KR101199149B1 - Carrier for chemical mechanical polishing and flexible membrane - Google Patents

Abstract

The present invention relates to a carrier for chemical mechanical polishing and to a flexible membrane mounted on the carrier. The chemical mechanical polishing carrier according to the present invention includes a base, a retaining ring mounted on the lower portion of the base to prevent separation of the wafer during the polishing process, and mounted inside the retaining ring to polish the entire wafer on the wafer during the polishing process. A flexible membrane having a protruding structure in a predetermined region on a contact back surface and applying a pressure, a pressure plate applying local polishing pressure through contact with the protruding structure, and a bladder connected to the pressure plate to generate the local polishing pressure It includes. In addition, the flexible membrane mounted on the carrier includes a generally circular wafer contact surface for contacting the wafer back surface to apply polishing pressure to the wafer during the polishing process, and a generally circular contact back surface positioned opposite the wafer contact surface. The contact back surface is characterized in that the projecting structure of a height of 0.3mm to 3mm in a predetermined area.

Chemical mechanical polishing, carrier, membrane

Description

Carrier and Flexible Membrane for Chemical Mechanical Polishing {CARRIER FOR CHEMICAL MECHANICAL POLISHING AND FLEXIBLE MEMBRANE}

1 is a cross-sectional view of a chemical mechanical polishing carrier according to an embodiment of the present invention,

2 is a plan view for explaining the structure of the bladder and the pressure plate,

3 is a plan view showing another example of the bladder;

4 and 5 are cross-sectional views for explaining the operation of the carrier,

6 is a plan view showing the contact back surface of the flexible membrane,

7 is a cross-sectional view of the protrusion structure,

8 and 9 are cross-sectional views showing another example of the protrusion structure,

10 is a plan view of a contact back surface for explaining another example of the projecting structure,

11 and 12 are plan views of the contact back surface showing another example of the projecting structure,

13 is a plan view of a contact back surface showing another example of the projecting structure;

14 is a cross-sectional view illustrating a case where a plurality of pressure plates and bladders are provided in a chemical mechanical polishing carrier according to an embodiment of the present invention;

15 is a cross-sectional view showing the structure of a pressure plate;

16 to 18 are cross-sectional views for explaining the operation of the carrier.

<Brief description of the major symbols in the drawings>

900, 910 carrier

100: base

120: retaining ring

200: membrane

202: wafer contact surface

204: contact back surface

220, 222, 224, 226, 228, 230, 232: protrusion structure

300, 302: bladder

320, 326: platen

240: outer area projecting structure

250: center region protrusion structure

400: first bladder

500: second bladder

420: first pressure plate

520: second pressure plate

700: wafer

The present invention relates to a chemical mechanical polishing apparatus, and more particularly, to a carrier for applying a polishing pressure to a wafer during a polishing process and a flexible membrane mounted on the carrier.

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 a predetermined stage of the semiconductor manufacturing process. Due to such necessity, chemical mechanical polishing (CMP) has been widely used in semiconductor manufacturing processes.

Chemical mechanical polishing of wafers is generally accomplished by attaching a polishing pad on a platen, mounting the wafer on a wafer mounting mechanism called a carrier or carrier head, and then applying the slurry to the polishing pad. And the carrier at the same time to create a friction between the polishing pad and the wafer. In this case, the polishing rate is controlled by applying an appropriate polishing pressure to the wafer. For this purpose, a flexible membrane having a thickness of 0.3 mm to 1 mm made of ethylene propylene rubber or silicon rubber in the carrier is used. After mounting and sealing and applying air pressure, the polishing pressure is applied to the wafer through the membrane. As such, when air pressure is applied to the wafer through the flexible membrane, a uniform pressure is transmitted to the back surface of the wafer so that the wafer polishing surface may be naturally polished with the polishing pad.

However, depending on the nature of the film being polished, the polishing pad, or the slurry, if a particular area of the wafer is polished late (e.g., at the edge or in the middle of the wafer) and worsens the polishing uniformity, it is necessary to apply an increased polishing pressure to this particular area. . That is, the polishing rate of the entire wafer must be made uniform by applying a uniform polishing pressure to the entire back surface of the wafer and applying a local additional pressure to a specific region having a slow polishing rate. However, the method of applying pressure through the flexible membrane is effective to apply uniform pressure to the wafer as a whole, but it is difficult to apply pressure to a specific region of the wafer.

