JP2010247260A - Retainer ring, polishing device, and polishing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide excellent polishing performance by preventing concentration of load at polishing and suppressing rising of a temperature of a polishing pad. <P>SOLUTION: The retainer ring 11 mounted to a polishing head 3 of the polishing device and retaining a wafer 9 is constituted so as to include a ring-like base part 13 and a plurality of block parts 14 provided on a lower surface of the base part 13 with an equal interval. A lateral cross section shape of an outer peripheral part 14b1 of the block part 14 and a connection part 14b3 in which the outer peripheral part 14b1 is connected to an opposed part 14b2 opposed to the adjacent block part 14 is made to a round shape. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a retainer ring, a polishing apparatus, and a polishing method for holding a semiconductor substrate being polished.

  In a polishing apparatus that performs CMP (chemical mechanical polish), polishing is performed by pressing a semiconductor substrate held by a retainer ring against a rotating polishing pad. This type of retainer ring is entirely made of resin. In general, a ring-shaped base portion and a plurality of block portions projecting from the lower surface portion of the base portion are used. In such a retainer ring, in order to avoid load concentration at the end portion of the semiconductor substrate, the lower surface of each block portion is brought into contact with the polishing pad, and the slurry being polished enters between adjacent block portions. The groove for improving the thickness is formed (see, for example, Patent Document 1).

  In the case of the above configuration, each block portion has a substantially rectangular cross-sectional shape, and the intersection between the lower surface and the outer peripheral side surface has an angle of approximately 90 degrees. For this reason, the outer part of the lower surface of the block part in contact with the polishing pad, particularly the both end parts of the outer part, that is, the apex part, may wear away quickly due to load concentration during polishing. Also, there has been a problem that it is difficult to obtain good polishing performance, such as a decrease in polishing speed due to the temperature rise of the polishing pad due to load concentration.

JP 2008-177248 A

  An object of the present invention is to provide a retainer ring, a polishing apparatus, and a polishing method capable of preventing load concentration at the time of polishing and suppressing a temperature increase of the polishing pad and obtaining good polishing performance.

  A retainer ring according to one aspect of the present invention is attached to a polishing head of a polishing apparatus and holds a wafer, and includes a ring-shaped base portion and a plurality of block portions projecting from a lower surface of the base portion. In addition, the cross-sectional shape of the connecting portion connected to the outer peripheral portion of the block portion and the opposing portion facing the adjacent block portion is rounded. .

  A polishing apparatus according to one embodiment of the present invention includes a polishing turntable that is rotatably provided and has a polishing pad attached to an upper surface thereof, and a wafer that is held by a retainer ring that is rotatably provided and attached to the lower surface. A polishing head for pressing, and the retainer ring is configured to have a ring-shaped base portion and a plurality of block portions projecting from the lower surface of the base portion, and an outer peripheral portion of the block portion, and The cross-sectional shape of the connecting portion where the outer peripheral portion is connected to the facing portion facing the adjacent block portion is characterized by a rounded shape.

  The polishing method according to one aspect of the present invention rotates a polishing turntable having a polishing pad attached to the upper surface, and presses the wafer held by a retainer ring attached to the lower surface of the polishing head against the polishing pad. A polishing method for polishing the wafer by rotating, wherein the retainer ring is configured to have a ring-shaped base portion and a plurality of block portions projecting from a lower surface of the base portion, The cross-sectional shape of the connection part which the said outer peripheral part connects to the outer peripheral part of a block part and the opposing part which opposes an adjacent block part is characterized by making it round shape.

  According to the present invention, load concentration at the time of polishing can be prevented, and a temperature increase of the polishing pad can be suppressed to obtain good polishing performance.

The perspective view of the polish device which shows a 1st embodiment of the present invention. Vertical section of polishing head Retainer ring bottom view Retainer ring partially enlarged bottom view Partial perspective view of retainer ring Graph showing wafer temperature during polishing FIG. 4 equivalent diagram showing a comparative example FIG. 4 equivalent view showing the second embodiment of the present invention

(First embodiment)
Hereinafter, a first embodiment of the present invention will be described with reference to FIGS. 1 to 6. First, FIG. 1 is a perspective view showing a schematic configuration of a polishing apparatus (CMP apparatus) 1 of the present embodiment. As shown in FIG. 1, the polishing apparatus 1 includes a polishing turntable 2, a polishing head 3, a diamond dresser 4, a polishing liquid supply port 5, a pure water supply port 6, and a cleaning liquid supply port 7. Configured.

