JP4189325B2 - Polishing equipment - Google Patents

Description

  The present invention relates to a polishing apparatus, and more particularly to a polishing apparatus that polishes an edge portion of an object to be polished to remove contamination.

  In order to form a circuit such as an LSI on a semiconductor wafer, it is necessary to go through multiple processes such as a diffusion process, a thin film formation process, an exposure process, a wafer surface state inspection process, and a cleaning process. During such a multi-step process, various unnecessary materials and foreign matter (contamination) may adhere to and accumulate on the semiconductor wafer. For example, when forming a copper wiring on a semiconductor wafer in a thin film formation process by CVD or the like, first, copper is deposited on almost the entire surface of the semiconductor wafer, and then chemical mechanical polishing (CMP). Thus, unnecessary copper is removed, but copper may remain on the outer peripheral portion and the outer edge portion (hereinafter referred to as “edge portion”) of the semiconductor wafer. Copper as such a contamination easily diffuses into the oxide film and lowers the adhesion between the films, which causes a significant deterioration in circuit quality. For this reason, it is required to remove the copper remaining on the edge portion of the semiconductor wafer immediately after the copper film forming process or the CMP process.

  In addition, when a semiconductor wafer with copper or other such contamination is transferred, inspected or stored, the contamination is transferred to a transfer device, inspection table, etc., and another semiconductor is transferred via the transfer device, inspection table, etc. Contamination may also indirectly adhere to the wafer, that is, cross contamination may occur. For this reason, it is necessary to sufficiently remove the contamination adhering to the edge portion of the semiconductor wafer between the respective processes to prevent cross contamination.

  In order to remove such contamination, polishing of the edge portion of the semiconductor wafer is often performed by CMP, for the following reason. In recent years, when polishing and removing the contamination on the edge portion of the semiconductor wafer, it is required to polish the oxide film on the edge portion. This is because, if the oxide film is polished and removed, there is a risk that, when the semiconductor wafer is a silicon wafer, metal foreign matter adhering to the edge portion in the subsequent process penetrates into the inside of the semiconductor wafer and is contaminated. Because there is sex. When polishing such that the oxide film remains and removes contamination, it is difficult to control the polishing thickness because mechanical polishing alone results in rough polishing. On the other hand, chemical polishing alone is difficult. Some types of metal to be removed cannot be removed because they do not react with chemicals. Accordingly, CMP using both mechanical polishing and chemical polishing is considered advantageous for polishing the edge portion of a semiconductor wafer.

  As a technique for polishing the edge portion of the semiconductor wafer by such CMP, Patent Document 1 describes a technique of polishing and removing metal atoms deposited on the edge portion of the semiconductor wafer with a polishing tape. Describes a method of polishing an edge portion of a semiconductor wafer using a cylindrical polishing pad and an abrasive slurry.

JP 2002-25952 A JP 2002-110593 A JP 2001-33459 A JP 2000-757 A

  However, the method using the polishing tape described in Patent Document 1 has a problem that scratches due to abrasive grains are likely to occur. In other words, since the polishing tape that holds the abrasive grains is thin, it is difficult to make the height of the abrasive grains uniform, and because the abrasive grains are easily detached because the force to hold the abrasive grains is weak, Scratches may occur at the edge of the semiconductor wafer.

  On the other hand, in the method using the cylindrical pad described in Patent Document 2, it is difficult to control the removal amount by polishing, and it is not suitable for the purpose of polishing with an oxide film remaining.

  Further, as a problem different from the above, in CMP, the surface of the semiconductor wafer can be uniformly polished by moving the free abrasive grains contained in the polishing liquid on the surface of the polishing pad. There is a problem that the surface has a recess, and if abrasive grains are fixed in the recess, polishing cannot be performed uniformly. In order to solve such a problem, it is conceivable to make the abrasive grains easily escape from the recesses by relatively vibrating or swinging the polishing pad and the semiconductor wafer. For example, Patent Document 3 proposes a technique of swinging a semiconductor wafer and a surface plate that is a polishing means.