SUMMARY OF THE INVENTION An object of the present invention is to solve the problems of the prior art, and to provide a chemical mechanical polishing carrier and a flexible membrane capable of applying a local polishing pressure to a specific region of a wafer during chemical mechanical polishing.

A chemical mechanical polishing carrier according to an embodiment of the present invention for achieving the above object is a base, a retaining ring mounted on the lower portion of the base to prevent separation of the wafer during the polishing process, and mounted inside the retaining ring. A flexible membrane having a protruding structure in a predetermined area on a contact back surface while applying an overall polishing pressure to the wafer during a polishing process, a pressing plate for applying a local polishing pressure through contact with the protruding structure, and connected to the pressing plate A bladder for generating a local polishing pressure.

In addition, the flexible membrane for a chemical mechanical polishing carrier according to another embodiment of the present invention for achieving the above object is a wafer contact surface for contacting the wafer back surface to apply a polishing pressure to the wafer during the polishing process, and is located opposite the wafer contact surface It includes a contact back surface, characterized in that the contact back surface is formed with a projecting structure of a height of 0.3mm to 3mm in a predetermined area.

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

1 is a cross-sectional view of a chemical mechanical polishing carrier according to an embodiment of the present invention. The chemical mechanical polishing carrier 900 is configured based on a base 100 that receives power from the rotating shaft 110. First, a retaining ring 120 is mounted below the base 100, and the retaining ring 120 serves to prevent separation of a wafer (not shown) during the polishing process. Inside the retaining ring 120, a flexible membrane 200 is mounted, which is sealed from the periphery to form a membrane chamber 210 therein. The membrane chamber 210 maintains a predetermined gas pressure by confining the gas supplied through the membrane gas passage 212, and thus the gas pressure by the membrane 200 is controlled through the wafer contact surface 202 during the polishing process. It is applied at a polishing pressure to a wafer (not shown). A projecting structure 220 is formed in a predetermined region (eg, the outer region of the contact back surface as shown) on the contact back surface 204 located opposite the wafer contact surface 202. The pressure plate 320 is positioned on the protruding structure 220, and the pressure plate 320 is connected to the bladder 300. The pressure plate 320 is preferably made of a metal alloy or plastic so that deformation does not occur easily. Bladder 300 is also sealed from the periphery to form bladder chamber 310, preferably made of a flexible material such as rubber. The bladder chamber 310 maintains the pressure by confining the gas supplied through the bladder gas passage 312, and thus the gas pressure by the bladder 300 is the pressure plate 320 connected to the bladder 300. ) Is moved downward to contact the pressure plate 320 with the protruding structure (220).

2 is a plan view for explaining the structure of the bladder 300 and the pressure plate 320. The bladder 300 may have a ring shape as shown, and a bladder gas passage 312 ′ is formed to inject gas into the bladder 300. The pressure plate 320 connected to the bladder 300 has a generally circular shape and a hole 322 is formed so that the gas can freely move up and down the pressure plate 320.

3 is a plan view illustrating another example of the bladder, as shown, two bladders 302 may be coupled to the pressure plate 326. At this time, since the bladder 302 is an open structure, the gas may move freely around the pressure plate 326 without forming a gas passage such as the hole 322 in the pressure plate 326.

4 and 5 are cross-sectional views illustrating the operation of the carrier 900.

First, referring to FIG. 4, when air pressure P1 is applied through the membrane gas passage 212, the air pressure acts uniformly inside the membrane chamber 210 ′ including the contact back surface 204 of the membrane 200. (Represented by a small arrow). Atmospheric pressure P1 applied to the contact back surface 204 serves to expand the membrane 200, and the wafer contact surface 202 of the membrane 200 contacts the wafer back surface 702 by the above action during the polishing process. Apply a global polishing pressure to the

Subsequently, referring to FIG. 5, when air pressure P2 is applied to the bladder chamber 310 ′ through the bladder gas passage 312, the bladder 300 expands and the pressure plate 320 connected to the bladder 300 is connected. It moves downward to come into contact with the protruding structure 220 formed on the contact back surface 204 of the membrane 200. Then, a pressure P 'proportional to the air pressure P2 is locally applied to the protruding structure 220, and the pressure is locally applied to an outer region of the wafer 700 positioned below the protruding structure 220 during the polishing process. polishing pressure). Although not shown, when the protruding structure is formed in the central region of the contact back surface 204, the central region of the wafer is subjected to local pressure.

