KR20060117148A - Retaining ring for chemical mechanical polishing and its manufacturing method - Google Patents

Abstract

The present invention relates to a retaining ring for suppressing the detachment of a wafer during a polishing process in a chemical mechanical polishing apparatus. The retaining ring according to the present invention supports a side of the wafer to prevent the detachment of the wafer during the polishing process. A retaining pieces and a generally annular base ring to which the plurality of retaining pieces are attached, wherein the surfaces of the plurality of retaining pieces that come into contact with the polishing pad during the polishing process have a root mean square (RMS) roughness value. It is characterized by the above-mentioned.

Description

Retaining ring for chemical mechanical polishing and manufacturing method thereof {RETAINING RING FOR CHEMICAL MECHANICAL POLISHING AND METHOD OF MANUFACTURING THE SAME}

1 is a cross-sectional view showing a chemical mechanical polishing process,

2a to 2d are perspective views illustrating a retaining ring and a manufacturing process according to the prior art,

3A to 3F are perspective views and a plan view for explaining a retaining ring manufacturing method according to an embodiment of the present invention;

4a to 4f are perspective views and plan views for explaining a retaining ring manufacturing method according to another embodiment of the present invention,

 5A and 5B are a perspective view and a plan view for explaining a retaining ring manufacturing method according to another embodiment of the present invention.

<Description of the code | symbol about the principal part of drawing>

100, 120: plastic sheet

200, 220: retaining piece

300, 320: base ring

400, 420: retaining ring

TECHNICAL FIELD The present invention relates to a chemical mechanical polishing apparatus, and more particularly, to a retaining ring for preventing release of a wafer during a polishing process.

As miniaturization and multilayering of semiconductor integrated circuits are required, there is a need to planarize the wafer surface or selectively remove the conductive layer formed on the wafer surface at certain stages of the semiconductor manufacturing process. Due to this necessity, chemical mechanical polishing (CMP) is widely used in semiconductor manufacturing processes. In general, the CMP process smoothes the surface of the wafer or selectively removes the conductive layer by applying a slurry to the polishing pad and moving the polishing pad and the wafer relative to the wafer under pressure.

1 is a cross-sectional view schematically showing a wafer polishing process by a CMP apparatus. Specifically, the polishing pad 12 is attached to the upper surface of the platen 10, and the slurry 14 is applied on the polishing pad 12, and the wafer 16 is applied to the polishing pad 12 and the polishing pad 12. The surface of the wafer is flattened by friction with the polishing pad 12 which is in rotational or orbital motion in contact with the slurry 14. Here, the part that applies the polishing pressure to the wafer 16 during the CMP process and performs the rotational movement and, in some cases, transfers the wafer 16 is called a polishing head or a carrier 18. do. The carrier 18 rotates the wafer in contact with the carrier base 22 and the wafer 16 top surface, which are largely powered from the rotating shaft 20 and provide space for fixing other carrier components. In addition, the pressure transfer means 24 made of a plate or a bladder to apply the polishing pressure to the wafer, and to prevent the separation of the wafer 16 due to friction with the polishing pad 12 during the CMP process It consists of a retaining ring 26. The role of the retaining ring 26 supports the side of the wafer 16 during the CMP process to prevent the wafer from coming off, and also presses the polishing pad 12 to a predetermined pressure, so that the edge of the wafer 16 is near the edge. By maintaining the deformation of the polishing pad 12 evenly in the polishing uniformity (uniformity) is improved.