  In Patent Document 4, CMP is performed using a rectangular polishing pad smaller than a semiconductor wafer and a polishing liquid containing loose abrasive grains while vibrating the polishing pad linearly with respect to the semiconductor wafer. The method is described. However, this technique is a technique for polishing the entire surface of the semiconductor wafer, not a technique for polishing only the edge portion of the semiconductor wafer. Therefore, the technique described in Patent Document 4 cannot be applied to the polishing of the edge portion as it is.

  In other words, when the technique described in Patent Document 4 is used for polishing the edge portion, it is conceivable to polish the edge portion which is a limited region by setting the vibration direction of the polishing pad to the radial direction of the semiconductor wafer. When it is vibrated in the radial direction, the inner part of the semiconductor wafer is difficult to be polished because the contact time with the polishing pad is short, and only the outer part is excessively polished. For this reason, there exists a problem that the contamination adhering to an edge part cannot be removed uniformly. On the other hand, if the polishing pad is vibrated in a direction perpendicular to the radial direction of the semiconductor wafer, there is a problem that the polishing efficiency is lowered.

  Accordingly, the present invention has been made in view of the above problems, and an object of the present invention is to uniformly and efficiently polish an edge portion of an object to be polished to suitably remove contamination. It is an object of the present invention to provide a new and improved polishing apparatus.

In order to solve the above-described problems, according to a first aspect of the present invention, there is provided a polishing apparatus for polishing an edge portion of a substantially disc-shaped object to be polished, the object being rotatably held by the object to be polished. A polishing pad having a surface area smaller than that of the object to be polished; a polishing pad holding means for holding the polishing pad; and a swinging means for swinging the polishing pad holding means. While rotating the workpiece by the object holding means, the polishing pad holding means presses the polishing pad against the edge of the object to be polished, and the swinging means pushes the polishing pad to the radius of the object to be polished. The one side of the polishing pad on the center side of the object to be polished has a substantially arc shape corresponding to the swinging locus of the polishing pad. Features To.

  With this configuration, a limited region called an edge portion of the object to be polished can be uniformly polished by swinging a small polishing pad in a direction substantially perpendicular to the radial direction of the object to be polished. Further, by rotating the polishing pad in a circular arc, the abrasive grains can be moved in a random direction, and the abrasive grains can be held on the surface of the polishing pad for a long time, so that the polishing efficiency is not lowered. Therefore, the edge portion can be uniformly and efficiently polished by the polishing pad, and contamination attached to the edge portion can be suitably removed. At this time, since the removal amount by polishing is relatively easy to control, for example, it is possible to suitably polish and remove only the contamination while leaving the oxide film of the semiconductor wafer. Further, since the polishing pad is small, the polishing pad can be replaced as necessary without increasing the replacement cost and the replacement work time.

  Further, one side of the polishing pad on the center side of the object to be polished (one side outside the arc swing of the polishing pad) may have a substantially arc shape corresponding to the swing trajectory of the polishing pad. With this configuration, the circularly oscillating polishing pad can be brought into contact more evenly with the entire polishing region at the edge of the object to be polished, so that contamination can be removed more evenly.

  The polishing pad may be replaced every time the edge portion of at least one workpiece is polished. With this configuration, polishing is performed using a new polishing pad for each object to be polished, so that cross-contamination through the polishing pad can be prevented and product yield can be improved.

The terms used in this specification are defined below.
-"Edge part of to-be-polished object" means the outer peripheral part and outer edge part of the to-be-polished object which has a substantially disc shape.
-"Outer peripheral part of the workpiece" means the outer peripheral surface of the workpiece having a substantially disk shape, and the curved outer peripheral surface when the outer edge of the workpiece is rounded by chamfering. Shall also be included.
• “Outer edge of the object to be polished” means a part of the front or back surface of the object to be polished having a substantially disk shape, and is within a predetermined distance from the boundary with the outer periphery. A substantially ring-shaped flat region extending to the circumferential side. Note that a circuit such as an LSI is not formed on the outer edge.
・ "Surface of the object to be polished" refers to the plane on which the circuit or the like is formed of the two planes of the object to be polished having a substantially disk shape, while the "back surface of the object to be polished" A plane opposite to the surface on which a circuit or the like is formed (that is, the surface).
“Contamination” refers to an unnecessary object or foreign matter such as a metal such as copper or aluminum, an oxide film, a nitride film, etc. adhering to an object to be polished.
・ "Cross contamination" means that the contamination that has adhered to one workpiece is indirectly attached to the other workpiece via another medium (conveying device, polishing pad, etc.). Say.

