TW201311395A - Two-part plastic retaining ring - Google Patents

Abstract

A retaining ring includes a generally annular lower portion and a generally annular upper portion. The lower portion has a bottom surface for contacting a polishing pad during polishing and a top surface. The upper portion has a bottom surface secured to the top surface of the lower portion and a top surface configured to be mechanically affixed to and abut a rigid base of a carrier head. The lower portion is a first plastic, and the upper portion is a different second plastic that is about the same or more rigid than the first plastic.

Description

Two-piece plastic retaining ring

The present disclosure relates to a retaining ring for a carrier head for chemical mechanical polishing.

The conductive layer, the semi-conductive layer or the insulating layer is usually deposited on the substrate in sequence, in particular, an integrated circuit is formed on the germanium wafer. One manufacturing step involves depositing a layer of filler on a non-planar surface and planarizing the layer of filler. For some applications, the filler layer is planarized until the top surface of the patterned layer is exposed. For example, a layer of conductive filler can be deposited over the patterned insulating layer to fill the trenches or holes in the insulating layer. After planarization, portions of the conductive layer remaining between the raised patterns of the insulating layer form vias, plugs, and wires that provide a conductive path between the thin film circuits on the substrate. For other applications such as oxide milling, the filler layer is planarized until a predetermined thickness is left on the non-planar surface. In addition, photolithography typically requires planarization of the substrate surface.

Chemical mechanical polishing (CMP) is an accepted planarization method. This planarization method typically requires mounting the substrate on a carrier head. The exposed surface of the substrate is typically placed against a rotating polishing pad. The carrier head provides a controllable load on the substrate to push the substrate against the polishing pad. A slurry such as a slurry having abrasive particles is usually supplied to the surface of the polishing pad.

The substrate is typically secured under the carrier head by a retaining ring. despite this, Because the retaining ring contacts the polishing pad, the retaining ring is subject to wear and needs to be replaced from time to time. Some of the retaining rings have a metal forming upper portion and a wear resistant plastic forming lower portion, while other retaining rings are a single plastic component.

The retaining ring can be expensive, and as noted above, the retaining ring needs to be replaced periodically during wear. The bottom of the fixing ring that contacts the polishing pad is formed of plastic, but the selection of a suitable plastic component is limited due to restrictions required for the bottom of the fixing ring such as rigidity, wear rate, chemical resistance, etc., and thus the plastic may be quite expensive. . One technique is to form both the upper part and the lower part of the fixing ring from plastic, and the plastic forming the upper part is different from the plastic forming the lower part. This technique allows the upper portion of the retaining ring to be made of a low cost material.

In one aspect, the retaining ring includes a generally annular lower portion and a generally annular upper portion. The lower portion has a bottom surface for contacting the polishing pad during grinding and also has a top surface. The upper portion has a bottom surface that is secured to the top surface of the lower portion and a top surface that is configured to be mechanically attached to and abuts the rigid base of the carrier head. The lower part is a first plastic, and the upper part is a different second plastic which is substantially the same as the first plastic or more rigid than the first plastic.

Implementations may include one or more of the following features. The lower portion may be fixed to the upper portion, and a top surface may be provided to allow the retaining ring to be removed from the base as a unit such that the upper portion remains fixed to the lower portion when the retaining ring is removed. The lower portion may lack any porosity from the top surface of the lower portion to the bottom surface of the lower portion. The lower portion may be attached to the upper portion by an adhesive such as an epoxy resin. under The portion may have a durometer measurement between about 80 and 95 Shore hardness. The upper portion may have a durometer measurement having a Shore hardness of at least 70. The upper portion may have an elastic modulus greater than the elastic modulus of the lower portion. The lower part can be thicker than the upper part. The first plastic may be selected from the group consisting of polyphenylene sulfide (PPS), polyaryletherketone (PAEK), polyetheretherketone (PEEK), and polyetherketoneketone; PEKK). The second plastic can be selected from the group consisting of polyvinyl chloride (PVC), polypropylene (PP), polycarbonate (PC), polyaryletherketone (PAEK), and poly Polyetheretherketone (PEEK), polyetherketoneketone (PEKK), polybutylene terephthalate (PBT), polyoxymethylene (POM), polyethylene terephthalate Polyethylene terephthalate (PET), perfluoroalkoxy (PFA), polyamideimide (PAI) or polytetrafluoroethylene (PTFE). The bottom surface of the lower portion may have a channel for slurry transport. The fixing ring may have an inner side wall and an outer side wall, and the inner side wall and the outer side wall may be vertically positioned from the top surface of the upper part to the bottom surface of the lower part. The inner surface and the outer surface of the lower portion and the upper portion of the lower portion and the upper joint portion may be flush. The top surface of the upper portion can include a hole for receiving a fastener to mechanically attach the retaining ring to the substrate.

