BACKGROUND OF THE INVENTION 1. Field of the Invention
The present invention relates to a chemical mechanical polishing system, and more particularly, to a carrier head for applying polishing pressure to a substrate during chemical mechanical polishing process.
2. Description of the Related Art
When manufacturing semiconductor or glass substrates, and fabricating integrated circuits, a need to polish or planarize the surface of a substrate at particular steps has been increased. As a technology to satisfy the need, a chemical mechanical polishing (CMP) has been widely used.
In general, the CMP of a substrate is performed by attaching a polishing pad on a platen, mounting the substrate to a substrate receiving unit called a carrier head, and then, while applying slurry to the polishing pad, rotating the platen and carrier head simultaneously to generate friction between the polishing pad and the substrate.
Basically, the carrier head comprises a base which receives motive power from a drive shaft and provides space in which carrier parts are capable of being installed, a substrate receiving member to which a substrate is mounted, and a retaining ring which supports a side surface of the substrate during the polishing process to prevent the substrate from slipping out from the beneath of the carrier head. During CMP, the substrate is applied with polishing pressure through the substrate receiving member. However, even though the polishing pressure is applied uniformly on the entire substrate, a specific area of the substrate (for example, an edge area of the substrate) may have a different polishing rate from those of other area according to the nature of polished layer, polishing pad, or slurry. In this case, in order to maintain good polishing rate uniformity, there is a need to adjust the polishing rate at specific areas by independently controlling the polishing pressure applied to each predetermined area of the substrate.
SUMMARY OF THE INVENTION The present invention has been made in an effort to provide a carrier head for a chemical mechanical polishing system capable of independently applying polishing pressure to each predetermined area of a substrate during a chemical mechanical polishing.
In one aspect, the invention is directed to a carrier head for use in a chemical mechanical polishing system. The carrier head comprises: a base; a substrate receiving member connected to a lower part of the base, having an outer surface against which a substrate can be mounted; at least two bladders positioned inside of the substrate receiving member and connected to the lower part of the base, wherein the at least two bladders can apply pressure independently to predetermined areas of an inner surface of the substrate receiving member by expanding and contacting the inner surface; and at least one wall structure connected to the lower part of the base, wherein the at least one wall structure can limit lateral expansions of the at least two bladders.
In another aspect, the carrier head comprises: a base; a substrate receiving member connected to a lower part of the base, having an outer surface against which a substrate can be mounted; a bladder positioned inside of the substrate receiving member and connected to the lower part of the base, wherein the bladder can apply pressure to a predetermined area of an inner surface of the substrate receiving member by expanding and contacting the inner surface; and at least one wall structure connected to the lower part of the base, wherein the at least one wall structure can limit a lateral expansion of the bladder.
BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic cross-sectional view of a carrier head according to a preferred embodiment of the present invention.
FIG. 2 is a perspective view illustrating an exemplary embodiment of a center bladder.
FIG. 3 is a perspective view illustrating an exemplary embodiment of an edge bladder.
FIG. 4 is a top view illustrating an exemplary embodiment of a bladder clamp for securing a center bladder.
FIG. 5 is a top view illustrating an exemplary embodiment of a bladder clamp for securing an edge bladder.
FIG. 6 is a perspective view illustrating an exemplary embodiment of a wall structure.
FIG. 7 is a perspective view illustrating another exemplary embodiment of a wall structure.
FIG. 8 is a schematic cross-sectional view of a carrier head that includes an edge bladder which is clamped externally according to another exemplary embodiment.
FIG. 9 is a perspective view illustrating an exemplary embodiment of the edge bladder shown in FIG. 8.
FIG. 10 is a cross-sectional view along line AA′ of FIG. 9.
FIG. 11 is a cross-sectional view illustrating an exemplary embodiment of an edge bladder that includes a round bottom portion.
FIG. 12 is a cross-sectional view illustrating an exemplary embodiment of an edge bladder that includes pleats at side portions.
FIGS. 13 and 14 are cross-sectional views illustrating exemplary embodiments of asymmetric edge bladders.
FIG. 15 is a cross-sectional view illustrating another exemplary embodiment of a substrate receiving member.
FIG. 16 is a cross-sectional view illustrating still another exemplary embodiment of a substrate receiving member.