  As described above, according to the present invention, the polishing pad and the edge portion can be evenly contacted by swinging a small polishing pad in an arc substantially perpendicular to the radial direction of the object to be polished. At the same time, it is possible to suppress a decrease in polishing efficiency by keeping the abrasive grains on the surface of the polishing pad for a long time while moving the abrasive grains in a random direction. For this reason, the edge part of a to-be-polished object can be grind | polished equally and efficiently, and the contamination which exists in the said edge part can be removed suitably.

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the present specification and drawings, components having substantially the same functional configuration are denoted by the same reference numerals, and redundant description is omitted.

(First embodiment)
First, based on FIG. 1, the whole structure of the grinding | polishing apparatus concerning the 1st Embodiment of this invention is demonstrated. FIG. 1 is a plan view (a) and a front view (b) showing the overall configuration of the polishing apparatus 10 according to the present embodiment. In the following, an example of a semiconductor wafer will be described as a substantially disk-shaped object to be polished, but the object to be polished is not limited to such an example.

  As shown in FIG. 1, the polishing apparatus 10 according to the present embodiment includes, for example, a chuck table 14 that holds a semiconductor wafer 12, a polishing pad 20 that polishes the semiconductor wafer 12, and a polishing pad holding that holds the polishing pad 20. Means 30, a rocking means 50 for rocking the polishing pad holding means 30 about the rocking shaft 40, and a polishing liquid supply means 60 for supplying a polishing liquid to the polishing surface are provided.

  The chuck table 14 is configured as a workpiece holding means according to the present embodiment, and has a function of holding the semiconductor wafer 12 rotatably. The chuck table 14 is a substantially disk-shaped rotary table made of, for example, stainless steel or ceramics, and its upper surface is, for example, a flat horizontal surface. The chuck table 14 includes, for example, a vacuum suction mechanism (not shown), and can hold the semiconductor wafer 12 placed on the upper surface by vacuum suction. Note that the orientation of the semiconductor wafer 12 placed on the chuck table 14 may be either when the front surface on which the circuit is formed faces upward or when the rear surface faces upward.

  The table diameter of the chuck table 14 is set to be smaller than the diameter of the semiconductor wafer 12. For this reason, the semiconductor wafer 12 is held in a state in which the edge portion 12 a protrudes from the outer peripheral edge of the chuck table 14.

  Further, the chuck table 14 is configured to be rotatable by, for example, a drive motor 16 provided below the chuck table 14. Thereby, at the time of polishing, the chuck table 14 can rotate the held semiconductor wafer 12 at, for example, 500 rpm. In order to prevent the semiconductor wafer 12 thus rotated from being shaken, the semiconductor wafer 12 is held on the chuck table 14 so that the center of the semiconductor wafer 12 and the rotation axis of the chuck table 14 coincide with each other. The rotation direction of the chuck table 14 may be opposite to the illustrated direction.

  The polishing pad 20 is disposed at a position where it can come into contact with the edge portion 12a of the semiconductor wafer 12, and has a function of polishing the edge portion 12a. The polishing pad 20 has, for example, a two-layer structure including a surface polishing cloth and an inner elastic layer, and does not include abrasive grains. The abrasive cloth is an artificial leather-like cloth made of, for example, a nonwoven fabric or urethane foam, has a predetermined friction resistance and appropriate hardness, and is excellent in hydrophilicity, viscoelasticity, and chemical resistance. The elastic layer is made of an elastic material and can elastically support the polishing cloth pressed against the edge portion 12a of the semiconductor wafer 12. Note that the polishing pad 20 may not necessarily include this elastic layer.

  Further, the polishing pad 20 is characterized in that it is formed in small pieces that have a surface area sufficiently smaller than that of the semiconductor wafer 12. That is, the object to be polished by the polishing pad 20 is not the entire front surface (or back surface) of the semiconductor wafer 12 but a limited region called the edge portion 12a. Therefore, the polishing pad 20 only needs to have a necessary and sufficient size for polishing the edge portion, so that the surface area can be made sufficiently smaller than that of the semiconductor wafer 20.

