KR100727485B1 - Polishing pads and methods for manufacturing the same, and chemical mechanical polishing apparatus and method - Google Patents

Abstract

The present invention provides a polishing pad for use in a chemical mechanical polishing apparatus. Pores are formed on the top and inside of the polishing pad to store the polishing liquid during the process. The polishing pad is centrally located and includes an inner pad provided with pores on and in the top and inside, and a plurality of outer pads provided with pores on and in the top and inside. The densities of the pores formed in adjacent ones of the inner and / or outer pads are provided differently from each other. The inner pads are provided in a circular shape, and each of the outer pads may be provided in an annular shape.

Polishing pad, pore, density, chemical mechanical polishing

Description

Polishing pads and methods of manufacturing the same, and chemical mechanical polishing apparatus and method TECHNICAL TECHNICAL TECHNICAL FIELD OF MEUFODURING THE POLISHING PAD, AND CHEMICAL MECHANICAL POLISHING APPARATUS AND METHOD

1 is a perspective view showing an example of the chemical mechanical polishing apparatus of the present invention;

2 is a perspective view of the polishing pad of FIG. 1;

FIG. 3A illustrates an example of region-specific removal rate of a wafer according to a change in density of pores provided in a polishing pad; FIG.

FIG. 3B shows the average removal rate of the wafer with varying density of pores provided in the polishing pad in FIG. 3A;

FIG. 4A shows another example of the removal rate by region of the wafer according to the change in density of the pores provided in the polishing pad; FIG.

FIG. 4B shows the average removal rate of the wafer with varying density of pores provided in the polishing pad in FIG. 4A; FIG.

5 shows another example of the average removal rate of a wafer as the size of the pores provided in the polishing pad changes;

6A and 6B show examples of polishing pads in which pores are provided at different densities according to regions, respectively;

6C shows an example of a polishing pad in which pores are provided in different sizes according to regions;

7 illustrates an example of a structure of the polishing pad of FIG. 2;

8A is a perspective view showing an example of the polishing pad of the present invention;

FIG. 8B is a cross-sectional view taken along the line A-A 'of FIG. 8A;

9A is a perspective view showing another example of the polishing pad of the present invention;

FIG. 9B is a cross-sectional view taken along the line BB ′ in FIG. 9A;

10A to 10C are cross-sectional views each showing another example of the polishing pad of the present invention;

11 is a flowchart showing an example of the chemical mechanical polishing method of the present invention;

12 is a view showing a process of manufacturing the polishing pad of the present invention; and

FIG. 13 is a view illustrating removal rates of regions of a wafer when a process is performed by using each of the sample pads of FIG. 12 and a polishing pad manufactured by combining them.

Explanation of symbols on the main parts of the drawings

Polishing pads: 100, 200, 300, 400, 600c

102 groove

104: fore

700: Sample Pad

The present invention relates to an apparatus and method for manufacturing a semiconductor device, and more particularly, to an apparatus for chemical mechanical polishing of a semiconductor substrate, and a polishing pad used therein and a method for manufacturing the same.

The semiconductor device manufacturing process includes a deposition process for forming a thin film layer on a wafer and an etching process for forming a fine circuit pattern on the thin film layer. These processes are repeated until the required circuit pattern is formed on the wafer, and there are very many bends on the surface of the wafer. These flexures make it difficult to apply the conductive layer evenly in subsequent processes and cause problems such as defocusing in the photographic process.

In order to solve this problem, a process of planarizing the surface of the wafer is required. Recently, as the wafer is large-sized, a chemical mechanical polishing method that can obtain excellent flatness in a large area as well as a narrow area is mainly used.

According to the chemical mechanical polishing method described above, by pressing and rotating the wafer on the polishing pad, the wafer surface is mechanically polished by friction between the polishing pad and the wafer surface, and at the same time, a slurry is supplied between the polishing pad and the wafer to be subjected to chemical reaction. Polish the wafer. Generally, a chemical mechanical polishing apparatus is provided with a platen to which a polishing pad is attached, and the polishing head adsorbs the wafer so that the polishing surface of the wafer faces the polishing pad. The polishing head provides adjustable pressure to the backside of the wafer to press the wafer onto the polishing pad. The polishing pad is formed with grooves for guiding the movement of the slurry on the polishing pad and fine hole-shaped pores for storing the slurry on the polishing pad for a long time.

It is important to uniformly polish the entire wafer area when performing the polishing process. Factors affecting the polishing rate of the wafer in the polishing pad include the surface area of the polishing pad in contact with the wafer, the roughness of the polishing pad, the hardness of the polishing pad, and the compressibility of the polishing pad. ). In order to improve the polishing uniformity in connection with the above factors, a method for uniformly providing the above-mentioned factors in the entire area of the polishing pad has been studied. In addition, a method for improving the structure of the polishing head, the component ratio of the abrasive, and the like has been studied in order to improve the removal rate of the nonuniform wafer according to the area.

