Patent Publication Number: US-RE46648-E

Title: Polishing pad, polishing method and method of forming polishing pad

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application is a divisional of U.S. application Ser. No. 12/428,231, filed on Apr. 22, 2009, which claims the priority benefit of Taiwan application serial No. 97125981, filed on Jul. 9, 2008, the entireties of which are incorporated herein. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a polishing pad, a polishing method and a method of forming a polishing pad. More particularly, the polishing pad can provide a different slurry flow distribution. 
     2. Description of Related Art 
     With the progress of the industry, a planarization process is often adopted as a process for manufacturing various devices. A chemical mechanical polishing (CMP) process is often used in the planarization process in the industry. General speaking, the chemical mechanical polishing process supplies slurry having a chemical on the polishing pad, applies a pressure on the substrate to be polished to press it on the polishing pad, and provides a relative motion between the substrate and the polishing pad. Through the mechanical friction generated by the relative motion and the chemical effects of the slurry, a portion of the surface layer of the substrate is removed to make the surface flat and smooth so as to achieve planarization. 
       FIG. 1  is a schematic top view of a conventional polishing pad.  FIG. 1A  is a cross-section view of the polishing pad taken along a line A-A′ in  FIG. 1 . Referring to  FIG. 1 , a polishing pad  100  includes a polishing layer  102  and a plurality of circumferential grooves  104 . The polishing layer  102  is in contact with a surface of a substrate  105  (e.g. a wafer). The plurality of circumferential grooves  104  is disposed in the polishing layer  102  in the manner of concentric circles. The circumferential grooves  104  are used to contain slurry. When the polishing process is performed, the polishing pad  100  moves in a rotational direction  101 , for example, a counterclockwise direction as shown in  FIG. 1 . At the same time when the polishing pad  100  rotates, the slurry is continuously supplied to the polishing pad  100  and flows between the polishing layer  102  and the substrate  105 . 
     As shown in  FIG. 1A , part of the slurry flows to the surface of the polishing layer  102  through the centrifugal force generated from the rotation of the polishing pad  100 , as shown in a flow direction  103 . However, most of the slurry  108  is still contained in the circumferential grooves  104  and only a small portion thereof flows to the surface of the polishing layer  102 . The distribution of the slurry has an effect on polishing characteristics during the polishing process. 
     Therefore, it is needed to provide a polishing pad which can provide a different slurry flow distribution for industry in response to the requirements of various polishing processes. 
     SUMMARY OF THE INVENTION 
     Accordingly, the present invention provides a polishing pad and a polishing method using the polishing pad. The polishing pad can provide a different slurry flow distribution. 
     The present invention further provides a forming method of a polishing pad, wherein the formed polishing pad provides a different slurry flow distribution. 
     The present invention provides a polishing pad and a polishing method using the polishing pad. The polishing pad includes a polishing layer and a plurality of arc grooves. The plurality of arc grooves are disposed in the polishing layer. Each of the plurality of arc grooves has two ends, and at least one end thereof has an inclined wall. The angle between the inclined wall and the surface plane of the polishing layer is less than 90 degrees. 
     The present invention further provides a polishing pad and a polishing method using the polishing pad. The polishing pad includes a polishing layer, a plurality of arc grooves, and a polishing surface. The plurality of arc grooves are disposed in the polishing layer and surrounding the rotational axis of the polishing pad. The polishing surface is disposed between the arc grooves and including a first polishing region and a second polishing region. The first polishing region is disposed between neighboring two arc grooves in the circumferential direction. The second polishing region is disposed between neighboring two arc grooves in the radial direction. The first polishing region becomes larger gradually as the polishing surface is abraded downward. 
     The present invention further provides a polishing pad and a polishing method using the polishing pad. The polishing pad includes a polishing layer and a plurality of arc grooves. The plurality of arc grooves are disposed in the polishing layer to form a plurality of fan-shaped regions, wherein the arc grooves in the same fan-shaped region are concentric arc grooves with unequal radii, and the center of the concentric arc grooves in at least one fan-shaped region does not overlap with the rotational axis of the polishing pad. 
     The present invention provides a method of forming a polishing pad. First, a polishing layer is provided. Thereafter, a plurality of concave regions is formed in the polishing layer. Afterwards, a plurality of arc grooves is formed in regions outside the concave regions. 
     The polishing pad of the present invention is a polishing pad which can provide a different slurry flow distribution. 
     In order to make the above and other objects, features and advantages of the present invention more comprehensible, several embodiments accompanied with figures are described in detail below. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The accompanying drawings are included to provide a further understanding of the invention, and are incorporated in and constitute a part of this specification. The drawings illustrate embodiments of the invention and, together with the description, serve to explain the principles of the invention. 
         FIG. 1  is a schematic top view of a conventional polishing pad. 
         FIG. 1A  is a cross-section view of the polishing pad taken along a line A-A′ in  FIG. 1 . 
         FIG. 2A  is a schematic top view of a polishing pad according to a first embodiment of the present invention. 
         FIG. 2B  is a schematic top view of a polishing pad according to a second embodiment of the present invention. 
         FIG. 2C  is a schematic top view of a polishing pad according to a third embodiment of the present invention. 
