid arrow), a pressurization line L2 (shown by a white arrow), and a drain line L3 (shown by a dotted arrow) are connected to the steam / water separation tank 35. Has been. Each line will be described with reference to FIG. 2. The vacuum suction line L1 is a line connecting the ripple chamber 6 of the top ring 1 and the vacuum source 131, and the vacuum suction line L1 is provided with a vacuum valve V2-2. It has been. The elastic film (membrane) 4 of the top ring 1 is formed with a vacuum suction through hole in the area of the ripple chamber 6, and the ripple chamber 6 is connected via the vacuum suction line L 1 by opening the vacuum valve V 2-2. A negative pressure is formed in the ripple chamber 6 by communicating with the vacuum source 131, and the substrate W is configured to be vacuum-sucked by the elastic film 4 through a vacuum suction through hole (not shown). The pressurization line L2 is a line that connects the ripple chamber 6 of the top ring 1 and the pressure adjusting unit 30, and the pressurization line L2 is provided with a pressurization valve V2-1. By opening the pressurizing valve V2-1, the ripple chamber 6 and the pressure adjusting unit 30 are communicated with each other via the pressurizing line L2, and a pressure fluid (compressed air or the like) is supplied to the ripple chamber 6, and the substrate W is polished to the polishing pad. 101 is pressed. The drain line L3 pressurizes the tank by connecting the inside of the tank of the steam separation layer 35 to the pressure adjusting unit 30 and opening the drain valve V2-3 provided at the bottom of the steam separation tank 35. This is a line for draining the liquid (water) inside.

  As shown in FIG. 3, the reason why the vacuum adsorption line L1, the pressurization line L2, and the drainage line L3 are connected to the steam separation tank 35 is as follows. That is, a vacuum suction line L1 is provided to vacuum-suck the substrate W, but when the substrate W is vacuum-sucked, the vacuum suction line L1 remains on the atmosphere and the substrate from the vacuum suction through hole. In order for the washing water to be sucked, it is necessary to separate these moisture in the steam / water separation tank 35. Therefore, the steam / water separation tank 35 is connected to the vacuum suction line L1. If these water | moisture content is isolate | separated in the steam-water separation tank 35, since water | moisture content will accumulate in the tank of the steam-water separation tank 35, it needs to drain. In order to drain the liquid (water) in the tank from the steam / water separation tank 35, a drain line L3 is provided. When draining the liquid (water) in the tank from the steam / water separation tank 35, it is necessary to open the drain valve V2-3 and pressurize the tank. Therefore, a pressurization line L <b> 2 provided for pressurizing the substrate W is connected to the steam / water separation tank 35. The drainage valve V2-3 is closed when the substrate W is vacuum-adsorbed by the elastic film 4 and when the substrate W is pressurized by the elastic film 4. When the substrate W is released from the top ring 1, the drain valve V <b> 2-3 is opened and the inside of the steam / water separation tank 35 is pressurized, and the liquid (water) accumulated in the tank of the steam / water separation tank 35 is drained. In order to release the substrate W from the top ring 1, a predetermined time is required. By keeping the drain valve V2-3 open for the predetermined time, the liquid ( Water) can be drained sufficiently.

  As shown in FIG. 3, a liquid level gauge 36 indicating a liquid level in the steam / water separation tank 35 is installed in the steam / water separation tank 35. The liquid level gauge 36 includes a transparent tube 37 extending in the vertical direction, and displays the liquid level in the tank of the steam-water separation tank 35 by the liquid column of the tube 37. The tube 37 communicates with the inside of the steam / water separation tank 35 through upper and lower connectors 38U and 38L, and a full water sensor S is installed at a predetermined height position of the tube 37. The full water sensor S includes a light projecting / receiving unit provided so as to sandwich the tube 37, and the liquid level in the tank of the steam / water separation tank 35 reaches the optical axis position of the light projecting / receiving unit to block the optical axis. Thus, the full water in the steam / water separation tank 35 is detected.

