JP6065208B2 - Polishing pad and manufacturing method thereof - Google Patents

Description

  The present invention relates to a polishing pad and a method for manufacturing the same, and more particularly to a polishing pad used in a chemical mechanical polishing method and a method for manufacturing the same.

  Conventionally, a chemical mechanical polishing method (CMP method) has been used as a method for polishing and flattening the surface of an object to be polished such as a semiconductor wafer, a glass substrate for a liquid crystal display, a glass substrate for a photomask, or a glass substrate for a magnetic disk. Is used. When polishing an object to be polished using the CMP method, the polishing pad is pressed against the object to be polished, and the polishing pad and the object to be polished are rotated while supplying the polishing slurry between them. The polishing slurry flows from the center side toward the outside by centrifugal force accompanying the rotation of the polishing pad, and is finally discharged to the outside of the polishing pad.

  In recent years, the polishing slurry is evenly and sufficiently spread over the surface of the object to be polished, thereby flattening the object to be polished uniformly and with high precision, reducing consumption of expensive polishing slurry, and causing scratches. In order to achieve efficient discharge of polishing debris, it is a common practice to control the flow of polishing slurry by forming grooves of various shapes on the surface of the polishing pad. By controlling the flow of the polishing slurry in the groove, the polishing slurry can be evenly and sufficiently distributed over the surface of the object to be polished, consumption of the polishing slurry can be suppressed, and polishing debris can be efficiently removed from the polishing surface and the surface to be polished. It can be discharged from between the polished objects. As such a technique, for example, one described in Patent Document 1 is known.

  Patent Document 1 describes a polishing pad in which a groove is formed on the surface of the polishing pad, and a mixed structure for mixing a polishing slurry is formed in the groove. The mixed structure is composed of a series of peaks and valleys. And the polishing pad of patent document 1 is preventing the laminar flow of the slurry flow in a groove | channel by the mixed structure.

Japanese Patent No. 4688241

  By the way, generally, the polishing slurry flows between the polishing pad and the object to be polished from the vicinity of the center of the polishing pad, and is directed outward from the vicinity of the center of the polishing pad by centrifugal force when the polishing pad is rotated. Flowing. The flow rate of the polishing slurry changes according to the distance from the center of rotation of the polishing pad, and the flow rate increases in the peripheral portion where the centrifugal force is strong, and the flow rate decreases in the central portion where the centrifugal force is weak. Due to such a speed difference, the amount of slurry discharged increases at a location where the flow rate is high, and the amount of slurry discharge decreases at a location where the flow rate is low.

  Therefore, in order to make the amount of the polishing slurry uniform over the entire polishing surface of the polishing pad, it is desirable to make the flow rate of the polishing slurry in the groove uniform over the entire length of the groove.

  However, according to the mixing structure of Patent Document 1, although the mixing structure is provided in the groove, laminar flow of the polishing slurry in the groove can be prevented and the polishing slurry can be used evenly. However, the polishing slurry in the groove can be used. Therefore, the amount of the polishing slurry cannot be made uniform over the entire polishing surface of the polishing pad.

  Accordingly, the present invention has been made to solve the above-described problems, and an object thereof is to provide a polishing pad that can make the amount of slurry uniform over the entire polishing surface of the polishing pad and a method for manufacturing the same. To do.

  In order to solve the above-described problems, the present invention provides a polishing pad in which a plurality of grooves for flowing a polishing slurry therein are formed on a polishing surface, and each of the plurality of grooves is directed toward the outer periphery of the polishing pad. The downstream end of the polishing pad reaches the outer periphery of the polishing pad, and the flow of the polishing slurry in the groove is formed on the surface of the groove at a position where the flow rate of the polishing slurry is relatively high in the groove. An inhibition structure for inhibiting is provided, and this inhibition structure is characterized by having a plurality of protrusions whose tops are directed to the upstream side of the groove.

  According to the present invention configured as described above, it is possible to prevent an increase in the flow rate of the polishing slurry by providing the blocking structure at a position where the flow rate of the polishing slurry is relatively increased in the groove. Thereby, the flow rate of the polishing slurry can be reduced at a position where the flow rate of the polishing slurry becomes relatively high, and the flow rate of the polishing slurry in the groove can be made more uniform. By making the flow rate of the polishing slurry in the groove more uniform, the distribution of the polishing slurry in the groove can be made more uniform.