2a to 2d are views for explaining a retaining ring and a manufacturing process according to the prior art. First, Figure 2a is a perspective view showing a retaining ring 60 according to the prior art. Here, the retaining ring 60 consists of two parts, one of which is a base ring 50 which serves to connect the retaining ring 60 to a carrier base (not shown) and the other is a base ring. A pad contact ring 40 attached to 50 to support the wafer side during the CMP process to serve as a wafer retaining and to contact the polishing pad to improve polishing uniformity. The upper surface of the base ring 50 is provided with a screw hole 52 necessary for fixing the retaining ring 60 to the carrier base, and the pad contact ring 40 has a groove 42 for promoting the flow of slurry. Is formed. The base ring 50 is generally made of a metal with good corrosion resistance and processability such as stainless steel, and the pad contact ring 40 is made of polyphenylene sulfide (“PPS”) or polyetheretherketone (“PPS”). "PEEK") is made of plastic. The thickness of the pad contact ring 40 is about 5 mm, and the pad contact ring 40 is generally manufactured from the plastic tube 30 as shown in FIG. 2B. Cutting the plastic tube 30 in the direction of the dashed line 34 creates a plastic ring 36 as shown in FIG. 2C. Subsequently, when the groove is formed on the surface of the plastic ring 36, the pad contact ring 40 having the groove 42 and defined by the inner radius Ri and the outer radius Ro as shown in FIG. 2D is completed. . The inner radius Ri is preferably about 0.5 mm to 2 mm larger than the radius of the wafer being polished. The outer radius Ro may be about 10 mm to 40 mm larger than the inner radius Ri. Subsequently, the base ring 50 and the pad contact ring 40 are attached to each other using an adhesive such as epoxy (not shown) to manufacture the retaining ring 60 shown in FIG. 2A. FIG. 2D is a perspective view immediately before assembling the retaining ring 60. When the base ring 50 and the pad contact ring 40 are attached to each other, the retaining ring 60 shown in FIG. 2A is turned upside down. Thus, the figure shows the surface 44 of the pad contact ring 40 which comes into contact with the polishing pad during the CMP process. In the case of the pad contact ring 40 made of plastic, the roughness of the surface 44 generally exceeds several micrometers (eg 3-5 μm). The surface 44 of the rough pad contact ring 40 is polished and smoothed by friction between the polishing pad and the slurry during the CMP process, wherein the polished plastic material may block pores of the polishing pad and It can also adsorb on the surface. Therefore, in general, the retaining ring is pre-polished through the retaining ring break-in process in the CMP apparatus to smooth the contact surface with the pad and then use the actual CMP process. The retaining ring brake process using the CMP device causes a decrease in the utilization rate of the CMP device and consumes expensive polishing pads and slurry used in the manufacture of semiconductor integrated circuits. Before attaching the pad contact ring 40 to the base ring 50, the surface 44 of the pad contact ring 40 may be processed to make it smooth. Because of the large size, the productivity of processing decreases.

SUMMARY OF THE INVENTION An object of the present invention is to provide a retaining ring having a smooth surface in contact with a polishing pad so that a break-in process is not required in the CMP apparatus. Another object of the present invention to provide a retaining ring manufacturing method.

Retaining ring of the chemical mechanical polishing apparatus according to the present invention for achieving the above object, a plurality of retaining pieces and the plurality of retaining pieces to support the side of the wafer to prevent the separation of the wafer during the polishing process And a generally annular base ring to which the plurality of retaining pieces are brought into contact with the polishing pad during the polishing process, characterized in that the root mean square (RMS) roughness value is 0.1 nm to 200 nm.

In addition, in order to achieve the above object, a retaining ring manufacturing method according to an embodiment of the present invention, the step of having a plastic plate having a thickness of 0.5mm to 5mm, and at least one surface of the front or back Is processed into a smooth surface having a root mean square (RMS) roughness value of 0.1 nm to 200 nm, cutting the plate having the smooth surface to form retaining pieces, and the retaining pieces being generally annular. And attaching the retaining pieces to the base ring when attaching the retaining pieces to the base ring.

In addition, in order to achieve the above another object, a method of manufacturing a retaining ring according to another embodiment of the present invention, the step of having a plastic plate having a thickness of 0.5mm to 5mm, and cutting the plate to form retaining pieces And processing at least one of the front or back side of the retaining pieces into a smooth surface having a root mean square (RMS) roughness of between 0.1 nm and 200 nm, and the retaining pieces having a generally annular base. Attaching the retaining pieces so that when the retaining pieces attach to the base ring, the retaining pieces are exposed outwardly.

In addition, in order to achieve the above another object, a method of manufacturing a retaining ring according to another embodiment of the present invention, molding the plastic retaining pieces having a thickness of 0.5mm to 5mm, and the front surface of the retaining pieces or Processing at least one of the backsides into a smooth surface having a root mean square (RMS) roughness of between 0.1 nm and 200 nm, and attaching the retaining pieces to a generally annular base ring; When attaching inning pieces to the base ring, the retaining pieces are attached so that the smooth surface is exposed outward.

Hereinafter, exemplary embodiments of the present invention will be described with reference to the accompanying drawings. However, the embodiments of the present invention are provided to more completely explain the present invention to those skilled in the art. Therefore, the shape of the elements in the drawings and the like are exaggerated in order to emphasize a more clear description, elements denoted by the same reference numerals in the drawings means the same element.

3A to 3F are perspective views and a plan view illustrating a retaining ring manufacturing method according to an embodiment of the present invention. Referring to these drawings, the manufacturing method according to an embodiment of the present invention proceeds as follows.