However, even in the various studies as described above, the polishing uniformity is not well improved in the entire wafer area.

It is an object of the present invention to provide a chemical mechanical polishing apparatus capable of improving polishing uniformity in the entire region of a wafer, a polishing pad used therein, and a method of manufacturing the same.

It is also an object of the present invention to provide a chemical mechanical polishing apparatus capable of polishing a wafer at a removal rate selected according to a region of a wafer, a polishing pad used therein, and a method of manufacturing the same.

The present invention provides an apparatus for chemically and mechanically polishing a semiconductor substrate such as a wafer. The apparatus of the present invention is a platen, a polishing pad attached to the top of the platen and a plurality of pores (pore) in which the slurry is stored on the top and inside are formed, and adsorbs and secures the semiconductor substrate, It has a polishing head which presses a semiconductor substrate. According to one feature of the invention, the density of the pores formed in and on the upper surface of the polishing pad is provided differently depending on the area of the polishing pad.

In one example, the polishing pad includes an inner pad positioned at the center and provided with pores on the top and inside, and an outer pad disposed to surround the inner pad and with the pores provided on the top and inside. The density of the pores formed in the inner pad is provided differently from the density of the pores provided in the outer pad. The inner pad may have a circular shape, and the outer pad may have an annular shape.

In another example, the polishing pad includes an inner pad positioned at the center and provided with pores on and in the top and inside, and a plurality of outer pads provided to surround the inner pad and provided with pores on the top and inside. The densities of the pores formed in the adjacent pads of the inner pad and / or the outer pads are provided differently from each other. The inner pad may be provided in a circular shape, and each of the outer pads may have an annular shape.

For example, when the polishing pad provided with a high density of pores in the film polished on the wafer, the polishing rate of the wafer is lower and the polishing rate is higher in the edge region of the wafer than in the center region of the wafer. In the edge region of the polishing pad, pores are provided with a higher density than the central region.

In addition, the more the polishing pad provided with a lower density of pores in the film polished on the wafer, the lower the polishing rate of the wafer and the higher the polishing rate in the edge region of the wafer than in the center region of the wafer. The edge region of the polishing pad is provided with a lower density of pores than the central region.

In addition, the more the polishing pad provided with a higher density of pores in the film polished on the wafer, the lower the polishing rate of the wafer and the lower the polishing rate in the edge region of the wafer than in the center region of the wafer. The edge region of the polishing pad is provided with a lower density of pores than the central region.

In another example, the polishing pad includes an upper pad disposed on an upper side of the polishing pad and a lower pad positioned below the upper pad and having pores formed therein. Pores are formed on an upper surface and an inside of the upper pad, and pores are formed inside the lower pad. The densities of the pores formed in and on the upper surface of the upper pad may be provided differently depending on the area. Optionally, the density of the pores formed inside the lower pad may be provided differently depending on the area. Optionally, the density of the pores formed in the upper pad and the lower pad may be provided differently depending on the area.

According to one embodiment, the diameter of the polishing pad has a length of more than twice the diameter of the semiconductor substrate, the semiconductor substrate is positioned so as to contact the polishing pad at a position deviated to one side from the center of the polishing pad during the process do. The polishing pad has an edge polishing pad contacting the edge region of the semiconductor substrate during the polishing process and a central polishing pad contacting the center region of the semiconductor substrate more than the edge region of the semiconductor substrate during the polishing process. The densities of the pores formed in the edge polishing pad and the central polishing pad are provided differently from each other.

In another embodiment, the center of the semiconductor substrate is positioned to face the center of the polishing pad during the process. The polishing pad includes an edge polishing pad contacting the edge region of the semiconductor substrate during the polishing process and a central polishing pad contacting the central region of the semiconductor substrate during the polishing process. The densities of the pores formed in the edge polishing pad and the central polishing pad are provided differently from each other.

The present invention also provides a polishing pad for use in a chemical mechanical polishing apparatus. According to an aspect of the present invention, pores in which the polishing liquid is stored during the process are formed on the top and inside of the polishing pad, and the pores are provided at different densities according to the area of the polishing pad.

In addition, the polishing pad may be provided in the same manner as the polishing pad of various structures used in the above-described chemical mechanical polishing apparatus.

The present invention also provides a method of manufacturing a polishing pad for use in an apparatus for chemically and mechanically polishing a semiconductor substrate. According to the method, the polishing pad is divided into a plurality of regions, and pores in which polishing liquids supplied to the polishing pad are stored are formed on the top and inside of each region, and adjacent regions among the regions. To prepare the polishing pad by providing the pores at different densities from each other.

According to an example, the polishing pad may be manufactured by combining a plurality of pads having pores formed at different densities from each other and then combining them. Each of the plurality of pads may be provided in a circular or annular shape.

The polishing rate decreases as the film polished on the semiconductor substrate is provided with a higher density of pores, and when the polishing rate at the edge region of the semiconductor substrate is lower than the polishing rate at the center region, the polishing pad is at the center region. The density of the pores in the edge region is lower than that of.

