JP2005057086A - Device and method for loading semiconductor wafer - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To set the deviation of a wafer from a chuck to an allowable quantity or less by centering the wafer without being influenced by fitting errors of the chuck and a retainer. <P>SOLUTION: A centering pin 22 approaches the side face of the semiconductor wafer 30 mounted on a top plate 21 and side face of the chuck 11 without interfering in the retainer 12, and stops at a position corresponding to the diameter of the chuck 11. Since there is a centering deviation between the center axis 11c of the chuck 11 and the center axis 21c of the top plate 21, the top plate 21 is moved in the moving direction of the centering pin 22 together with an upper base 26 when the centering pin 22 is abutted on the side face of the semiconductor wafer 30 on the top plate 21. When the centering pin 22 stops on the position corresponding to the diameter of the chuck 11, the center axis 21c of the top plate 21 almost coincides with the center axis 11c of the chuck 11, and the centering deviation (d) can be made almost zero. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a loading apparatus and a loading method for adsorbing and loading a semiconductor wafer such as a silicon wafer on a chuck, and more particularly to an apparatus and method suitable for loading a semiconductor wafer onto a polishing head of a single wafer type polishing apparatus. It is about.

  One of the processes for manufacturing a semiconductor wafer such as a silicon wafer is a polishing process for polishing the surface of the semiconductor wafer into a mirror surface.

  In the polishing step, the surface of the semiconductor wafer is polished by a polishing apparatus.

  The polishing apparatus includes a batch type polishing apparatus that performs polishing by adsorbing a plurality of semiconductor wafers with one polishing head, and a single wafer type that performs polishing by adsorbing one semiconductor wafer with one polishing head. There is a polishing device.

  A polishing head of a single wafer polishing apparatus includes a chuck (polishing plate) having the same diameter as that of the semiconductor wafer. The surface of the semiconductor wafer is polished by adsorbing the semiconductor wafer with the chuck of the polishing head, pressing the polishing head against the polishing cloth on the surface plate, and rotating the polishing head and the surface plate relatively reversely.

  The polishing apparatus is provided with a loading mechanism for loading the semiconductor wafer carried from the previous process by adsorbing it to the chuck of the polishing head.

  The polishing process includes a plurality of rough polishing processes and a final polishing process, and the surface of the semiconductor wafer is polished stepwise. For this reason, the polishing apparatus includes a stage for performing rough polishing and a stage for performing final polishing.

  The semiconductor wafer loaded on the polishing head by the loading mechanism is sent to a rough polishing stage for rough polishing, and then sent to a final polishing stage for final polishing.

  In each stage, a load is applied to the polishing head from above, and the semiconductor wafer is polished while being pressed against the surface of the polishing cloth. During polishing, an abrasive liquid (slurry) is flowed to the contact surface of the semiconductor wafer on the polishing cloth. Since the polishing cloth is elastic, a quality defect that impairs the flatness of the semiconductor wafer called “surface sagging” occurs at a portion corresponding to the outer peripheral side of the chuck on the surface of the semiconductor wafer.

  Here, “sagging” means that the edge of the semiconductor wafer is rounded, and the surface on the outer peripheral side of the semiconductor wafer is tilted and scraped, and the flatness of the semiconductor wafer is impaired.

  FIG. 4A shows a state where the semiconductor wafer 30 is adsorbed by the chuck 11 of the single wafer type polishing head.

  In order to prevent surface sagging, a retainer 12 formed in an annular shape is provided on the outer periphery of the chuck 11 of the single-wafer polishing head so as to be separated from the side surface of the chuck 11 by a predetermined distance. When the semiconductor wafer 30 is pressed against the polishing cloth, the retainer 12 is also pressed against the polishing cloth at the same time, thereby preventing the surface sagging.

  For this reason, the retainer 12 is arranged so that the lower surface thereof is at the same position as the lower surface of the semiconductor wafer 30 adsorbed by the chuck 11.

  Here, the components of the abrasive liquid used in the stage for rough polishing and the abrasive liquid used in the stage for final polishing are different. As the abrasive liquid used in the stage for rough polishing, one that easily aggregates on the surface of the semiconductor wafer is used, and as the abrasive liquid used in the stage for finishing, one that does not easily aggregate on the surface of the semiconductor wafer is used. If the abrasive liquid used in the stage for rough polishing is transported to the stage for final polishing, it may agglomerate on the surface of the semiconductor wafer and scratch the surface of the semiconductor wafer, affecting the quality of the final polishing. is there. For this reason, the purpose of finish polishing cannot be achieved.

