TWI679083B - Polishing pad - Google Patents

Abstract

The present invention proposes a polishing pad having a circular polishing surface, and a plurality of semi-circular arc-shaped first grooves are located in the polishing surface and are distributed in a concentric circle form the center of the polishing surface at a certain distance outward. And the first grooves in the grinding surface in a semicircle and the first grooves in the grinding surface in another semicircle are arranged in a concentric circle staggeredly, and a plurality of arc-shaped second grooves The grooves are spirally distributed at a certain pitch angle from each other, and the second grooves intersect the first grooves, respectively.

Description

Polishing pad

The present invention relates to a polishing pad, and more specifically, it relates to a polishing pad with a special groove pattern design, which can increase the polishing rate and reduce the number of defects generated by polishing.

In the semiconductor manufacturing process, a chemical mechanical polishing (CMP) process is mainly used to completely flatten the layer structure formed in the previous process, making subsequent processes easier. Generally, the CMP process is to provide a polishing liquid with a chemical mixture on a polishing pad, apply a pressure to the object to be polished to place it on the polishing pad, and perform relative movement between the object and the polishing pad. The mechanical friction caused by the relative movement and the chemical action of the abrasive fluid remove part of the surface of the object and gradually flatten its surface to achieve the purpose of flattening. The CMP process is essentially a non-isotropic process. This non-isotropy is mainly achieved by the mechanical action in the CMP process. Therefore, it can determine the polishing uniformity according to the different characteristics of the polishing pad.

In the CMP process, a polishing liquid is used to polish the wafer, and the polishing particles are added into the polishing liquid with particles of SiO ₂ , Al ₂ O ₃ or CeO ₂ material to achieve the polishing effect. Due to the small particle size of these particles, they easily condense to form large particles and cause scratch defects during the CMP process. In addition, the pores of the polishing pad are easily blocked by the polishing liquid and by-products of grinding after repeated use. Therefore, a good polishing pad must have good retention of the polishing liquid to achieve a high-efficiency polishing effect. The grinding by-products can be smoothly discharged for good grinding reproducibility.

In view of the foregoing lack of knowledge and general characteristics for general polishing pads, this case hereby proposes a novel polishing pad with a special groove pattern design, which can quickly fill the entire polishing pad with polishing liquid and The by-products are discharged, thereby increasing the grinding rate and reducing the occurrence of scratches.

The claimed invention is a polishing pad having a circular polishing surface, and a plurality of semi-circular arc-shaped first grooves are located in the polishing surface and adopt a form of concentric circles at a certain distance from the center of the polishing surface. The first grooves located in a semicircle and the first grooves located in another semicircle are arranged in a staggered concentric circle, and a plurality of arc-shaped second grooves are spaced from each other by a certain pitch Angled and spirally distributed, each of the second trenches intersects the first trenches, respectively.

These and other objects of the present invention will certainly become more apparent after the reader has read the detailed description of the preferred embodiments described in various figures and drawings below.

100‧‧‧ grinding system

102‧‧‧ Abrasive pad

104‧‧‧wafer

106‧‧‧Grinding disc

108‧‧‧ Wafer Carrier

110‧‧‧ polished surface

112‧‧‧ Polished surface

114‧‧‧ grinding media

116‧‧‧Entrance

118‧‧‧ Trench

120‧‧‧ abrasive layer

122‧‧‧Backing layer

124‧‧‧first groove

124a‧‧‧part

124b‧‧‧part

126‧‧‧Second Groove

126a‧‧‧The first group of second grooves

126b‧‧‧Second group of second groove

a, b, c, d‧‧‧points

d ₁ ‧‧‧ pitch

α‧‧‧ Pitch Angle

D‧‧‧ diameter

F‧‧‧force

R1‧‧‧Shaft

R2‧‧‧Shaft

This specification contains drawings and constitutes a part of this specification in the text, so that readers have a further understanding of the embodiments of the present invention. These illustrations depict some embodiments of the invention and together with the description, explain the principles. In these illustrations: FIG. 1 is a schematic view of a polishing system according to an embodiment of the present invention; FIG. 2 is a schematic cross-sectional view of a polishing pad according to an embodiment of the present invention; and FIG. A plan view of a polishing pad in the embodiment.

It should be noted that all the illustrations in this manual are of the nature of illustrations. For clarity and convenience of illustration, the components in the illustrations may be exaggerated or reduced in size and proportion. Generally speaking, the illustrations The same reference symbols will be used to identify corresponding or similar elements in modified or different embodiments. Sign.