In addition, when using a pad provided with a high density of pores in the film polished on the semiconductor substrate, the polishing rate increases, and when the polishing rate in the edge region of the semiconductor substrate is higher than the polishing rate in the center region, the polishing pad is The density of the pores is provided at the edge region in comparison to the central region.

In addition, when the film polished on the semiconductor substrate is an oxide film and the abrasive used is a silica slurry, the polishing pad is provided with a higher density of pores in the edge region than in the central region.

In addition, when the film polished in the semiconductor substrate is a tungsten film and the abrasive used is a silica slurry, the polishing pad is provided with a lower density of pores in the edge region than in the central region.

According to another example, the method of manufacturing the polishing pad of the present invention includes providing sample pads having pores formed at different densities from each other, and measuring and measuring a removal rate according to the type of film polished on the semiconductor substrate using each of the sample pads. Storing the results in a database, setting a process removal rate of each semiconductor substrate on which the process is to be performed, and providing pads provided with pores at the same density as sample pads having removal rates corresponding to the process removal rates, respectively. And combining the pads.

According to an example, the data stored in the database may be a profile showing the removal rate of each region of the semiconductor substrate. Optionally, the data stored in the database may be an average removal rate over the entire area of the wafer.

Hereinafter, with reference to the accompanying drawings, Figures 1 to 13 will be described the present invention in more detail. Embodiment of the present invention may be modified in various forms, the scope of the present invention should not be construed as limited to the embodiments described below. This example is provided to more completely explain the present invention to those skilled in the art. Therefore, the shape of the elements in the drawings are exaggerated for clarity.

1 shows an example of the chemical mechanical polishing apparatus 1 of the present invention. Referring to FIG. 1, the chemical mechanical polishing apparatus 1 includes a polishing head assembly 10, a platen 20, a slurry supply arm 40, and a polishing pad. A polishing pad 100. The platen 20 has a cylindrical plate shape and is supported by a rotating body (not shown) coupled to the bottom surface. A motor (not shown) is coupled to the rotating body to rotate the platen 20 during the process. The rotor and motor may be located in the base 50. A polishing pad 100 is attached to an upper surface of the platen 20, and a pad conditioner (not shown) is provided on one side of the platen 20 to maintain polishing conditions of the polishing pad 100 during the polishing process. A slurry supply arm 40 for supplying a polishing liquid such as a slurry to the surface of the polishing pad 100 is disposed.

The polishing head assembly 10 is positioned above the platen 20 during the polishing process. The polishing head assembly 10 sucks and fixes the wafer W so that the polishing surface of the wafer (W in FIG. 8B) faces the polishing pad 100 and pressurizes the wafer W against the polishing pad 100 during the process. Has a polishing head 12. The polishing head 12 is a membrane (not shown) that adsorbs and pressurizes the wafer W, and a retaining ring (not shown) to prevent the wafer W from being separated from the polishing head 12 during the process. ), Etc. The polishing head 12 may use various structures known in the art. An upper surface of the polishing head 12 has a drive shaft 14 supporting the polishing head 12. The drive shaft 14 is rotated by the motor 16 during the process. During the process, the polishing head 12 is rotated in the same direction as the rotation direction of the platen 20 about the drive shaft 14.

The polishing pad 100 has a circular shape and is attached onto the platen 20 by an adhesive. The upper surface, which is the polishing surface of the polishing pad 100, has a rough surface and is in direct contact with the wafer W to mechanically polish the wafer W. The polishing pad 100 has at least twice the diameter of the retaining ring of the polishing head 12. For example, when the diameter of the wafer W is 300 mm, the polishing pad 100 may have a diameter of about 700 mm to 800 mm. During the process, the polishing head 12 is disposed at one side from the center of the polishing pad 100 to rotate about the drive shaft 14, and the polishing pad 100 is rotated together with the platen 20. During the process, the polishing head 12 may vibrate in the radial direction of the polishing pad 100.

2 is a perspective view of the polishing pad 100 of FIG. 1. Referring to FIG. 2, a plurality of grooves 102 are formed on the top surface of the polishing pad 100. During the process, the slurry supplied onto the polishing pad 100 is moved between the polishing pad 100 and the wafer W through the groove 102. According to one example, the grooves 102 may have a circular ring shape and may be arranged to form concentric circles.

The slurry supplied onto the polishing pad 100 is discharged out of the polishing pad 100 by centrifugal force due to the rotation of the polishing pad 100. In order to improve the polishing rate, it is preferable that a plurality of slurry particles exist on the top surface of the polishing pad 100 to participate in polishing. To this end, a plurality of pores 104 formed as fine holes are provided on the top and inside of the polishing pad 100. The pores 104 exposed on the top surface of the polishing pad 100 store slurry particles supplied onto the polishing pad 100. Then, when the wafer W presses the polishing pad 100, the slurry particles are ejected from the pores 104 to participate in polishing. The pores 104 formed in the polishing pad 100 do not store slurry particles during the process. However, when the polishing pad 100 is worn out or pad conditioning is performed due to prolonged use, the pores 104 formed in the polishing pad 100 are exposed to the outside.