  The polishing pad holding means 30 has, for example, a function of holding the polishing pad 20 on the lower surface side thereof and pressing the held polishing pad 20 against the surface side (or back side) edge portion 12a of the semiconductor wafer 12 from above. The polishing pad holding means 30 includes, for example, a holding block 32 to which the polishing pad 20 is attached at the tip of the lower surface, a base portion 36 fixed to the swing shaft 40, and the holding block 32 and the base portion 36. And a connecting portion 34 that is elastically connected. Details of the polishing pad holding means 30 will be described later.

  The swinging means 50 swings the polishing pad holding means 30 about the swinging shaft 40, and swings the polishing pad 20 attached to the tip of the polishing pad holding means 30 with an arcuate locus. (Hereinafter referred to as “arc swing”).

  The swinging means 50 includes, for example, a drive motor 52, an eccentric shaft 54 having a variable eccentric amount connected to a rotation shaft of the drive motor 52, and a primary link 56 connected to the eccentric shaft 54 at one end. The secondary link 58 is connected to the primary link 56 at one end and to the swing shaft 40 at the other end. The swinging means 50 having such a configuration rotates the eccentric shaft 54 by the rotational driving force of the drive motor 52, and drives the primary link 56 and the secondary link 58 by the rotation of the eccentric shaft 54, thereby rotating the swing shaft. 40 is rotated so as to reciprocate within a predetermined rotation angle range. As a result, the polishing pad holding means 30 is swung about the rocking shaft 40. As a result, the polishing pad 20 at the tip is moved in the radial direction of the semiconductor wafer 12 (X-axis direction in FIG. 1). Thus, the arc can be swung in a substantially vertical direction (substantially Y-axis direction in FIG. 1).

  Thus, the swinging means 50 is a swinging mechanism having a relatively simple configuration, and any electric motor can be used as long as the drive motor 54 can control the speed. Therefore, it is possible to obtain a high polishing effect as described later by swinging the polishing pad 20 in a circular arc with a low-cost apparatus.

  The polishing liquid supply means 60 has a function of supplying, for example, a polishing liquid (slurry) containing loose abrasive grains to the polishing surface between the polishing pad 20 and the semiconductor wafer 12. This polishing liquid is, for example, a polishing agent containing a chemically reactive substance, and includes various chemical solutions and free abrasive grains. By supplying such a polishing liquid, chemical mechanical polishing (CMP) by the polishing pad 20 becomes possible. The polishing liquid is supplied to the holding block 32 from the outside via a tube, for example, by the polishing liquid supply means 60, passes through the inside of the polishing pad 20, and is supplied to the polishing surface. As a result, a minimum amount of polishing liquid can be supplied, which is very economical. The polishing liquid supply means 60 is not limited to the above example. For example, the polishing liquid is directly supplied onto the semiconductor wafer 12 by a supply nozzle, and the polishing liquid enters the polishing surface as the semiconductor wafer 12 rotates. You may make it the structure which makes it.

  The overall configuration of the polishing apparatus 10 has been described above. The polishing apparatus 10 having such a configuration supplies the polishing liquid by the polishing liquid supply means 60 and rotates the semiconductor wafer 12 by the polishing table 14 while the polishing pad holding means 30 moves the polishing pad 20 to the edge portion 12 a of the semiconductor wafer 12. Press on. At this time, the polishing pad 20 is rocked in a circular arc in a direction substantially perpendicular to the radial direction of the semiconductor wafer 20 in a horizontal plane (XY plane), for example. As a result, the polishing pad 20 and the edge portion 12a of the semiconductor wafer 12 are rubbed in a complicated direction, and the edge portion 12a on one side of the semiconductor wafer 12 is polished (CMP) as shown in FIG. be able to. By this polishing, it is possible to remove contamination that has adhered and deposited on the edge portion 12a.