The details of one or more implementations are set forth in the accompanying drawings. Other features, aspects, and advantages of the invention will be apparent from the description and drawings.

One or more substrates may be ground by a chemical mechanical polishing (CMP) device including carrier head 100 during the grinding operation. A description of a CMP apparatus can be found in U.S. Patent No. 5,738,574.

Referring to FIG. 1, an exemplary simplified carrier head 100 includes a housing 102, a flexible membrane 104 that provides a mounting surface for the substrate, a pressurizable chamber 106 between the membrane 104 and the housing 102, and a fixed proximity housing 102. The edge is to hold the fixing ring 110 of the substrate below the film 104. Although FIG. 1 illustrates the film 104 being clamped between the retaining ring 110 and the substrate 102, one or more other components, such as a clamp ring, can be used to hold the film 104. A drive shaft 120 can be provided to rotate and/or move the carrier head across the polishing pad. The pump fluid can be fluidly coupled to the chamber 106 via a passage 108 in the housing to control the pressure within the chamber 106 and thus the downward pressure of the flexible membrane 104 on the substrate.

The retaining ring 110 can be a generally annular ring that is secured to the outer edge of the base 102 by, for example, a screw or screw 136 that extends through the passage 138 in the base 102 into the upper surface 112 of the retaining ring 110. The thread receiving groove 139 (see Fig. 2C, which illustrates a groove). In some implementations, the drive shaft 120 can be raised and lowered to control the pressure of the bottom surface 114 of the retaining ring 110 on the polishing pad. Or solid The retaining ring 110 can be movable relative to the base 120, and the carrier head 100 can include an inner chamber that can be pressurized to control the downward pressure on the retaining ring, as described in, for example, U.S. Patent No. 6,183,354 or 7,575,504. U.S. Patent is incorporated herein by reference. A distinguishing feature of the retaining ring is that the retaining ring can be moved from the base 102 (and the remainder of the carrier head) as a unit. With respect to the retaining ring 110, this condition means that the upper portion 142 of the retaining ring 110 remains fixed to the lower portion 140 of the retaining ring when the retaining ring 110 is removed without removing the base 102 from the carrier head 100 or removing the substrate 102.

The inner surface 116 of the retaining ring 110, along with the lower surface of the flexible film 104, defines a substrate receiving recess. The retaining ring 110 prevents the substrate from being detached from the substrate receiving recess.

The bottom surface 114 of the retaining ring 110 can be substantially flat, or as illustrated in Figures 2A and 2B. In some implementations, the bottom surface 114 of the retaining ring 110 can have a plurality of cells 130, and the plurality of cells 130 are self-retaining rings. The inner surface 116 extends to the outer surface 118 of the retaining ring to facilitate transport of the slurry from outside the retaining ring to the substrate. The channels 130 can be evenly spaced around the retaining ring. In some implementations, each of the channels 130 can be offset by an angle relative to the radius of the passageway, such as by 45°. The channels can have a width of about 0.125 inches. In some implementations, the channels are flared at the outer surface of the retaining ring.

Referring to Figures 2A and 2C, the retaining ring 110 includes a plurality of vertically stacked sections including an annular lower portion 140 having a bottom surface 114 that can contact the polishing pad and a ring attached to the substrate 104. Part 142. Lower portion 140 is bonded to upper portion 142 via adhesive layer 144.

