JP5115839B2 - Polishing equipment - Google Patents

Description

  The present invention relates to a polishing apparatus for polishing an object to be polished such as a semiconductor wafer or a glass substrate.

  A polishing apparatus used for polishing an object to be polished such as a semiconductor wafer (hereinafter referred to as a wafer) or a glass substrate is, for example, a polishing apparatus using a polishing pad having a smaller diameter than the wafer, or a polishing pad having a larger diameter than the wafer. A (conventional) polishing apparatus is known. In a polishing apparatus using a polishing pad having a diameter smaller than that of a wafer, polishing is performed while the polishing pad swings with respect to the wafer (see, for example, Patent Document 1). Therefore, like a polishing apparatus using a polishing pad having a diameter larger than that of the wafer, the entire surface of the wafer is not covered with the polishing pad, so that the back surface of the wafer is fixed to a chuck serving as a table, etc. It is necessary to perform polishing in a state where the wafer does not fall off from the chuck. Therefore, a method is used in which the back surface of the wafer is sucked and held by a negative pressure by using vacuum suction.

A wafer holding device used in such a polishing apparatus is configured to include, for example, a rotatable disk-shaped chuck and a retainer ring that supports a protruding portion of the polishing pad from the wafer. The back surface of the wafer comes into contact. The chuck upper surface is provided with a number of suction holes connected to a vacuum source. The back surface of the wafer is brought into contact with the upper surface of the chuck, and negative pressure is applied to the plurality of suction holes so that the back surface of the wafer is chucked. It is designed to be vacuum-adsorbed on the upper surface of the substrate. In this manner, the wafer is sucked and held by the holding device in a state where the back surface of the wafer is vacuum sucked on the upper surface of the chuck.
JP 2002-217141 A

  However, since the conventional retainer ring was more easily worn by polishing than the wafer held by suction on the upper surface of the chuck, the function of supporting the protruding portion of the polishing pad from the wafer was immediately reduced, and the vicinity of the edge of the wafer This was one of the causes for the deterioration of the polishing characteristics.

  The present invention has been made in view of such a problem, and an object of the present invention is to provide a polishing apparatus having improved polishing characteristics in the vicinity of an end portion of an object to be polished.

In order to achieve such an object, a polishing apparatus according to the present invention includes a holding device that holds an object to be polished, and a polishing member that can polish the object to be polished held by the holding device, and the polishing member In the polishing apparatus configured to perform the polishing of the object to be polished by relatively moving the polishing surface in contact with the object to be polished, the holding device includes a chuck portion that holds the object to be polished; A retainer that surrounds the periphery of the chuck portion and is disposed so as to be movable toward and away from the polishing member. The retainer has a guide surface that can contact the polishing surface of the polishing member. a biasing member that gives a biasing force to said retainer in a direction coming close to the polishing member, is configured with the retainer regardless of the biasing force and a retainer fixing portion for fixing at a predetermined position, the retail Fixing portion, in contact with guide position wherein the guide surface receives the biasing force on the polishing surface when the polishing surface of the polishing member is brought into contact with the object to be polished, to secure the retainer.

  In the above-mentioned invention, it is preferable that the holding device includes a retainer retracting portion that retracts the retainer from the guide position in a direction away from the polishing member against the biasing force. .

  Moreover, in the above-mentioned invention, it is preferable that the material of the retainer constituting the guide surface is the same as the material of the object to be polished.

  In the above-described invention, it is preferable that the holding device includes a rotation mechanism that rotates the retainer together with the chuck portion that holds the object to be polished.

  According to the present invention, it is possible to improve the polishing characteristics in the vicinity of the end of the object to be polished.

  Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings. A part of a CMP apparatus (chemical mechanical polishing apparatus) which is a typical example of the polishing apparatus according to the present invention is shown in FIG. The CMP apparatus C includes a cassette index unit, a wafer cleaning unit, and a polishing unit according to the polishing process. The polishing unit includes three polishing chambers and one polishing chamber provided in each section of the index table divided into four. In this embodiment, only one polishing chamber will be described.