  Here, based on FIG. 2, the polishing region of the semiconductor wafer 12 by the polishing apparatus 10 will be described. FIG. 2 is a plan view (a) showing the semiconductor wafer 12 having the edge portion 12a polished by the polishing apparatus, and an enlarged sectional view (b) showing the edge portion 12a in an enlarged manner. In FIG. 2, the polishing area is hatched.

  As shown in FIG. 2A, the edge portion 12 a on one side (front surface or back surface) of the semiconductor wafer 12 extends along the circumferential direction of the semiconductor wafer 12 by polishing using the polishing apparatus 10 as described above. Polished in a ring shape.

  Further, in the polishing apparatus 10, the semiconductor wafer 12 to be polished is extremely thin (for example, 30 μm), and the edge portion of the semiconductor wafer 12 is held in a state of protruding from the outer edge of the chuck table 14. For this reason, the polishing pad 20 having elasticity is not only the outer edge portion 12b of the front surface (or back surface) of the semiconductor wafer 12, but also the outer peripheral portion 12c on the front surface side (or back surface side), as shown in FIG. It can act suitably also for. Therefore, even when the polishing pad 20 is pressed from above, both the outer edge portion 12b and the outer peripheral portion 12c (that is, the edge portion 12a on the front surface or the back surface side) of the front surface side (or the back surface side) of the semiconductor wafer 12 are polished. Can do.

  Next, the polishing pad 20 and the polishing pad holding means 30 according to the present embodiment will be described in detail with reference to FIG. FIG. 3 is a front view (a) and a bottom view (b) showing the polishing pad 20 and the polishing pad holding means 30 according to the present embodiment.

As shown in FIG. 3, the polishing pad holding means 30 includes, for example, a substantially rectangular parallelepiped holding block 32, a base portion 36 fixed to the swing shaft 40, and a support block 32 and the base portion 36 connected to each other. Connecting portion 34 to be connected. As shown in FIG. 3A, the connecting portion 34 includes, for example, two upper and lower resin parallel springs 34a and 34b. For this reason, it is possible to apply a polishing load to the polishing pad 20 by utilizing the bending of the parallel springs 34a and 34b. More specifically, as shown by the two-dot chain line in FIG. 3A, the parallel springs 34a and 34b are bent by moving the holding block 32 upward in the vertical direction (Z-axis direction). A vertically downward elastic force is generated in 34a and 34b. As a result, the polishing pad 20 attached to the lower surface of the holding block 32 can be pressed against the semiconductor wafer 12 with a predetermined polishing pressure. This polishing pressure is continuously variable, for example, in the range of 0 to 0.1 MPa (about 0 to 1 kg / cm ² ). Since an appropriate value of this polishing pressure is considered to be, for example, about 500 kg / cm ² , the shape and arrangement of each part of the polishing pad holding means 30 are adjusted so that the polishing pressure is applied.

  Next, the arrangement and shape of the polishing pad 20 will be described in detail. The polishing pad 20 is attached to, for example, the front end side (the semiconductor wafer 12 center side) of the lower surface of the holding block 32. The attachment of the polishing pad 20 is realized, for example, by fixing a resin plate attached to the back surface of the polishing pad 20 to the lower surface of the holding block 32 by suction or clamping. With this attachment method, the polishing pad 20 can be easily fixed to the holding block 32 in a detachable manner. Therefore, the polishing pad 20 can be automatically exchanged by an automatic exchange unit (not shown) as an external device, or can be easily exchanged manually.

  As described above, when the same polishing pad 20 is continuously used for a plurality of semiconductor wafers 12, there is a possibility that cross contamination occurs through the polishing pad 20. Therefore, in the polishing apparatus 10 according to the present embodiment, in the polishing process in which contamination is a problem, for example, the polishing pad 20 is replaced for each semiconductor wafer 12 to be disposable. Thereby, generation | occurrence | production of the cross contamination through the polishing pad 20 can be prevented. In addition, it is possible to replace the polishing pad 20 with a new one during the polishing process of one semiconductor wafer 12 and perform final finish polishing.

  In the present embodiment, even if the polishing pad 20 is disposable in this way, the size of the polishing pad 20 is very small, so there is no significant increase in cost, and a large polishing pad such as the cylindrical pad of Patent Document 3 above. It is economical compared with the case of exchanging. Furthermore, since the polishing pad 20 can be replaced quickly or easily automatically or manually by the above attachment method, the efficiency of polishing work is not reduced by the replacement work.