         FIG. 2D  is a schematic top view of a polishing pad according to a fourth embodiment of the present invention. 
         FIG. 2E  is a schematic top view of a polishing pad according to a fifth embodiment of the present invention. 
         FIG. 3  is a schematic top view of a polishing pad according to a sixth embodiment of the present invention. 
         FIG. 4  is a schematic top view of a method of forming the polishing pad according to the first embodiment of the present invention. 
         FIG. 5A  is a cross-section view of the polishing pad structure taken along a line I-I′ in  FIG. 4  according to a first method of the present invention. 
         FIG. 5B  is a cross-section view of the polishing pad structure taken along a line I-I′ in  FIG. 4  according to a second method of the present invention. 
         FIG. 6  is a schematic top view of a method of forming the polishing pad according to the second embodiment of the present invention. 
         FIG. 7  is a schematic top view of a method of forming the polishing pad according to the fifth embodiment of the present invention. 
       FIG. 8 is a schematic top view of a polishing pad according to a seventh embodiment of the present invention.  
       FIG. 9 is a schematic top view of a polishing pad according to an eighth embodiment of the present invention.  
       FIG. 10 is a schematic top view of a polishing pad according to a ninth embodiment of the present invention.  
       FIG. 11 is a schematic top view of a polishing pad according to a tenth embodiment of the present invention.  
       FIG. 12 is a schematic top view of a polishing pad according to an eleventh embodiment of the present invention.  
       FIG. 13 is a schematic top view of a polishing pad according to a twelfth embodiment of the present invention.  
     
    
    
     DESCRIPTION OF EMBODIMENTS 
     Several embodiments are provided below to illustrate the polishing pad of the present invention. The material of the polishing pad and the structure of the arc grooves in the embodiments are the same and will be described only in the first embodiment. The descriptions of other embodiments will only point out the differences from the first embodiment. 
     The First Embodiment 
       FIG. 2A  is a schematic top view of a polishing pad according to a first embodiment of the present invention. On the upper right corner of  FIG. 2A  is a magnified cross-section view of an arc groove  208 a. 
     Referring to  FIG. 2A , a polishing pad  200  comprises a polishing layer  202  and a plurality of arc grooves  208 a,  208 b,  208 c,  208 d,  210 a,  210 b,  210 c,  210 d,  212 a,  212 b,  212 c, and  212 d. The polishing pad  200  may be made of polymer materials such as polyester, polyether, polyurethane, polycarbonate, polyacrylate, polybutadiene, or other polymers synthesized using suitable thermosetting resins or thermoplastic resins. In addition to the polymer materials, the polishing pad  200  may further include conductive materials, abrasive particles, or soluble additives in the polymer materials. 
     The plurality of arc grooves  208 a,  208 b,  208 c,  208 d,  210 a,  210 b,  210 c,  210 d,  212 a,  212 b,  212 e, and  212 d are disposed in the polishing layer  202  to form a plurality of fan-shaped regions  204 a,  204 b,  204 c, and  204 d. As shown in  FIG. 2A , the fan-shaped region  204 a comprises the arc grooves  208 a,  210 a, and  212 a. The fan-shaped region  204 b comprises the arc grooves  208 b,  210 b, and  212 b. The fan-shaped region  204 c comprises the arc grooves  208 c,  210 c, and  212 c. The fan-shaped region  204 d comprises the arc grooves  208 d,  210 d, and  212 d. 
     In addition, the arc grooves  208 a,  208 b,  208 c,  208 d,  210 a,  210 b,  210 c,  210 d,  212 a,  212 b,  212 c, and  212 d are concentric arc grooves with their center overlapping with a rotational axis C 1  of the polishing pad, and their central angles (not shown) are all less than 180 degrees. As shown in  FIG. 2A , the polishing pad includes four fan-shaped regions with central angles all less than 90 degrees. In addition, the polishing pad may selectively include two to several fan-shaped regions such that the central angles are all less than 180 degrees. For example, a selection for the polishing pad is to have three fan-shaped regions (the corresponding central angles are less than 120 degrees) to twelve fan-shaped regions (the corresponding central angles are less than 30 degrees). The corresponding central angles are from 25 degrees to 115 degrees, for example. The arc grooves  208 a,  208 b,  208 c, and  208 d are concentric arc grooves with the same radius and are distributed at the first circle counting from the rotational axis C 1  of the polishing pad to the outside. The arc grooves  210 a,  210 b,  210 c, and  210 d are concentric arc grooves with the same radius and are distributed at the second circle counting from the rotational axis C 1  of the polishing pad to the outside. The arc grooves  212 a,  212 b,  212 c, and  212 d are concentric arc grooves with the same radius and are distributed at the third circle counting from the rotational axis C 1  of the polishing pad to the outside. In one embodiment, the total length of the concentric arc grooves with the same radius is 55% to 95% of the projected circumference, for example. For instance, the arc grooves  208 a,  208 b,  208 c, and  208 d have the same radius r 1  (not shown) and a total length thereof is between 55% and 95% of the projected circumference 2πr 1 . 