Figure 3a is a perspective view of a plastic sheet 100 used in this embodiment, the plastic constituting the sheet is PPS, PEEK, polyimide, polyamide-imide, polyester (polyester) or polyether It is preferable that they are engineering plastics having good abrasion resistance such as polyetherimide or the like. In order to improve wear resistance, a reinforcing material such as carbon fiber may be further added to the plastic. The thickness t of the plastic sheet material 100 may have a value of about 0.5 mm to about 5 mm depending on the type of retaining ring to be manufactured. The plastic sheet 100 is generally made by compression molding or extrusion molding. The roughness of the surface 150 after molding the plastic sheet 100 is several micrometers (for example, 3-5 μm). )).

Then, as shown in Figure 3b, the roughness of the surface processed by processing at least one of the front or back surface of the plastic plate 100 is 0.1nm to 200nm as the root mean square (RMS) value Plastic plate 102 having a smooth surface 152. Processing methods that reduce the roughness of plastic surfaces include polishing or buff polishing. A method may be used, wherein the surface roughness after processing is determined according to the size of the abrasive particles used.

Next, as shown in the plan view of FIG. 3C, the plastic sheet 102 having the smooth surface 152 is cut into a plurality of retaining pieces 200 shown in dashed lines. Here, the retaining pieces 200 are defined by an arc having an inner radius of Ri and an arc having an outer radius of Ro. The values of Ri and Ro are the radius of the wafer to be polished and the retaining ring to be manufactured as described in FIG. 2D. It depends on the width of.

3D is a perspective view of the retaining piece 200 cut from the plastic plate 102, wherein at least one of the front and back surfaces of the retaining piece 200 is a smooth surface 152 and that the retaining piece 200 is of the retaining piece 200. The inner face is the face defined by the arc with radius Ri, and the outer face is the face defined by the arc with radius Ro.

3E illustrates a retaining ring 400 in accordance with the present invention. The retaining ring 400 is completed by attaching the plurality of retaining pieces 200 to the base ring 300, which is generally annular, using an adhesive material such as epoxy. When attaching the retaining pieces 200 to the base ring 300, the smooth surface 152 is exposed outward. Then, since the smooth surface 152 is in contact with the polishing pad during the CMP process, the retaining ring 400 break-in process may be omitted or the break-in process time may be greatly reduced. In the drawing, 12 retaining pieces 200 are attached to the base ring 300. The number of retaining pieces may be 4 to 72, and the size of the retaining pieces is determined by the number of retaining pieces to be attached. do. In addition, as shown, when forming the gap 350 between two adjacent retaining pieces 200, the width of the gap 350 (for example, 1mm to 5mm) is taken into consideration of the retaining pieces 200. Try to set the size.

The base ring 300 to which the retaining pieces 200 are attached may be made of a metal such as stainless steel having excellent corrosion resistance, a plastic such as PPS, or a ceramic such as alumina. The base ring 300 may be formed of one body as shown in FIG. 3E, and as shown in FIG. 3F, the lower base ring 302 and the upper base ring 304 are attached to the base ring 306. As shown in FIG. 2, two or more rings may be attached to each other. At this time, it is preferable that the upper base ring 304 to which the retaining pieces 200 are attached and come into contact with the slurry is made of plastic and the lower base ring 302 connected to the carrier base is made of metal such as stainless steel. .

4A to 4F are perspective views and plan views illustrating a retaining ring manufacturing method according to another exemplary embodiment of the present invention.

First, as shown in the perspective view of Figure 4a, to prepare a plastic sheet 120 made by a compression molding or extrusion molding method. The thickness t of the plastic plate 120 may have a value of about 0.5 mm to about 5 mm depending on the type of retaining ring to be manufactured. In general, the plate material 120 produced by the molding method has a roughness of the surface 170 exceeds a few micrometers (μm).

Subsequently, as shown in the plan view of FIG. 4B, the plastic plate 120 is cut into a plurality of retaining pieces 210 shown in dashed lines. Here, the retaining pieces 210 are defined by an arc having an inner radius of Ri and an arc having an outer radius of Ro. The values of Ri and Ro are the radius of the wafer to be polished and the retaining ring to be manufactured as described in FIG. 2D. It depends on the width of.

4C is a perspective view of the retaining piece 210 cut from the plastic plate 102, the inner face of the retaining piece 210 being defined by an arc with a radius Ri and the outer face being a radius. The surface 170 of the retaining piece 210 is the same as after the plastic sheet 120 is molded, so that the surface roughness exceeds several micrometers (µm).