  In the present invention, preferably, the inhibition structure is provided only in the vicinity of the downstream end of the groove.

  According to the present invention configured as described above, the inhibition structure can be provided only in the vicinity of the downstream end of the groove where the flow rate of the polishing slurry in the groove is high. By limiting the position of the inhibition structure, the flow of the polishing slurry can be prevented from being inhibited at a position where the flow velocity is low, while the flow of the polishing slurry can be inhibited at a position where the flow velocity is high. Thereby, the flow rate of the polishing slurry in the groove can be made more uniform, and the distribution of the polishing slurry in the groove can be made more uniform.

  In the present invention, preferably, the polishing pad is made of foamable polyurethane, and the protrusions having the inhibition structure are formed by rubbing the surface of the groove toward the upstream side.

  According to the present invention configured as described above, the protrusion formed on the surface of the groove by rubbing the surface of the groove of the foaming polyurethane polishing pad toward the upstream side of the groove is used as the protrusion of the inhibition structure. be able to.

  In the present invention, it is preferable that the structure further includes an accelerating structure that is formed on the surface of the groove on the upstream side of the groove with respect to the obstructing structure and that promotes the flow of the polishing slurry. A plurality of protrusions directed toward the surface.

  According to the present invention configured as described above, the flow rate of the polishing slurry can be promoted on the upstream side of the groove from the hindering structure where the flow rate of the polishing slurry is slow, and thereby the flow rate of the polishing slurry in the groove Can be made more uniform over the entire length of the groove, and the distribution of the polishing slurry in the groove can be made more uniform.

  Further, in order to solve the above-described problems, the polishing pad manufacturing method according to the present invention has a plurality of grooves formed on the polishing surface for flowing polishing slurry therein, and each of the plurality of grooves is formed on the outer periphery of the polishing pad. A polishing pad manufacturing method in which the downstream end of the polishing pad reaches the outer periphery of the polishing pad, and the groove surface faces the upstream side at a position where the flow rate of the polishing slurry is relatively high in the groove. Rubbing and forming a hindering structure that hinders the flow of the polishing slurry in the groove, the hindering structure having a plurality of protrusions whose top is directed upstream of the groove. Features.

  According to the present invention configured as described above, the inhibition structure is provided at a position where the flow rate of the polishing slurry is relatively increased in the groove, and the inhibition structure prevents the increase in the flow rate of the polishing slurry. A polishing pad can be manufactured. Thereby, in the position where the flow rate of the polishing slurry becomes relatively high, the flow rate of the polishing slurry can be decreased, and the flow rate of the polishing slurry in the groove can be made more uniform. By making the flow rate of the polishing slurry in the groove more uniform, the distribution of the polishing slurry in the groove can be made more uniform.

  As described above, according to the present invention, it is possible to provide a polishing pad that can make the amount of slurry uniform over the entire polishing surface of the polishing pad and a method for manufacturing the same.

It is sectional drawing which shows a polishing apparatus provided with the polishing pad by embodiment of this invention. It is a top view which shows the polishing surface of the polishing pad by embodiment of this invention. It is sectional drawing along the III-III cross section of FIG. It is a principal part perspective view which shows the inhibition structure by embodiment of this invention. It is a top view which shows the polishing surface of the polishing pad by the modification of embodiment of this invention. It is a top view which shows the polishing surface of the polishing pad by the modification of embodiment of this invention. It is a top view which shows the polishing surface of the polishing pad by the modification of embodiment of this invention.

  Hereinafter, a polishing pad and a method for manufacturing a polishing pad according to embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a cross-sectional view showing a polishing apparatus including a polishing pad according to the present invention.

  First, as shown in FIG. 1, a polishing apparatus 1 is for flattening a surface of an object to be polished 3 by a CMP method. The polishing apparatus 1 includes a polishing surface plate 5 that rotates about a rotation axis, a polishing pad 7 that is fixed to the upper surface of the polishing surface plate 5, a dresser 31 that sets the polishing surface 9 of the polishing pad 7, and an object to be polished. A holding tool 33 for holding the object 3 and a polishing slurry supply device 35 for supplying the polishing slurry to the polishing surface 9 are provided.

