Polishing pad and polishing method

A polishing pad and a polishing method for polishing a substrate are described. The polishing pad includes a polishing layer and at least two grooves. The grooves form polishing tracks respectively. The polishing tracks collectively construct an even tracking zone. A better polishing uniformity of a substrate surface is achieved with the even tracking zone.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a polishing pad and a polishing method. More particularly, the present invention relates to a polishing pad and a polishing method capable of achieving a better polishing uniformity of a substrate surface.

2. Description of Related Art

As progressing of industries, devices of integrated circuits, microelectromechanical systems, power conversion, communications, storage disks, and displays are becoming more and more advanced and complex. In order to ensure the reliability of the devices, the surface of substrates (e.g., semiconductor wafers, III-V wafers, storage device carriers, ceramic substrates, polymer substrates, and glass substrates) for fabricating these devices must be smooth and even.

Among the planarization processes, a polishing process is often adopted in the industry. Generally speaking, in the polishing process, a pressure is applied on a substrate, so as to press the substrate on a polishing pad, and a relative motion between the substrate and the polishing pad is provided. Through the friction generated by the relative motion, a portion of the substrate surface is removed, such that the surface is planarized gradually.

FIG. 1is a schematic top view of a conventional polishing pad. The polishing pad100includes a polishing layer110and a plurality of circumferential grooves120. The polishing layer110is in contact with a surface of a substrate130. The plurality of circumferential grooves120are arranged in concentric circles, and a center of the circumferential grooves120coincides with a rotational axis C0of the polishing pad100. The circumferential grooves120are used to accommodate or remove the polishing residues or byproducts, and enable the substrate130to be easily detached away from the polishing pad100when the polishing is completed.

During polishing, in addition to the rotation of the polishing pad100, the substrate130on the surface of the polishing pad100rotates as well, expecting that all positions of the surface of the substrate130are able to contact with the circumferential grooves120. However, since the circumferential grooves120of the conventional polishing pad100are concentric circular grooves, and the substrate130rotates around its central axis, when a specific point of the substrate130moves to a region parallel to tangential direction of the grooves120, the specific point will be constantly on the groove portion or the non-groove portion. For example, when the specific point is on the groove portion, points near the specific point will be constantly on the non-groove portion, which results in an unfavorable polishing uniformity. In addition, the closer the position is to the central portion of the substrate130, the more serious the uniformity problem will be. In the entire polishing process, the central portion of the substrate130is almost constantly in contact with a specific portion (e.g., the groove portion or the non-groove portion) on the polishing pad100. Therefore, the polishing rate at the central portion of the substrate130will be lower or higher than the polishing rate of other near portions, depending on whether the central portion is constantly positioned on the groove portion or the non-groove portion. The problem that the polishing rate of the substrate130is not uniform may eventually suffer the reliability of the devices.

Thus, a polishing pad providing a better polishing uniformity is needed.

SUMMARY OF THE INVENTION

Accordingly, the present invention is directed to a polishing pad, which enables polishing rates of a substrate surface to have a better uniformity.

The present invention is also directed to a polishing method, which helps to obtain a substrate with a planar surface.

The present invention provides a polishing pad suitable for polishing a substrate. The polishing pad includes a polishing layer and at least two grooves. The polishing layer has an even tracking zone disposed around a rotational axis. The grooves are disposed in the even tracking zone, and satisfy the following relation:
D(i)max≅D(i+n)min

where D(i)maxis the largest distance from the rotational axis to the (i)thgroove; D(i+n)minis the smallest distance from the rotational axis to the (i+n)thgroove; i is an ordinal number of a groove counting from the groove closest to the rotational axis to an outer periphery of the even tracking zone, and n is an integer.

The present invention further provides a polishing pad suitable for polishing a substrate. The polishing pad includes a polishing layer and at least two grooves. The polishing layer has an even tracking zone. The grooves are disposed in the even tracking zone. Each of the grooves forms one polishing track, and the polishing tracks are adjoining one another.

The present invention still provides a polishing pad suitable for polishing a substrate. The polishing pad includes a polishing layer. The polishing layer has an even tracking zone. The even tracking zone is divided into at least two polishing tracks, and the polishing tracks are adjoining one another. In addition, at least one groove is disposed in each of the polishing tracks, and the at least one groove has a uniformly distributed trajectory in each of the polishing tracks.