  Further, as shown in FIG. 3B, the polishing pad 20 is characterized in that one side 20a outside the arc swing is formed in an arc shape corresponding to the arc swing by the swing means 50. Is. More specifically, for example, of the four sides of the polishing pad 20, one side 20 a on the center side of the semiconductor wafer 12 has an arc shape with the swing shaft 40 as the center. With this configuration, when polishing the edge portion 12a of the semiconductor wafer 12, the polishing pad 20 is always brought into contact with the edge portion 12a evenly when the polishing pad 20 is rocked in an arc around the rocking shaft 40. be able to.

  Next, based on FIG. 4, operation | movement of the grinding | polishing apparatus 10 concerning this embodiment is demonstrated in detail. FIG. 4 is a plan view showing a state where the polishing pad 20 and the polishing pad holding means 30 according to the present embodiment are swinging.

  In the polishing apparatus 10 according to the present embodiment, the polishing pad holding means 30 is moved by the swinging means 50 while the polishing pad 20 is pressed against the edge portion 12a of the semiconductor wafer 12, as shown in FIG. Are oscillated periodically within a predetermined angle range around the oscillating shaft 40.

  Since the center of oscillation at this time is on, for example, a line connecting the oscillation shaft 40 and the center of the semiconductor wafer 12, the polishing pad 20 can be applied to the edge portion 12a evenly. The swing angle α of this swing is slightly over 19 °, for example, but the swing angle α is made larger or smaller by adjusting the eccentric amount of the eccentric shaft 54 of the swing means 50. It is also possible. When the swing angle α is slightly above 19 °, the amplitude of the holding block 32 and the polishing pad 20 is, for example, about 23.2 mm. The oscillation frequency is determined according to, for example, the type of semiconductor wafer 12 or contamination, the amount of polishing, and the like, for example, by changing the rotational speed of the drive motor 52 of the oscillation means 50, for example, from 0 to 0. Variable between 60 Hz. Note that this oscillation frequency can be easily increased by, for example, mounting a drive motor 52 capable of rotating at a higher speed.

  By swinging the polishing pad holding means 30 as described above, the polishing pad 20 attached to the tip of the polishing pad holding means 30 is pressed against the edge portion 12a of the semiconductor wafer 12, and the radius of the semiconductor wafer 12 is increased. The arc can be swung in a direction substantially perpendicular to the direction (substantially Y-axis direction). Specifically, the polishing pad 20 is moved to the maximum in the positive direction along the Y axis with the position indicated by the solid line 20 in FIG. 4 as the center of oscillation (position indicated by the two-dot chain line 20 ′ in FIG. 4). And a position reciprocally moved in a negative direction in the Y-axis direction (a position indicated by a two-dot difference line 20 ″ in FIG. 4) along an arc-shaped locus centering on the swing shaft 40.

  By polishing the polishing pad 20 in a circular arc in this way, the edge portion 12a of the semiconductor wafer 12 is uniformly polished with high polishing efficiency (CMP), and the contamination of the edge portion 12a is preferably removed. Can do.

  More specifically, first, the swinging direction of the polishing pad 20 is roughly perpendicular to the radial direction of the semiconductor wafer 12. For this reason, the entire front side or back side of the edge portion 12a regardless of whether it is a portion on the radially inner side (wafer center side) or the outer side (wafer outer peripheral side) of the edge portion 12a of the semiconductor wafer 12. The polishing pad 20 can be evenly contacted with respect to the surface. That is, when the polishing pad is swung in the radial direction of the semiconductor wafer 12 as described in Patent Document 4, the outer side portion of the edge portion 12a of the semiconductor wafer 12 is more than the inner side portion. However, since it contacts the polishing pad 20 for a long time, there is a problem that the outer portion is inevitably polished more than the inner portion. On the other hand, in the present embodiment, the polishing pad 20 is swung in a direction substantially perpendicular to the radial direction of the semiconductor wafer 12, so that a difference in polishing amount does not occur depending on the position in the radial direction. The entire front side or back side can be evenly polished. It should be noted that, by swinging the polishing pad 20, there is of course an effect that the free abrasive grains can easily escape from the recesses on the surface of the polishing pad 20.