  Such a polishing apparatus 1 is held by the holding tool 33 by rotating the polishing platen 5 and the holding tool 13 while supplying the polishing slurry from the polishing slurry supply device 35 to the polishing surface 9 of the polishing pad 7. Further, the surface of the workpiece 3 is flattened.

FIG. 2 is a top view showing the polishing surface of the polishing pad.
The polishing pad 7 is made of foaming polyurethane, and a plurality of grooves 11 for flowing polishing slurry are formed on the polishing surface 9 thereof. The groove 11 extends straight from the center of the polishing surface 9 to the outer periphery of the polishing pad 7 in the radial direction. In the example shown in FIG. 2, 16 grooves extend on the polishing surface 9 of the polishing pad 7 linearly from the center of the polishing surface 9.

  The supply portion of the polishing slurry supply device 35 is disposed immediately above the center of the polishing surface 9, and the polishing slurry supplied from the polishing slurry supply device 35 is supplied to the center of the polishing surface 9. A part of the supplied polishing slurry enters the groove 11 from the center of the polishing surface 9 and flows from the vicinity of the center of the polishing surface 9 toward the outer periphery of the polishing pad 7. That is, the groove 11 forms a flow path for flowing the polishing slurry from the vicinity of the center of the polishing surface 9 to the outer periphery of the polishing pad 7, and this flow path is upstream from the vicinity of the center of the polishing surface 9. The outer periphery of 7 is downstream.

  The plurality of grooves 11 are formed by a conventionally used turning groove machining tool such as a lathe or a machining center.

3 is a cross-sectional view taken along the line III-III in FIG. The III-III cross section is a cross section along the groove 11 formed in the polishing surface 9.

  As shown in FIG. 3, an inhibition structure 17 that inhibits the flow of the polishing slurry in the groove 11 and an accelerating structure 19 that promotes the flow of the polishing slurry in the groove are formed in the groove 11.

  The inhibition structure 17 is formed at a position where the flow rate of the polishing slurry is relatively high in the groove 11, and has a plurality of protrusions 21 whose top portions are directed to the upstream side of the groove 11. The position where the flow rate of the polishing slurry is relatively high in the groove 11 means a position closer to the downstream of the groove 11 or a position away from the center of the polishing surface 9. That is, as described above, the flow rate of the polishing slurry in the groove 11 corresponds to the distance from the center of the polishing surface 9 that is the rotation center of the polishing pad 7. As the distance from the distance increases, the flow rate of the polishing slurry increases. Therefore, by forming the blocking structure 17 at a position near the downstream of the groove 11 where the flow rate of the polishing slurry is increased, the flow rate of the polishing slurry can be decreased at a position near the downstream of the groove 11.

  The specific position where the inhibition structure 17 is provided is preferably determined by the properties of the polishing slurry, such as the viscosity of the polishing slurry and the abrasive content. As an example, the inhibition structure 17 can be formed from the downstream end of the groove 11 to a position that is about 1/3 upstream of the entire length of the groove 11. Further, in order to improve the discharging property of the polishing slurry from the groove 11, the inhibition structure 17 may not be provided at the outlet of the groove 11, that is, at the downstream end of the groove 11. In consideration of the function of the inhibition structure 17, it is preferable that the inhibition structure 17 is not formed near the upstream of the groove 11, but only on the downstream side of the groove 11, or in some cases only near the downstream end.

FIG. 4 is a main part perspective view showing the inhibition structure.
As described above, the inhibition structure 17 has a plurality of protrusions 21 formed at the bottom of the groove 11. Each protrusion 21 is formed by, for example, pressing a polishing tool such as a rotating brush with abrasive grains or a grindstone against the bottom surface of the groove 11 and rotating the polishing tool toward the upstream side. When the polishing tool is pressed against the bottom surface of the groove 11 and rotated, the bottom surface of the groove 11 made of foamable polyurethane is pushed toward the upstream side. Thereby, a plurality of protrusions 21 are formed on the bottom surface of the groove 11, and the bottom surface of the groove 11 has a waved shape. The protrusion 21 protrudes from the bottom surface of the groove 11, and the top 23 faces the upstream side of the groove 11.