FIG. 17 is a cross-sectional view illustrating still another exemplary embodiment of a substrate receiving member.
FIG. 18 is a cross-sectional view illustrating an exemplary embodiment of a substrate receiving member having at least two perimeter portions.
FIG. 19 is a schematic cross-sectional view of a carrier head in which the substrate receiving member of FIG. 18 is mounted.
FIG. 20 is a schematic cross-sectional view of a carrier head according to another exemplary embodiment of the present invention.
FIG. 21 is a schematic cross-sectional view of a carrier head according to still another exemplary embodiment of the present invention.
FIG. 22 is a schematic cross-sectional view of a carrier head according to still another exemplary embodiment of the present invention.
FIGS. 23 and 24 are schematic cross-sectional views explaining the operation of a carrier head according to a preferred embodiment of the present invention.
FIGS. 25, 26 and 27 are cross-sectional views explaining lateral expansions of a center bladder and an edge bladder according to the difference of their chamber pressures, and explaining the role of a wall structure.
FIGS. 28 and 29 are schematic cross-sectional views explaining the structure and operation of a carrier head further comprising an edge wall structure.
FIG. 30 is a schematic cross-sectional view of a carrier head according to still another exemplary embodiment of the present invention.
FIG. 31 is a schematic cross-sectional view of a carrier head according to still another exemplary embodiment of the present invention.
FIG. 32 is a schematic cross-sectional view of a carrier head according to still another exemplary embodiment of the present invention.
FIG. 33 is a schematic cross-sectional view illustrating a carrier head further comprising an intermediate bladder according to another exemplary embodiment of the present invention.
FIGS. 34, 35 and 36 are schematic cross-sectional views explaining the operation of the carrier head of FIG. 33.
FIG. 37 is a schematic cross-sectional view illustrating gaps between the wall structures and the inner surface of substrate receiving member in a carrier head according to the present invention.
FIG. 38 is a schematic cross-sectional view of a carrier head according to still another exemplary embodiment of the present invention.
FIG. 39 is a schematic cross-sectional view of a carrier head according to still another exemplary embodiment of the present invention.
FIG. 40 is a schematic cross-sectional view illustrating an exemplary embodiment of a carrier head without a center bladder.
FIG. 41 is a schematic cross-sectional view illustrating an exemplary embodiment of a carrier head without an intermediate bladder.
FIG. 42 is a schematic cross-sectional view of a carrier head comprising an edge bladder according to an embodiment of the present invention.
FIG. 43 is a schematic cross-sectional view of a carrier head further comprising an edge wall structure.
FIG. 44 is a schematic cross-sectional view of a carrier head comprising an edge bladder which is clamped externally.
FIG. 45 is a schematic cross-sectional view of a carrier head including a connecting member acting also as a wall structure.
FIG. 46 is a schematic cross-sectional view of a carrier head comprising a center bladder according to another embodiment of the present invention.
FIG. 47 is a schematic cross-sectional view of a carrier head including a connecting member acting also as a wall structure.
DETAILED DESCRIPTION Hereinafter, preferred embodiments of the present invention will be described with reference to the accompanying drawings. Rather, these embodiments of the present invention are provided in order to fully explain the present invention to those skilled in the art. Therefore, in the drawings, the shapes of components may be exaggerated for clarity, and the same reference numerals will be used throughout to designate the same or like components.
FIG. 1 is a schematic cross-sectional view of a carrier head 900 according to a preferred embodiment of the present invention. The carrier head 900 is configured to, as a basic component, comprise a base 100 receiving motive power from a drive shaft 110. A retaining ring 120, which is mounted on a lower part of the base 100, serves to prevent the substrate (not shown) from slipping out from the beneath of the carrier head 900 during CMP. Inside of the retaining ring 120, a substrate receiving member 600 is connected to the lower part of the base 100.