  Secondly, in this embodiment, the polishing pad 20 is rocked in an arc rather than simply rocking linearly. By this arc swing, loose abrasive grains existing between the surface of the polishing pad 20 and the semiconductor wafer 12 are not only perpendicular to the radial direction of the semiconductor wafer 20 (X-axis direction) but also in the radial direction ( (Y-axis direction) can also be moved. For this reason, the abrasive grains can be moved in a random direction, and the abrasive grains can be retained on the polishing pad 20 for a long period of time. It is possible to suppress a decrease in polishing efficiency due to the substantially vertical direction (X-axis direction) with respect to the 12 radial directions.

  Third, as described with reference to FIG. 3B, the side 20a on the outer side of the arc swing of the polishing pad 20 is formed in an arc shape matching the locus of the arc swing. Thus, when the polishing pad 20 is swung in a circular arc, the polishing pad 20 can be evenly contacted with the edge portion 12a of the semiconductor wafer 12, so that the edge portion 12a can be more evenly polished. it can.

  In this polishing process, as shown in FIG. 4, for example, the polishing pad 20 has only a part on the center side of the semiconductor wafer 12 (a part extending from one side 20a on the outer side of the circular arc swing to a predetermined distance inside) as a semiconductor. The edge 12a of the wafer 12 is in contact with the entire surface, but not the entire surface. That is, a play portion that does not come into contact with the edge portion 12a is provided inside the circular arc swing of the polishing pad 20. As a result, the entire front surface side or back surface side of the edge portion 12a of the semiconductor wafer 20 can be reliably brought into contact with the polishing pad 40, so that more uniform polishing is possible.

  As described above, in the polishing apparatus 10 according to the present embodiment, the polishing pad 20 and the semiconductor wafer are moved while the free abrasive grains are moved in a random direction by the rotation of the semiconductor wafer 12 and the arc swing of the polishing pad 20. By rubbing with the 12 edge portions 12a, the edge portions 12a can be evenly and efficiently polished. Further, in polishing the edge portion 12a of the semiconductor wafer 12, it is relatively easy to control the polishing removal amount. Accordingly, it is possible to suitably polish and remove only the contamination while leaving the oxide film. The inventors of the present application conducted an experiment to polish the edge portion 12a of the semiconductor wafer 20 by swinging the polishing pad 20 in an arc as described above. In this experiment, it was confirmed that a good polished surface was obtained and the contamination was suitably removed.

  In addition, since the polishing pad 20 is small and the mounting method is devised in the polishing apparatus 10 according to the present embodiment, the polishing pad 20 can be replaced quickly and easily, and the polishing pad 20 is frequently replaced. The cost will not increase. Therefore, it is possible to frequently replace the polishing pad 20 as necessary (for example, for each semiconductor wafer 12). Therefore, contamination of the semiconductor wafer 12 (silicon substrate or the like) due to cross contamination through the polishing pad 20, diffusion of metal ions, generation of microcracks, etc. can be prevented, and a high product yield can be ensured.

  As mentioned above, although preferred embodiment of this invention was described referring an accompanying drawing, it cannot be overemphasized that this invention is not limited to the example which concerns. It will be apparent to those skilled in the art that various changes and modifications can be made within the scope of the claims, and these are naturally within the technical scope of the present invention. Understood.

  For example, in the above embodiment, the example of the disk-shaped semiconductor wafer 12 is described as an object to be polished, but the present invention is not limited to such an example. The object to be polished may be any substrate as long as it is a substantially disk-shaped substrate that requires edge exclusion. Further, the semiconductor wafer 12 does not have to be a complete disk, and for example, a notch such as an orientation flat or a nodge may be formed.

  Further, the shape of the polishing pad 20 is not limited to the shape as shown in FIG. As long as the polishing pad 20 has a surface area smaller than that of the object to be polished, the polishing pad 20 may have any shape such as a disk shape, an ellipse shape, and a ring shape.