  A polishing chamber 1 into which a workpiece W such as a glass substrate is carried from a transfer chamber is divided into four parts and is rotated and fed every 90 degrees by an operation of a stepping motor, a polishing arm 3, and a dressing device 4, a pad exchange base 5, and a surface shape measuring device 6 are disposed. Each section of the index table 2 is provided with a holding device 20 that sucks and holds a square plate-shaped workpiece W as an object to be polished from the back surface, and moves the workpiece W to the polishing chamber 1 by sucking and holding it. .

  The polishing arm 3 is configured to be turnable in the horizontal direction with respect to the index table 2 and to be vertically movable in the vertical direction. A polishing head 10 is rotatably attached to the oscillating end of the polishing arm 3. The polishing head 10 has a polishing member 11 having a polishing pad 12 attached to the lower surface side as shown in FIG. Is detachably held. A polishing surface 13 is formed on the surface (lower surface) of the polishing pad 12 to be in contact with the surface (surface to be polished) of the workpiece W for polishing.

  Such a polishing head 10 is rotationally driven by a rotation driving mechanism (not shown) disposed in the polishing arm 3 and is configured to be rotatable at high speed in a horizontal plane. Further, the polishing head 10 is driven to rotate in a direction opposite to the rotation direction of the chuck portion 31 and the retainer 36 constituting the holding device 20 described above, and the polishing head 10 is relatively moved at high speed while contacting the polishing surface 13 of the polishing pad 12 with the workpiece W. By rotating, the surface (surface to be polished) of the workpiece W is polished flat. Further, as shown in FIG. 1, the polishing head 10 can be moved above the holding device 20, the dressing device 4, the pad changer 5, and the surface shape measuring device 6 by the rotation of the polishing arm 3. It is like that.

  The dressing device 4 shown in FIG. 1 is a device that corrects clogging or unevenness of the polishing pad 12 caused by polishing the workpiece W (dressing, sharpening), and detailed illustration is omitted. And a disk having diamond abrasive grains or the like fixed on its surface and a rotatable disk, and a cleaning nozzle for cleaning the polishing pad with pure water by spraying pure water onto the surface of the dressed polishing pad. The pad changer 5 is a device for exchanging the used polishing pad 12 with a new one, and the surface shape measuring device 6 is a device for measuring the surface shape of the polishing pad 12.

  As shown in FIG. 2, the holding device 20 is disposed so as to surround the base portion 26 connected to the rotation shaft 21, the chuck portion 31 attached to the upper surface of the base portion 26, and the periphery of the chuck portion 31. The retainer 36, a retainer support 41 that supports the retainer 36 so as to be movable toward and away from the polishing member 11 (that is, vertically), and a side portion of the retainer support 41 are rotatably supported. The rotation support part 61 is mainly configured.

  The base portion 26 is formed in a substantially disc shape using a material having high rigidity such as stainless steel (for example, SUS316) or ceramic, and is horizontally attached to the upper end portion of the rotating shaft 21 by fixing means such as screws. A water channel 27 for supplying cooling chiller water or water sealing pure water to the chuck unit 31 is formed in the base unit 26, and a water supply passage 23 formed in the rotary shaft 21 is provided on the upstream side. Via an open / close solenoid valve and a pure water supply source (not shown).

  Similar to the base portion 26, the chuck portion 31 is formed in a rectangular parallelepiped shape having a disk-like flange portion 31a using a material having high rigidity such as stainless steel (for example, SUS316), ceramic, etc. It is attached to the upper surface of the base part 26 by the fixing means. The chuck portion 31 is supported by the index table 2 so as to be rotatable in a horizontal plane via the base portion 26 and the rotating shaft 21, and driving means such as an electric motor or an air motor (not shown) disposed inside the index table 2. Is rotated at high speed. The flat cross-sectional shape of the upper portion of the chuck portion 31 is a square according to the shape of the workpiece W.

  A plurality of suction holes (not shown) are formed on the upper surface of the chuck portion 31, and the back surface (lower surface) of the workpiece W is brought into contact with the upper surface of the chuck portion 31 to apply a negative pressure to each suction hole. Thus, the back surface of the work W is vacuum-sucked on the upper surface of the chuck portion 31. Thus, the workpiece W is sucked and held on the chuck portion 31 of the holding device 20 in a state where the back surface of the workpiece W is vacuum-sucked on the upper surface of the chuck portion 31. The suction hole is connected to an air operated valve, a vacuum source, and an air source (not shown) via an suction air passage (not shown) formed in the chuck portion 31 and an air passage 22 formed in the rotary shaft 21. ing.