  Moreover, the groove | channel and the protrusion-shaped object 21 can also be formed simultaneously by using the multiblade tool in which the blade part was provided with two or more in parallel with respect to the cutting direction. In this case, the cutting speed is reduced, several blades of the multi-blade tool blade are made of different materials, the protruding height of several blades of the multi-blade tool blade is increased, the multi-blade tool A technique such as changing the shape of the blade tip at several points of the blade is used.

  The size of the protrusion 21 varies depending on the strength with which the polishing tool is pressed against the bottom surface of the groove 11 and the number of rotations of the polishing tool. The size of the protrusion 21 is measured from the upstream side toward the downstream side when the contact-type surface roughness measuring instrument is applied to the bottom surface of the groove 11 where the blocking structure 17 is formed and the surface roughness is measured. It is preferable that the difference between the numerical value of the measured maximum height Rz (JIS B 0601: 2001) and the numerical value of the maximum height Rz measured from the downstream side toward the upstream side is preferably 5 μm or more, and 20 μm. It is more preferable that the setting is made as described above.

  In addition, FIG. 4 is a drawing schematically represented for convenience of explanation. When a polishing tool is actually pressed against the bottom surface of the groove of the polishing pad made of foamable polyurethane to roughen the surface to form a protrusion, Protrusions having a geometric shape as shown in FIG. 4 are not formed, and the urethane surface becomes fluffy toward the upstream side. A plurality of fluffy objects having different sizes and shapes are formed on the bottom surface of the groove. At this time, each fluff-like object has a projection shape protruding from the bottom surface of the groove, protrudes from the bottom surface of the groove toward the upstream side, and its top portion is directed to the upstream side of the groove.

  The promotion structure 19 is provided on the upstream side of the inhibition structure 17. Like the inhibition structure 17, the promotion structure 19 has a plurality of protrusions 25, and the top of the protrusions 25 is directed to the downstream side of the groove.

  The position where the accelerating structure 19 is provided may be on the upstream side of the groove 11 with respect to the inhibiting structure 17 and can be determined by the properties of the polishing slurry, such as the viscosity of the polishing slurry and the abrasive content, similarly to the inhibiting structure 17. preferable. As an example, the accelerating structure 19 can be formed from the upstream end of the groove 11 to a position that is about 1/3 of the entire length of the groove 11 and downstream. Further, the promotion structure 19 may be formed so as to be continuous with the inhibition structure 17 or may be formed at a position away from the inhibition structure 17 by a predetermined distance.

  The protrusion 25 of the accelerating structure 19 has the same configuration as the protrusion 23 of the inhibition structure 17 except that the apex faces the downstream side of the groove 11, and a predetermined polishing tool is inserted into the groove 11. The polishing tool is rotated toward the downstream side while being pressed against the bottom surface of the steel plate.

  Next, the operation of the polishing pad 7 will be described in detail.

  By providing the blocking structure 17 and the accelerating structure 19 in the groove 11 of the polishing pad 7, the flow of the polishing slurry is promoted upstream of the groove 11 in one groove 11, and the polishing slurry is downstream of the groove 11. The flow of is obstructed. In the groove not having the inhibition structure 17 and the promotion structure 19, the flow rate of the polishing slurry becomes faster toward the downstream side. However, the inhibition structure 17 and the promotion structure 19 are formed in the groove 11, and the flow of the polishing slurry is promoted by the promotion structure 19 on the upstream side of the groove 11, and the flow of the polishing slurry by the inhibition structure 17 on the downstream side of the groove 11. By inhibiting this, the flow rate of the polishing slurry can be made to approach uniformly over the entire length of the groove 11. Thereby, the amount of the polishing slurry can be made uniform over the entire length in the groove 11. Since a plurality of grooves 11 are formed on the polishing surface 9 of the polishing pad 7, the amount of polishing slurry in the entire polishing surface 9 is made uniform by making the amount of polishing slurry in each groove 11 uniform. Accordingly, the amount of the polishing slurry between the object 3 and the polishing surface 9 can be made uniform regardless of which part of the polishing surface 9 the object 3 is in contact with.