The substrate receiving member 600 comprises a plate portion 602, a perimeter portion 604, and a securing portion 606. The plate portion 602 provides two surfaces defined as an outer surface 608 and an inner surface 610 of the substrate receiving member 600, respectively. The size and shape of the plate portion 602 conforms to the size and shape of a substrate to be polished. The outer surface 608 is a substrate receiving surface against which a substrate can be mounted. The inner surface 610, which is opposite to the outer surface 608, is a surface to which a pressure is applied by a fluid or by a contact through the expansion of bladders 200, 300. The perimeter portion 604 is a wall-shaped part extending away from the plate portion 602 in order to connect the perimeter portion 602 to the securing portion 606. The securing portion 606 is a part connected to the base 100, which may comprise a flap or an O-ring. The securing portion 606 seals the inner portion of the substrate receiving member 600 from the outside to form a substrate receiving member chamber 650. The substrate receiving member chamber 650 may contain a fluid supplied through a substrate receiving member fluid passage 612 to maintain a predetermined pressure, which can be a polishing pressure applied through the plate portion 602 to a substrate (not shown) during CMP. As a fluid, gas or liquid may be used, and air or nitrogen may be preferably used. The substrate receiving member 600 may be wholly made of a single material as shown in FIG. 1, and a flexible material may be used for the substrate receiving member 600. Rubber may be used as a flexible material, and preferably, rubber having good water and chemical resistances, such as silicone rubber and ethylene propylene diene monomer (EPDM) rubber, may be used. The substrate receiving member 600 made of a flexible material may be fabricated using molding method, by which the plate portion 602 may have a thickness of 0.5 mm to 3.0 mm.
As shown in FIG. 1, inside of the substrate receiving member 600, a center bladder 200 located over a center area of the inner surface 610 of substrate receiving member 600 is connected to the lower part of the base 100. An edge bladder 300 over an edge area of the inner surface 610 of the substrate receiving member 600 is also connected to the lower part of the base 100.
The center area of the inner surface 610 may be defined as an area including the center of the inner surface 610, and the size of the center area may be represented by a radius R from the center of the inner surface 610 as shown in FIG. 1. In the case in which the inner surface is circular, R may have a value between 20 to 90% of the radius of inner surface. In the case in which the inner surface is rectangular-shaped, the center area may be defined as an area including the center of the inner surface, and the size of the center area may be a reduced size of the inner surface to 20 to 90% in length.
The edge area may be represented by a distance d from the end of the inner surface 610 as shown in FIG. 1. The distance d may have a value between 1 to 20% of a diameter in case of a circular inner surface. For example, in the case in which the inner surface 610 has a diameter of 300 mm, the edge area may be an area ranging from the end of the inner surface 610 to 3 mm inward or from the end to 60 mm inward. In the case of a rectangular-shaped inner surface, d may have a value between 1 to 20% of the diagonal length of an inner surface. In a certain circumstance, some positions of an inner surface may belong to a center area or to an edge area. In this case, the positions may be considered to belong to a center area when the bladder on them applies pressure also to the center of the inner surface, and to belong to an edge area when the bladder on them is an edge bladder. In addition, an area between center and edge areas may be explained by an intermediate area to be described below.
FIGS. 2 and 3 are perspective views illustrating exemplary embodiments of the center bladder 200 and edge bladder 300. The center bladder 200 includes a disk-shaped bottom portion 202, a wall-shaped side portion 204, and a ring-shaped top portion 206 as shown in FIG. 2. For a secure sealing, an O-ring part may be formed at the top portion 206. The edge bladder 300 may include a ring-shaped bottom portion 302 and side portions 304, 304′, and top portions 306, 306′ as shown in FIG. 3. An O-ring part may be also formed at the top portions 306, 306′ for a secure sealing. The bladders 200, 300 may be made of flexible material. Rubber is suitable for the flexible material, and the rubber includes natural rubber, silicone rubber, EPDM rubber, chloroprene rubber and the like. The surface of the bladders 200, 300 may be coated with polymer material and the bladders 200, 300 may be protected by attaching a plastic or metal sheet having a thickness of 0.05 mm to 0.3 mm to the inner or outer surface of the bottom portions 202, 302.
Referring to FIG. 1, the center and edge bladders 200, 300 are spaced from the inner surface 610 by a distance e, wherein e may have a value between 0 mm to 5 mm when the pressure applied to the bladders 200, 300 is same as the pressure applied to the substrate receiving member 600, for example when all the pressures are atmospheric pressure. That is, when the two pressures are the same as each other, the bladders 200, 300 don't necessarily have to be spaced away from the inner surface 610 as depicted in FIG. 1, and rather, may extend further toward the inner surface 610 to contact the inner surface 610, so that e is 0 mm.