  As shown in FIGS. 2 and 3, the retainer 36 is formed so as to be able to contact the polishing surface 13 of the polishing pad 12, and to extend downward from the guide portion 38, and is supported by the retainer support portion 41. And a carriage 39. The guide portion 38 is formed in a frame plate shape surrounding the upper side of the chuck portion 31, and a guide surface 37 with which the polishing surface 13 of the polishing pad 12 abuts is formed on the upper surface of the guide portion 38. Thereby, as shown in FIG. 2, the retainer 36 (guide portion 38) supports the protruding portion of the polishing pad 12 from the workpiece W, and further restricts the movement of the workpiece W on the extended surface of the upper surface of the chuck portion 31. It can be done.

  The material of the guide portion 38 is the same material as that of the workpiece W. By doing so, the amount of wear of the guide portion 38 becomes substantially the same as the amount of polishing of the workpiece W, so that polishing near the end of the workpiece W can be more stably improved and the polishing characteristics of the portion can be improved. Become.

  As shown in FIG. 3, the carriage 39 is formed in a bottomed cylindrical shape having an opening on the lower side, and is coupled to the lower surface side of the guide portion 38. The carriage 39 is accommodated in the sub-housing 45 of the retainer support portion 41 in a state of being slidably fitted to the head of the support member 49 constituting the retainer support portion 41 in the vertical direction. The retainer 36 is supported by the retainer support portion 41 so as to be movable in the vertical direction, that is, in the direction approaching and separating from the polishing member 11.

  The retainer support portion 41 includes a main housing 42, a sub housing 45 accommodated in the main housing 42, and a support member 49 accommodated in the sub housing 45. The main housing 42 is formed in a frame shape surrounding the upper periphery of the chuck portion 31, and is attached to the upper surface of the flange portion 31a of the chuck portion 31 by fixing means such as screws. Accordingly, the retainer support portion 41 and the retainer 36 can be rotated together with the chuck portion 31 that holds the workpiece W. In this case, since the retainer 36 rotates integrally with the workpiece W, the state of wear of the guide portion 38 in the retainer 36 is close to the state of polishing of the workpiece W. Therefore, the polishing in the vicinity of the end portion of the workpiece W is performed. However, it becomes possible to improve the polishing characteristics of the part more stably.

  The sub-housing 45 is formed in a bottomed cylindrical shape having an opening on the upper side, and is accommodated in an accommodation hole formed in the main housing 42. The carriage 39 and the support member 49 of the retainer 36 are accommodated in the sub housing 45 as described above. A plurality of carriages 39 of the retainer 36 are provided along the guide portion 38, and the sub-housing 45 and the support member 49 are provided according to the number of carriages 39.

  The support member 49 is formed in a cylindrical shape into which the center pin 50 can be inserted, and is fixed to the inner bottom portion of the sub housing 45. The outer peripheral portion of the head portion of the support member 49 has a diameter slightly smaller than the inner diameter of the carriage 39, and the carriage 39 is slidably fitted in the vertical direction as described above. The inner peripheral portion of the head of the support member 49 has a diameter slightly larger than the diameter of the center pin 50, so that the center pin 50 can slide in the vertical direction inside the head of the support member 49. Inserted. In addition, spherical ball members 51 are respectively disposed in the plurality of horizontal holes formed in the head portion of the support member 49, and each ball member 51 always has a tapered portion formed at the tip of the center pin 50. Each is in sliding contact.

  The body portion of the support member 49 has an inner diameter and an outer diameter larger than the head portion, and a biasing spring 48 is attached to the outer peripheral side. The urging spring 48 is a compression coil spring, and an upper end portion of the urging spring 48 abuts on a lower portion of the carriage 39 of the retainer 36, and a lower end portion abuts on a leg portion of the support member 49 so that the retainer 36 moves upward. A biasing force is applied to the retainer 36 in the moving direction, that is, in a direction in which the retainer 36 is close to the polishing member 11.