  A polishing pad 8 is attached to the upper surface of the polishing turntable 2. The polishing turntable 2 is configured to be rotationally driven at, for example, 10 to 200 rpm by a driving device (not shown) including a motor or the like. The polishing head 3 is configured to be rotationally driven at 10 to 200 rpm, for example, by a driving device (not shown) including a motor or the like. The polishing head 3 is configured to be able to press the upper surface of the polishing pad 8 of the polishing turntable 2 with a predetermined pressure while rotating a semiconductor substrate, for example, a wafer 9 (see FIG. 2). In this case, the load for pressing the wafer 9 against the polishing pad 8 is usually set to about 50 to 500 hPa. A specific configuration of the polishing head 3 will be described later.

  The diamond dresser 4 is for conditioning the surface of the polishing pad 8 and is driven to rotate at, for example, 10 to 200 rpm by a driving device (not shown) made of a motor or the like, and about 50 to 300 hPa on the polishing pad 8. It is comprised so that it may be pressed with a load. A predetermined flow rate (for example, a flow rate of 50 to 500 cc / min) of polishing liquid (slurry, etc.), pure water and cleaning liquid is supplied to the polishing pad 8 from the polishing liquid supply port 5, pure water supply port 6 and cleaning liquid supply port 7. It is comprised so that it can be supplied with.

  Next, a specific structure of the polishing head 3 will be described with reference to FIG. The polishing head 3 is configured by a disk-shaped head main body 10 supported by an arm (not shown). A retainer ring 11 is attached to the lower surface of the head main body 10 and is in contact with the lower surface of the head main body 10. The membrane 12 held by the retainer ring 11 is provided. The retainer ring 11 holds the wafer 9 so as to contact the lower surface of the membrane 12. The wafer 9 held by the retainer ring 11 is pressed onto the polishing pad 8 by the head body 10 and the membrane 12. At this time, the retainer ring 11 is also pressed onto the polishing pad 8 by the head main body 10 so that the load is less likely to vary between the central portion and the end portion of the wafer 9, and the local load within the wafer surface during polishing is reduced. Concentration can be prevented.

  The retainer ring 11 is entirely made of resin. As shown in FIGS. 3 to 5, as shown in FIGS. 3 to 5, a large number (a plurality) of protrusions are provided at equal intervals on the ring-shaped base portion 13 and the lower surface portion of the base portion 13. And a block portion 14 provided. The block section 14 has a substantially semicircular cross-sectional shape. The inner surface 14a of the block portion 14 is formed to have a curved surface having the same curvature as the inner peripheral surface 13a of the base portion 13, and the outer peripheral portion of the wafer 9 is held in contact with the inner surface 14a. Yes. The outer peripheral portion of the membrane 12 is held in contact with the inner surface 14 a of the block portion 14 and the inner peripheral surface 13 a of the base portion 13.

  The outer peripheral surface 14b of the block part 14 is formed so that the cross-sectional shape is a semicircular curved surface (that is, a semicylindrical curved surface). The outer peripheral surface 14b of the block part 14 includes an outer peripheral part 14b1 of the block part 14, an opposing part 14b2 facing the adjacent block part 14, and a connection part 14b3 connecting the outer peripheral part 14b1 to the opposing part 14b2. The cross-sectional shapes of the outer peripheral portion 14b1, the connection portion 14b3, and the facing portion 14b2 are all rounded. In other words, the connection portion 14b3 has no apex (corner).

  In the case of the above configuration, when the wafer 9 held on the retainer ring 11 is pressed against the polishing pad 8 and polished, the lower surface of the block portion 14 of the retainer ring 11 is also pressed onto the polishing pad 8. As described above, since the retainer ring 11 can be pressed on the surface, the polishing head 3 presses the entire wafer 9 and the block portion 14 against the polishing pad 8. It is possible to suppress variation in load at the end, and it is possible to prevent the polishing characteristics from being deteriorated due to local load concentration in the wafer surface during polishing.

  At this time, since the cross-sectional shape of the outer peripheral surface 14b of the block portion 14 is semicircular, there is no apex at the lower portion of the outer peripheral surface 14b of the block portion 14, and the lower surface of the block portion 14 and the outer peripheral surface 14b The length of the intersection line intersecting with is shorter than that of the substantially rectangular block portion (conventional configuration). For this reason, the size of the portion where the corner of the block portion 14 contacts the polishing pad 8 is smaller than that of the substantially rectangular block portion (conventional configuration). As a result, the load at the time of polishing is less likely to concentrate on the outer peripheral side portion of the lower surface of the block portion 14 in contact with the polishing pad 8, so that the wear of the block portion 14 is difficult to proceed.