  When rough polishing is performed on the stage for rough polishing, as shown in FIG. 4A, the abrasive liquid for rough polishing accumulates in the gap 40 between the semiconductor wafer 30 adsorbed by the chuck 11 and the retainer 12. End up. The polishing head is sent from the stage for rough polishing to the stage for final polishing while the lower surface of the retainer 12 is in the same position as the lower surface of the semiconductor wafer 30 attracted by the chuck 11. For this reason, the abrasive liquid for rough polishing is sent to the stage for final polishing in a state where it is stored in the gap 40, and when the semiconductor wafer is subjected to final polishing in the stage for final polishing in this state, There was a possibility that the surface of the semiconductor wafer might be scratched by the abrasive liquid for rough polishing.

  Therefore, the present inventors move the retainer 12 relatively upward with respect to the chuck 11 to discharge the abrasive liquid for rough polishing from the gap 40 and place it on the stage for final polishing. A patent application has already been filed for an invention that prevents the abrasive liquid from being brought in (Japanese Patent Application No. 2002-282549). This application has not been published yet and is not a known technique.

  By the way, in recent years, there is a demand for cutting out more chips from one semiconductor wafer. In order to meet this demand, it is necessary to cut chips with a high yield even at the outer peripheral portion near the edge (side surface) of the semiconductor wafer, and the outer peripheral portion is required to have the same level of flatness as the inner peripheral portion.

  FIG. 4A shows the diameters φD1, D2 and D3 of each part of the chuck 11, the diameters φD4 and D5 of each part of the semiconductor wafer 30, and the inner diameter φD6 of the retainer 12 formed in an annular shape.

  The chuck 11 has a diameter of φD 3, and a seal portion 11 d having a width of (D 2 −D 1) / 2 having an inner diameter of φD 1 and an outer diameter of φD 2 is provided on the lower surface (semiconductor wafer suction surface) of the chuck 11. It is formed along the direction. A plurality of pins 11f and grooves 11e are formed on the lower surface of the chuck 11 and inside the seal portion 11d. A hole for evacuation is formed in the groove 11e. In order to improve the flatness of the outer peripheral portion of the semiconductor wafer 30, it is desirable to dispose the seal portion 11d on the outer periphery of the chuck 11 as much as possible.

  The diameter of the semiconductor wafer 30 is φD5, and the diameter of the non-chamfered portion is φD4. Therefore, the length in the diameter direction of the chamfered portion 30a is (D5−D4) / 2.

  The size of the gap 40 between the semiconductor wafer 30 attracted to the chuck 11 and the retainer 12 is represented by (D6−D5) / 2.

  When the chuck 11 sucks the semiconductor wafer 30, it is desirable that the center of the chuck 11 and the center of the semiconductor wafer 30 coincide with each other.

  If the center of the chuck 11 and the center of the semiconductor wafer 30 are deviated, the size of the gap 40 becomes uneven in the circumferential direction, and the effect of preventing the surface sag by the retainer 12 varies in the circumferential direction. For this reason, the flatness of the outer peripheral part of the semiconductor wafer 30 varies.

  If the center of the chuck 11 and the center of the semiconductor wafer 30 are shifted, a vacuum leak occurs at the outer periphery of the semiconductor wafer 30 and the abrasive liquid is sucked into the groove 11e, generating dimples and generating an outer periphery of the semiconductor wafer 30. The flatness of the deteriorates.

  The allowable deviation of the center of the semiconductor wafer 30 with respect to the center of the chuck 11 is represented by (D4−D1) / 2. When the suction position deviation exceeding the allowable displacement occurs, the chamfered portion 30a of the semiconductor wafer 30 is positioned in the groove 11e as shown in FIG. 4B, and the lower surface of the chuck 11 and the semiconductor wafer 30 are separated. A gap E is formed between them, and a vacuum leak or suction of the abrasive liquid occurs.

  There are the following conventional techniques for preventing the deviation of the center of the semiconductor wafer 30 from the center of the chuck 11. The process of making the center of the semiconductor wafer 30 coincide with the center of the chuck 11 is referred to as “centering”.

(Prior art 1)
The polishing apparatus shown in FIG. 5 is already commercially available.