At the time of connecting the center and edge bladders 200, 300 to the base 100, bladder clamps 220, 320 may be used as shown in FIG. 1. The bladder clamps 220, 320 are inserted first into the bladders 200, 300, respectively, and then clamped to the lower part of the base 100, and thereby the bladders 200, 300 are sealed.
FIGS. 4 and 5 are top views illustrating exemplary embodiments of bladder clamps 220, 320 for securing the center and edge bladders 200, 300, respectively. All of which represent the surfaces that are mounted on the lower part of the base 100 shown in FIG. 1. First, referring to FIG. 4, the center bladder clamp 220 may be disk-shaped, and have screw holes 226 for connecting to the base 100, and a clamp fluid passage 222 through which a fluid may pass. In the case in which an O-ring part is in the center bladder 200, a groove 224 may be formed on the top of the center bladder camp 220 for a secure sealing. Referring to FIG. 5, the edge bladder clamp 320 may be ring-shaped and have a clamp fluid passage 322 through which a fluid may pass. In addition, the bladder clamp 320 may have screw holes 326 so that it may be connected to the base 100. In the case in which O-ring parts are in the edge bladder 300, grooves 324 may be formed on the top of the edge bladder clamp 320 for a secure sealing. Iron alloys, aluminum alloys, or plastics may be used for the material of the bladder clamps 220, 320. The bladders 200, 300 may be expanded by the pressure of a fluid supplied through bladder fluid passages 212, 312 in FIG. 1 and the clamp fluid passages 222, 322. As a fluid, gas or liquid may be used, and air or nitrogen may be preferably used.
FIGS. 6 and 7 are perspective views illustrating exemplary embodiments of wall structures 700, 710. Referring to FIG. 6, the wall structure 700 may have a cylindrical shape in which the center is empty. The wall structure 700 may include a flange 702 at the top which is to be connected to the base 100. At the top, screw holes 704 may be formed for connecting to the base 100. In addition, a wall structure fluid passage 706 may be formed from the top surface to the bottom surface of the wall structure 700. Although not shown, the flange 702 may have grooves for O-rings to seal securely at the time of connecting the wall structure 700 to the base 100. The wall structure fluid passage 706 may be connected to the substrate receiving member fluid passage 612 for fluid supplying to the substrate receiving member chamber 650. Referring to FIG. 7, the wall structure 710 has screw holes 714 at the top for connecting to the base 100. Grooves 718 may be formed on surfaces of the inner and outer sides 716, such that a fluid supplied through the substrate receiving member fluid passage 612 may be easily released into the substrate receiving member chamber 650. The wall structures 700, 710 serve to limit the expansion of the bladders 200, 300, therefore, they may be preferably made of material capable of maintaining rigidity so as not to be easily bent, such as aluminum alloys or iron alloys.
FIG. 8 is a schematic cross-sectional view of a carrier head including an edge bladder 370 according to another exemplary embodiment, wherein the edge bladder 370 is clamped externally such that no clamp is needed in the internal portion thereof. Meanwhile, as shown in FIG. 8, the edge bladder 370 is clamped by an outside clamp 380 and an inside clamp 770. Here, the inside clamp 770 may have a lower portion extended toward the inner surface 610 so that it may serve as a wall structure simultaneously, where it can be noted that a clamp and a wall structure may be integrally formed in one body. The inside clamp 770 may have a fluid passage (not shown) so that a fluid may pass therethrough. The edge bladder 370 forms a bladder chamber 340 isolated from the substrate receiving member chamber 650, and expands by a fluid supplied through the bladder fluid passage 312 and contracts by a vacuum. The bottom portion of the edge bladder 370 in FIG. 8 is depicted to be spaced away from the inner surface 610. However, when the pressure applied to the edge bladder 370 is same as the pressure applied to the substrate receiving member 600, the edge bladder 370 does not necessarily have to be spaced away from the inner surface 610, and may rather have a shape extending toward the inner surface 610 so as to contact the inner surface 610.
FIG. 9 is a perspective view illustrating an exemplary embodiment of the edge bladder 370 described above, wherein the annular space between an inside portion 374 and an outside portion 376 forms the bladder chamber 340 when the edge bladder 370 is connected to the base 100.