  In the above embodiment, the polishing pad 20 is pressed against the semiconductor wafer 12 located below to polish the semiconductor wafer 12, but the present invention is not limited to this example. For example, by reversely using the top and bottom of the polishing apparatus 10, the edge portion 12a can be polished from below the semiconductor wafer 12 or the like. Specifically, for example, the polishing pad 20 may be attached to the upper surface of the holding block 32, and the polishing pad 20 may be pressed against the lower surface side of the edge portion 12a of the semiconductor wafer 12 for polishing. Further, a plurality of sets of polishing pads 20 and polishing pad holding means 30 may be provided so that the upper surface side and lower surface side of the edge portion 12a of the semiconductor wafer 12 can be polished simultaneously.

  Further, for example, a rotational movement mechanism of the polishing pad holding means 30 may be provided so that the polishing pad 20 can be pressed from directions other than the vertical direction. As a result, the polishing pad 20 can be pressed against the edge portion 12a of the semiconductor wafer 12 held horizontally to be polished from an oblique direction or a horizontal direction. As a result, the outer peripheral portion 12c and the like of the semiconductor wafer 12 can be intensively polished.

  Further, the swinging means 50 is not limited to the example of the above embodiment, and the design can be arbitrarily changed as long as the polishing pad 20 can swing in an arc. For example, the holding means 50 may be configured to be able to swing (vibrate) the polishing pad 20 in a predetermined cycle using an ultrasonic motor, an electromagnetic motor, a piezoelectric element, a voice coil, or the like.

  Further, the rocking angle α, amplitude, rocking frequency, rocking radius, etc. of the arc rocking of the polishing pad 20 are not limited to the example of the above embodiment, and the type of the object to be polished, the polishing pad or the polishing liquid It can be changed arbitrarily according to the above.

  In addition, the chuck table 14 according to the above embodiment sucks and holds the semiconductor wafer 12 using a vacuum suction mechanism, but is not limited to this example, and the semiconductor wafer 12 is attached using an adhesive means such as an adhesive or an adhesive tape. You may comprise so that attachment or detachment is possible. The object holding means is not limited to the example of the chuck table 14 as long as it can hold the object to be polished. Also good.

  The present invention can be applied to a polishing apparatus, and in particular, can be applied to a polishing apparatus that polishes and removes contamination at an edge portion of an object to be polished.

It is the top view (a) and front view (b) which show the whole structure of the grinding | polishing apparatus concerning the 1st Embodiment of this invention. It is the top view (a) which shows the semiconductor wafer by which the edge part was grind | polished with the grinding | polishing apparatus concerning the embodiment, and the expanded sectional view (b) of the edge part. It is the front view (a) and bottom view (b) which show the polishing pad and polishing pad holding | maintenance means concerning the embodiment. It is a top view which shows the state which the polishing pad and polishing pad holding | maintenance means concerning the embodiment rock | fluctuate.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10: Polishing apparatus 12: Semiconductor wafer 12a: Edge part of one side of semiconductor wafer 12b: Outer edge part of one side of semiconductor wafer 12c: Outer peripheral part of one side of semiconductor wafer 14: Chuck table 20: Polishing pad 20a: Polishing pad 30: Polishing pad holding means 32: Holding block 34: Connection part 34a, 34b: Parallel spring 36: Base part 40: Oscillating shaft 50: Oscillating means 60: Polishing liquid supply means α: Oscillating Moving angle

Claims (2)

A polishing apparatus for polishing an edge portion of a substantially disk-shaped workpiece:
An object holding means for rotatably holding the object to be polished;
A polishing pad having a smaller surface area than the object to be polished;
A polishing pad holding means for holding the polishing pad;
Rocking means for rocking the polishing pad holding means;
With
While the object to be polished is rotated by the object to be polished holding means, the polishing pad is pressed against the edge of the object to be polished by the polishing pad holding means, and the polishing pad is polished by the swinging means. Swing along a substantially arc-shaped locus in a direction substantially perpendicular to the radial direction of the object,
The polishing apparatus according to claim 1, wherein one side of the polishing pad on the center side of the object to be polished has a substantially arc shape corresponding to a swing locus of the polishing pad. The polishing apparatus according to claim 1, wherein the polishing pad is replaced every time an edge portion of at least one of the objects to be polished is polished.

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