  That is, as shown in FIG. 5A, the polishing apparatus moves the semiconductor head by moving the polishing head provided with the chuck 11, the top plate 21 on which the semiconductor wafer 30 is placed, and the semiconductor wafer 30 toward the center. The loading mechanism is provided with centering pins 22 that come into contact with the side surfaces of the wafer 30.

  The amount of misalignment between the center axis 21c of the top plate 21 and the center axis 11c of the chuck 11 is assumed to be d.

  As shown in FIG. 5B, when the centering pin 22 moves in the center direction A of the semiconductor wafer 30, the centering pin 22 contacts the side surface of the semiconductor wafer 30. Thereby, the deviation of the semiconductor wafer 30 with respect to the top plate 21 is corrected.

  Next, the chuck 11 is lowered as shown by an arrow B in FIG. 5C, and the top plate 21 is raised as shown by an arrow C. As a result, the upper surface of the semiconductor wafer 30 contacts the lower surface of the chuck 11. In this state, the lower surface of the chuck 11 is evacuated and the semiconductor wafer 30 is attracted to the chuck 11.

(Prior art 2)
The following Patent Documents 1 and 2 describe a technique for performing centering that makes the center of the semiconductor wafer 30 coincide with the center of the chuck 11 with the retainer 12 as a reference. Patent Document 1 describes a technique for performing centering by fitting the outer periphery of a retainer to a guide pin on the loading mechanism side. Patent Document 2 describes a technique for performing centering by fitting a ring having a floating structure to the outer peripheral portion of the lower surface of the retainer.
JP-A-10-172930 JP 2000-176827 A

  According to the prior art 1, although the deviation of the semiconductor wafer 30 with respect to the top plate 21 is corrected, the misalignment itself (center misalignment amount d) between the center axis 11c of the chuck 11 and the center axis 21c of the top plate 21 is not corrected. . For this reason, there is a limit to the centering, and when the chuck 11 attracts the semiconductor wafer 30, it is inevitable that the deviation of the semiconductor wafer 30 with respect to the chuck 11 is larger than the deviation tolerance (FIG. 4A).

  Prior art 2 performs centering with the retainer 12 as a reference. However, since the chuck 11 has an attachment error and the retainer 12 also has an attachment error, the accuracy of centering of the semiconductor wafer 30 is affected by the attachment accuracy of the chuck 11 and the retainer 12. For this reason, it is inevitable that the deviation of the semiconductor wafer 30 with respect to the chuck 11 is larger than the deviation tolerance (FIG. 4A). Although it is conceivable to increase the accuracy of the attachment parts of the chuck 11 and the retainer 12, this causes an increase in the manufacturing cost of the apparatus.

  The present invention has been made in view of such a situation, and it is a solution to improve the flatness of the outer peripheral portion of the semiconductor wafer by accurately adsorbing the semiconductor wafer so that the deviation of the semiconductor wafer relative to the chuck is less than the allowable deviation. It is what. Another object of the present invention is to reduce the manufacturing cost of the apparatus by enabling centering without being affected by the mounting error of the chuck and the retainer.

The first invention is
A loading mechanism provided with a plate on which the semiconductor wafer is placed, a centering member that moves toward the side of the semiconductor wafer by moving in the center direction of the semiconductor wafer, and holds the semiconductor wafer on the plate to hold the semiconductor wafer In a semiconductor wafer loading apparatus comprising a chuck for loading
A centering member provided to be accessible to both the side surface of the chuck and the side surface of the semiconductor wafer on the plate;
And a plate moving mechanism that moves the plate in the moving direction of the centering member by contacting the side surface of the semiconductor wafer on the plate with the centering member.

The second invention is
A loading mechanism provided with a plate on which a semiconductor wafer is placed, and a centering member that moves in the direction of the center of the semiconductor wafer so as to be close to the side surface of the semiconductor wafer; In a semiconductor wafer loading apparatus comprising: a chuck for loading a wafer; and a polishing head provided with a retainer disposed at a predetermined distance from a side surface of the chuck.
A retainer moving mechanism for moving the retainer relative to the chuck so that the centering member can approach the side surface of the chuck;
A centering member provided to be accessible to both the side surface of the chuck and the side surface of the semiconductor wafer on the plate;
And a plate moving mechanism for moving the plate in the moving direction of the centering member by contacting the side surface of the semiconductor wafer on the plate with the centering member.