The lower portion 140 is a first plastic such as polyphenol sulfide (PPS), whereas the upper portion 142 of the fixing ring 110 is such as polyvinyl chloride (PVC), polypropylene (PP) or polycarbonate ( Polycarbonate; PC) different second plastic. The first plastic has almost the same rigidity as the second plastic, or the first plastic is a material that is more rigid than the second plastic (ie, has a larger modulus of elasticity).

The plastic of the lower portion 140 is chemically inert during the CMP process. In addition, the lower portion 140 should have sufficient resilience such that contact of the edge of the substrate against the retaining ring does not cause chipping or cracking of the substrate. On the other hand, the lower portion 140 should be sufficiently rigid to have sufficient service life under wear from the polishing pad (on the bottom surface) and the substrate (on the inner surface). The plastic of the lower portion 140 can have a durometer measurement having a Shore hardness of about 80-95. In general, the material of the lower portion 180 may have a modulus of elasticity in the range of about 0.3-1.0 x 10 ⁶ psi. While the lower portion may have a low wear rate, the lower portion 140 will gradually be acceptable for wear as this condition appears to prevent the substrate edge from being cut into the deep groove in the inner surface 188.

The first plastic of the lower portion 140 can be (for example, composed of the following materials) polyphenylene sulfide (PPS), polyaryletherketone (PAEK), polyetheretherketone (PEEK) or polyetherketone. Ketone (polyetherketoneketone; PEKK). The advantage of polyphenol sulfide (PPS) is that the polyphenol sulfide system is reliable and fixed. The material commonly used in the ring.

The thickness T _{1 of the} lower portion 140 should be greater than the thickness T _{S of the} substrate 10. In detail, the lower portion should have a sufficient thickness such that the substrate does not contact the adhesive layer when the substrate 10 is clamped by the carrier. On the other hand, if the lower portion is too thick, the bottom surface of the retaining ring 110 will be easily deformed due to the flexible nature of the lower portion. The initial thickness of the lower portion 140 can range from about 50 mils to 1000 mils, for example, from 100 mils to 400 mils, depending on the manufacturing needs and the desired frequency of replacement. The lower portion can be replaced when the channel 130 has worn out.

The inner surface 116 of the lower portion 140 of the retaining ring may have an inner diameter D that is slightly larger than the diameter of the substrate (see FIG. 2B). For example, the inner diameter D of the inner surface 116 is greater than the diameter of the substrate by about 1-2 mm to accommodate the substrate loading system. Positioning tolerance. The retaining ring 110 can have a radius of about half a turn.

As noted above, the bottom surface 114 of the lower portion 180 can be substantially flat or can have a plurality of cells 136. The tunnel 130 extends partially, but not entirely, through the lower portion 180.

The upper portion 142 of the retaining ring 110 is formed from a second plastic that is substantially equal in rigidity or more rigid. The advantage that the second plastic is greater than the hardness of the first plastic is that the overall rigidity of the retaining ring 110 can be increased, thereby reducing the deformation of the lower portion 140 when the retaining ring is attached to the carrier head 100, and reducing the break-in time. . However, the second plastic is slightly softer than the first plastic. For example, the second plastic is reduced to a Shore hardness of 75 or 70, but the second plastic is not significantly softer than the first plastic, otherwise the retaining ring will Become too flexible. The material of the lower portion 180 may have a modulus of elasticity in the range of from about 0.25 to about 50 x 10 ⁶ psi. In some implementations, for example, if carbon fibers are added to the plastic of the upper portion 142 to increase rigidity, the upper portion can have an elastic modulus comparable to or greater than that of stainless steel, for example, having an elastic modulus of about 10-50 x 10 ⁶ psi. The material, that is, the elastic modulus of the upper material is about ten to one hundred times the elastic modulus of the material of the lower portion 140.

In some implementations, the thickness T _{2 of the} upper portion 140 can be less than the initial thickness T _{1 of the} lower portion 142. Nevertheless, this condition is not necessary, the manufacturer may have a thickness T ₂ of the upper portion 140 is equal to or greater than the initial thickness of the lower portion 142 of the fixing ring 110 T _1. An advantage of the thickness T _{2 of the} upper portion 140 being less than the initial thickness T ₁ of the lower portion 142 is to increase the useful life of the retaining ring.