FIG. 1 illustrates a schematic diagram of a polishing system 100 according to an embodiment of the present invention, which is suitable for use with a polishing pad 102 to polish objects, such as a wafer 104 and the like. The polishing system 100 may include a polishing disc 106 on which the polishing pad 102 is mounted. The polishing disc 106 can rotate around the rotation axis R1. The polishing system 100 further includes a wafer carrier 108 that rotates around the rotation axis R2 and holds the entire wafer 104 during polishing. The wafer 104 has a polishing surface 110 that faces the polishing surface 112 of the polishing pad 102 during polishing and is planarized. The wafer carrier 108 rotates the wafer 104 and provides a downward force F to press the polishing surface 110 of the wafer 104 on the polishing pad 102, so that the required pressure is provided between the polishing surface 110 and the polishing pad 102. The polishing medium 114, such as a polishing liquid, may be supplied onto the polishing surface 112 of the polishing pad 102 via the inlet 116. During polishing, the polishing pad 102 and the wafer 104 will rotate with their respective rotation axes R1 and R2, and the polishing medium 114 will drip on the rotating polishing surface 112. By centrifugal force, it can be evenly distributed on the entire surface. The gap between the wafer 104 and the polishing pad 102 is included.

Please refer to FIG. 2, which is a schematic cross-sectional view of a polishing pad according to an embodiment of the present invention. As shown in FIG. 2, the polishing pad 102 includes a plurality of grooves 118 formed on a polishing layer 120, which has a polishing surface 112, thus defining a groove pattern. Each of the grooves 118 may actually have a predetermined cross-sectional shape and size suitable for a special grinding design. Therefore, the rectangular cross-sectional shape of the grooves 118 shown in FIG. 2 is only an example. The polishing layer 120 is supported by a backing layer 122, which may be formed together with the polishing layer 120 or separately. The material of the abrasive layer 120 may include, but is not limited to, polymer plastic, such as polyurethane, polybutadiene, polycarbonate, polymethylacrylate, and the like.

Please refer to FIG. 3, which is a plan view of a polishing pad 102 according to a preferred embodiment of the present invention. FIG. 3 specifically shows the groove patterns defined on the polishing pad 102 of the present invention. The following embodiments illustrate the detailed features of the groove patterns and their effects. The trench pattern of the present invention is mainly composed of a plurality of first trenches 124 and a plurality of second trenches 126. As shown in FIG. 3, the first grooves 124 are semi-circular arcs, and they are distributed concentrically from the center of the grinding surface 112 to the grinding surface at a certain distance d ₁ (eg, 5.2 mm (mm)). At the circumference of 112. The first groove 124 is divided into a portion 124a on the left semicircle of the grinding surface 112 and a portion 124b on the right semicircle of the grinding surface 112. The first groove 124a on the left semicircle and the first groove 124b on the right semicircle are staggered concentrically. Set and discontinuous. More specifically, on the diameter D at the junction of the left semicircle and the right semicircle along the grinding surface 112, the concentric semicircular arc first groove pattern will be set such that the endpoint a of its left semicircle portion 124a will be right End points b of the semicircular portion 124b are staggered. In the present invention, the discontinuous multiple semi-circular arc staggered groove design can effectively increase the efficiency of the flow of the polishing liquid to the surface of the polishing pad, and improve the polishing rate.

In other embodiments, the end points of the left semicircular first groove 124a and the right semicircular first groove 124b may not be located at the diameter D. As shown by the dashed circle in Figure 3, the first semicircle 124a of the left semicircle may also partially overlap with the first semicircle 124b of the right semicircle, depending on the actual needs and the design of the invention.

In addition to the groove design of the first trench 124, the depth of the first trench 124 also has its design variation. In the embodiment of the present invention, the depth of each first trench 124 gradually becomes deeper from the two ends (such as the end point a or b) to the middle of the trench, and the depth may be between 0 and 2 mm ( mm). The deeper groove design helps to retain the polishing liquid located in the middle of the groove. Compared with the conventional groove without depth change, it has a significant improvement in the retention of the polishing liquid on the polishing pad.

Refer back to Figure 3. In addition to the first trench 124, the trench pattern of the present invention includes a second trench 126. As shown in FIG. 3, in the embodiment of the present invention, the second grooves 126 are arc-shaped and spaced apart from each other by a certain pitch angle α, and are spirally distributed around the center of the circle of the grinding surface 112. More specifically, the term "pitch angle" as used herein is defined as the distance between two points on a concentric circle, such as point c and point d on the adjacent second groove 126, and the pitch The angle α is the two lines obtained by the two points making a straight line to the center of the circle Angle between.