The present invention also provides a polishing method for polishing a substrate. Firstly, a polishing pad is provided. Then, a pressure is applied on the substrate to press the substrate on the polishing pad. Next, a relative motion is provided between the substrate and the polishing pad. The polishing pad includes a polishing layer and at least two grooves. The polishing layer has an even tracking zone disposed around a rotational axis. The grooves are disposed in the even tracking zone, and satisfy the following relation:
D(i)max≅D(i+n)min

where D(i)maxis the largest distance from the rotational axis to the (i)thgroove; D(i+n)minis the smallest distance from the rotational axis to the (i+n)thgroove; i is an ordinal number of a groove counting from the groove closest to the rotational axis to an outer periphery of the even tracking zone, and n is an integer.

The present invention further provides a polishing method for polishing a substrate. Firstly, a polishing pad is provided. Then, a pressure is applied on the substrate to press the substrate on the polishing pad. Next, a relative motion is provided between the substrate and the polishing pad. The polishing pad includes a polishing layer and at least two grooves. The polishing layer has an even tracking zone. The grooves are disposed in the even tracking zone. Each of the grooves forms one polishing track, and the polishing tracks are adjoining one another.

The present invention still provides a polishing method for polishing a substrate. Firstly, a polishing pad is provided. Then, a pressure is applied on the substrate to press the substrate on the polishing pad. Next, a relative motion is provided between the substrate and the polishing pad. The polishing pad includes a polishing layer. The polishing layer has an even tracking zone. The even tracking zone is divided into at least two polishing tracks, and the polishing tracks are adjoining one another. At least one groove is disposed in each of the polishing tracks, and the at least one groove has a uniformly distributed trajectory in each of the polishing tracks.

The polishing pad and the polishing method of the present invention adopt the polishing pad with a specific groove design, so a polishing process using the polishing pad may achieve a better polishing uniformity of a polished substrate surface.

In order to make the aforementioned features and advantages of the present invention comprehensible, preferred embodiments accompanied with figures are described in detail below.

DESCRIPTION OF EMBODIMENTS

The polishing method of the present invention is suitable for polishing a substrate. Firstly, a polishing pad is provided. The polishing pad, for example, has a specific groove design, in which each groove forms a corresponding polishing track, and the polishing tracks form an even tracking zone. Then, a pressure is applied on the substrate to press the substrate on the polishing pad. Next, a relative motion is provided between the substrate and the polishing pad, so as to remove a portion of a substrate surface to achieve planarization. As the polishing pad has the even tracking zone, the polishing method of the present invention may achieve a better polishing uniformity of the substrate surface. In addition, according to the polishing method of the present invention, slurry or solution may be optionally supplied during polishing. Thus, the polishing method becomes a chemical mechanical polishing (CMP) process.

The polishing pads with specific groove designs of the polishing method will be described below. Persons skilled in the art can implement the present invention according to the following detailed description of the present invention, which, however, does not intend to limit the scope of the present invention.

FIG. 2Ais a schematic top view of a polishing pad according to an embodiment of the present invention. Referring toFIG. 2A, the polishing pad200is suitable for polishing a surface of a substrate240during polishing. The polishing pad200, for example, is made of a polymer base material, and the polymer base material may be polyester, polyether, polyurethane, polycarbonate, polyacrylate, polybutadiene, or other polymer base materials formed by appropriate thermosetting resins or thermoplastic resins. In addition to the polymer base material, the polishing pad200may further include conductive materials, abrasives, or soluble additives in the polymer base material.

The polishing pad200includes a polishing layer210and at least two grooves220. The polishing layer210has an even tracking zone212. The even tracking zone212is an area formed by uniformly distributed trajectories along which the grooves220relatively pass when the polishing pad200rotates. In one embodiment, the even tracking zone212, for example, is disposed corresponding to a central portion of the substrate240. The even tracking zone212, for example, is disposed around a rotational axis C1. The rotational axis C1extends in a direction perpendicular to the polishing layer210. In detail, as shown inFIG. 2A, the even tracking zone212is substantially disposed in a middle region between the innermost portion and the outermost portion of the polishing pad200, i.e., in an area between a border212aand a border212b. The even tracking zone212, for example, is annular, and has a geometrical center coinciding with the rotational axis C1. In the entire polishing process of this embodiment, the central portion of the substrate240will alternately pass the groove portion and the nor-groove portion instead of constantly contacting the groove portion or the non-groove portion on the polishing pad200. Therefore, the polishing rates of the central portion and other near portions of the substrate240are more consistent.