The density of the pores 104 formed in the polishing pad 100 greatly affects the polishing rate of the wafer W. That is, the density of the pores 104 formed in the polishing pad 100 may include the surface area of the polishing pad 100 in contact with the wafer W, the amount of slurry reacted with the wafer W, and the polishing pad 100. ), The hardness of the polishing pad 100, and the like. Here, the surface area of the polishing pad 100, the compressibility of the polishing pad 100, and the hardness of the polishing pad 100 affect mechanical polishing, and the amount of slurry reacted with the wafer W affects chemical polishing. Crazy

The higher the density of the pores 104 exposed on the top surface of the polishing pad 100, the smaller the surface area of the polishing pad 100 in contact with the wafer W is. In addition, as the density of the pores 104 formed on the upper surface and the inside of the polishing pad 100 increases, the compressibility of the polishing pad 100 increases and the hardness of the polishing pad 100 decreases. In addition, the higher the density of the pores 104 exposed on the upper surface of the polishing pad 100, the greater the amount of slurry stored in the pore 104. Therefore, the lower the density of the pores 104 formed in the polishing pad 100, the better the mechanical polishing. The higher the density of the pores 104, the better the chemical polishing.

Hereinafter, providing different densities of the pores 104 to the polishing pad 100 means that the density of the pores 104 differs from the top surface of the polishing pad 100 and the inside of the polishing pad 100 if there is no other substrate. Include providing the service. In addition, the removal rate of the wafer W refers to a rate at which the film quality formed on the wafer W is removed.

3A to 4B are diagrams showing the removal rate of the wafer W during the process while changing the density of the pores 104 formed in the polishing pad 100 while maintaining the other polishing conditions the same. In FIGS. 3A-4B, the pore 104 is formed substantially uniform in size and the spacing between the pores 104 is varied to provide the polishing pad 100 with different densities of pores 104. The slurry used in FIGS. 3A and 3B is a silica slurry, and the film to be polished is an inter layer dielectrics film. The slurry used in FIGS. 4A and 4B is a ceria slurry and the polished film is a shallow trench isolation film. 3A and 4A show removal rates of regions of the wafer W, and FIGS. 3B and 4B show average removal rates of the wafer W. FIGS. 3A-4B, the removal rate of the wafer W decreases as the spacing of the pores 104 provided in the polishing pad 100 is reduced (ie, as the density of the pores 104 is increased). You can see that.

3A to 4B, examples of the removal rate of the polishing pad 100 having the high density of the pores 104 are reduced. This is because the above-described film materials are polished better when polished by a method such as mechanical friction than polishing by chemical reaction. Therefore, the opposite result may occur depending on the type of the film to be polished. For example, in the case where the film to be polished is tungsten, although not provided in the drawing, the higher the density of pores, the higher the removal rate is, as opposed to FIG. 3A.

In addition, when the film is polished using a silica slurry as shown in FIG. 3A, the wafer edge region We is generally polished better than the center region Wc regardless of the kind of the film. However, when polishing using a ceria slurry, the edge region may be polished better than the center region, or the center region may be polished better than the edge region, depending on the type of film.

5 shows a case where the density of the pores 104 is provided substantially uniformly, and the sizes (diameters) of the pores 104 are provided differently. The slurry used in FIG. 5 is a silica slurry and the film to be polished is tungsten. Referring to FIG. 5, it can be seen that as the size of the pores 104 provided in the polishing pad 100 increases, the polishing rate of the wafer W decreases. Therefore, it can be seen that the size of the pores 104 also affects the polishing rate depending on the type of film.

In general, the removal rate during the polishing process varies depending on the area of the wafer W due to various causes. Therefore, it is necessary to vary the polishing conditions in accordance with the regions so that uniform polishing is performed in the entire region of the wafer W. As described with reference to FIGS. 3A to 5, the density or size of the pores 104 formed in the polishing pad 100 affects the removal rate of the wafer W. Therefore, the present invention uses the polishing pad 100 provided with different densities or sizes of the pores 104 depending on the region to adjust the removal rate of each region of the wafer (W). In the following embodiments, only the case where the densities of the pores 104 are provided differently will be described as an example. However, the density of the pores 104 is equally provided in the entire area of the wafer, but the size of the pores may be applied to the following embodiments even if the sizes of the pores are provided differently according to the area of the wafer.

6A and 6B show methods for providing different densities of pores 104 depending on the region, respectively. According to one example, as shown in FIG. 6A, the sizes of the pores 104 are formed substantially the same in the entire area of the polishing pad 100, and the spacing between the pores 104 is the area of the polishing pad 100. By forming differently according to the present invention, the density of the pores 104 may be differently provided according to the area of the polishing pad 100.