  The lower part of the carriage 39 of the retainer 36 has an outer diameter slightly smaller than the inner diameter of the sub-housing 45, while the upper part of the carriage 39 has a smaller outer diameter than the lower part of the carriage 39. A first air supply space 55 is formed between the upper portion of the first housing and the sub housing 45. The first air supply space 55 includes a first air supply passage 46 formed in the sub housing 45, a first rotation side air passage 43 formed in the main housing 42, and a first fixed formed in the rotation support portion 61. The side air passage 63 and the joint J are connected to an electropneumatic regulator (not shown) and an air source via a pipe (not shown) connected to the joint J.

  A lock release spring 52 is attached to a space formed between the body portion of the support member 49 and the center pin 50. The unlocking spring 52 is a compression coil spring. The upper end of the unlocking spring 52 abuts on the inside of the support member 49, the lower end abuts on the base end of the center pin 50, and the center pin 50 moves downward. A biasing force is applied to the center pin 50 in a direction (in a direction in which a lock by a ball member 51 described later is released).

  A recess is formed at the base end of the center pin 50 facing the bottom of the sub housing 45, and a second end is formed between the base end of the center pin 50 where the recess is formed and the sub housing 45. An air supply space 56 is formed. The second air supply space 56 includes a second air supply passage 47 formed in the sub housing 45, a second rotation side air passage 44 formed in the main housing 42, and a second fixed formed in the rotation support portion 61. It is connected to an electropneumatic regulator and an air source (not shown) through a side air passage 64 and a joint (not shown) and a pipe (not shown) connected to the joint.

  The rotation support portion 61 includes a main body portion 62, a bearing 65 and a mechanical seal 67 attached to the main body portion 62. The main body 62 is formed in a frame shape surrounding the periphery of the main housing 42, and is attached and fixed to a housing (not shown) fixed on the index table 2 by fixing means such as screws. Bearings 65 and 65 are vertically attached to the inside of the main body 62, and the main body 62 rotatably supports the flange portion 42 a of the main housing 42 via the bearings 65 and 65. Note that seal members 66 are attached to the inner upper and lower ends of the main body 62, respectively.

  Mechanical seals 67 and 68 are attached vertically to the groove portion of the main body portion 62 in which the flange portion 42a of the main housing 42 is accommodated. The upper mechanical seal 67 is disposed so as to face the upper surface of the flange portion 42a, and is formed in the main housing 42 of the rotatable retainer support portion 41 (extending to the flange portion 42a). And the first fixed-side air passage 63 formed in the fixed-side main body 62. On the other hand, the lower mechanical seal 68 is disposed so as to face the lower surface of the flange portion 42a, and is formed in the second rotation-side air passage 44 formed in the main housing 42 (extending to the flange portion 42a) and the main body portion 62. The second fixed side air passage 64 formed is connected.

  In the CMP apparatus C having such a configuration, first, an unprocessed workpiece W is placed on the upper surface of the chuck portion 31 of the holding device 20 that stands by in the transfer chamber by a transfer apparatus (not shown). At this time, compressed air is supplied from the air source (not shown) to the first air supply space 55 via the first fixed air passage 63, the first rotation air passage 43, and the first air supply passage 46, 1 Using the air pressure supplied to the air supply space 55, the retainer 36 is positioned at a retracted position retracted downward so as to separate from the polishing member 11 (against the biasing force from the biasing spring 48). However, when the unprocessed workpiece W is placed on the upper surface of the chuck portion 31, the compressed air is discharged from the first air supply space 55 through the first air supply passage 46 and the like, and the retainer 36 is biased by the biasing spring. In response to the urging force from 48, it rises in the direction approaching the polishing member 11.

  When the unprocessed workpiece W is placed on the upper surface of the chuck portion 31, the workpiece W is sucked and held by the chuck portion 31 of the holding device 20 using vacuum suction, and in this state, the holding device 20 is attached to the index table 2. It is sent to the polishing chamber 1 by rotation. Subsequently, the polishing head 3 is moved above the holding device 20 by the operation of the polishing arm 3, and the polishing head 10 is moved to a polishing height at which the polishing surface 13 of the polishing pad 12 contacts the workpiece W as shown in FIG. Descend.