  FIG. 4 is a diagram showing a state when the full water sensor S detects the full water in the steam / water separation tank 35 in the steam / water separation tank 35 configured as shown in FIG. 3. As shown in FIG. 4, when the liquid level in the steam / water separation tank 35 rises and the liquid level in the tank reaches the optical axis position of the full water sensor S to block the optical axis, the full water sensor S A full water in the water separation tank 35 is detected. When the full water sensor S detects that the air / water separation tank 35 is full, a full water detection signal is transmitted to a control unit (not shown). The control unit issues a full water error and stops the operation of the polishing apparatus.

The present inventors have determined that there are the following problems in the process of continuously operating the top ring 1 including the steam separation tank 35 configured as shown in FIGS. 3 and 4.
FIG. 5 is a schematic diagram showing the operating state of the steam / water separation tank 35 configured as shown in FIGS. 3 and 4. In FIG. 5, when the substrate W is vacuum-sucked to the elastic membrane (membrane) 4 via the vacuum suction line L1 by opening the vacuum valve V2-2, or the pressure line L2 is opened by opening the pressure valve V2-1. When the substrate W is pressurized with the elastic membrane (membrane) 4 via the water or by opening the drain valve V2-3, the liquid stored in the steam / water separation tank 35 is discharged (drained) to the outside via the drain line L3. In some cases, water droplets may enter the tube 37 from the upper connector 38U or the lower connector 38L of the liquid level gauge 36. When a water drop enters the tube 37, the water level in the gas / water separation tank 35 rises only to the vicinity of the lower connector 38L. Since the shaft is shielded from light, there is a problem that the full water sensor S operates and erroneously detects full water.

FIG. 6 is a schematic view showing an improvement measure 1 for preventing erroneous detection of full water due to water droplets entering the tube 37. The improvement measure 1 is an improvement of the structure of the liquid level gauge 36 composed of the tube 37 and the upper and lower connectors 38U and 38L.
In the improvement measure 1, as shown in FIG. 6, the tube 37 is removed from the upper connector 38U and extended upward, and the upper end of the tube 37 is connected to the pressurization line L2 at a position directly below the pressurization valve V2-1. Yes. The lower connector 38L that connects the tube 37 to the steam separator 35 is the same as that shown in FIG. By connecting the tube 37 to the pressurization line L2 to form the liquid level detection line L4, when the substrate W is pressurized through the pressurization line L2 by opening the pressurization valve V2-1, The water droplets and liquid are discharged into the steam / water separation tank 35. The upper connector 38U is closed by a plug. Further, the position of the full water sensor S is changed upward.

As a result of experiments on the top ring 1 having the steam-water separation tank 35 configured as shown in FIG. 6, the present inventors have found that there are the following problems.
Fig.7 (a) is the schematic which shows the state at the time of the operation | movement of the steam-water separation tank 35 comprised as shown in FIG. FIG.7 (b) is typical sectional drawing which shows the flow path in the steam-water separation tank 35 shown to Fig.7 (a). 7A and 7B show a vacuum pressure sensor VS provided at the upper end of the steam separation tank 35.
As shown in FIG. 7B, the steam / water separation tank 35 includes a chamber 35CH which is a space for storing liquid therein, a vertical flow path 35vp extending upward from the chamber 35CH, and a vertical flow path 35vp. The upper and lower lateral flow paths 35up and 35lp that communicate with each other are formed. The steam / water separation tank 35 is formed with a suction / pressure port 35P for connecting the chamber 35CH and the ripple chamber 6 of the top ring 1. A vacuum suction line L1 (pressure line L2) extends from the suction / pressure port 35P to the ripple chamber 6 of the top ring 1 (see FIG. 7A). Among the portions in the steam / water separation tank 35 shown in FIG. 7B, the suction / pressurization port 35P, the chamber 35CH, the vertical flow path 35vp, and the upper horizontal flow path 35up constitute a vacuum suction line L1. . Further, the suction / pressurization port 35P, the chamber 35CH, the vertical flow path 35vp, and the lower horizontal flow path 35lp constitute a pressurization line L2.