  In the above-described embodiment, the inhibition structure 17 and the promotion structure 19 are formed in one groove 11, but it is not always necessary to form the inhibition structure 17 and the promotion structure 19 in one groove 11. Only the inhibition structure 17 may be formed, or only the promotion structure 19 may be formed. Further, the obstructing structure 17 and the accelerating structure 19 are not necessarily formed on the bottom surface of the groove 11, but formed on the side wall of the groove 11, or on the side wall of the groove having a V-shaped cross section, the surface of the groove having an arc-shaped cross section, or the like. Or may be formed. In addition, the length of the inhibition structure 17 and / or the promotion structure 19 with respect to the groove 11 does not have to be the same in all the grooves 11, and the inhibition structure 17 and / or the promotion structure having different lengths between adjacent grooves 11. 19 may be included.

  Further, in the above-described embodiment, the detailed description has been given by taking the polishing pad 7 including the polishing surface 9 having the grooves 11 extending linearly as an example. However, it is also possible to apply the present invention to a polishing pad provided with polishing having a grid-like groove as shown in FIG. 5, a curved radiation groove as shown in FIG. 6, or a spiral groove as shown in FIG. is there.

  A plurality of grooves 55 are formed on the polishing surface 53 of the polishing pad 51 shown in FIG. 5 so as to draw a lattice. Then, the inhibition structure 17 and the promotion structure 19 described above may be formed in the groove 55 of the polishing pad 51. In such a polishing pad 51, there is a groove that does not pass near the center C of the polishing surface 53, for example, a groove 55x. The flow of the polishing slurry in the groove 55x starts from the center C of the polishing surface 53. Since the flow rate of the slurry corresponds to the magnitude of the centrifugal force, when the inhibition structure 17 is formed in the groove 55, the inhibition structure may be formed in the shortest groove path direction from the outer periphery toward the center C.

  In the example shown in FIGS. 6 and 7, the groove extends in a curved shape starting from the center C of the polishing surface, but the upstream side of the curved groove is not the direction of the center C of the polishing surface, but the groove. When an arbitrary point is seen, the direction in which the polishing slurry flows with respect to that point is the upstream side, and the direction in which the polishing slurry flows from that point is the downstream side.

7, 51 Polishing pad 9, 53 Polishing surface 11, 55 Groove 17 Inhibition structure 19 Promotion structure 21 Protrusion 23 Vertex 25 Protrusion

Claims (5)

A polishing pad in which a plurality of grooves for flowing polishing slurry therein is formed on the polishing surface,
Each of the plurality of grooves extends toward the outer periphery of the polishing pad, and its downstream end reaches the outer periphery of the polishing pad.
An obstruction structure is formed on the surface of the groove at a position where the flow rate of the polishing slurry is relatively high in the groove, and hinders the flow of the polishing slurry in the groove,
This inhibition structure is a polishing pad having a plurality of protrusions whose tops are directed to the upstream side of the groove.   The polishing pad according to claim 1, wherein the inhibition structure is provided only in the vicinity of the downstream end of the groove. The polishing pad is made of foamable polyurethane,
The polishing pad according to claim 1, wherein the protrusions having the inhibition structure are formed by rubbing the surface of the groove toward the upstream side. Provided with an accelerating structure formed on the surface of the groove on the upstream side of the groove with respect to the obstructing structure to promote the flow of the polishing slurry;
The polishing pad according to claim 1, wherein the promotion structure has a plurality of protrusions whose tops are directed to the downstream side of the groove. A plurality of grooves for flowing a polishing slurry therein are formed on the polishing surface, each of the plurality of grooves extends toward the outer periphery of the polishing pad, and the downstream end thereof reaches the outer periphery of the polishing pad. A manufacturing method of
Rubbing the surface of the groove toward the upstream side at a position where the flow rate of the polishing slurry is relatively high in the groove, and forming a blocking structure that inhibits the flow of the polishing slurry in the groove;
This inhibition structure is a method for manufacturing a polishing pad, which has a plurality of protrusions whose tops are directed to the upstream side of the groove.

Images