JP2007190614A - Polishing device and polishing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent defect such as scratch by preventing abrasive waste and slurry scattering in the process of polishing a semiconductor substrate from again adhering to a polishing pad through a scattering preventing cover. <P>SOLUTION: This polishing device includes: a polishing head 1 holding a work W; a rotatable polishing surface plate 3 on which the polishing pad 2 is mounted; a slurry supply part 4 for supplying polishing slurry to the polishing surface of the polishing pad on the polishing surface plate 3; and a slurry scattering preventing cover 5 surrounding the periphery of the polishing surface plate 3, wherein a flowing water film forming part 7 is provided to form a flowing water film 6 for covering the inner wall of the slurry scattering preventive cover 5 in the process of polishing. Scattering slurry S and abrasive waste can be washed away without reaching the inner wall of the slurry scattering preventive cover 5 by the formed flowing water film 6, so that the slurry S and the abrasive waste can be prevented from bounding from the scattering preventive cover 5 and again adhering to the polishing pad 2. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a polishing apparatus and a polishing method used in a chemical mechanical polishing (CMP) process when manufacturing a semiconductor device or the like.

  In recent years, higher integration, higher functionality, and higher speed of semiconductor devices have progressed, and in the manufacturing process of semiconductor devices, the interlayer dielectric film tends to have a lower dielectric constant due to the problem of wiring delay. As the dielectric constant of the interlayer insulating film is lowered, the film quality becomes highly porous with pores, and the mechanical strength tends to decrease and become brittle. In such a manufacturing process that involves the miniaturization of a semiconductor device, it is required to prevent damage to the film during the polishing process even in the CMP process, and the polishing pressure on the semiconductor substrate is improved in controllability at a low pressure. It is becoming. When the polishing pressure is lowered, the polishing speed of the film to be polished is lowered, so that the rotational speed of the polishing surface plate needs to be controlled at a higher speed. As the polishing plate rotates faster, polishing slurries and polishing debris used during polishing scatter to the surrounding electrical equipment, which may cause malfunction of equipment. Various proposals have been made to prevent this. Has been made.

For example, in the polishing apparatus shown in FIG. 3, the workpiece W such as a semiconductor substrate is held by the polishing head 1 while the polishing platen 3 is rotated and the polishing slurry S is supplied to the polishing surface of the polishing pad 2 on the polishing platen 3. The surface of the workpiece W is polished and flattened by pressing against the polishing surface of the polishing pad 2 while rotating the polishing pad 2, and polishing scraps and polishing slurry S generated at this time are rotated by the polishing platen 3. Therefore, a scattering prevention cover 21 is provided so that the scattered matter does not scatter to the outside of the polishing unit 20 and the shower head 22 is used to prevent scattering. A water curtain 23 is created below the cover 21. In addition, in order to prevent the scattered matter adhering to the inside of the scattering prevention cover 21 from reattaching to the polishing pad 2, a shower head 24 is provided inside the scattering prevention cover 21, and the scattering prevention cover 21 is provided between polishing processes. The inner wall is cleaned (Patent Document 1).
JP 2001-53040 A

  Along with the miniaturization of semiconductor devices, defects such as scratches and particles generated on the workpiece in the CMP process lead to defects such as a short circuit between wirings of the semiconductor device, causing a decrease in yield.

  In the above-described conventional polishing apparatus, the cause of the scratch was investigated in detail. As a result, scattered objects such as polishing debris scattered during the polishing process not only adhered to the anti-scattering cover 21 but also rebounded from the anti-scattering cover 21. This was caused by redeposition on the polishing pad 2. As for the reattachment of the scattered matter on the polishing pad 2, as described above, measures are taken to clean the anti-scattering cover 21 between the polishing processes, but the polishing surface plate 3 is accompanied with the miniaturization of the semiconductor device. Since the rotation of the polishing plate has been increased, and the polishing surface plate 3 has been enlarged with the increase in the diameter of the semiconductor substrate (workpiece), the scattering speed of scattered matter such as polishing debris has increased. It seems that the rebound from the prevention cover 21 to the polishing pad 3 has become remarkable.