Moreover, it can be seen from the figure that the second grooves 126 are further divided into a first group of second grooves 126a and a second group of second grooves 126b, which are respectively distributed on the grinding surface 112 more than the inner ring and the outer ring. Among the parts, the pitch angle of the first group of second grooves 126a located in the inner ring will be smaller than the pitch angle of the second group of second grooves 126b located in the outer ring. In the embodiment of the present invention, the inner ring portion is 15 to 100 mm (mm) from the center of the grinding surface 112, and the outer ring portion is 100 to 300 mm (mm) from the center of the grinding surface. ). The pitch angle of the first group of second grooves 126a is set to 30 degrees, and the pitch angle of the second group of second grooves 126b is 45 degrees. As such, the number of the first group of second trenches 126a will be greater than the number of the second group of second trenches 126b. It should be noted that the setting of the inner and outer ring diameters and pitch angles of the grinding surfaces described here are for illustration only and are not limited.

In the present invention, the arc-shaped spirally distributed second grooves 126 will help promote the movement of the abrasive liquid and by-products on the abrasive surface 112 during grinding. More specifically, the first group of second grooves 126a located in a larger number of inner rings will allow the abrasive liquid supplied at the center of the circle to quickly and uniformly cover the entire grinding surface 112 as it rotates, while the number of located in the outer ring is smaller. However, the second group of second grooves 126b with a large distance from each other will allow the by-products generated during the grinding to be quickly discharged out of the polishing pad with rotation without hindrance.

In addition to the above features, in a preferred embodiment of the present invention, the width of the semi-circular arc-shaped first trench 124 will be significantly smaller than the width of the arc-shaped second trench 126. For example, the width of the first trench 124 is set as 0.5 mm (mm), and the width of the second groove 126 is 2 mm (mm). The reason for this design is that the main function of the first groove 124 is to store the polishing liquid to provide the polishing effect, so the number of the grooves is large and the width is thin. The main function of the second grooves 126 is as described above, which is to quickly transfer the polishing liquid and uniformly fill it, and to quickly and unimpededly remove the by-products of grinding. Therefore, the number of the grooves will be less, but the width Wider. It should be noted that the settings of the first trench width and the second trench width described here are for illustration only and are not limited.

The above are only the preferred embodiments of the present invention. Changes and modifications should all fall within the scope of the present invention.

Claims (8)

A polishing pad includes: a polishing layer for polishing a substrate in the presence of a polishing medium, the polishing layer having a circular polishing surface; a plurality of first grooves in the polishing surface, wherein The first grooves are semi-circular arcs. They are distributed concentrically from the center of the grinding surface outwards at a certain distance to the circumference of the grinding surface. The semicircular first grooves are arranged in a staggered concentric circle; and a plurality of second grooves are located in the grinding surface, wherein the second grooves are arc-shaped and spirally spaced from each other by a certain pitch angle. Each of the second grooves intersects the first grooves, and the second groove is further divided into a first group of second grooves and a second group of second grooves, which are respectively distributed in the inner circle and In the abrasive surface of the outer ring, the pitch angle of the first group of second grooves is smaller than the pitch angle of the second group of second grooves. The polishing pad according to item 1 of the scope of the patent application, wherein the grinding surface of the inner ring is at a position 15 to 100 mm (mm) from the center of the grinding surface, and the grinding surface of the outer ring is at a distance from The center of the polished surface is at a position of 100 to 300 mm (mm). According to the polishing pad described in item 1 of the patent application scope, the pitch angle of the first group of second grooves is 30 degrees, and the pitch angle of the second group of second grooves is 45 degrees. The polishing pad according to item 1 of the scope of patent application, wherein the depth of each of the first grooves gradually becomes deeper from both ends of the first groove to the middle of the groove. The polishing pad according to item 4 of the scope of patent application, wherein the depth of the first groove is 0 to 2 mm (mm). The polishing pad according to item 1 of the scope of patent application, wherein the first grooves in the semicircle partially overlap with the first grooves in the other semicircle. The polishing pad according to item 1 of the scope of the patent application, wherein the width of the first groove is 0.5 mm (mm), and the width of the second groove is 2 mm (mm). The polishing pad according to item 1 of the scope of the patent application, wherein the pitch of the first groove is 5.2 millimeters (mm).