In another example, as shown in FIG. 6B, the spacing between the pores 104 is formed substantially the same throughout the entire area of the polishing pad 100 and the size of the pores 104 is the area of the polishing pad 100. By forming differently according to the present invention, the density of the pores 104 may be differently provided according to the area of the polishing pad 100. In contrast, the horizontal widths of the pores 104 are formed to be substantially the same in the entire area of the polishing pad 100, and the vertical widths of the pores 104 are formed differently according to the area of the polishing pad 100. The density of the pores 104 may be differently provided according to the area of the polishing pad 100.

In addition, in order to make the sizes of the pores 104 different, as shown in FIG. 6C, the volumes of the pores 104 are provided substantially the same in the whole area, and the size of the pores 104 is provided with a polishing pad ( It can be formed differently according to the area | region of 100).

In the above-described embodiment, in order to provide different densities of the pores 104 according to the area of the polishing pad, the sizes of the respective pores are the same but the spacing between the pores is the same, and the spacing of the pores is the same. The case where the sizes of the pores are provided differently has been described as an example. However, providing the density of the pores differently according to the area of the polishing pad in this embodiment includes the case where the volume or size of each pore is provided differently between the areas even though the overall density of the pores between the areas is the same.

In the examples described above, the size of the pores 104 may be provided in one or a plurality of sizes selected from about 5 micrometers (μm) to 500 micrometers (μm), and the pores ( 104 is provided to occupy a volume of 0 to 80 percent (%) per unit volume of the polishing pad 100 depending on the area, and the pores 104 on the top surface of the polishing pad 100 are 0 to per unit area depending on the area. It may be provided to occupy an area of 80 percent (%). Here, the volume or area of 0% means that the pore 104 is not formed in a specific region of the polishing pad 100.

7 shows an example of the structure of the polishing pad 100 provided with pores 104 of different densities depending on the area. The polishing pad 100 has a plurality of pads. Pores 104 are provided at different densities between adjacently located pads. The pads are shaped to be combined with each other. Each pad may be provided in a circular or annular ring shape. For example, when the polishing pad 100 is partitioned into three regions, as shown in FIG. 7, the polishing pad 100 has one inner pad 120 and two outer pads 140. The inner pad 120 is located at the center and has a circular shape. The outer pad 140 is provided with a first outer pad 142 and a second outer pad 144 having an annular shape. The first outer pad 142 has an inner diameter equal to the diameter of the inner pad 120 and is positioned to surround the inner pad 120. The second outer pad 144 has an inner diameter equal to the outer diameter of the first outer pad 142 and is disposed to surround the first outer pad 142. The inner pad 120 and the outer pads 142 and 144 may be combined in various ways such as adhesive or mechanical fastening means. In the above-described example, the case in which two outer pads 140 are provided has been described as an example. Alternatively, one or three outer pads 140 may be provided.

In the above examples, it has been described that the inner pad and the outer pad are provided separately. However, this is only one example, and the polishing pad has an inner pad and an outer pad, in addition to providing the inner pad and the outer pad separately, one pad covers two or more areas provided with different densities of pores. Includes cases. In this case, the center area becomes an inner pad, and the area surrounding the center area becomes one or a plurality of outer pads.

Next, the case where the polishing pad 200 of the present invention has a structure for polishing the center region and the edge region of the wafer W under different polishing conditions will be described.

FIG. 8A is a plan view illustrating an example of the polishing pad 200, and FIG. 8B is a cross-sectional view of the polishing pad 200 taken along the line A-A 'of FIG. 8A. 8A and 8B, the diameter of the polishing pad 200 has a length more than twice the diameter of the wafer W, and the wafer W moves toward one side from the center of the polishing pad 200 during the process. In contact with the polishing pad 200 at one side. The polishing pad 200 has one central polishing pad 220 and two edge polishing pads 240. The edge polishing pad 240 has a first pad 242 having a circular shape and a second pad 244 having an annular shape. The pores 104 are provided at the same density on the first pad 242 and the second pad 244, and the pores 104 are provided on the edge polishing pad 240 and the central polishing pad 220 at different densities. do. The first pad 242 of the edge polishing pad 240 is located at the center. The central polishing pad 220 has an inner diameter that is substantially the same length as the outer diameter of the first pad 242, and is disposed to surround the first pad 242. The second pad 244 of the edge polishing pad 240 has an inner diameter that is substantially the same length as the outer diameter of the center polishing pad 220 and is disposed to surround the center polishing pad 220. Due to the structure described above, the edge polishing pad 240 is in contact with the edge region of the wafer W, and the central polishing pad 220 is mainly in contact with the center region of the wafer W compared with the edge region of the wafer W. .