  The present invention solves the above-mentioned problem, and it is an object of the present invention to prevent scattered matters such as polishing debris scattered during the polishing process from reattaching to the polishing pad through the anti-scattering cover and to prevent defects such as scratches. And

  In order to solve the above problems, a polishing apparatus of the present invention includes a polishing head for holding a workpiece, a rotatable polishing surface plate to which a polishing pad is attached, and a polishing slurry on a polishing surface of the polishing pad on the polishing surface plate. In a polishing apparatus including a slurry supply unit that supplies a slurry and a slurry scattering prevention cover that surrounds the periphery of the polishing platen, a flowing water film is formed to form a flowing water film that covers an inner wall of the slurry scattering prevention cover during a polishing process A feature is provided.

  Further, the polishing method of the present invention rotates the polishing platen and supplies the polishing slurry to the polishing surface of the polishing pad on the polishing platen, while pressing the work held on the polishing head against the polishing surface of the polishing pad. During the polishing process for polishing, a flowing water film covering the inner wall of the slurry scattering prevention cover surrounding the polishing surface plate is formed.

  According to the above polishing apparatus and polishing method, the formed flowing water film allows the scattered slurry and polishing debris to flow away without reaching the inner wall of the slurry splash prevention cover, preventing slurry and polishing debris from scattering. It is possible to prevent rebounding from the cover and reattaching to the polishing pad.

  The flowing water film forming unit may have a structure having an overflow tank having the upper end portion of the slurry scattering prevention cover as an overflow wall and a water supply system for supplying water into the overflow tank. This makes it possible to create a uniform flowing water film.

  It is preferable that the slurry scattering prevention cover is configured to be rotatable at the same rotational speed in the same direction as the polishing surface plate. This is because, in the unlikely event that the slurry or polishing scraps that scatters reach the slurry scatter prevention cover, the rebounding involves the speed at which they collide with the slurry scatter prevention cover, so that this speed is minimized.

For this purpose, a rotary motor for rotating the slurry scattering prevention cover may be provided, or the slurry scattering prevention cover may be fixed below the polishing surface of the polishing platen.
It is preferable that a hydrophilic material is used for the inner wall of the slurry scattering prevention cover. This is because a hydrophilic material has high wettability with water and a flowing water film becomes uniform. For example, a hydrophilic urethane resin can be used as the hydrophilic material.

  According to the polishing apparatus and the polishing method of the present invention, the slurry and polishing debris that are scattered can be captured and washed away in front of the inner wall of the slurry scattering prevention cover by the formed flowing water film. Therefore, it is possible to prevent rebound and reattachment to the polishing pad and to prevent the occurrence of scratch defects.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1A is a sectional view and FIG. 1B is a top view of a polishing apparatus according to an embodiment of the present invention. This polishing apparatus includes a polishing head 1 that is a rotating body that holds a workpiece W, a polishing surface plate 3 that is a rotating body to which a polishing pad 2 is attached, and a slurry supply that supplies a polishing slurry S to the polishing surface of the polishing pad 2. A chemical mechanical polishing (CMP) apparatus including a portion 4 and includes a slurry scattering prevention cover 5 (hereinafter referred to as a cover 5) surrounding the polishing surface plate 3 and at least a portion where the slurry is scattered. The workpiece W is a semiconductor substrate on which an interlayer insulating film as described above is formed, for example.

  With the configuration described above, the polishing surface plate 3 is rotated, and the polishing slurry S is supplied to the polishing surface of the polishing pad 2 on the polishing surface plate 3 while the workpiece W is held and rotated by the polishing head 1 while rotating the polishing pad 2. By pressing against the polishing surface, the surface of the workpiece W is polished and flattened. The cover 5 prevents the polishing scraps and polishing slurry S generated at this time from scattering to the periphery of the polishing surface plate 3, for example, the electrical equipment (not shown) due to the rotation of the polishing surface plate 3.

  This polishing apparatus is different from the conventional apparatus in that it has a flowing water film forming portion 7 that forms a flowing water film 6 that covers the inner wall of the cover 5 during the polishing process. Specifically, the cover 5 is a cylindrical body having an inner wall extending in a substantially vertical direction, and the flowing water film forming portion 7 is formed along the upper outer periphery of the cover 5 so that the upper end portion 5a of the cover 5 is an overflow wall. The pure water supplied from the pure water supply nozzle 9 has a ring-shaped overflow tank 8 formed and a water supply system such as a pure water supply nozzle 9 for supplying pure water wa into the overflow 8 tank. Wa is stored in the overflow tank 8, overflows from there, flows along the inner wall of the cover 5, and creates a uniform flowing water film 6 covering the inner wall of the cover 5.