  7A, when the substrate W is vacuum-sucked to the elastic membrane (membrane) 4 via the vacuum suction line L1 by opening the vacuum valve V2-2, the chamber 35CH of the steam-water separation tank 35 is pressurized. To suck a line L2-1 that is a part of the line L2 and connects the steam-water separation tank 35 and the pressurizing valve V2-1 and a liquid level detection line L4 that is connected to the line L2-1. The liquid level detection line L4 becomes negative pressure. That is, when the vacuum valve V2-2 is opened, as shown by a white arrow, a line L1-1 that is a part of the vacuum adsorption line L1 and connects the vacuum valve V2-2 and the steam / water separation tank 35. The upper horizontal flow path 35up, the vertical flow path 35vp, the lower horizontal flow path 35lp, and a part of the pressurization line L2, which connects the steam / water separation tank 35 and the pressurization valve V2-1. The liquid level detection line L4 is sucked through the line L2-1 and the liquid level detection line L4 becomes negative pressure. A connector 41 for connecting the line L1-1 to the steam-water separation tank 35 and a connector 42 for connecting the line L2-1 to the steam-water separation tank 35 are connected to a position near the steam-water separation tank 35. In the steam / water separation tank 35, a shortcut for connecting the line L1-1 and the line L2-1 (consisting of an upper horizontal flow path 35up, a vertical flow path 35vp, and a lower horizontal flow path 35lp) is formed. Therefore, a water droplet enters the liquid level detection line L4 as in the state sucked by the straw. That is, as shown by the solid line arrow in FIG. 7A, the liquid in the air / water separation tank 35 is sucked up by the liquid level detection line L4, the full water sensor S is activated, and the full water is erroneously detected. There is a problem.

FIG. 8 is a schematic diagram showing an improvement measure 2 for preventing erroneous detection of full water caused by the liquid in the tank of the steam separation tank 35 being sucked up by the liquid level detection line L4. The improvement measure 2 changes the position of the line L2-1 which connects the steam-water separation tank 35 and the pressurization valve V2-1.
In the improvement measure 2, the position of the connector 42 for connecting the line L2-1, which is a part of the pressurization line L2, to the steam separation tank 35 is lowered so that the connector 42 communicates directly with the chamber 35CH. . Further, the lower lateral flow path 35 lp connected to the connector 42 in FIG. 7 is closed by a plug 43. The configuration of the liquid level detection line L4 is the same as that in FIG. 7, but the full water sensor S is lowered slightly from the position in FIG.

  FIG. 9 is a side view of the steam / water separation tank 35 shown in FIG. 8 and shows each connector for connecting the vacuum adsorption line L1, the pressurization line L2, and the liquid level detection line L4 to the steam / water separation tank 35. It is. 9 shows a connector 41 for connecting the vacuum adsorption line L1 to the steam-water separation tank 35, a connector 42 for connecting the pressurization line L2 to the steam-water separation tank 35, and a liquid level detection line L4 for steam-water separation. A connector 38L for connecting to the tank 35 and a suction / pressure port 35P for connecting the chamber 35CH and the ripple chamber 6 of the top ring 1 are shown. In FIG. 9, the chamber 35CH formed in the steam-water separation tank 35 is illustrated by a broken line. As shown in FIG. 9, the connector 42 for connecting the pressurization line L2 to the steam-water separation tank 35 is open to the chamber 35CH.