In the above, how the air pressures P1 and P2 applied to the membrane 200 and the bladder 300 respectively act on the wafer 700 is described. May be applied simultaneously. Then, the wafer 700 is first applied with the overall polishing pressure P1, and the area under the protruding structure 220 is further subjected to a local polishing pressure proportional to the bladder pressure P2 to the overall polishing pressure P1.

FIG. 6 is a plan view showing the contact back surface 204 of the flexible membrane 200. As shown, the protrusion structure 220 is formed in a ring shape based on the center of the contact back surface 204 having a generally circular shape. Can be.

7 is a cross-sectional view when the protrusion structure 220 is cut in the radial direction of the circle defining the contact back surface 204. The cross section of the protrusion structure 220 may have a semicircular shape as shown, and the protrusion structure. The height (shown in h) of 220 is preferably between 0.3 mm and 3 mm. The width (shown as w) of the protrusion may have a value of 0.5 mm to 50 mm.

Protruding structure 220, After forming the intaglio structure corresponding to the protrusion structure 220 in the mold (mold) for manufacturing the membrane 200, it may be formed together when molding the membrane 200. At this time, the material of the protrusion structure 220 is the same as the material of the flexible membrane 200. Another method of forming the protruding structure 220 is to first fabricate the membrane 220 and then to attach the protruding structure 220 to the contact back surface 204, wherein the protruding structure 220 is formed of the flexible membrane 220. It can be different from the material and can be made of materials that are not easily deformed, such as rubber as well as plastic.

8 and 9 are cross-sectional views showing other examples of the protruding structures 222 and 224, which are rectangular or triangular when cut in the radial direction of the circle defining the contact back surface 204 as shown. Can be. In addition, although not shown, the cross section of the protrusion structure may be formed by a combination of semicircles, squares, and triangles.

FIG. 10 is a plan view of the contact back surface 204 for explaining another example of the protrusion structure 226. As shown, the protrusions 226 having a circular shape in plan view from the center of the contact back surface 204 are shown. It can usually be scattered at a certain distance. As such, the protrusion structure 226 may be in the form of a bump having a hemisphere, a cylinder, a cone, or the like to have a circular shape in a plane. In addition, although not shown, the protruding structure may be formed of a polyhedral bump as well as the figure.

11 and 12 are plan views of the contact back surface 204 showing another example of the projecting structure, as shown in FIG. 11, the projecting structure 228 may be configured in the form of a plurality of rings, and also As shown in FIG. 12, bump-shaped protrusions 230 may be distributed in a region from the center of the contact back surface 204, for example, in the region between R1 and R2 as shown.

13 is a plan view of a contact back surface 204 showing another example of the protrusion structure, as shown in the protrusion structure 232 is formed in the central region of the contact back surface 204, the pressing plate during the polishing process The pressure can be locally applied to the center region of the wafer. Although not illustrated, bump structures may be formed by scattering bump structures in the central region of the contact back surface.

The protrusion structure may have various structures as described above, and may be formed in the outer region or the central region of the contact back surface according to the polishing characteristics of the wafer. The area occupied by the protruding structure is preferably 0.5% to 50% of the total area of the contact back surface.

FIG. 14 is a cross-sectional view illustrating a case in which a plurality of pressure plates and bladders are provided in a chemical mechanical polishing carrier according to an exemplary embodiment of the present invention. The chemical mechanical polishing carrier 910 is configured based on the base 100 that receives power from the rotating shaft 110. First, the retaining ring 120 is mounted below the base 100, and the flexible membrane 200 is mounted inside the retaining ring 120. The membrane chamber 210 maintains a predetermined gas pressure by confining the gas supplied through the membrane gas passage 212, and thus the gas pressure by the membrane 200 is transferred to the wafer through the wafer contact surface 202 ( Not shown) is applied at full polishing pressure. Protruding structures 240 and 250 are formed on the contact back surface 204 opposite to the wafer contact surface 202 in the outer and center regions of the contact back surface 204, respectively. The first pressing plate 420 connected to the first bladder 400 is mounted on the outer region protrusion structure 240, and the second pressing plate 520 connected to the second bladder 500 is mounted on the central region protrusion structure 250. Is mounted. The first and second bladders 400 and 500 are sealed from the periphery to form the first bladder chamber 410 and the second bladder chamber 510, respectively. The first and second bladder chambers 410 and 510 maintain pressure by confining the gas supplied through the first bladder gas passage 412 and the second bladder gas passage 512, respectively. The gas pressure by the first bladder 400 moves the first pressure plate 420 connected to the first bladder 400 downward to contact the first pressure plate 420 with the outer region protruding structure 240. Similarly, the gas pressure by the second bladder 500 moves the second pressure plate 520 connected to the second bladder 500 downward to contact the second pressure plate 520 with the central region projecting structure 250. Let's do it.