     The polishing pad  200  may further include a plurality of interposed regions  206 a,  206 b,  206 c, and  206 d alternately disposed with the fan-shaped regions  204 a,  204 b,  204 c, and  204 d. In other words, each interposed region is between two neighboring fan-shaped regions. 
     It should be noted that each of the arc grooves  208 a,  208 b,  208 c,  208 d,  210 a,  210 b,  210 c,  210 d,  212 a,  212 b,  212 c, and  212 d has two ends. At least one end of each of the arc grooves has an inclined wall, and the angle between the inclined wall and the surface plane of the polishing layer  202  is less than 90 degrees. The arc grooves have similar structures. The structure of the arc groove  208 a is described hereinafter for the purpose of illustration. As shown in the magnified cross-section view of the arc groove  208 a on the upper right corner of  FIG. 2A , the arc groove  208 a has two ends  208 a′ and  208 a″. A rotational direction  201  of the polishing pad  200  is counterclockwise, for example. Then, corresponding to the direction of the relative motion of the polishing pad, the front end is  208 a′ and the back end is  208 a″. In the present embodiment, the inclined wall of the arc groove  208 a at the back end  208 a″ forms an angle θ with the surface plane of the polishing layer  202  and the angle θ is less than 90 degrees, for example, and preferably between 5 degrees and 60 degrees. The angle θ formed between the inclined wall of the arc groove  208 a at the back end  208 a″ and the surface plane of the polishing layer  202  is less than 90 degrees. Therefore, due to the inertial force and the centrifugal force, the slurry may flow to the polishing surface of the polishing layer  202  in the interposed region  206 b and the fan-shaped region  204 b along the inclined wall of the arc groove  208 a at the back end  208 a″ so as to perform polishing. Certainly, the angle formed between the inclined wall of the arc groove  208 a at the front end  208 a′ and the surface plane of the polishing layer  202  may also be designed to be less than 90 degrees as in the case of the back end  208 a″, such that this polishing pad  200  is applicable for a polishing system in which the rotational direction of the polishing pad is clockwise or counterclockwise. Based on the above, the present invention provides discontinuous arc grooves in addition to a design of inclined walls of the arc grooves to effectively improve slurry flowing to the polishing surface of the polishing pad. 
     In addition, the polishing surface can be divided into first polishing regions and second polishing regions. The first polishing regions are between neighboring two arc grooves in the circumferential direction; that is, the first polishing regions are the interposed regions  206 a,  206 b,  206 c, and  206 d. The second polishing regions are between two neighboring arc grooves in the radial direction; that is, the second polishing regions are the fan-shaped regions  204 a,  204 b,  204 c, and  204 d. The first polishing regions (i.e. the interposed regions) will become larger gradually as the polishing surface is abraded downward. For example, because the angle formed between the inclined wall of the arc groove  208 a and the surface plane of the polishing layer  202  is less than 90 degrees, or the angle formed between the inclined wall of the arc grooves  208 a and the surface plane of the polishing layer  202  and the angle formed between the inclined wall of the arc grooves  208 b and the surface plane of the polishing layer  202  are both less than 90 degrees, the first polishing region (i.e. the interposed region)  206 b will become larger gradually along the circumferential direction as the surface of the polishing pad  200  is abraded downward. In other words, the total area of the polishing surface will become larger gradually as the polishing surface is abraded downward. 
     The Second Embodiment 
       FIG. 2B  is a schematic top view of a polishing pad according to a second embodiment of the present invention. The differences between the second and the first embodiments lie in that the arc grooves in the same fan-shaped region are concentric arc grooves with unequal radii but the radii of the concentric arc grooves in a fan-shaped region are unequal to the radii of the concentric arc grooves in a neighboring fan-shaped region. In other words, the projected circumferences of the concentric arc grooves in two neighboring fan-shaped regions do not overlap. Furthermore, the radii of the arc grooves in a fan-shaped region may selectively be equal to the radii of the arc grooves in a non-neighboring fan-shaped region. In other words, the projected circumferences of the concentric arc grooves in two non-neighboring fan-shaped regions overlap. 
     Take  FIG. 2B  as an example, the radii of the arc grooves in the fan-shaped regions  204 a and  204 c are equal and the radii of the arc grooves in the fan-shaped regions  204 b and  204 d are equal. However, the radii of the arc grooves in the fan-shaped regions  204 a or  204 c are not equal to the radii of the arc grooves in the neighboring fan-shaped regions  204 b or  204 d. In the present embodiment, the radii of the arc grooves in the fan-shaped regions  204 a or  204 c are all greater than the radii of the arc grooves in the neighboring fan-shaped regions  204 b or  204 d. For example, the radius of the arc groove  208 a is greater than the radius of the arc groove  208 b, the radius of the arc groove  210 a is greater than the radius of the arc groove  210 b, and the radius of the arc groove  212 a is greater than the radius of the arc groove  212 b. In one embodiment, the total length of the concentric arc grooves with the same radius is 15% to 45% of the projected circumference. For instance, the arc grooves  208 b and  208 d have the same radius r 1  (not shown) and the total length between 10% and 45% of the projected circumference 2πr 1 . 