The third invention is
In the semiconductor wafer loading method of loading the semiconductor wafer by gripping the semiconductor wafer on the plate with a chuck,
Moving the chuck relative to the plate to a position where the chuck can grip the semiconductor wafer; and
Moving the centering member toward the center of the semiconductor wafer to bring the centering member into close proximity to both the side surface of the chuck and the side surface of the semiconductor wafer on the plate;
Moving the plate in the direction of movement of the centering member by bringing the centering member into contact with the side surface of the semiconductor wafer on the plate;
And holding the semiconductor wafer on the plate with a chuck and loading the semiconductor wafer.

The fourth invention is
In the semiconductor wafer loading method of loading the semiconductor wafer by gripping the semiconductor wafer on the plate with the chuck of the polishing head,
Moving the retainer relative to the chuck so that the centering member can approach the side surface of the chuck;
Moving the chuck relative to the plate to a position where the chuck can grip the semiconductor wafer; and
Moving the centering member toward the center of the semiconductor wafer to bring the centering member into close proximity to both the side surface of the chuck and the side surface of the semiconductor wafer on the plate;
Moving the plate in the direction of movement of the centering member by bringing the centering member into contact with the side surface of the semiconductor wafer on the plate;
And holding the semiconductor wafer on the plate with a chuck and loading the semiconductor wafer.

  In the loading apparatus of the second invention and the loading method of the fourth invention, the semiconductor wafer 30 is loaded as follows.

  First, the unpolished semiconductor wafer 30 is placed on the top plate 21 of the loading mechanism 20 shown in FIG.

  The state at this time is shown in FIG. Here, it is assumed that there is a misalignment of a misalignment amount d between the center axis 11 c of the chuck 11 and the center axis 21 c of the top plate 21. Due to the retainer moving mechanism, the retainer 12 is positioned relatively above the chuck 11, and the distance between the lower surface of the chuck 11 and the lower surface of the retainer 12 is f2.

  Next, the polishing head cylinder is driven, and the polishing head 10 is lowered as indicated by an arrow B in FIG.

  Next, as shown in FIG. 2C, the six centering pins 22 are simultaneously moved in the center direction A of the semiconductor wafer 30 on the top plate 21.

  Next, the cylinder 23 is driven and the top plate 21 is raised. In this manner, the chuck 11 is moved downward relative to the top plate 21 to a position where the semiconductor wafer 30 on the top plate 21 can be sucked. At this time, the distance between the upper surface of the semiconductor wafer 30 and the upper end of the centering pin 22 is f1.

  Since the relationship f2> f1 is established, the centering pin 22 can approach both the side surface of the semiconductor wafer 30 and the side surface of the chuck 12 on the top plate 21 without interfering with the retainer 12.

  The centering pin 22 approaches the side surface of the chuck 11, and the centering pin 22 stops at a position corresponding to the diameter of the chuck 11 (the closest approach distance D 5 + α (the diameter of the semiconductor wafer 30 + α)).

  Since there is a misalignment between the center axis 11 c of the chuck 11 and the center axis 21 c of the top plate 21, the centering pin 22 contacts the side surface of the chuck 11. When the centering pin 22 comes into contact with the side surface of the chuck 11, the top plate 21 moves in the moving direction of the centering pin 22 together with the upper base 26 until the centering pin 22 stops thereafter. Therefore, when the centering pin 22 stops at a position corresponding to the diameter of the chuck 11 (the closest distance D5 + α (the diameter of the semiconductor wafer 30 + α)), the center axis 21c of the top plate 21 is substantially equal to the center axis 11c of the chuck 11. In addition, the misalignment amount d can be made substantially zero.

  The central axis 21 c of the top plate 21 coincides with the central axis 11 c of the chuck 11, and the vacuum pump is driven and the semiconductor wafer 30 is attracted to the chuck 11 with the misalignment amount being zero. For this reason, the deviation of the semiconductor wafer 30 with respect to the chuck 11 can be made equal to or less than the allowable deviation ((D4−D1) / 2) shown in FIG.

  When the semiconductor wafer 30 is loaded on the polishing head 10, the cylinder 23 is driven and the top ring 21 is lowered to the original retracted position. Further, the centering pin 22 moves to the original retracted position.

  According to the present invention, since the centering is performed with reference to the chuck 11, the semiconductor wafer 30 can be attracted to the chuck 11 with high accuracy, and the displacement of the semiconductor wafer 30 with respect to the chuck 11 is allowed to be displaced ((D 4 -D1) / 2) or less. For this reason, the flatness of the outer peripheral portion of the semiconductor wafer 30 is improved. In addition, according to the present embodiment, since centering is performed with reference to the chuck 11, the centering is performed without being affected by mounting errors of the chuck and the retainer. For this reason, the accuracy of the attachment parts can be allowed to a low level, and the manufacturing cost of the apparatus can be reduced.