  At this time, the retainer 36 receives the urging force from the urging spring 48 and rises to a height exceeding the upper surface of the work W attracted and held by the chuck portion 31, but the polishing head 10 reaches the above-described polishing height. When lowered, the guide surface 37 of the retainer 36 is lowered by the weight of the polishing head 10 and the polishing member 11 in a state where the guide surface 37 of the retainer 36 is in contact with the polishing surface 13 of the polishing pad 12, as shown by a two-dot chain line in FIG. 37 are arranged on the same surface as the upper surface of the workpiece W (that is, when the polishing surface 13 of the polishing pad 12 is brought into contact with the workpiece W, the guide surface 37 of the retainer 36 receives the urging force from the urging spring 48. It moves to the guide position (abutting the polishing surface 13).

  When the retainer 36 moves to the above-described guide position, the retainer 36 is compressed into the second air supply space 56 from the air source (not shown) via the second fixed side air passage 64, the second rotation side air passage 44, and the second air supply passage 47. Air is supplied, and the center pin 50 is raised (against the urging force from the lock release spring 52) using the air pressure supplied to the second air supply space 56. At this time, the plurality of ball members 51 slidably in contact with the tapered portion of the center pin 50 are respectively pressed laterally by the rising center pin 50 and abut against the carriage 39 of the retainer 36 and receive a pressing force from the center pin 50. Thus, each ball member 51 presses the carriage 39 in the lateral direction, so that the retainer 36 is locked and fixed at the guide position regardless of the urging force of the urging spring 48.

  With the retainer 36 fixed in the guide position in this way, the polishing surface 12 of the polishing pad 12 is rotated and held by the chuck portion 31 while rotating the polishing pad 12 (polishing member 11) together with the polishing head 10. The polishing process is performed in contact with the upper surface. At this time, the polishing pad 12 reciprocates (oscillates) in the horizontal direction with respect to the workpiece W while rotating, so that the entire surface of the workpiece W is polished flat. Is done. At this time, an abrasive (slurry) is supplied between the polishing pad 12 and the workpiece W. Further, when the polishing pad 12 polishes the vicinity of the end portion of the workpiece W, the retainer 36 fixed at the guide position supports the protruding portion of the polishing pad 12 from the workpiece W.

  When the polishing of the workpiece W is completed, the compressed air is discharged from the second air supply space 56 through the second air supply passage 47 and the like, and the center pin 50 is lowered by receiving a biasing force from the lock release spring 52. At this time, the plurality of ball members 51 that have been in contact with the carriage 39 of the retainer 36 are separated from the carriage 39 as the center pin 50 is lowered, and the lock of the retainer 36 by the ball member 51 is released.

  Subsequently, compressed air is supplied to the first air supply space 55 from the air source (not shown) via the first fixed-side air passage 63, the first rotation-side air passage 43, and the first air supply passage 46, and the first air Using the air pressure supplied to the supply space 55, the retainer 36 moves downward to move away from the polishing member 11 (against the biasing force from the biasing spring 48) and moves to the retracted position. With the retainer 36 thus moved to the retracted position, the polishing head 10 is raised above the holding device 20, and the workpiece W that has been subjected to the polishing process is washed and carried out, and the upper surface of the chuck portion 31 is cleaned. . Thereby, cleaning etc. of the upper surface of the chuck part 31 can be easily performed.

  When the polishing of the workpiece W is completed a predetermined number of times, the polishing arm 3 is operated to move the polishing head 10 from above the holding device 20 to above the dressing device 4, where the polishing pad 12 is dressed. After the dressing is completed, the polishing arm 10 is moved from above the dressing device 4 to above the surface shape measuring device 6 by the operation of the polishing arm 3, and the surface shape (groove depth, pad thickness, etc.) of the polishing pad 12 is measured there. Is done.

  If the pad thickness or groove depth is less than the specified value, the polishing head 10 is moved above the pad changer 5 to replace the polishing pad 12 (polishing member 11). Is moved above the holding device 20, and the workpiece W is newly polished. On the other hand, if the pad thickness or groove depth is equal to or greater than the prescribed value, the polishing head 10 is returned to above the holding device 20 and polishing of a new workpiece W is started.