     The angle θ formed between the inclined wall at the back end of each of the arc grooves and the surface plane of the polishing layer is less than 90 degrees. Therefore, due to the inertial force and the centrifugal force, the slurry may flow to the polishing surface of the polishing layer along the inclined wall at the back end of each of the arc grooves so as to perform polishing. The present invention provides discontinuous arc grooves in addition to a design of inclined walls of the arc grooves to more effectively improve slurry flowing to the polishing surface of the polishing pad. 
     The Third Embodiment 
       FIG. 2C  is a schematic top view of a polishing pad according to a third embodiment of the present invention. The differences between the third and the first embodiments lie in that the arc grooves include concentric arc grooves with unequal radii and concentric arc grooves with the same radius. However, the concentric arc grooves at even-numbered circles and the concentric arc grooves at odd-numbered circles are alternately arranged. 
     For example, the arc grooves  208 a,  208 b,  208 c,  208 d,  210 a,  210 b,  210 c,  210 d,  212 a,  212 b,  212 c, and  212 d are concentric arc grooves with their center overlapping with the rotational axis C 1  of the polishing pad. The arc grooves  208 a,  208 b,  208 c, and  208 d on the first circle counting from the rotational axis C 1  of the polishing pad to the outside are alternately arranged with the arc grooves  210 a,  210 b,  210 c, and  210 d on the second circle counting from the rotational axis C 1  of the polishing pad to the outside, partly overlapping with each other in the radial direction. The overlapping ratio in the radial direction is between 10% and 90% of a 360 degree angle, for example. Similarly, the arc grooves  212 a,  212 b,  212 c, and  212 d on the third circle counting from the rotational axis C 1  of the polishing pad to the outside are alternately arranged with the arc grooves  210 a,  210 b,  210 c, and  210 d on the second circle counting from the rotational axis C 1  of the polishing pad to the outside, partly overlapping with each other in the radial direction. In other words, the arc grooves in the present embodiment are alternately arranged, so that the groups of fan-shaped regions and interposed regions in the first embodiment are not formed. 
     The angle θ formed between the inclined wall at the back end of each of the arc grooves and the surface plane of the polishing layer is less than 90 degrees. Therefore, due to the inertial force and the centrifugal force, the slurry may flow to the polishing surface of the polishing layer (including the polishing surface between two neighboring arc grooves in the circumferential direction and the polishing surface between two neighboring arc grooves in the radial direction) along the inclined wall at the back end of each of the arc grooves so as to perform polishing. The present invention provides discontinuous arc grooves in addition to a design of inclined walls of the arc grooves to more effectively improve slurry flowing to the polishing surface of the polishing pad. 
     The Fourth Embodiment 
       FIG. 2D  is a schematic top view of a polishing pad according to a fourth embodiment of the present invention. The differences between the fourth and the first embodiment lie in that the interposed regions  206 a,  206 b,  206 c, and  206 d in the first embodiment are radially arranged from the rotational axis C 1  of the polishing pad toward the outside and are symmetric corresponding to the radius. The direction of the lengthwise extension of the interposed regions  206 a,  206 b,  206 c, and  206 d in the fourth embodiment does not pass through the rotational axis C 1  of the polishing pad  200  and the interposed regions  206 a,  206 b,  206 c, and  206 d in the fourth embodiment are asymmetric corresponding to the radius. The direction of the lengthwise extension of the interposed regions  206 a,  206 b,  206 c, and  206 d forms an angle of less than 90 degrees with the radial direction. 
     Take  FIG. 2D  as an example, the direction of the lengthwise extension of the interposed regions  206 a,  206 b,  206 c, and  206 d, along the opposite direction (i.e. the clockwise direction) of the rotational direction of the polishing pad, forms an angle α of less than 90 degrees with the radial direction. Compared to the first embodiment, the slurry may more easily flow from the back end  208 a″ of the arc groove  208 a in an inner circle to the polishing surface and then to the arc groove  210 b in an outer circle in the fourth embodiment. As such, the slurry that flows out of the polishing pad from the interposed region  206 b may be reduced. Thus, the slurry may be more effectively used. 
     On the contrary, the direction of the lengthwise extension of the interposed regions, along the rotational direction of the polishing pad, may selectively form an angle of less than 90 degrees with the radial direction. As such, the slurry may more easily flow from the back ends of the arc grooves to the interposed regions and out of the polishing pad. The advantage of this design is that the polishing residues or byproducts generated from the polishing may be more easily removed. 
     The angle θ formed between the inclined wall at the back end of each of the arc grooves and the surface plane of the polishing layer is less than 90 degrees. Therefore, due to the inertial force and the centrifugal force, the slurry may flow to the polishing surface of the polishing layer along the inclined wall at the back end of each of the arc grooves so as to perform polishing. The present invention provides discontinuous arc grooves in addition to a design of inclined walls of the arc grooves to more effectively improve slurry flowing to the polishing surface of the polishing pad. In addition, the direction of the lengthwise extension of the interposed regions may depend on the requirements of the polishing process and be designed to reduce the slurry directly flowing out of the interposed regions or to efficiently remove the polishing residues or byproducts generated from the polishing. 