  In the loading device of the first invention and the loading method of the third invention, the retainer 12 is omitted, and the process of positioning the retainer 12 relative to the chuck 11 by the retainer moving mechanism is omitted.

  Embodiments of a semiconductor wafer loading apparatus and loading method according to the present invention will be described below with reference to the drawings.

  In the following description, a silicon wafer is assumed as a semiconductor wafer.

  FIG. 3 shows the overall configuration of the single wafer polishing apparatus 1 of the embodiment. FIG. 3 is a view of the polishing apparatus 1 as viewed from above.

  The polishing apparatus 1 includes a load / unload stage 2, a first stage 3, a second stage 4, a third stage 5, a polishing head support 6, a carry-in device 7, and a carry-out device 8. ing.

  Each of the first stage 3, the second stage 4, and the third stage 5 is provided with a surface plate 9 having a polishing cloth adhered to the upper surface. The first stage 3 and the second stage 4 are stages in which a rough polishing process for rough polishing the surface of the semiconductor wafer 30 is performed, and the third stage 5 has a final polishing process for finish polishing the surface of the semiconductor wafer 30. It is a stage to be performed.

  The carry-in device 7 carries in the load / unload stage 2 the semiconductor wafer 30 that has been processed in the previous process (etching process). The unloading device 8 unloads the semiconductor wafer 30 that has been polished in the polishing device 1 and unloaded by the load / unload stage 2 to the next step (cleaning step).

  The polishing head support 6 supports the polishing head 10 so as to be rotatable in the direction indicated by the arrow so that two polishing heads 10 are sequentially arranged per stage. One semiconductor wafer 30 is adsorbed per polishing head 10.

  The loading / unloading stage 2 performs a process of loading the semiconductor wafer 30 carried in by the carry-in device 7 onto the polishing head 10 (loading), and a process of attaching and detaching the semiconductor wafer 10 after the polishing process is completed from the polishing head 10 ( This is a stage for performing (unloading). The loading / unloading stage 2 is provided with a loading mechanism 20 (unloading mechanism) shown in FIG.

  FIG. 1A is a side view of the polishing head 10 and the loading mechanism 20 in the load / unload stage 2. The polishing head 10 and the loading mechanism 20 constitute the loading device of this embodiment.

  That is, as shown in FIG. 1A, the loading mechanism 20 has a smaller diameter than the semiconductor wafer 30 and moves in the center direction A of the semiconductor wafer 30. Six centering pins 22 that can freely come close to the side surface of the semiconductor wafer 30 on the top plate 21 are arranged at equal intervals in the circumferential direction of the top plate 21. A view of the positional relationship between the semiconductor wafer 30 and the centering pins 22 on the top plate 21 as viewed from the top is shown in FIG.

  The distance D7 between the pins in the diameter direction of the semiconductor wafer when the centering pin 22 is closest to the semiconductor wafer 30 is set to a distance D5 + α obtained by adding α to the diameter D5 of the semiconductor wafer 30. The centering pin 22 is slidably provided on the upper base 26.

  A concave float chamber 21 a is formed on the top plate 21. A water channel 27 communicates with the float chamber 21a. Water is supplied to the float chamber 21 a through the water channel 27. For this reason, when the semiconductor wafer 30 is placed on the top plate 21, the water supplied to the float chamber 21 a flows out through the gap between the semiconductor wafer 30 and the top plate 21, and floats the semiconductor wafer 30. Support in the state.

  The top plate 21 is provided on the upper base 26 so as to be movable in the vertical direction in the drawing. The rod of the cylinder 23 is mechanically connected to the top plate 21. When the cylinder 23 is driven, its rod moves in the vertical direction, and the top plate 21 moves in the vertical direction.

  The upper base 26 is provided on the lower base 25 via the guide member 24 so as to be movable in the horizontal direction (a plane perpendicular to the drawing). As the guide member 24, an air float, a ball guide, or the like can be used. The lower base 25 is fixed to the ground. The upper base 26, the guide member 24, and the lower base 25 constitute the plate moving mechanism of this embodiment.

  For this reason, when the centering pin 22 contacts the side surface of the chuck 11, the top plate 21 moves in the moving direction of the centering pin 22 together with the upper base 26 until the centering pin 22 stops thereafter.