In one embodiment, the even tracking zone212has a width of at least 35 mm, for example, between 40 mm and a maximum dimension of the substrate240. In addition, other grooves may also be disposed in the portion outside the even tracking zone212. The even tracking zone212may also be optionally disposed in almost entire surface of the polishing pad200. For example, the width of the even tracking zone212may be up to 95% of a radius of the polishing pad200.

The grooves220are disposed in the even tracking zone212. The grooves220, for example, are enclosed grooves, and are not interconnected. Moreover, each of the grooves220, for example, forms one polishing track230, and the polishing tracks230collectively construct the even tracking zone212. A better polishing uniformity of the surface of the substrate240is achieved with the even tracking zone212.

In this embodiment, the grooves220are elliptical grooves, and the grooves220, for example, have a common geometrical center. That is to say, the geometrical center of the elliptical grooves coincides with the rotational axis C1. As shown inFIG. 2A, a major axis of each elliptical groove, for example, is set on the same axis, i.e., the grooves220are coaxial. Moreover, for example, the radial pitches between the grooves220are the same. In addition, when the polishing pad200rotates about the rotational axis C1, each of the grooves220will generate one polishing track230. The polishing tracks230are concentric with the rotational axis C1. Furthermore, the polishing tracks230are adjoining one another. For example, the polishing tracks230have the same width W. In other words, the even tracking zone212, for example, is divided into at least two polishing tracks230adjoining one another, and at least one groove220is disposed in each of the polishing tracks230, such that the at least one groove220may form a uniformly distributed trajectory in each of the polishing tracks230.

As the polishing tracks230generated corresponding to the grooves220are adjoining one another in this embodiment, when the substrate240is polished, the polishing pad200may provide a uniform polishing rate on every portion of the surface of the substrate240.

It should be noted that the grooves220satisfy the following relation:
D(i)max≅D(i+n)max

where D(i)maxis the largest distance from the rotational axis C1to the (i)thgroove220; D(i+n)minis the smallest distance from the rotational axis C1to the (i+n)thgroove220; i is an ordinal number of a groove220counting from the groove220closest to the rotational axis C1to an outer periphery of the even tracking zone212, and n is an integer between 1 and 5, for example. In other words, the largest distance D(i)maxfrom the rotational axis C1to the (i)thgroove220is approximately equal to or substantially equal to the smallest distance from the rotational axis C1to the (i+n)thgroove220.

For example, as shown inFIG. 2A, for example n=1, the grooves220satisfies the relation: D(i)max≅D(i+1)min. When i=1, D(1)max≅D(2)min; when i=2, D(2)max≅D(3)min; other situations when i=3, 4, 5, . . . can be derived in the same way. That is, as shown inFIG. 2A, the largest distance D(1)maxfrom the rotational axis C1to the first groove220is the major axis of the first groove220, and the smallest distance D(2)minfrom the rotational axis C1to the second groove220is the minor axis of the second groove220, wherein D(1)max≅D(2)min. Moreover, in this embodiment, the polishing tracks230formed by the grooves220are adjoining one another to construct the even tracking zone212, i.e., no non-track region is formed between the polishing tracks230.

InFIG. 2A, n=1 is taken as an example, but the present invention is not limited to this.FIG. 2Bis a schematic top view of a polishing pad according to another embodiment of the present invention. In the polishing pad200aofFIG. 2B, n=2 is taken as an example, and grooves220asatisfy the relation: D(i)max≅D(i+2)min. As shown inFIG. 2B, the largest distance D(1)maxfrom the rotational axis C1to the first groove220ais the major axis of the first groove220a, and the smallest distance D(3)minfrom the rotational axis C1to the third groove220is the minor axis of the third groove220, wherein D(1)max≅D(3)min. In this embodiment, the polishing tracks230a, for example, have a width of Wa. Different from the grooves220shown inFIG. 2A, the grooves220ainFIG. 2Bare elliptical grooves in which the major axis and the minor axis differ more. Therefore, the polishing tracks230agenerated corresponding to the grooves220amay have a larger width Wa, and the polishing tracks230amay be partially overlapped one another. Areas of the same overlapping ratio (areas between the border212aand the border212b) of the polishing tracks230aconstruct the even tracking area212. A better polishing uniformity of the surface of the substrate240ais achieved with the even tracking zone212.