     The Fifth Embodiment 
       FIG. 2E  is a schematic top view of a polishing pad according to a fifth embodiment of the present invention. The differences between the fifth and the first embodiments lie in that the arc grooves in the same fan-shaped region are concentric arc grooves with unequal radii but the center of the concentric arc grooves in one fan-shaped region does not overlap with the center of the concentric arc grooves in another fan-shaped region. In addition, the center of the concentric arc grooves of at least one fan-shaped region does not overlap with the rotational axis C 1  of the polishing pad  200 . 
     For example, the concentric arc grooves  208 a,  210 a, and  212 a in the fan-shaped region  204 a are concentric arc grooves with unequal radii and with a center C 2  (not shown). The concentric arc grooves  208 b,  210 b, and  212 b in the fan-shaped region  204 b are concentric arc grooves with unequal radii and with a center C 3  (not shown). The concentric arc grooves  208 c,  210 c, and  212 c in the fan-shaped region  204 c are concentric arc grooves with unequal radii and with a center C 4  (not shown). The concentric arc grooves  208 d,  210 d, and  212 d in the fan-shaped region  204 d are concentric arc grooves with unequal radii and with a center C 5  (not shown). However, the centers of the concentric arc grooves in the fan-shaped regions do not overlap with one another. In other words, any two of the centers C 2 , C 3 , C 4 , and C 5  do not overlap with each other. Furthermore, the centers C 2 , C 3 , C 4 , and C 5  do not overlap with the rotational axis C 1  of the polishing pad  200 . 
     That is, each of the concentric arc grooves in the fan-shaped regions whose centers do not overlap with the rotational axis C 1  of the polishing pad  200  has a front end and a back end with respect to the direction of the relative motion of the polishing pad  200 , and a distance to the rotational axis C 1  gradually becomes shorter from the front end to the back end. For example, as shown in  FIG. 2E , the front end of the arc groove  208 a is  208 a′ and the back end of the arc groove  208 a is  208 a″ with respect to the relative motion of the polishing pad  200 . The front end  208 a′ has a longer distance to the rotational axis C 1  and the back end  208 a″ has a shorter distance to the rotational axis C 1 . 
     In the present embodiment, the slurry flows from the back end  208 a″ of the arc groove  208 a and then flows to the arc groove  208 b through the surface of the interposed region  206 b. The differences between the fifth and the fourth embodiments lie in that the slurry in the fourth embodiment flows more easily from the arc groove  208 a on the first circle, counting from the rotational axis C 1  of the polishing pad to the outside, to the are groove  210 b on the second circle counting from the rotational axis C 1  of the polishing pad to the outside. However, the slurry in the fifth embodiment flows more easily from the arc groove  208 a on the first circle, counting from the rotational axis C 1  of the polishing pad to the outside, to the arc groove  208 b on the same first circle. As such, the slurry may stay on the polishing pad  200  for longer time and be more effectively used. 
     On the contrary, each of the concentric arc grooves in the fan-shaped regions whose centers do not overlap with the rotational axis of the polishing pad may selectively be designed to have a front end and a back end with respect to the direction of the relative motion of the polishing pad, and a distance to the rotational axis gradually becomes longer from the front end to the back end. As such, the slurry may more easily flow from the back ends of the arc grooves to the interposed regions and out of the polishing pad. The advantage of this design is that the polishing residues or byproducts generated from the polishing may be more easily removed. 
     The angle θ formed between the inclined wall at the back end of each of the arc grooves and the surface plane of the polishing layer is less than 90 degrees. Therefore, due to the inertial force and the centrifugal force, the slurry may flow to the polishing surface of the polishing layer along the inclined wall at the back end of each of the arc grooves so as to perform polishing. The present invention provides discontinuous arc grooves in addition to a design of inclined walls of the arc grooves to more effectively improve slurry flowing to the polishing surface of the polishing pad. In addition, the arrangement of the fan-shaped regions may be selectively designed to keep the slurry on the polishing pad for longer time so as to more effective use the slurry, or to more efficiently remove the polishing residues or byproducts generated from the polishing. 
     The abovementioned five embodiments use circular arc grooves as examples for the purpose of illustration, which is not intended to limit the scope of the present invention. The shapes of the arc grooves in the present invention may be selected from the group consisting of circular arcs, elliptical arcs, parabolic arcs, irregular arcs, and combinations thereof. 
     In addition, in the above embodiments, the arc grooves are arranged in three circles for the purpose of illustration. However, the present invention does not limit the number of the circles of the arc grooves, which may also be less or more than three. Similarly, in the above embodiments, the polishing pad includes four fan-shaped regions for the purpose of illustration. The present invention does not limit the number of the fan-shaped regions, which may be less or more than four. Thus, the number of the interposed regions between two neighboring fan-shaped regions will also vary according to the number of the fan-shaped regions. 
     In addition, in the abovementioned first, second, and fifth embodiments, the interposed regions between two neighboring fan-shaped regions are rectangular or trapezoidal and are symmetric with respect to the radii. The present invention does not limit the interposed regions to be symmetric with respect to the radii. For example, in the fourth embodiment, the direction of the lengthwise extension of the interposed regions forms an angle with the radial direction, and the interposed regions are asymmetric with respect to the radii. The interposed regions may be of other shapes such as a V shape, an arc shape, or other shapes asymmetric with respect to the radii. Optionally, at least one radial extending groove may be designed in the interposed regions. The following illustrates an embodiment including radial extending grooves. 