FIG. 15 is a cross-sectional view taken along line AA ′ of the first and second pressure plates 420 and 520 in FIG. 14, and a gap 450 is formed between the first pressure plate 420 and the second pressure plate 520. When the 420 and 520 move up and down in the carrier 910, they are not disturbed. In addition, a hole 522 is formed in the second pressure plate 520 to allow the gas to move freely up and down the second pressure plate 520.

16 to 18 are cross-sectional views for describing the operation of the carrier 910.

Referring to FIG. 16, the air pressure P1 applied through the membrane gas passage 212 acts uniformly inside the membrane chamber 210 ′ including the contact back surface 204 of the membrane 200 and moves the membrane 200. It acts as an overall polishing pressure on the wafer 700 through.

Referring to FIG. 17, when air pressure P2 is applied to the first bladder chamber 410 ′ through the first bladder gas passage 412, the first bladder 400 expands and the first bladder 400 is separated from the first bladder 400. The connected first pressing plate 420 moves downward to come into contact with the protruding structure 240 formed in the outer region of the contact back surface 204. Then, a pressure P 'proportional to the air pressure P2 is locally applied to the outer region projecting structure 240, and the pressure is applied at a polishing pressure local to the outer region of the wafer 700 located below the outer region projecting structure 240. Works.

Referring to FIG. 18, when air pressure P3 is applied to the second bladder chamber 510 ′ through the second bladder gas passage 512, the second bladder 500 expands and the second bladder 500 The connected second pressure plate 520 moves downward to come into contact with the protruding structure 250 formed in the center area of the contact back surface 204. Then, a pressure P ″ proportional to the air pressure P3 is locally applied to the central region protrusion structure 250, and the pressure is a polishing pressure local to the central region of the wafer 700 located below the center region protrusion structure 250. Acts as.

In the above, the air pressure applied to the membrane 200 and the first and second bladders 400 and 500 is applied to the wafer 700, respectively, and the air pressure P1 and the first bladder 400 are applied to the membrane 200. Atmospheric pressure P2 may be applied simultaneously to the membrane 200, or the atmospheric pressure P1 may be simultaneously applied to the membrane 200 and the pressure P3 may be simultaneously applied to the second bladder 500. Alternatively, air pressure P1 may be applied to the membrane 200, air pressure P2 to the first bladder 400, and air pressure P3 may be simultaneously applied to the second bladder 500. Then, the wafer 700 is applied with the polishing pressure P1 as a whole, and the area under the protruding structures 240 and 150 is a local polishing pressure proportional to the overall polishing pressure P1 in proportion to the first bladder pressure P2 or the second bladder pressure P3. Will be granted more.

In the above embodiment, a local polishing pressure is applied to the wafer by using two pressure plates and two bladders connected thereto. Although not shown, a local polishing pressure may be applied to the wafer using three or more press plates and three or more bladders on the same principle.

As described above, the polishing carrier and the flexible membrane of the present invention can easily control the polishing uniformity by applying a local polishing pressure to the wafer specific region during the polishing process.

On the other hand, the present invention is not limited to the above-described embodiment, various modifications are possible by those skilled in the art within the spirit and scope of the present invention described in the claims to be described later.

Claims (9)

As a chemical mechanical polishing carrier, Base; A retaining ring mounted under the base to prevent separation of the wafer during the polishing process; A flexible membrane mounted inside the retaining ring to apply an overall polishing pressure to the wafer during the polishing process and having a protruding structure in a predetermined area on the contact back surface; A pressure plate applying local pressure to the protruding structure through contact; And And a bladder connected with the pressure plate to generate the local pressure. delete delete delete delete delete delete delete delete

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