FIG. 9A is a plan view illustrating another example of the polishing pad 300, and FIG. 9B is a cross-sectional view of the polishing pad 300 taken along the line BB ′ of FIG. 9A. 9A and 9B, the diameter of the polishing pad 300 has a length substantially similar to that of the wafer W, and the center of the wafer W is opposed to the center of the polishing pad 300 during the process. To be located. The polishing pad 300 has a central polishing pad 320 in contact with the center region of the wafer W and an edge polishing pad 340 in contact with the edge region of the wafer W. As shown in FIG. The central polishing pad 320 has a circular shape, and the edge polishing pad 340 has an annular shape. The edge polishing pad 340 has an inner diameter equal to the diameter of the central polishing pad 320 and is disposed to surround the central polishing pad 320.

In the above-described examples, it was explained that the center polishing pad and the edge polishing pad are provided separately in the polishing pad. However, this is only one example, and the fact that the polishing pad has a center polishing pad and an edge polishing pad, in addition to providing a center polishing pad and an edge polishing pad separately, a single pad has a central area and an edge provided at different densities of pores. This includes the case of having an area. In this case, the center region becomes the center polishing pad, and the region surrounding the center region becomes the edge polishing pad.

For example, as in the case of polishing an interlayer insulating film using a silica slurry as shown in FIG. 3A, the more a polishing pad provided with a higher density of pores is used, the lower the polishing rate of the wafer and When the polishing rate is higher in the edge region of the wafer than in the center region, the density of the pores is provided in the edge region of the polishing pad as compared with the center region so that the polishing uniformity is high in the entire wafer region.

On the other hand, when using a polishing pad provided with a lower density of pores, such as when the film polished on the wafer is tungsten, when the polishing rate of the wafer is lower and the polishing rate is higher in the edge region of the wafer than in the center region of the wafer, the entire wafer The edge area of the polishing pad is provided with a lower density of pores than the central area so that the polishing uniformity in the area is high.

In addition, as in the case of polishing the trench device isolation layer using a ceria slurry as shown in FIG. 4A, the use of a polishing pad provided with a high density of pores in the film to be polished on the wafer results in a lower polishing rate of the wafer compared to the center region of the wafer. When the polishing rate is low in the edge region, the density of pores is provided in the edge region of the polishing pad as compared with the center region so that the polishing uniformity is high in the entire wafer region.

According to another example, the polishing pad 400 has upper and lower pads 420a, 420b, and 420c and lower pads 440a, 440b, and 440c. The lower pads 440a, 440b, and 440c may be made of a relatively softer material than the upper pads 420a, 420b, and 420c. Lower pads 440a, 440b, 440c are attached by adhesive on platen 20, and upper pads 420a, 420b, 420c are attached by adhesive on lower pads 440a, 440b, 440c. As shown in FIG. 10A, the upper pads 420a may be provided with pores 104 having substantially the same density, and the lower pads 440a may be provided with different densities throughout the region. have. Optionally, as shown in FIG. 10B, the upper pad 420b is provided with different densities of pores 104 throughout the region, and the lower pad 440b has pores 104 having substantially the same density, depending on the region. Can be provided. Optionally, the pores 104 may be provided at different densities depending on the area in both the upper pad 420c and the lower pad 440c as shown in FIG. 10C. The density difference of the pores 104 along the region of the upper pads 420b and 420c is dependent on the compressibility and hardness of the polishing pad 400, the surface area in contact with the wafer W, and the amount of slurry provided on the wafer W. Influence, and the difference in density of the pores 104 along the region of the lower pads 440a and 440c affects the compressibility of the polishing pad 400.

In the above-described examples, the polishing pad is formed by combining a plurality of pads on which pores 104 of different densities are formed. Alternatively, however, the polishing pad may consist of a single pad and the pores 104 may be provided at different densities depending on the area within the single pad.

Next, an example of a method of manufacturing the polishing pad 300 described above with reference to FIGS. 11 to 13 will be described. 11 is a flow chart sequentially showing a process of manufacturing a polishing pad. First, sample pads having pores formed on the top and inside are fabricated. In each sample pad, the pores 104 are formed at a substantially uniform density in the entire region, and the pore 104 is formed at different densities in the sample pads (step S12). Each sample pad is used to polish the wafer W and the removal rate of the wafer W is measured. The removal rate is measured for each of the various membranes. The measured removal rate is stored in a database (not shown) (step S14). The stored data may be a profile showing removal rates of regions of the wafer W as shown in FIG. 3A or 4A. The selectively stored data may be an average removal rate in the entire area of the wafer W as shown in FIG. 3B or 4B.

Subsequently, the wafer W on which the process is to be performed is divided into a plurality of regions, and a process removal rate is set for each region (step S16). It is preferable to set this so that uniform grinding | polishing can be performed in the whole area | region of the wafer W. When the removal rate is set for each wafer W region, pads that provide the same removal rate as the sample pads capable of removing the corresponding removal rate are selected (step S18). Thereafter, the pads are combined and combined to complete the polishing pad 300 to be used in the actual process (step S20). The pads have a shape suitable for the position provided in the polishing pad 300. For example, the pads may have a circular or annular shape.