Further, when the retainer ring 11 of the present embodiment is used, the temperature rise of the wafer 9 (that is, the polishing pad 8) being polished can be suppressed. Specifically, the oxide film formed on the surface of the wafer 9 was polished by the polishing apparatus 1 using the retainer ring 11 of the present embodiment, and the maximum temperature of the wafer 9 being polished was measured. In this case, 15 wafers 9 were polished, and the temperature of each wafer 9 was measured. As the polishing liquid, for example, a slurry obtained by adding a dispersant called TK-75 made by Kao to a slurry called DLS-2 made by Hitachi Chemical. As polishing conditions, the polishing load is 400 gf / cm ² , the rotation speed of the polishing head 3 is 107 min ⁻¹ (rpm), the rotation speed of the polishing turntable 2 is 100 min ⁻¹ (rpm), and the slurry flow rate is It was 190 cc / min and the dispersant flow rate was 3.0 cc / min. As the polishing pad 8, for example, IC1000 manufactured by RODEL was used. Then, polishing was performed for 300 seconds, for example, under the above-described polishing conditions. FIG. 6 shows a graph of the temperature measurement results.

  In FIG. 6, a solid line A indicates a temperature measurement result when the retainer ring 11 of the present embodiment is used. A solid line B shows a temperature measurement result when the retainer ring 15 of the comparative example shown in FIG. 7 is used. As shown in FIG. 7, the retainer ring 15 of this comparative example includes a ring-shaped base portion 16 and a large number of substantially rectangular block portions 17. The shape of the block portion 17 of the retainer ring 15 is the same as the shape of the block portion of the conventionally known retainer ring. The load during polishing is concentrated on the outer portion of the lower surface of the block portion 17 of the comparative example (particularly, at the apexes at both ends of the outer portion). For this reason, wear of the block part 17 comes to advance early.

  Then, from the solid lines A and B in FIG. 6, when the retainer ring 11 of the present embodiment is used, the temperature rise of the wafer 9 (that is, the polishing pad 8) being polished can be suppressed. It can be seen that the maximum temperature can be reduced by about 5 ° C. For this reason, according to this embodiment, since it becomes possible to suppress the temperature rise of the polishing pad 8, a polishing rate does not fall and it is possible to stabilize the polishing characteristics. In the case where the retainer ring 15 of the comparative example is used, the polishing pad 8 rises in temperature and the polishing rate decreases, so that the polishing characteristics become unstable.

  FIG. 8 shows a second embodiment of the present invention. In addition, the same code | symbol is attached | subjected to the same structure as 1st Embodiment. In this 2nd Embodiment, as shown in FIG. 8, the cross-sectional shape of the outer peripheral part 19 of the block part 18 of the retainer ring 11 is more than the curvature of the circular-arc cross-sectional shape of the inner peripheral part 20 of the block part 18. It was formed in an arc shape having a large curvature. In the case of this configuration, the block portion 18 has an outer peripheral portion 19, a facing portion 21 that faces the adjacent block portion 18, and a connecting portion 22 that connects the outer peripheral portion 19 to the facing portion 21. Of these, the cross-sectional shapes of the outer peripheral portion 19 and the connecting portion 22 are rounded.

  The configurations of the second embodiment other than those described above are the same as the configurations of the first embodiment. Therefore, in the second embodiment, substantially the same operational effects as in the first embodiment can be obtained.

  In the drawings, 1 is a CMP apparatus, 2 is a polishing turntable, 3 is a polishing head, 5 is a polishing liquid supply port, 8 is a polishing pad, 9 is a wafer, 11 is a retainer ring, 12 is a membrane, 13 is a base portion, 14 Is a block part, and 18 is a block part.

Claims (5)

A retainer ring attached to a polishing head of a polishing apparatus and holding a wafer,
A ring-shaped base,
A plurality of block portions projecting from the lower surface of the base portion,
A retainer ring, wherein a cross-sectional shape of a connection portion connected to the outer peripheral portion of the block portion and an opposing portion facing the adjacent block portion is rounded.   The retainer ring according to claim 1, wherein a cross-sectional shape of the block portion is a semicircular shape that is convex in an outer peripheral direction.   2. The retainer ring according to claim 1, wherein the cross-sectional shape of the outer peripheral portion of the block portion is an arc shape having a curvature larger than the curvature of the arc-shaped cross-sectional shape of the inner peripheral portion of the block portion. . A polishing turntable provided rotatably and having a polishing pad attached to the upper surface;
A polishing head that presses a wafer held by a retainer ring that is rotatably provided and is attached to the lower surface, against the polishing pad;
The retainer ring is configured to have a ring-shaped base portion and a plurality of block portions projecting from the lower surface of the base portion,
The cross-sectional shape of the connecting portion connected to the outer peripheral portion of the block portion and the opposing portion facing the adjacent block portion is configured to have a rounded shape. Polishing equipment. The polishing turntable having a polishing pad attached to the upper surface is rotated, and the wafer held by a retainer ring attached to the lower surface of the polishing head is rotated while being pressed against the polishing pad, thereby polishing the wafer. A polishing method comprising:
The retainer ring is configured to have a ring-shaped base portion and a plurality of block portions projecting from the lower surface of the base portion,
A polishing method, characterized in that a cross-sectional shape of a connection portion connected to the outer peripheral portion of the block portion and an opposing portion facing an adjacent block portion is rounded.

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