  As shown in FIGS. 8 and 9, the pressurization line L <b> 2 communicates directly with the chamber 35 </ b> CH via the connector 42. The vacuum suction line L1 communicates with the chamber 35CH via the upper lateral flow path 35up and the vertical flow path 35vp. That is, both the vacuum suction line L1 and the pressurization line L2 are connected to the chamber 35CH which is a large space. Therefore, when the substrate W is vacuum-sucked to the elastic film 4 (membrane) via the vacuum suction line L1 by opening the vacuum valve V2-2, the vacuum suction line L1 and a part of the pressurization line L2 The line L2-1 connecting the steam-water separation tank 35 and the pressurizing valve V2-1 communicates via the chamber 35CH. Since the chamber CH has a large space, the pressure sucked in the line L2-1 is lost when the line L2-1 which is a part of the pressurizing line L2 is not in the state sucked by the straw, and is separated from the vacuum suction line L1. Even during suction, there is no longer any liquid flow in the liquid level detection line L4 as shown in FIG. 7, and no water droplets enter the liquid level detection line L4. Accordingly, no liquid is sucked up in the liquid level detection line L4, and thus it is possible to prevent erroneous detection of full water.

1 Top ring 2 Top ring body (carrier)
3 Retainer ring 4 Elastic membrane (membrane)
4a Partition 5 Center chamber 6 Ripple chamber 7 Outer chamber 8 Edge chamber 9 Pressurizing chamber 11 Channel 12 Channel 13 Channel 14 Channel 16 Top ring shaft 18 Top ring head 21 Channel 23 Channel 24 Channel 25 Rotary joint 26 Flow path 30 Pressure adjusting unit 31 Vacuum source 35 Air / water separation tank 35CH Chamber 35lp Horizontal flow path 35P Suction / pressurization port 35up Horizontal flow path 35vp Vertical flow path 36 Liquid level gauge 37 Tube 38L Connector 38U Connector 41 Connector 42 Connector 43 Plug 101 Polishing pad 100a Table shaft 101 Polishing pad 101a Polishing surface 105 Polishing liquid supply mechanism 131 Vacuum source F1, F2, F3, F4, F5 Flow rate sensor L1 Vacuum adsorption line L1-1 Line L2 Pressure line L2-1 Line L3 Drainage line L4 Liquid level detection line 1, P2, P3, P4, P5 pressure sensor R1, R2, R3, R4, R5 pressure regulator S-full level sensor V2-1 pressure valve V2-2 vacuum valve VS vacuum pressure sensor

Claims (5)

An elastic membrane that forms a pressure chamber to which a fluid is supplied is provided, and the substrate is vacuum-adsorbed and held by communicating the pressure chamber with a vacuum source, and the pressure chamber communicates with a pressure adjusting unit that supplies pressure fluid. A substrate holding device comprising a top ring that presses the substrate against the polishing surface, and a steam / water separation tank provided in a vacuum adsorption line connecting the pressure chamber and the vacuum source,
The air / water separation tank includes a chamber that is a space for storing liquid therein, and a liquid that is provided outside the chamber and extends upward from a lower portion of the chamber and communicates with the chamber and is stored in the chamber. A liquid level detection line for detecting the liquid level, and a sensor for detecting the liquid level in the liquid level detection line and detecting that the chamber is full,
A vacuum line for connecting the pressure chamber and the vacuum source, and a pressure line for connecting the pressure chamber and the pressure adjusting unit are provided so as to pass through the chamber of the steam-water separator,
An upper end of the liquid level detection line is connected to a line that is a part of the pressurization line and connects the pressure adjusting unit and the chamber. The line connecting the pressure adjusting unit and the chamber includes an open / close valve,
The substrate holding apparatus according to claim 1, wherein an upper end of the liquid level detection line is connected to a downstream side of the opening / closing valve.   The substrate holding apparatus according to claim 1, wherein the liquid level detection line includes a tube, and the sensor includes a light projecting and receiving unit provided so as to sandwich the tube. The vacuum suction line is connected to the chamber via a connector provided in the line and a flow path formed in the steam / water separation tank,
4. The substrate holding apparatus according to claim 1, wherein the pressure line is directly connected to the chamber via a connector provided on the line. A substrate holding device according to any one of claims 1 to 4,
A polishing apparatus comprising: a polishing table that supports a polishing pad having a polishing surface.

Images