FIG. 12 is a diagram illustrating an example of a process of manufacturing the polishing pad 600 according to the method of FIG. 11, and FIG. 13 is a diagram illustrating a first sample pad 720 and a second sample pad 740 of FIG. The removal rate of each region of the wafer W when the polished pad 600 is used is shown. In FIG. 13, lines 'a' and 'b' are removal rates of regions of the wafer W when the first sample pad 720 and the second sample pad 740 are used, respectively, and the line 'c' is a manufactured polishing pad ( 300 is a view showing the removal rate of each region of the wafer (W) in use.

As shown in FIG. 13, the removal rate of the wafer W is different when using the first sample pad 720 and when polishing using the second sample pad 740. In this case, as the center polishing pad described above, the pad 620 having the pores 104 formed at the same density as the first sample pad 720 is selected to uniformly polish the entire polishing pad 600, and the edge As the polishing pad, pads 642 and 644 having the pores 104 formed at the same density as the second sample pad 740 are selected. Next, the pads 620, 642, 644 are cut in a circular or annular shape according to the shape or size of the polishing pad 600 used, and the pads 620, 642, 644 are cut by an adhesive or other fastening means. To combine. When the wafer W was polished using the polishing pad 600 manufactured using the above method, as shown in FIG. 13, the variation in the removal rate between the center portion of the wafer and the edge region was reduced.

 In the above-described example, a case in which a polishing pad is manufactured by combining two sample pads is described as an example. However, in contrast, the polishing pad 300 may be manufactured by combining three or more sample pads, and as the number of pads used in the polishing pad 300 increases, polishing uniformity for each region of the wafer W may be improved.

In addition, in the above-mentioned example, it was demonstrated that a polishing pad is comprised so that polishing uniformity may be improved in the whole area | region of the wafer W. As shown in FIG. Alternatively, however, the polishing pad may be configured such that the removal rate in a particular area of the wafer is different from the removal rate in another area.

According to the present invention, the polishing uniformity of the wafer can be improved by differently forming the densities of the pores according to the regions of the polishing pad.

Claims (35)