  For this reason, even if polishing debris or slurry generated during the polishing process of the workpiece W is scattered toward the cover 5 due to the centrifugal force due to the rotation of the polishing surface plate 3, the flowing water film 6 covering the inner wall of the cover 5. Thus, it is washed away without adhering to the cover 5. Accordingly, as described above, the rotation of the polishing platen 3 has been increased, and the polishing platen 3 has been increased in size with the increase in the diameter of the semiconductor substrate serving as the workpiece W. Even if the scattering speed of slurry and polishing scraps from the board 3 increases, these scattered objects do not rebound from the cover 5, and reattachment to the polishing pad 2 can be prevented. Therefore, scratches generated in this chemical mechanical polishing step can be reduced as compared with the conventional case, and it is possible to prevent a short circuit failure between wires of a semiconductor device manufactured from the workpiece W.

  In the unlikely event that the slurry S or polishing scraps reach the inner wall of the cover 5, the speed at which these scattered matter collides with the cover 5 is involved in the rebound. It is preferable to rotate the polishing platen 3 in the same direction as the polishing platen 3 at an approximately equal rotational speed, desirably the same rotational speed. For this purpose, the cover 5 is rotated by using a motor 10 having a rotating shaft 10 a that meshes with the outer peripheral surface of the cover 5. As shown in FIG. 2, the cover 5 may be fixed below the polishing surface of the polishing platen 3 by a plurality of support members 11 and rotated integrally with the polishing platen 3.

  Furthermore, if a hydrophilic material such as a hydrophilic urethane resin is used for the inner wall of the cover 5, the wettability to the water wa is high and the flowing water film 6 becomes uniform. It can be effectively shielded. On the other hand, when a hydrophobic material such as Teflon (registered trademark) is used for the inner wall of the cover 5, the pure water wa flowing from the overflow tank 8 is repelled. A bias occurs in the flow of the water wa, and the uniform flowing water film 6 cannot be obtained.

  As described above, the polishing apparatus and the polishing method of the present invention can reduce scratches in the CMP process, and are useful for preventing a short circuit failure between wirings when used for manufacturing a semiconductor device.

Sectional drawing and top view of the polisher in one embodiment of the present invention Sectional drawing and top view of the grinding | polishing apparatus in other embodiment of this invention. Sectional view of conventional polishing equipment

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Polishing head 2 Polishing pad 3 Polishing surface plate 4 Slurry supply part 5 Spattering prevention cover 6 Flowing water film 7 Flowing water film formation part 8 Overflow tank 9 Pure water supply nozzle
10 Motor
11 Support material W Work S Polishing slurry
Wa pure water

Claims (8)

  A polishing head for holding a workpiece, a rotatable polishing surface plate to which a polishing pad is attached, a slurry supply unit for supplying polishing slurry to the polishing surface of the polishing pad on the polishing surface plate, and a periphery of the polishing surface plate A polishing apparatus provided with an enclosed slurry scattering prevention cover, wherein a flowing water film forming unit is provided that forms a flowing water film that covers an inner wall of the slurry scattering prevention cover during a polishing process.   The polishing apparatus according to claim 1, wherein the flowing water film forming section includes an overflow tank having an upper end portion of the slurry scattering prevention cover as an overflow wall, and a water supply system for supplying water into the overflow tank.   The polishing apparatus according to claim 1, wherein the slurry scattering prevention cover is configured to be rotatable at the same rotational speed in the same direction as the polishing surface plate.   The polishing apparatus according to claim 3, further comprising a rotation motor that rotates the slurry scattering prevention cover.   The polishing apparatus according to claim 3, wherein the slurry scattering prevention cover is fixed below the polishing surface of the polishing platen.   The polishing apparatus according to claim 1, wherein a hydrophilic material is used for the inner wall of the slurry scattering prevention cover.   The polishing apparatus according to claim 6, wherein the hydrophilic material is a hydrophilic urethane resin.   During the polishing process of rotating the polishing platen and pressing the work held by the polishing head against the polishing surface of the polishing pad while supplying the polishing slurry to the polishing surface of the polishing pad on the polishing platen, A polishing method for forming a flowing water film covering an inner wall of a slurry scattering prevention cover surrounding a polishing surface plate.

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