It should be noted that in the above embodiments, the polishing pads200,200awith elliptical grooves are exemplified for illustration, but the present invention is not limited to this. In other embodiments, the grooves may also be in other shapes. Hereinafter, the grooves of different patterns will be illustrated.

FIGS. 3A to 3Eare schematic top views of groove patterns according to several embodiments of the present invention. InFIGS. 3A to 3F, the same components inFIG. 2are indicated by the same reference numerals, and will not be described again. Moreover, in order to simplify the figures, only two grooves are shown, which satisfy the condition of n=1 in the above relation, which are provided for persons skilled in the art to implement the present invention, and are not intended to limit the scope of the present invention.

As shown inFIG. 3A, the grooves220c, for example, are polygonal grooves. In one embodiment, the grooves220care quadrangular grooves with four round corners300. The grooves220cthus will form the polishing tracks230cwith a width Wcand adjoining one another. The polishing tracks230ccollectively construct the even tracking zone. A better polishing uniformity of the substrate surface is achieved with the even tracking zone.

In addition, the grooves220dmay also be corrugated grooves with a plurality of round corners as shown inFIG. 3B. The corrugated grooves thus form the polishing tracks230dwith a width Wdand adjoining one another. The polishing tracks230dcollectively construct the even tracking zone. A better polishing uniformity of the substrate surface is achieved with the even tracking zone.

In another embodiment, the grooves220emay be annular grooves having at least one protrusion and/or at least one recession. As shown inFIG. 3C, the grooves220e, for example, are a plurality of annular grooves having a plurality of protrusions310, and the protrusions310protrude from projected peripheries of the annular grooves. The annular grooves having the protrusions310, for example, will from polishing tricks230ewith a width Wcand adjoining one another. The polishing tracks230ecollectively construct the even tracking zone. A better polishing uniformity of the substrate surface is achieved with the even tracking zone.

As shown inFIG. 3D, the grooves220fmay also be circumferential grooves with a geometrical center, for example, deviated from the rotational axis C1. In one embodiment, the grooves220fare circular grooves with a center C2deviated from the rotational axis C1, i.e., the center C2does not coincide with the rotational axis C1. As the center C2of the grooves220fis deviated from the rotational axis C1, the grooves220fwill form polishing tracks230fwith a width Wfand adjoining one another. The polishing tracks230fcollectively construct the even tracking zone. A better polishing uniformity of the substrate surface is achieved with the even tracking zone.

In one embodiment, at least two grooves may be formed in a polishing track, and the grooves may be optionally arranged in symmetry. As shown inFIG. 3E, the grooves220bin each of the polishing tracks230bmay include two intersecting elliptical grooves with the same length of major axis and the same length of minor axis. The major axes of the two elliptical grooves may be perpendicular to each other. In other words, the grooves220b, for example, are dual-elliptical grooves formed by two elliptical grooves. The grooves220bwill form polishing tracks230bwith a width Wband adjoining one another. The polishing tracks230bcollectively construct the even tracking zone. A better polishing uniformity of the substrate surface is achieved with the even tracking zone.

It should be noted that as shown inFIGS. 3A to 3E, the largest distance from the rotational axis C1to the first groove220c,220d,220e,220f, and220bis equal to the smallest distance from the rotational axis C1to the second groove220c,220d,220e,220f, and220b. In other words, the grooves220c,220d,220e,220f, and220ball satisfy the relation D(1)max≅D(2)min. Therefore, the grooves220c,220d,220e,220f, and220bmay construct the even tracking zone, so as to provide a better polishing uniformity of the substrate surface.

Definitely, in other embodiments, the grooves of the polishing pad may be in other irregular shapes, or any combination of the grooves220c,220d,220e,220f, and220bin different patterns as shown inFIGS. 3A to 3E, as long as the grooves on the polishing pad satisfy the relation D(i)max≅D(i+n)min. Persons skilled in the art can make proper adjustment according to actual requirements.