     The Sixth Embodiment 
       FIG. 3  is a schematic top view of a polishing pad according to a sixth embodiment of the present invention. The interposed regions  206 a,  206 b,  206 c, and  206 d in the sixth embodiment include at least one of the radial extending grooves  216 a,  216 b,  216 c, and  216 d. Each of the radial extending grooves  216 a,  216 b,  216 c, and  216 d has a plurality of intersections with radii of various degrees and a most backward intersection with respect to the rotational direction of the polishing pad. The radial extending grooves  216 a,  216 b,  216 c, and  216 d are respectively in the shape of a bent line, for example. The most backward part of the bent-line-shaped radial extending grooves have intersections with the radii at deflection points  217 a,  217 b,  217 c, and  217 d with respect to the rotational direction of the polishing pad. The positions of the deflection points are corresponding to the center of the substrate  205  to be polished. 
     With respect to the rotational direction  201  of the polishing pad, when the slurry flows from the arc grooves to the radial extending grooves  216 a,  216 b,  216 c, and  216 d, the flow of the slurry will be directed at the positions of the deflection points  217 a,  217 b,  217 c, and  217 d in order to adjust polishing profile. The deflection points correspond to the center of the substrate to be polished, which is not limited herein by the present invention. The positions of the deflection points may be designed to correspond to the edge of the substrate to be polished or other positions. 
     The angle θ formed between the inclined wall at the back end of each of the arc grooves and the surface plane of the polishing layer is less than 90 degrees. Therefore, due to the inertial force and the centrifugal force, the slurry may flow to the polishing surface of the polishing layer along the inclined wall at the back end of each of the arc grooves so as to perform polishing. The present invention provides discontinuous arc grooves in addition to a design of inclined walls of the arc grooves to more effectively improve slurry flowing to the polishing surface of the polishing pad. In addition, the radial extending grooves may be selectively designed to direct the flow of slurry at certain positions according to the requirements of different polishing processes. 
     In the abovementioned sixth embodiment, a single bent-line-shaped radial extending groove is described for the purpose of illustration, which is not intended to limit the scope of the present invention. Variations such as multiple radial extending grooves or discontinuous radial extending grooves are possible according to design requirements. Certainly, the shape of each of the radial extending grooves may vary according to design requirements and may be selected from the group consisting of a straight line, a bent line, an arc, or combinations thereof, for example. 
     The polishing method of the present invention using the polishing pad as above-embodied includes applying a pressure to press a substrate on the polishing pad, providing a relative motion between the substrate and the polishing pad, and optionally in conjunction with supplying a slurry or a chemical solution on the polishing pad. The characteristics of the polishing pad have been described in the description of the above-mentioned embodiments, which will not be further illustrated herein. The polishing method of the present invention may be applied in polishing the substrate for producing an industrial device of semiconductor, integrated circuit, optic, storage disk, energy conversion, micro-electro-mechanical system, communication, and display, etc, but is not intended to limit the scope of the present invention. The substrate for producing the industrial device may include semiconductor wafer, III V group wafer, storage device carrier, ceramic substrate, polymer substrate, and glass substrate, etc, but is not intended to limit the scope of the present invention. 
     The following describes the method of forming the polishing pad of the present invention using the polishing pad in the first embodiment shown in  FIG. 2A .  FIG. 4  is a schematic top view of a method of forming the polishing pad according to the first embodiment of the present invention. 
     First, referring to  FIG. 4 , a polishing pad  200  including a front surface  202  (i.e. the polishing layer) and a back surface  222  is provided. The materials of the polishing pad  200  have been described in the description of the first embodiment, which will not be further illustrated herein. Thereafter, a plurality of concave regions  406 a,  406 b,  406 c, and  406 d is formed in the polishing layer  202 . Afterwards, referring to  FIG. 2A , a plurality of arc grooves  208 a,  208 b,  208 c,  208 d,  210 a,  210 b,  210 c,  210 d,  212 a,  212 b,  212 c, and  212 d is formed in regions outside the concave regions  406 a,  406 b,  406 c, and  406 d. 
     It should be noted that the concave regions  406 a,  406 b,  406 c, and  406 d are corresponding to the interposed regions  206 a,  206 b,  206 c, and  206 d. The concave regions  406 a,  406 b,  406 c, and  406 d are temporary made recess and become flat again after the required arc grooves are formed and hence, are also called concave regions in the forming method. Therefore, the regions outside the concave regions  406 a,  406 b,  406 c, and  406 d are the corresponding fan-shaped regions  204 a,  204 b,  204 c, and  204 d. In other words, each of the concave regions is between two neighboring fan-shaped regions. Furthermore, in the method of forming the present invention, the depth of the concave regions is greater than the depth of the arc grooves. 
     Three forming methods of the concave regions and the arc grooves are respectively illustrated below. 