FIG. 10 is a cross-sectional view along line AA′ of FIG. 9, wherein the edge bladder 370 includes also an inside securing portion 372, an outside securing portion 373, and a bottom portion 378. The inside and outside securing portions 372, 373 extend outwardly from the inside and outside portions 374, 376 in order to enable the edge bladder 370 to be clamped externally. A round surface, indicated as R, may be formed between the side portions 374, 376 and the bottom portion 378. The edge bladder 370 may have an internal width W of 2 mm to 30 mm and an internal depth H of 10 mm to 40 mm.
FIGS. 11 to 14 are cross-sectional views illustrating still other exemplary is embodiments of edge bladders. Referring to FIG. 11, an edge bladder 380 may have a bottom portion 382 with an entirely round surface. Referring to FIG. 12, an edge bladder 384 may include an inside portion 374′ and an outside portion 376′ having pleats 386. When the pleats 386 are smoothed out, the internal depth H may be increased more easily than without the pleats 386. In addition, in the case in which the edge bladder 384 contracts due to a pressure difference, the pleats 386 may help a bottom portion 388 move upwardly. Referring to FIG. 13, an edge bladder 390 may have a structure in which an inside portion 392 and an outside portion 394 are asymmetric with respect to a center line CC′ so that the inside portion 392 and the outside portion 394 may be elongated in different degrees. For example, the outside portion 394 may be formed longer than the inside portion 392 so that the outside portion 394 may be elongated longer than the inside portion 392. Referring to FIG. 14, in an edge bladder 396, the number of pleats of an inside portion 398 may be different from that of an outside portion 399 so that they may be elongated in different degrees.
FIG. 15 is a cross-sectional view illustrating another exemplary embodiment of a substrate receiving member 620, wherein a plate portion 626 comprises a first plate 622 made of a flexible material like the perimeter portion 604 and a second plate 624 made of a material having higher stiffness than that of the first plate 622. It is preferable that the size of the second plate 624 is similar to the size of the first plate 622, and it is more preferable that the diameter or side length difference between them is less than 1%. The first plate 622 may be made of a rubber having good chemical resistance, such as silicone rubber or EPDM rubber, and the second plate 624 may be made of plastic such as polycarbonate or polyethylene terephthalate (PET). The first plate 622 may have a thickness of 0.5 mm to 2.5 mm, and the second plate 624 may have a thickness of 0.2 mm to 1.0 mm. The second plate 624 may be attached to the upper surface of the first plate 622 using adhesive, or the perimeter portion 604 may have a groove (not shown) to insert the second plate 624 thereby making it possible to couple the second plate 624 to the first plate 622. When the second plate 624 is attached to the upper surface of the first plate 622, then an upper surface 628 of the second plate 624 becomes an inner surface of the substrate receiving member 620 to which bladders may contact. Although the above mentioned exemplary embodiment has described the case in which the plate portion 626 is formed with the two plates 622, 624, a plate portion may be formed with more than two plates.
FIG. 16 is a cross-sectional view illustrating still another exemplary embodiment of a substrate receiving member 630, wherein a plate portion 634 is made of a material having higher strength than that of the perimeter portion 604 and the securing portion 606. By increasing the strength of the plate portion 634, a substrate (not shown) may not respond too sensitively to a local polishing pressure. The plate portion 634 may be made of a plastic, such as polycarbonate or PET, and have a thickness of 0.5 mm to 2.5 mm. Referring to FIG. 17, a substrate receiving member 630′ may include a felt type mounting film 636 (for example, R301 mounting film from Nitta Haas) attached to the lower surface of the plate portion 634.
FIG. 18 is a cross-sectional view illustrating an exemplary embodiment of a substrate receiving member 640 having at least two perimeter portions. The substrate receiving member 640 may comprise a plate portion 642 providing an outer surface 641 for receiving a substrate, and a vertical perimeter portion 644 extending from the plate portion 642 wherein the vertical perimeter portion forms an angle of 84° to 96° with respect to the plate portion 642, and an inclined perimeter portion 645 extending from the vertical perimeter portion 644 wherein the inclined perimeter portion extends outwardly forming an angle of 6° to 40° (θ in FIG. 18) with respect to the vertical perimeter portion 644. A securing portion 646 is also included for connecting the substrate receiving member 640. Although not shown, the angle at the intersection of the inclined perimeter portion 645 with the vertical perimeter portion 644 may be formed smoothly so that it may have a round surface. A radius of curvature forming the round surface may have a value of 0.5 mm to 5 mm. The substrate receiving member 640 may be made of flexible materials, but the vertical perimeter portion 644 may be stiffer than the inclined perimeter portion 645. For example, the hardness of the vertical perimeter portion 644 may be 60 to 90 Shore-A in Durometer value, and the hardness of the inclined perimeter portion 645 may be 30 to 60 Shore-A. The securing portion 646 may include an O-ring structure for secure sealing. Although the above mentioned exemplary embodiment has described only two perimeter portions, more perimeter portions can be included to the above vertical-inclined perimeter structure.