The second plastic of the upper portion 142 may be (for example, composed of the following materials) polyvinyl chloride (PVC), polypropylene (PP), polycarbonate (PC), polyaryletherketone (polyaryletherketone; PAEK), polyetheretherketone (PEEK), polyetherketoneketone (PEKK), polybutylene terephthalate (PBT), polyoxymethylene (POM), polyparaphenylene Polyethylene terephthalate (PET), perfluoroalkoxy (PFA), polyamideimide (PAI) or polytetrafluoroethylene (PTFE), or a combination of the above. Additionally, the upper portion 142 can be a composite material comprising one or more of the above materials and carbon fibers for increasing the rigidity of the material. In general, the second plastic can be cheaper than the first plastic, thus lowering the retaining ring 110 The total cost.

The upper surface 142 of the upper portion 142 can include a plurality of thread receiving grooves 139. In some implementations, the thread receiving groove 139 extends partially, but not entirely, through the upper portion 142. Nonetheless, in some implementations, the thread receiving recess 139 extends all the way through the upper portion 142 and into the lower portion 140. The thread receiving recesses 139 may be spaced apart at equal angular intervals around the retaining ring 110. The threads of the receiving recess 139 may be directly machined from the second plastic material of the upper portion 142 or may be provided by a screw sheath inserted into the bore.

Adhesive layer 144 can be used to secure upper portion 140 to lower portion 142. The bonding layer can be made of an adhesive material such as a slow setting epoxy or a fast setting epoxy. The high temperature epoxy prevents degradation of the bonding layer 236 due to the high temperatures during the polishing process. In a particular implementation, the epoxy resin comprises polyamine and an aliphatic amine.

Alternatively, without the use of an adhesive attachment, the upper portion 140 and the lower portion 142 may be connected via a screw (eg, the screw extends through an aperture in the upper portion 140 into a receiving threaded groove or screw sheath in the lower portion 142), crimped together or Bonded together by acoustic molding.

When the upper portion 142 and the lower portion 140 of the retaining ring 110 are engaged, the upper surface of the lower portion 140 is positioned adjacent to the lower surface of the upper portion 142. The inner and outer diameters of the two portions on the abutment faces generally have substantially the same dimensions such that the upper portion 142 and the lower portion 140 form a flush surface at the junction of the two portions when joined.

Although the retaining ring 110 can include a channel 130 for slurry transport in the bottom surface 114 of the lower portion 140, and may be present in the top surface of the lower portion 140 The recesses assist in securing the lower portion 140 to the upper portion 142, but the lower portion 140 lacks any aperture extending from the top surface of the lower portion to the bottom surface of the lower portion.

In some implementations, the retaining ring 110 has one or more through holes that extend from the inner diameter to the outer diameter horizontally or through the body of the retaining ring horizontally or at a small angle offset from the horizontal to allow for, for example, The air or water fluid circulates from the inside to the outside of the retaining ring or from the outside to the inside of the retaining ring during grinding. The through hole may extend through the upper portion 142. The through holes can be evenly spaced around the retaining ring.

While the sidewalls of the retaining ring 110 are shown as being completely vertical, the retaining ring 110 can include other features such as a lip or groove on the outer surface to assist in placing the retaining ring in the center of the substrate loader or for securing The ring provides a hard stop against the inner edge of the top end of the wrap, and the inner or outer surface of the retaining ring 110 may be slightly tapered (although the upper portion 142 and the lower portion 140 may still form a flush surface at the contact).

The invention has been described in terms of several embodiments. Nevertheless, the invention is not limited to the embodiments depicted and described. Rather, the scope of the invention is defined by the scope of the accompanying claims.