An apparatus for chemically and mechanically polishing a semiconductor substrate, Platen; A polishing pad attached to the platen and having pores formed on and in an upper surface thereof; And A polishing head configured to suck and fix the semiconductor substrate and to press the semiconductor substrate onto the polishing pad; The density of the pores formed in and on the upper surface of the polishing pad is provided differently depending on the area of the polishing pad. The method of claim 1, The polishing pad is, An inner pad centrally located and provided with pores in the top and inside; The outer pad is disposed to surround the inner pad, and includes an outer pad provided with pores on an upper surface and an inside thereof. And the density of the pores formed in the inner pad is different from the density of the pores provided in the outer pad. The method of claim 2, The inner pad has a circular shape, And the outer pad has an annular shape. The method of claim 1, The polishing pad is, An inner pad centrally located and provided with pores in the top and inside; Is disposed to surround the inner pad, including a plurality of outer pads provided with pores on the top and inside, And the densities of the pores formed in the adjacent pads of the inner pad and / or the outer pads are different from each other. The method of claim 4, wherein The inner pad is provided in a circular shape, And each of said outer pads is provided in an annular shape. delete delete delete The method of claim 1, The diameter of the polishing pad has a length of at least two times the diameter of the semiconductor substrate, and the semiconductor substrate is positioned to contact the polishing pad at a position deviated to one side from the center of the polishing pad during the process. The polishing pad is, An edge polishing pad in contact with an edge region of the semiconductor substrate during the polishing process; Including a central polishing pad in contact with the central region of the semiconductor substrate compared to the edge region of the semiconductor substrate during the polishing process, And the densities of the pores formed in the edge polishing pad and the central polishing pad are different from each other. The method of claim 1, During the process, the center of the semiconductor substrate is positioned to face the center of the polishing pad, The polishing pad is, An edge polishing pad in contact with an edge region of the semiconductor substrate during the polishing process; Including a central polishing pad in contact with the central region of the semiconductor substrate during the polishing process, And the densities of the pores formed in the edge polishing pad and the central polishing pad are different from each other. delete delete delete delete A polishing pad used in a chemical mechanical polishing apparatus, A polishing pad, characterized in that pores are provided on the top and inside of the polishing pad at different densities depending on the area of the polishing pad. The method of claim 15, The polishing pad is, An inner pad centrally located and provided with pores in the top and inside; The outer pad is disposed to surround the inner pad, and includes an outer pad provided with pores on an upper surface and an inside thereof. And the density of the pores formed in the inner pad is different from the density of the pores provided in the outer pad. The method of claim 15, The polishing pad is, An inner pad centrally located and provided with pores in the top and inside; Is disposed to surround the inner pad, including a plurality of outer pads having pores formed on the top and inside, And the density of pores formed in adjacent ones of the inner pad and / or the outer pads are different from each other. The method of claim 17, The inner pad is provided in a circular shape, And each of said outer pads is provided in an annular shape. The method of claim 15, The polishing pad is, An upper pad disposed on the upper side and in contact with the wafer and having pores formed on and in the upper surface; A lower pad positioned below the upper pad and having pores formed therein, The density of the pores formed in and on the upper surface of the upper pad is different depending on the area of the upper pad polishing pad. The method of claim 15, The polishing pad is, An upper pad disposed on the upper side and in contact with the wafer and having pores formed on and in the upper surface; A lower pad positioned below the upper pad and having pores formed therein, And the density of the pores formed in the lower pad is different depending on the area of the lower pad. The method of claim 15, The polishing pad is, An upper pad disposed on the upper side and in contact with the wafer and having pores formed on and in the upper surface; A lower pad positioned below the upper pad and having pores formed therein, And the density of the pores formed on the upper and inner surfaces of the upper pad and inside the lower pad is different depending on the area. The method of claim 15, The diameter of the polishing pad is provided as a length of at least two times the diameter of the semiconductor substrate, the semiconductor substrate is positioned so as to contact the polishing pad in a region deviating to one side from the center of the polishing pad during the process, The polishing pad is, An edge polishing pad in contact with an edge region of the semiconductor substrate during the polishing process; Including a central polishing pad in contact with the central region of the semiconductor substrate in comparison with the edge region of the semiconductor substrate during the polishing process, And the densities of the pores formed in the edge polishing pad and the central polishing pad are different from each other. The method of claim 22, And the edge polishing pad is provided with a lower density of the pores than the central polishing pad. The method of claim 22, And the edge polishing pad is provided with a higher density of pores than the central polishing pad. A method of manufacturing a polishing pad for use in an apparatus for chemically polishing a semiconductor substrate, And dividing the polishing pad into a plurality of regions, and forming pores on the top and inside of each region, and providing the pores at different densities in adjacent regions among the regions. . The method of claim 25, The polishing pad is manufactured by manufacturing a plurality of pads in which pores are formed at different densities or different sizes, and then combining them. In the method of chemically and mechanically polishing a semiconductor substrate, The polishing pad is divided into a plurality of regions, and pores are formed on the top and inside of each region, When the film polished on the semiconductor substrate uses a pad provided with a higher density of pores, the polishing rate is lower, and the polishing rate is higher in the edge region of the semiconductor substrate than in the central region of the semiconductor substrate. Polishing the semiconductor substrate using a polishing pad provided with a high pore density in a region where the area mainly in contact with the edge region compared to the center region of the semiconductor substrate is higher than a region mainly in the center region relative to the edge region of the semiconductor substrate. Chemical mechanical polishing method. The method of claim 27, Wherein the film to be polished in the semiconductor substrate is an oxide film and the abrasive used is a silica slurry. In the method of chemically and mechanically polishing a semiconductor substrate, The polishing pad is divided into a plurality of regions, and pores are formed on the top and inside of each region, When the pad polished from the semiconductor substrate is used with a lower pore density, the polishing rate is lower, and the polishing rate is higher in the edge region of the semiconductor substrate than in the central region of the semiconductor substrate. Polishing the semiconductor substrate using a polishing pad provided with a lower pore density than a region mainly contacted at the edge region of the semiconductor substrate compared to a region mainly contacted at the edge region of the semiconductor substrate. Chemical mechanical polishing method. In the method of chemically and mechanically polishing a semiconductor substrate, The polishing pad is divided into a plurality of regions, and pores are formed on the top and inside of each region, When using a pad provided with a high density of pores of the film polished on the semiconductor substrate, the polishing rate is lower, and the polishing rate is lower in the edge region of the semiconductor substrate than in the center region of the semiconductor substrate, Polishing the semiconductor substrate using a polishing pad provided with a lower pore density than a region mainly contacted at the edge region of the semiconductor substrate compared to a region mainly contacted at the edge region of the semiconductor substrate. Chemical mechanical polishing method. The method of claim 30, Wherein the film to be polished in the semiconductor substrate is a trench element isolation film, and the abrasive used is a ceria slurry. In the method of manufacturing the polishing pad, Providing sample pads having pores formed at different densities or sizes on the upper surface and the inner surface according to a region; Measuring a removal rate for each type of film polished on the semiconductor substrate using each of the sample pads, and storing the measurement result in a database; Setting a process removal rate of each of the semiconductor substrates on which the process is to be performed for each region; Providing pads provided with pores on and in the same density or size as sample pads having removal rates corresponding to each of the process removal rates according to regions; And combining the pads. The method of claim 32, The pads constituting the polishing pad are each provided in a circular or annular shape. The method of claim 32, The data stored in the database is a polishing pad manufacturing method, characterized in that the profile showing the removal rate for each region of the substrate. The method of claim 32, And the data stored in the database is an average removal rate in the entire area of the substrate.

Images