It should be noted that in addition to the above embodiments, the present invention may also be implemented in other forms. In the embodiments ofFIGS. 2A,2B and3A to3E, the grooves are arranged corresponding to the same axis, the pitches between every two adjoining grooves are the same in radial direction, and the adjoining polishing tracks have the same width. However, the present invention is not limited to this. In other embodiments, the pitches of every two adjoining grooves may be different in the radial direction, which will be illustrated in detail below.

FIG. 4is a schematic top view of a groove arrangement according to an embodiment of the present invention. In the embodiment, as shown inFIG. 4, different grooves221are arranged corresponding to different axes, i.e., the grooves221are arranged non-coaxially. The grooves221will form polishing tracks231, and the polishing tracks231, for example, have the same width W1.

FIGS. 5A and 5Bare schematic top views of a groove arrangement according to other embodiments of the present invention. As shown inFIG. 5A, the grooves222,223, and224are the first, second, and third grooves sequentially counting from the one closest to the rotational axis C1. The grooves222,223, and224will form polishing tracks232,233, and234with widths W2, W3, and W4respectively. In another embodiment, the grooves222,223, and224are arranged corresponding to the same axis. However, the width W2of the polishing track232, the width W3of the polishing track233, and the width W4of the polishing track234, for example, are not completely the same.

As shown inFIG. 5B, the grooves225,226, and227are the first, second, and third grooves counting from the one closest to the rotational axis C1respectively. The grooves225,226, and227will form polishing tracks235,236, and237with widths W5, W6, and W7respectively. In another embodiment, the grooves225,226, and227are arranged non-coaxially. In addition, the widths W5, W6, and W7of the polishing tracks231,232, and233, for example, are not completely the same.

FIG. 6is a schematic top view of the grooves according to another embodiment of the present invention. Referring toFIG. 6, the grooves228on the polishing pad may also include a plurality of discontinuous sub-grooves228a. For example, the grooves228are in a discontinuous enclosure shape. Moreover, the sub-grooves228aconstructing each of the discontinuous enclosure shape of the grooves228will form a polishing track238with a width W8. The polishing tracks238collectively construct the even tracking zone. A better polishing uniformity of the substrate surface is achieved with the even tracking zone.

It should be noted that as shown inFIGS. 4,5A,5B, and6, the grooves of the above embodiments all satisfy the relation D(i)max≅D(i+n)min. Therefore, during polishing, the polishing tracks formed by the grooves will collectively construct the even tracking zone, which helps to achieve a uniform polishing rate on different portions of the substrate surface.

Moreover, in the embodiments ofFIGS. 4,5A,5B, and6, oily three grooves are shown and the elliptical grooves are taken as an example for simplifying the drawings, such that persons skilled in the art can implement the present invention accordingly. However, the present invention is not limited to this. Persons skilled in the art can appreciate the applications and variations of the present invention, which will not be described herein.

In the above embodiments, round polishing pads are taken as an example for illustrating the present invention. However, the present invention is not limited to this. The polishing pads may also in other shapes, e.g., rings, squares, or strips, depending on the requirements of polishing equipment. Moreover, the grooves in the polishing tracks may also be in other shapes, as long as the grooves may construct the even tracking zone and the polishing rate is uniform, which are not particularly limited in the present invention, and persons of ordinary skill in the art can make modifications according to actual requirements.

In one embodiment of the polishing method of the present invention, when slurry or solution is used in polishing, the slurries or solutions with different properties may be supplied in different polishing tracks. The properties, for example, include viscosity of the slurry or solution, concentration of chemicals (e.g., oxidizing agents, reducing agents, complex agents, inhibitors, and catalysts) in the slurry or solution, or solid content or abrasive content in the slurry. In the polishing pads of the above embodiments, the grooves in different polishing tracks are not interconnected, so the polishing capability differs in different polishing tracks, thereby adjusting the polishing rate distribution profile. For example, the slurry containing more abrasives may be optionally supplied into the polishing tracks corresponding to the near edge region of the substrate to increase the polishing rate of the near edge region of the substrate.

In view of the above, the groove design of the polishing pad of the present invention may construct the even tracking zone, and with the even tracking zone, a better polishing uniformity of the substrate surface may be achieved. In addition, the polishing method of the present invention adopts the polishing pad having the even tracking zone, thereby helping to provide a more uniform and planar substrate surface.