  In the state where the top plate 21 is raised by the cylinder 23, the centering pin 22 is disposed such that the upper end thereof is positioned above the upper surface of the semiconductor wafer 30 on the top plate 21. The distance from the upper surface of the semiconductor wafer 30 on the top plate 21 to the upper end of the centering pin 22 is defined as f1.

  On the other hand, the polishing head 10 is provided with a chuck 11 having a diameter D 3 that is the same as or substantially the same as the diameter D 5 of the semiconductor wafer 30. As described with reference to FIG. 4A, the chuck 11 has a seal portion 11d, a plurality of pins 11f, and a plurality of grooves 11e formed on the wafer suction surface which is the lower surface thereof. A hole for evacuation is formed in the groove 11e. A suction port of a vacuum pump (not shown) communicates with a hole formed in the groove 11a. When the vacuum pump is driven, evacuation is performed through a hole formed in the groove 11 e of the chuck 11, and the semiconductor wafer 30 can be adsorbed (gripped) by the lower surface of the chuck 11.

  An annular retainer 12 is provided on the outer periphery of the chuck 11 so as to be separated from the side surface of the chuck 11 by a predetermined distance. The retainer 12 moves up and down relatively with respect to the chuck 11 by a retainer moving mechanism (not shown). As the retainer moving mechanism, the one described in the prior application (Japanese Patent Application No. 2002-282549) of the present applicant can be used.

  The retainer moving mechanism allows the retainer 12 to move the lower surface of the retainer 12 above the lower surface of the chuck 11 by a predetermined distance f2. The relationship f2> f1 is established between the distance f2 and the distance f1 described above. The retainer moving mechanism may be any mechanism as long as the retainer 12 can be positioned relatively above the chuck 11, and may be a mechanism that raises the retainer 12 or a mechanism that lowers the chuck 11. Good.

  The polishing head 10 can be moved vertically by a polishing head cylinder (not shown).

  Next, the operation of the apparatus of the embodiment will be described with reference to FIG.

  First, the unpolished semiconductor wafer 30 is placed on the top plate 21 of the loading mechanism 20 shown in FIG.

  The state at this time is shown in FIG. Here, it is assumed that there is a misalignment of a misalignment amount d between the center axis 11 c of the chuck 11 and the center axis 21 c of the top plate 21. Due to the retainer moving mechanism, the retainer 12 is positioned relatively above the chuck 11, and the distance between the lower surface of the chuck 11 and the lower surface of the retainer 12 is f2.

  Next, the polishing head cylinder is driven, and the polishing head 10 is lowered as indicated by an arrow B in FIG.

  Next, as shown in FIG. 2C, the six centering pins 22 are simultaneously moved in the center direction A of the semiconductor wafer 30 on the top plate 21.

  Next, the cylinder 23 is driven and the top plate 21 is raised. In this manner, the chuck 11 is moved downward relative to the top plate 21 to a position where the semiconductor wafer 30 on the top plate 21 can be sucked. At this time, the distance between the upper surface of the semiconductor wafer 30 and the upper end of the centering pin 22 is f1.

  Since the relationship f2> f1 is established as described above, the centering pin 22 can approach both the side surface of the semiconductor wafer 30 on the top plate 21 and the side surface of the chuck 12 without interfering with the retainer 12. .

  The centering pin 22 approaches the side surface of the chuck 11, and the centering pin 22 stops at a position corresponding to the diameter of the chuck 11 (the closest approach distance D 5 + α (the diameter of the semiconductor wafer 30 + α)).

  Since there is a misalignment between the center axis 11 c of the chuck 11 and the center axis 21 c of the top plate 21, the centering pin 22 contacts the side surface of the chuck 11. When the centering pin 22 comes into contact with the side surface of the chuck 11, the top plate 21 moves in the moving direction of the centering pin 22 together with the upper base 26 until the centering pin 22 stops thereafter. Therefore, when the centering pin 22 stops at a position corresponding to the diameter of the chuck 11 (the closest distance D5 + α (the diameter of the semiconductor wafer 30 + α)), the center axis 21c of the top plate 21 is substantially equal to the center axis 11c of the chuck 11. In addition, the misalignment amount d can be made substantially zero. As described above, the distance D7 between both pins in the wafer diameter direction when the centering pin 22 is closest is set to a distance D5 + α obtained by adding α to the diameter D5 of the semiconductor wafer 30. Therefore, the centering accuracy can be ± α.