     The First Method 
       FIG. 5A  is a cross-section view of the polishing pad structure taken along a line I-I′ in  FIG. 4  according to a first method of the present invention. First, referring to  FIG. 4A  and  FIG. 5A , a sucker device  500  is provided and includes a plurality of recess regions  502 a,  502 b,  502 c, and  502 d respectively corresponding to the concave regions  406 a,  406 b,  406 c, and  406 d. The sucker device  500  includes a vacuum sucker device or an electrostatic sucker device. Thereafter, the concave regions  406 a,  406 b,  406 c, and  406 d are formed by using the sucker device  500  to fix the polishing pad  200 . The recess regions  502 a and  502 c of the sucker device  500  and the corresponding concave regions  406 a and  406 c will show in another cross-section view. Therefore, it is not illustrated in  FIG. 5A . Afterwards, referring to  FIG. 2A , a plurality of arc grooves  208 a,  208 b,  208 c,  208 d,  210 a,  210 b,  210 c,  210 d,  212 a,  212 b,  212 c, and  212 d is formed in regions outside the concave regions  406 a,  406 b,  406 c, and  406 d (i.e. the fan-shaped regions  204 a,  204 b,  204 c, and  204 d)  04 a,  204 b,  204 c, and  204 d). 
     The Second Method 
       FIG. 5B  is a cross-section view of the polishing pad structure taken along a line I-I′ in FIG.  4 according to a second method of the present invention. First, referring to  FIG. 4A  and  FIG. 5B , a sucker device  500  and a gasket  504  are provided. The gasket  504  includes a plurality of recess regions  506 a,  506 b,  506 c, and  506 d respectively corresponding to the concave regions  406 a,  406 b,  406 c, and  406 d. The sucker device  500  includes a vacuum sucker device or an electrostatic sucker device. Thereafter, the concave regions  406 a,  406 b,  406 c, and  406 d are formed by using the sucker device  500  and the gasket  504  to fix the polishing pad  200 . The recess regions  506 a and  506 c of the gasket  504  and the corresponding concave regions  406 a and  406 c will show in another cross-section view. Therefore, it is not illustrated in  FIG. 5B . Afterwards, referring to  FIG. 2A , a plurality of arc grooves  208 a,  208 b,  208 c,  208 d,  210 a,  210 b,  210 c,  210 d,  212 a,  212 b,  212 c, and  212 d is formed in regions outside the concave regions  406 a,  406 b,  406 c, and  406 d (i.e. the fan-shaped regions  204 a,  204 b,  204 c, and  204 d). 
     The Third Method 
     First, a plurality of recess regions (not shown) are formed in the back surface  222  of the polishing pad and respectively correspond to the concave regions  406 a,  406 b,  406 c, and  406 d. Thereafter, a sucker device  500  is provided to fix the polishing pad  200  to form the concave regions  406 a,  406 b,  406 c, and  406 d as shown in  FIG. 4 . The sucker device  500  includes a vacuum sucker device or an electrostatic sucker device. Afterwards, referring to  FIG. 2A , a plurality of arc grooves  208 a,  208 b,  208 c,  208 d,  210 a,  210 b,  210 c,  210 d,  212 a,  212 b,  212 c, and  212 d is formed in regions outside the concave regions  406 a,  406 b,  406 c, and  406 d (i.e. the fan-shaped regions  204 a,  204 b,  204 c, and  204 d). After the arc grooves are formed, the back surface  222  of the polishing pad including a plurality of recess regions may selectively be smoothed out. 
     The method of forming the polishing pad of the first embodiment may be slightly modified to form the polishing pads of the other embodiments. For example, as shown in  FIG. 2C , with the same arrangement of the concave regions as the first embodiment, the polishing pad of the third embodiment may be formed by finishing the process of forming the concave regions and arc grooves in two steps, wherein the grooves at even-numbered circles are formed in one step and the grooves at odd-numbered circles are formed in the other step. The polishing pad  200  is rotated by an angle between the two steps. As such, the concentric arc grooves at even-numbered circles and the concentric arc grooves at odd-numbered circles are alternately arranged. 
     Furthermore, when forming a plurality of concave regions in the polishing layer  202 , the arrangement of the concave regions in the first embodiment is changed from being radially arranged from the rotational axis C 1  of the polishing pad  200  to making the direction of the lengthwise extension of the concave regions foim an angle less than 90 degrees with the radial direction. Other steps of the method stay unchanged and the polishing pad of the fourth embodiment may be formed, as shown in  FIG. 2D . 
     The polishing pads of the first, third, and fourth embodiments formed by the method of the present invention have arc grooves including concentric arc grooves of unequal radii and concentric arc grooves of the same radius. The arc grooves in a same fan-shaped region are concentric arc grooves of unequal radii. Furthermore, the total length of the concentric arc grooves with the same radius is 55% to 95% of the projected circumference, for example. The above characteristics have been described in the description of the first embodiment, which will not be further illustrated herein. 
     The polishing pad of the second embodiment as shown in  FIG. 2B  or the polishing pad of the fifth embodiment as shown in  FIG. 2E  may selectively have the same arrangement of the concave regions as in the first embodiment. The arc grooves may be formed later using a milling machine process. Alternatively, the design of the concave region arrangement may also selectively be different from the first embodiment. The arc grooves may be formed using a lathe machine process, which is described in more detail in the following. 