  According to the CMP apparatus C configured as described above, the urging spring 48 that applies a urging force to the retainer 36 in the direction in which the retainer 36 approaches the polishing member 11 and the retainer 36 in a predetermined position regardless of the urging force. Since the center pin 50 and the ball member 51 are fixed to each other, the height of the guide surface 37 of the retainer 36 can be made equal to the height of the upper surface of the work W according to wear of the retainer 36. Thus, since the retainer 36 can stably support the protruding portion of the polishing pad 12 from the workpiece W, the polishing characteristics in the vicinity of the end portion of the workpiece W can be improved.

  Specifically, when the polishing surface 13 of the polishing pad 12 is brought into contact with the workpiece W, the guide surface 37 of the retainer 36 receives a biasing force from the biasing spring 48 and is in a guide position where the polishing surface 13 contacts the polishing surface 13. It is preferable to fix the retainer 36. In this way, the height of the guide surface 37 can be made the same as the height of the upper surface of the work W with reference to the polishing surface 13 of the polishing pad 12, so that the height of the retainer 36 is increased. No measuring instrument is required. Further, even if the retainer 36 is worn, the height of the guide surface 37 can be made the same as the height of the upper surface of the workpiece W by using the biasing force from the biasing spring 48. Therefore, the retainer 36 is used to the limit. Thus, the replacement frequency of the retainer 36 can be reduced.

  In the above-described embodiment, the polishing apparatus in which the workpiece W is attracted and held by the holding device 20 below the polishing member 11 has been described. However, the present invention is not limited to this, and the present invention holds the workpiece W above the polishing member. The present invention can also be used for a polishing apparatus having a configuration in which a workpiece is adsorbed and held by the apparatus.

  Further, in the above-described embodiment, the workpiece W that is an object to be polished is formed in a square plate shape like a glass substrate, but is not limited thereto, and is formed in a disk shape like a semiconductor wafer. It may be.

1 is a front view of a CMP apparatus which is an example of a polishing apparatus according to the present invention. It is a front sectional view of a holding device. It is an enlarged view which shows the retainer vicinity in a holding | maintenance apparatus.

Explanation of symbols

C CMP equipment (polishing equipment) W Workpiece (object to be polished)
DESCRIPTION OF SYMBOLS 10 Polishing head 11 Polishing member 12 Polishing pad 13 Polishing surface 20 Holding device 31 Chuck part 36 Retainer 37 Guide surface 41 Retainer support part (retainer retracting part) 48 Biasing spring (biasing member)
50 Center pin (retainer fixing part) 51 Ball member (retainer fixing part)
61 Rotation support

Claims (4)

A holding device for holding an object to be polished; and a polishing member capable of polishing the object to be polished held by the holding device, wherein the polishing surface of the polishing member is relatively moved while being in contact with the object to be polished. In a polishing apparatus configured to polish the object to be polished,
The holding device includes a chuck portion that holds the object to be polished,
A retainer having a guide surface that surrounds the periphery of the chuck portion and is movably disposed in a direction approaching and separating from the polishing member and capable of contacting the polishing surface of the polishing member;
An urging member that applies an urging force to the retainer in a direction in which the retainer approaches the polishing member;
A retainer fixing portion for fixing the retainer at a predetermined position regardless of the biasing force ;
The retainer fixing portion fixes the retainer at a guide position where the guide surface comes into contact with the polishing surface by receiving the urging force when the polishing surface of the polishing member is brought into contact with the object to be polished. A polishing apparatus characterized by the above. The holding device according to claim 1, characterized in that it is configured with a retainer retracting unit for retracting the direction away with respect to the polishing member from the guide position to the retainer against the biasing force Polishing equipment. The polishing apparatus according to claim 1 or 2 , wherein a material of the retainer constituting the guide surface is the same as a material of the object to be polished. The said holding | maintenance apparatus has a rotation mechanism which rotates the said retainer with the said chuck | zipper part holding the said to-be-polished object, It is comprised, It is any one of Claims 1-3 characterized by the above-mentioned. Polishing equipment.

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