100‧‧‧ Carrying head

102‧‧‧Shell

104‧‧‧Flexible film

106‧‧‧ Pressurizable chamber

108‧‧‧ channel

110‧‧‧Fixed ring

112‧‧‧ upper surface

114‧‧‧ bottom surface

116‧‧‧ inner surface

118‧‧‧ outer surface

120‧‧‧Base

130‧‧‧ Holes

136‧‧‧ hole / screw / screw

138‧‧‧ channel

139‧‧‧ Groove

140‧‧‧ lower

142‧‧‧ upper

144‧‧‧ adhesive layer

T ₁ , T ₂ ‧‧‧ thickness

Figure 1 is a schematic cross-sectional view of a carrier head.

Figure 2A is a side view of the retaining ring.

Figure 2B is a bottom view of the retaining ring.

Figure 2C is a cross-sectional view of the retaining ring.

The same element symbols in different figures indicate the same elements.

100‧‧‧ Carrying head

102‧‧‧Shell

104‧‧‧Flexible film

106‧‧‧ Pressurizable chamber

108‧‧‧ channel

110‧‧‧Fixed ring

112‧‧‧ upper surface

114‧‧‧ bottom surface

116‧‧‧ inner surface

118‧‧‧ outer surface

120‧‧‧Base

136‧‧‧ hole / screw / screw

138‧‧‧ channel

Claims (17)

A retaining ring comprising: a generally annular lower portion having a bottom surface for contacting a polishing pad during grinding, and a top surface, wherein the lower portion is a first plastic; and a large body An upper portion of the ring having a bottom surface secured to the top surface of the lower portion and a top surface of the rigid substrate disposed to be mechanically attached to and adjacent to a carrier head, wherein the upper portion is A different second plastic that is substantially identical or more rigid than the first plastic. The fixing ring of claim 1, wherein the lower portion is fixed to the upper portion, and the top surface is disposed such that the fixing ring can be removed from the substrate as a unit such that the upper portion is maintained when the fixing ring is removed Fixed to the lower part. The retaining ring of claim 1 wherein the lower portion lacks any porosity from the top surface of the lower portion to the bottom surface of the lower portion. The retaining ring of claim 1, wherein the lower portion is attached to the upper portion by an adhesive. The retaining ring of claim 4, wherein the adhesive is an epoxy resin. The retaining ring of claim 1 wherein the lower portion has a durometer measurement between about 80 and 95 Shore hardness. The retaining ring of claim 6, wherein the upper portion has a Shore hardness measurement of at least 70 Shore hardness The retaining ring of claim 7, wherein the upper portion has a modulus of elasticity greater than a modulus of elasticity of the lower portion. The retaining ring of claim 1, wherein the lower portion is thicker than the upper portion. The fixing ring according to claim 1, wherein the first plastic is selected from the group consisting of polyphenylene sulfide (PPS), polyaryletherketone (PAEK), and polyetheretherketone ( Polyetheretherketone; PEEK) and polyetherketoneketone (PEKK). The retaining ring of claim 10, wherein the first plastic is polyphenylene sulfide. The fixing ring according to claim 1, wherein the second plastic is selected from the group consisting of polyvinyl chloride (PVC), polypropylene (PP), and polycarbonate (PC). Polyaryletherketone (PAEK), polyetheretherketone (polyetheretherketone; PEEK), polyetherketoneketone (PEKK), polybutylene terephthalate (PBT), polyoxymethylene (POM), polyethylene terephthalate (polyethylene terephthalate) Polyethylene terephthalate; PET), perfluoroalkoxy (PFA), polyamideimide (PAI) or polytetrafluoroethylene (PTFE). The retaining ring of claim 12, wherein the second plastic is polyvinyl chloride. The retaining ring of claim 1, wherein the bottom surface of the lower portion has a channel for slurry transport. The fixing ring of claim 1, wherein the fixing ring has an inner side wall and an outer side wall, and the inner side wall and the outer side wall are vertically positioned from the top surface of the upper portion to the bottom surface of the lower portion. The retaining ring of claim 1, wherein the inner surface and the outer surface of the lower portion and the upper portion are flush with the lower portion and the upper portion. The retaining ring of claim 1 wherein the top surface of the upper portion includes a hole for receiving a fastener to mechanically attach the retaining ring to the base.