  Since the float chamber 21a of the top plate 21 is filled with water, the semiconductor wafer 30 is prevented from being scratched when the centering pin 22 contacts the side surface and the semiconductor wafer 30 moves. The

  The central axis 21 c of the top plate 21 coincides with the central axis 11 c of the chuck 11, and the vacuum pump is driven and the semiconductor wafer 30 is attracted to the chuck 11 with the misalignment amount being zero. For this reason, the deviation of the semiconductor wafer 30 with respect to the chuck 11 can be made equal to or less than the deviation tolerance ((D4−D1) / 2) described with reference to FIG.

  When the semiconductor wafer 30 is loaded on the polishing head 10 in this way, the cylinder 23 is driven and the top ring 21 is lowered to the original retracted position. Further, the centering pin 22 moves to the original retracted position.

  Next, the polishing head support portion 6 shown in FIG. 3 is rotated, and the polishing head 10 loaded with the semiconductor wafer 30 is sequentially sent to the first stage 3, the second stage 4, and the third stage 5. 30 rough polishing and finish polishing are performed.

  In each stage 3, 4, 5, the polishing head cylinder is driven and the polishing head 10 is moved downward. A load is applied to the polishing head 10 from above, and the semiconductor wafer 30 is polished while being pressed against the surface of the polishing cloth on the surface plate 9. During polishing, an abrasive liquid (slurry) is flowed to the contact surface of the semiconductor wafer on the polishing cloth.

  When rough polishing is performed, the retainer 12 is moved downward relative to the chuck 11 by the retainer moving mechanism, and the lower surface of the retainer 12 is brought into the same position as the lower surface of the semiconductor wafer 30 adsorbed by the chuck 11. The

  As a result, when the semiconductor wafer 30 is pressed against the polishing cloth, the retainer 12 is also pressed against the polishing cloth at the same time, thereby preventing surface sagging.

  When the rough polishing is performed in the first and second stages 3 and 4 for rough polishing, and the polishing head 10 is sent to the third stage 5 for the next finishing, the retainer 12 is moved to the chuck 11 by the retainer moving mechanism. The lower surface of the retainer 12 is positioned above the lower surface of the semiconductor wafer 30 adsorbed by the chuck 11. As a result, during the course of sending the polishing head 10 to the third stage 5 for final polishing, the rough polishing was collected in the gap 40 (FIG. 4A) between the semiconductor wafer 30 and the retainer 12 adsorbed by the chuck 11. The abrasive liquid is discharged.

  In the third stage 5 for final polishing, since the surface of the semiconductor wafer 30 is polished without bringing in the abrasive liquid for rough polishing, the final polishing is performed with high quality without scratching the surface of the semiconductor wafer 30. .

  Next, the polishing head support portion 6 shown in FIG. 3 further rotates, and the polishing head 10 that holds the semiconductor wafer 30 that has been finished is sent to the load / unload stage 2. The driving of the vacuum pump is stopped and the semiconductor wafer 30 is detached from the chuck 11 of the polishing head 10. The semiconductor wafer 30 detached from the chuck 11 falls on the top plate 21 of the loading mechanism 20 shown in FIG. Here, since the float chamber 21 a of the top plate 21 is filled with water, the semiconductor wafer 30 is prevented from being damaged when the semiconductor wafer 30 falls on the top plate 21. When the semiconductor wafer 30 is unloaded in this way, the semiconductor wafer 30 is taken out from the top plate 21 by the carry-out device 8 shown in FIG. 3, and the semiconductor wafer 30 is carried out to the next step (cleaning step).

  As described above, according to the present embodiment, since the centering is performed with reference to the chuck 11, the semiconductor wafer 30 can be accurately attracted to the chuck 11, and the deviation of the semiconductor wafer 30 from the chuck 11 can be prevented. The allowable deviation ((D4−D1) / 2) or less can be achieved. For this reason, the flatness of the outer peripheral portion of the semiconductor wafer 30 is improved. In addition, according to the present embodiment, since centering is performed with reference to the chuck 11, the centering is performed without being affected by mounting errors of the chuck and the retainer. For this reason, the accuracy of the attachment parts can be allowed to a low level, and the manufacturing cost of the apparatus can be reduced.

  In the embodiment, the polishing head 10 provided with the retainer 12 is assumed, but the present invention can also be applied to a polishing head not provided with the retainer 12. In this case, the retainer moving mechanism for positioning the retainer 12 relative to the chuck 11 is not necessary, and the process for positioning the retainer 12 above the chuck 11 shown in FIG. It becomes.