Next, as shown in FIG. 4D, the retaining pieces 210 are attached to a support 600 made of metal or plastic. At this time, it is preferable to use an adhesive material that can be easily separated, such as wax. Subsequently, when the surface 170 of the retaining pieces 210 attached to the support 600 is processed to have a surface roughness of about 0.1 nm to 200 nm with a root mean square (RMS) value, a smooth surface (as shown in FIG. 4E) Retaining pieces 220 with 172 are completed. As the surface treatment method, a polishing or buff polishing method can be used. After detaching the surface-treated retaining pieces 220 from the support 600, the retaining ring 420 according to the present invention is attached to the generally annular base ring 320 as shown in FIG. 4F. Is completed. When attaching retaining pieces 220 to base ring 320, smooth surface 172 is exposed outward. Then, since the smooth surface 172 is in contact with the polishing pad during the CMP process, it is possible to omit the process of the retaining ring 420 brake or to greatly reduce the process time of the brake.

 5A and 5B are a perspective view and a plan view for explaining a retaining ring manufacturing method according to another embodiment of the present invention.

First, referring to FIG. 5A, a plastic retaining piece 230 is formed using an injection molding or compression molding method. The retaining piece 230 includes surfaces defined by an arc having an inner radius of Ri and an arc having an outer radius of Ro, and the thickness t may have a value of about 0.5 mm to about 5 mm. In general, the surface 190 of the injection molded or extruded retaining piece 230 has a surface roughness of a few micrometers (μm) or more.

Next, as shown in FIG. 5B, the retaining pieces 230 are attached to the support 600 using an adhesive material such as wax. Subsequently, the surface 190 of the retaining pieces 230 attached to the support 600 is processed to have a surface roughness of about 0.1 nm to about 200 nm with a root mean square (RMS) value. The subsequent process proceeds in the same manner as the method shown in Figures 4e and 4f of the above-described embodiment to produce a retaining ring according to the present invention.

As described above, by implementing the present invention, the surface of the retaining ring, which comes into contact with the polishing pad during the CMP process, can be manufactured smoothly so that the retaining ring break-in process can be omitted or the break-in process time can be greatly reduced. have. This increases the utilization rate of the CMP unit and saves the consumables required for the brake-in process. On the other hand, the present invention is not limited to the above embodiments, various changes and modifications are possible without departing from the spirit of the invention.

Claims (9)

In the retaining ring of the chemical mechanical polishing device, A plurality of retaining pieces supporting the side of the wafer to prevent the wafer from leaving during the polishing process; A generally annular base ring to which the plurality of retaining pieces are attached; Including; The surface of the plurality of retaining pieces which come into contact with the polishing pad during the polishing process has a root mean square (RMS) roughness value of 0.1 nm to 200 nm. In claim 1, The retaining ring is characterized in that the number of retaining pieces of 4 to 72. In claim 1, And the retaining pieces are made of plastic. In claim 3, The plastic is polyphenylene sulfide, polyetheretherketone, polyimide, polyamide-imide, polyester or polyetherimide. Retaining ring. In claim 1, Retaining ring, characterized in that the base ring is made of stainless steel. In the method of manufacturing a retaining ring of a chemical mechanical polishing apparatus, Providing a plastic sheet having a thickness of 0.5 mm to 5 mm; Processing at least one of the front or back side of the sheet to a smooth surface having a root mean square (RMS) roughness of 0.1 nm to 200 nm; Cutting the plate having the smooth surface to form retaining pieces; Attaching the retaining pieces to a generally annular base ring; Including; When attaching the retaining pieces to the base ring, attaching the retaining pieces to reveal the smooth surface outwardly. In the method of manufacturing a retaining ring of a chemical mechanical polishing apparatus, Providing a plastic sheet having a thickness of 0.5 mm to 5 mm; Cutting the plate to form retaining pieces; Processing at least one of the front or back side of the retaining pieces into a smooth surface having a root mean square (RMS) roughness of 0.1 nm to 200 nm; Attaching the retaining pieces to a generally annular base ring; Including; When attaching the retaining pieces to the base ring, attaching the retaining pieces to reveal the smooth surface outwardly. In the method of manufacturing a wafer retaining ring of a chemical mechanical polishing apparatus, Molding plastic retaining pieces having a thickness of 0.5 mm to 5 mm; Processing at least one of the front or back side of the retaining pieces into a smooth surface having a root mean square (RMS) roughness of 0.1 nm to 200 nm; Attaching the retaining pieces to a generally annular base ring; Including; When attaching the retaining pieces to the base ring, attaching the retaining pieces so that the smooth surface is exposed outward. The compound according to any one of claims 6 to 8, Processing the smooth surface comprises a polishing or buff polishing process.

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