     As shown in  FIG. 2B , the polishing pad of the second embodiment may have the same arrangement of a concave region  606  as shown in  FIG. 6 . The process of forming the concave regions and the arc grooves is finished in two steps, wherein the arc grooves in the fan-shaped regions  204 a and  204 c as shown in  FIG. 2B  are formed in one step and the arc grooves in the fan-shaped regions  204 b and  204 d are formed in the other step. The polishing pad  200  is rotated by an angle of about 90 degrees between the two steps. As such, the radii of the concentric arc grooves in one fan-shaped region are unequal to the radii of the concentric arc grooves in a neighboring fan-shaped region but are equal to the radii of the concentric arc grooves in a non-neighboring fan-shaped region. 
     As shown in  FIG. 2E , the polishing pad of the fifth embodiment may have the same arrangement of a concave region  706  as shown in  FIG. 7 . The process of forming the concave regions and the arc grooves is finished in four steps. The polishing pad  200  is rotated by an angle of about 90 degrees and shifted for a distance between the four steps. As such, the center of the concentric arc grooves of each fan-shaped region does not overlap with the center of the concentric arc grooves of another fan-shaped region and also does not overlap with the rotational axis C 1  of the polishing pad  200 . 
     The abovementioned method of forming the arc grooves further includes a lathe machine process or a milling machine process, for example. For example, in the lathe machine process, the polishing pad  200  including the concave regions  406 a,  406 b,  406 c, and  406 d is placed on a lathe machine (not shown), and the cutting tool on the machine is moved in conjunction with rotating the polishing pad  200 , so as to form the plurality of arc grooves  208 a,  208 b,  208 c,  208 d,  210 a,  210 b,  210 c,  210 d,  212 a,  212 b,  212 c, and  212 d in the polishing pad  200 . Alternatively, the polishing pad  200  including the concave regions  406 a,  406 b,  406 c, and  406 d is fixed on the milling machine (not shown). The drill and other tools on the machine are rotated to form the plurality of arc grooves  208 a,  208 b,  208 c,  208 d,  210 a,  210 b,  210 c,  210 d,  212 a,  212 b,  212 c, and  212 d in the polishing layer  202 . The depth of the concave regions is greater than the depth of the arc grooves; thus, the distance of the vertical movement of the above mechanical processing tools can be fixed so that the arc grooves are not formed in the concave regions. Moreover, the depth at the edge of the concave regions gradually becomes deeper, so that the inclined walls at the ends of the arc grooves form an angle of less than 90 degrees with the surface plane of the polishing layer. 
     If a polishing pad with radial extending grooves is to be formed, as shown in  FIG. 3 , the milling machine process is used, for example. In the milling machine process, for example, the polishing pad  200  including the concave regions  406 a,  406 b,  406 c, and  406 d is fixed on the milling machine (not shown). The drill and other tools on the machine are rotated to form the plurality of radial extending grooves in the polishing layer  202 . 
     The Seventh Embodiment  
     FIG. 8 is a schematic top view of a polishing pad according to a seventh embodiment of the present invention. This embodiment is similar to the fifth embodiment depicted in FIG. 2E, but with the interposed regions 206a, 206b, 206c, and 206d including at least one of the bent line radial extending grooves 216a, 216b, 216c, and 216d.  
     The Eighth Embodiment  
     FIG. 9 is a schematic top view of a polishing pad according to an eighth embodiment of the present invention. This embodiment is similar to the fifth embodiment depicted in FIG. 2E, but with the interposed regions 206a, 206b, 206c, and 206d including at least one of the arc radial extending grooves 216a, 216b, 216c, and 216d.  
     The Ninth Embodiment  
     FIG. 10 is a schematic top view of a polishing pad according to a ninth embodiment of the present invention. This embodiment is similar to the fifth embodiment depicted in FIG. 2E, but with the interposed regions 206a, 206b, 206c, and 206d including at least one of the straight line radial extending grooves 216a, 216b, 216c, and 216d.  
     The Tenth Embodiment  
     FIG. 11 is a schematic top view of a polishing pad according to a tenth embodiment of the present invention. This embodiment is similar to the fifth embodiment depicted in FIG. 2E, but the arc grooves 208a, 210a, and 212a in the tenth embodiment are elliptical rather than circular.  
     The Eleventh Embodiment  
     FIG. 12 is a schematic top view of a polishing pad according to an eleventh embodiment of the present invention. This embodiment is similar to the fifth embodiment depicted in FIG. 2E, but the arc grooves 208a, 210a, and 212a in the eleventh embodiment are parabolic rather than circular.  
     The Twelfth Embodiment  
     FIG. 13 is a schematic top view of a polishing pad according to a twelfth embodiment of the present invention. This embodiment is similar to the fifth embodiment depicted in FIG. 2E, but the arc grooves 208a, 210a, and 212a in the twelfth embodiment are irregular rather than circular.  
     Although the present invention has been disclosed above by the embodiments, they are not intended to limit the present invention. Anybody skilled in the art can make some modifications and alterations without departing from the spirit and scope of the present invention. Therefore, the protected range of the present invention falls in the appended claims.