  In the embodiment, the centering pin 22 is used for centering the semiconductor wafer 30. However, the member can contact the side surface of the semiconductor wafer 30 and move toward the center from at least both sides in the diameter direction of the semiconductor wafer 30. It suffices, and implementation using a member other than the pin, for example, an arc-shaped member is also possible.

  In the embodiment, the case where the chuck 11 sucks the semiconductor wafer 30 by means of evacuation is described. However, any means can be used for the chuck 11 to suck the semiconductor wafer 30. For example, a suede pad may be attached to the surface of the chuck 11 made of ceramic, and the semiconductor wafer 30 may be adsorbed with the pad wetted with water. Moreover, the chuck | zipper 11 should just be able to hold | grip the semiconductor wafer 30, and may hold | grip the semiconductor wafer 30 using methods other than adsorption | suction.

FIG. 1A is a side view showing the configuration of the loading apparatus of the embodiment, and FIG. 1B is a top view showing the positional relationship between the centering pins shown in FIG. 1A and the semiconductor wafer. 2A, 2B, and 2C are diagrams illustrating a procedure of loading processing according to the embodiment. FIG. 3 is a top view showing the configuration of the single wafer polishing apparatus according to the embodiment. 4A is a cross-sectional view showing a state in which the semiconductor wafer is adsorbed by the chuck, and FIG. 4B is a cross-sectional view showing a state in which the semiconductor wafer is adsorbed while being displaced from the chuck. FIGS. 5A, 5B, and 5C are diagrams showing a procedure of loading processing according to the prior art.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Polishing head 11 Chuck 12 Retainer 20 Loading mechanism 21 Top plate 22 Centering pin 30 Semiconductor wafer

Claims (4)

A loading mechanism provided with a plate on which the semiconductor wafer is placed, a centering member that moves toward the side of the semiconductor wafer by moving in the center direction of the semiconductor wafer, and holds the semiconductor wafer on the plate to hold the semiconductor wafer In a semiconductor wafer loading apparatus comprising a chuck for loading
A centering member provided to be accessible to both the side surface of the chuck and the side surface of the semiconductor wafer on the plate;
A semiconductor wafer loading device comprising: a plate moving mechanism that moves the plate in the moving direction of the centering member by contacting the side surface of the semiconductor wafer on the plate with the centering member. A loading mechanism provided with a plate on which a semiconductor wafer is placed, and a centering member that moves in the direction of the center of the semiconductor wafer so as to be close to the side surface of the semiconductor wafer; In a semiconductor wafer loading apparatus comprising: a chuck for loading a wafer; and a polishing head provided with a retainer disposed at a predetermined distance from a side surface of the chuck.
A retainer moving mechanism for moving the retainer relative to the chuck so that the centering member can approach the side surface of the chuck;
A centering member provided to be accessible to both the side surface of the chuck and the side surface of the semiconductor wafer on the plate;
A semiconductor wafer loading device, comprising: a plate moving mechanism that moves the plate in a moving direction of the centering member when the centering member abuts against a side surface of the semiconductor wafer on the plate. In the semiconductor wafer loading method of loading the semiconductor wafer by gripping the semiconductor wafer on the plate with a chuck,
Moving the chuck relative to the plate to a position where the chuck can grip the semiconductor wafer; and
Moving the centering member toward the center of the semiconductor wafer to bring the centering member into close proximity to both the side surface of the chuck and the side surface of the semiconductor wafer on the plate;
Moving the plate in the direction of movement of the centering member by bringing the centering member into contact with the side surface of the semiconductor wafer on the plate;
Loading a semiconductor wafer by holding the semiconductor wafer on a plate with a chuck. In the semiconductor wafer loading method of loading the semiconductor wafer by gripping the semiconductor wafer on the plate with the chuck of the polishing head,
Moving the retainer relative to the chuck so that the centering member can approach the side surface of the chuck;
Moving the chuck relative to the plate to a position where the chuck can grip the semiconductor wafer; and
Moving the centering member toward the center of the semiconductor wafer to bring the centering member into close proximity to both the side surface of the chuck and the side surface of the semiconductor wafer on the plate;
Moving the plate in the direction of movement of the centering member by bringing the centering member into contact with the side surface of the semiconductor wafer on the plate;
Loading a semiconductor wafer by holding the semiconductor wafer on a plate with a chuck.

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