FIG. 19 is a schematic cross-sectional view illustrating a carrier head 904 in which the above mentioned substrate receiving member 640 is mounted. The carrier head 904 includes a retaining ring 124 that has an inclined upper portion in order to easily receive the inclined perimeter portion 645 of the substrate receiving member 640.
As described above, in the exemplary embodiments of the present invention, the substrate receiving members 600, 620, 630, 640, which are each made in a various way, may be used. However, for simplicity, the case in which the substrate receiving member is wholly made of a same flexible material as shown in FIG. 1 will be described.
FIG. 20 is a schematic cross-sectional view illustrating a carrier head 906 according to another exemplary embodiment of the present invention. Without direct connection to a base 150, the bladder clamps 220, 320 and the wall structure 700 may be clamped first to a connecting member 152, and then the connecting member 152 is fastened to the base 150 by screws (not shown), or the like, thereby making it possible to connect the center and edge bladders 200, 300 and the wall structure 700 to the lower part of the base 150. The connecting member 152 may have fluid passing holes 153 to connect the bladder fluid passages 212, 312 to the clamp fluid passages 222, 322, and the substrate receiving member fluid passage 612 to a fluid passage (not shown) formed in the wall structure 700.
FIG. 21 is a schematic cross-sectional view illustrating a carrier head 908 according to still another exemplary embodiment of the present invention. The bladder clamps 220, 320 are clamped first to a connecting member 162 in which a wall structure 700′ is integrally formed in one body. The connecting member 162 is fastened to a base 160 by screws (not shown) or the like to connect the center and edge bladders 200, 300 to the lower part of the base 160. The connecting member 162 may have fluid passing holes 163 to connect the bladder fluid passages 212, 312 to the clamp fluid passages 222, 322, and the substrate receiving member fluid passage 612 to a fluid passage (not shown) formed in the wall structure 700′.
FIG. 22 is a schematic cross-sectional view illustrating a carrier head 910 according to still another exemplary embodiment of the present invention. Fluid needed in the substrate receiving member chamber 650 may be supplied through the substrate receiving member fluid passage 612 and then holes 614 formed in the lower part of the base 100. Here, when the bladders 200, 300 expand, the holes 614 may be blocked. Therefore, the outer surface of the bladders 200, 300 may have groove-shaped textures (not shown) so that the fluid may flow even after the bladders 200, 300 block the holes 614.
FIGS. 23 and 24 are schematic cross-sectional views explaining the operation of the carrier head 900 described above. Referring to FIG. 23, pressures applied to the substrate receiving member fluid passage 612, the center bladder fluid passage 212, and the edge bladder fluid passage 312 are designated as P1, P2, and P3, respectively. The pressures P1, P2 and P3 may be controlled independently, and the fluid passages 612, 212, 312 may be applied with not only positive pressures relative to an atmospheric pressure, but also a negative pressure, that is, a vacuum. In addition, when each fluid passage is open to the atmosphere, P1, P2, and P3 may be in a vent state which is same as an atmospheric pressure. In FIG. 23, a positive pressure P1 is applied to the substrate receiving member fluid passage 612, and a vacuum or an atmospheric pressure (vent state) is applied to the center and edge bladder fluid passages 212, 213. Therefore, the substrate receiving member chamber 650 may maintain the pressure of P1, and the pressure of P1 may be applied to a substrate 50 through the plate portion 602 of the substrate receiving member 600. Referring to FIG. 24, positive pressures P2 and P3 are applied to the center bladder fluid passage 212 and the edge bladder fluid passage 312, respectively, and an atmospheric pressure is applied to the substrate receiving member fluid passage 612. The center bladder 200 to which the positive pressure P2 is applied expands and stops expanding downward at the moment of contacting the inner surface 610 and also stops expanding laterally at the moment of contacting the wall structure 700. The inner surface 610 contacted by the center bladder 200 may be a center area of the inner surface 610 defined by the wall structure 700. Here, the applied pressure to the inner surface 610 may be the pressure P2 in the center bladder chamber 250. More precisely, the applied pressure is to be obtained by subtracting or adding the stress needed in expanding or contracting the center bladder 200. However, since the subtracted or added stress is much smaller than that in the center bladder chamber 250, the pressure applied to the inner surface 610 is considered identical to the pressure in the center bladder chamber 250 for convenience. Again, the pressure P2 is applied through the plate portion 602 to a center area of the substrate 50. Likewise, the inner surface 610 of the substrate receiving member 600 contacted by the edge bladder 300 may be an edge area of the inner surface 610 defined by the wall structure 700. Here, the applied pressure to the edge area of the inner surface 610 may be the pressure P3 in the edge bladder chamber 350. The pressure P3 is applied through the plate portion 602 to an edge area of the substrate 50. Therefore, by adjusting P2 and P3 which are independently controllable, higher polishing pressure may be applied to the center area or to the edge area of the substrate 50, thereby making it possible to maintain good polishing rate uniformity.
Therefore, referring to FIG. 24, the carrier head 900 according to a preferred embodiment of the present invention comprises: the base 100; the substrate receiving member 600 connected to the lower part of the base 100, having the outer surface 608 against which the substrate 50 can be mounted; the two bladders 200, 300 positioned inside of the substrate receiving member 600 and connected to the lower part of the base 100, wherein the two bladders 200, 300 can apply pressure independently to the predetermined areas of the inner surface 610 of the substrate receiving member 600 by expanding and contacting the inner surface 610; and the wall structure 700 connected to the lower part of the base 100, wherein the wall structure 700 can limit lateral expansions of the two bladders 200, 300.
FIGS. 25 to 27 are cross-sectional views explaining lateral expansions of the center and edge bladders 200, 300 according to the difference of their chamber pressures, and explaining how the wall structure 700 serves. First, referring to FIG. 25 without the wall structure, when the pressure P2 in the center bladder chamber 250 is same as the pressure P3 in the edge bladder chamber 350, there exists no overlap between bladders 200, 300 in the area M in which two bladders 200, 300 and the substrate receiving member 600 meet each other because a balance of force is maintained. Therefore, the pressure may be uniformly applied to the substrate receiving member 600. However, as shown in FIG. 26, in the case in which the pressure P2 in the center bladder chamber 250 is higher than the pressure P3, the center bladder 200 pushes the edge bladder 300 and the edge bladder 300 is folded in the area N in which the two bladders 200, 300 and the substrate receiving member 600 meet each other. The pressure applied to the substrate receiving member 600 may be affected by the degree to which the edge bladder 300 is folded and the position in which it is folded, and as a result, the pressure may be applied irregularly to the substrate receiving member 600 in the area N.
Meanwhile, FIG. 27 shows an example in which lateral expansions are stopped by the wall structure 700. The center bladder 200 may not continuously expand as that of FIG. 26, and the expansion may be limited by the wall structure 700, and the pressure P2 is applied only to an area A2 of the inner surface 610 of the substrate receiving member 600. In addition, the edge bladder 300 to which the pressure P3 (which is smaller than P2) is applied may not be pushed back by the center bladder 200 and may rather expand up to an area where the wall structure 700 limits, such that the pressure P3 may be applied to an A3 area of the inner surface 610. The wall structure 700 is connected to the base 100 and spaced away from the inner surface 610 by h. The gap h may range from 1 mm to 10 mm during CMP. The center bladder 200 may contact the edge bladder 300 only through the gap h. The degree of expansion through the gap is proportional to the size of gap. By controlling the size of gap h, the center bladder 200 may be allowed to contact the edge bladder 300 partially, or may be prevented completely from contacting the edge bladder 300. When the two bladders 200, 300 are expanded, a positive pressure lower than P2 and P3 may be applied in a space between the two bladders 200, 300 through a wall structure fluid passage (not shown) connected to the substrate receiving member fluid passage 612.
FIGS. 28 and 29 are schematic cross-sectional views explaining the structure and operation of a carrier head 920 further comprising an edge wall structure 730. Referring to FIG. 28, the carrier head 920 includes the edge wall structure 730 connected to the lower part of the base 100 and located between the edge bladder 300 and the perimeter portion 604 of the substrate receiving member 600. The edge wall structure 730 may limit a lateral expansion of the edge bladder 300 toward outer direction and thus may limit a contact between the perimeter portion 604 and the edge bladder 300. The edge wall structure 730 also can have a hollow cylindrical shape. Referring to FIG. 29, when the edge bladder 300 is expanding, the edge wall structure 730 limits the contact with the perimeter portion 604. Depending on the size of a gap between the edge wall structure 730 and the inner surface 610, denoted w in FIG. 29, the edge bladder 300 may be allowed to contact the perimeter portion 604 partially, or may be prevented completely from contacting the perimeter portion 604. The substrate receiving member fluid passage 612 can be connected to the edge wall structure 730 so that a fluid can be supplied through a wall structure fluid passage (not shown) or grooves (not shown) formed in the edge wall structure 730.
FIGS. 30 to 32 are schematic cross-sectional views of carrier heads 922, 924, 926 according to still other exemplary embodiments of the present invention. Referring to FIG. 30, a fluid supplied to the substrate receiving member chamber 650 through the edge wall structure 730 may be separately controlled through a wall structure fluid passage 614. Referring to FIG. 31, without direct connection to the base 150, the bladder clamps 220, 320 and the wall structures 700, 730 may be clamped first to a connecting member 154 and then the connecting member 154 is fastened to the base 150 by screws (not shown), or the like, thereby making it possible to connect the center and edge bladders 200, 300 and the wall structures 700, 730 to the lower part of the base 150. The connecting member 154 may have fluid passing holes 155 to connect the bladder fluid passages 212, 312 to the clamp fluid passages 222, 322, and the substrate receiving member fluid passage 612 to fluid passages (not shown) formed in the wall structures 700, 730. Referring to FIG. 32, the bladder clamps 220, 320 are clamped first to a connecting member 164 in which wall structures 700′, 730′ are integrally formed in one body. The connecting member, or integrated wall structure, 164 is fastened to the base 160 by screws (not shown) or the like to connect the center and edge bladders 200, 300 to the lower part of the base 160. The connecting member 164 may have fluid passing holes 165 to connect the bladder fluid passages 212, 312 to the clamp fluid passages 222, 322, and the substrate receiving member fluid passage 612 to fluid passages (not shown) formed in the wall structure 700′, 730′.
FIGS. 33 to 36 are schematic cross-sectional views illustrating a carrier head 940 according to another exemplary embodiment of the present invention, and explaining the operation thereof. Referring to FIG. 33, the carrier head 940 further includes an intermediate bladder 400 to control independently a pressure in an intermediate area. The intermediate area may be defined as an area between edge and center bladders 300, 500 regardless of the number of bladders. In the case in which there is no center bladder, which means there is no bladder pressuring the center of the inner surface 610, the area between the edge bladder and the area without the center bladder may be defined as intermediate area. The center bladder 500 and the edge bladder 300 may expand by a fluid supplied through a center bladder fluid passage 512 and an edge bladder fluid passage 312, respectively. During expansion, the center bladder 500 is limited laterally by a center wall structure 760, by which the center bladder 500 contacts only a center area of the inner surface 610 in the entire inner surface 610 of the substrate receiving member 600. The lateral expansion of the edge bladder 300 is limited by an intermediate wall structure 750 and an edge wall structure 740, by which the edge bladder 300 contacts only an edge area in the entire inner surface 610. Similarly, the lateral expansion of the intermediate bladder 400 is limited by the intermediate wall structure 750 and the center wall structure 760, by which the intermediate bladder 400 contacts only an intermediate area in the entire inner surface 610. The intermediate bladder 400 may have a ring shape as the edge bladder 300. A fluid pressure, vacuum or atmospheric pressure can be applied to the intermediate bladder 400 through an intermediate bladder fluid passage 412. Also the intermediate bladder 400 may be connected to the lower part of the base 100 by inserting an intermediate bladder clamp 420 into the intermediate bladder 400 and then clamping the intermediate bladder clamp 420 to the base 100. A clamp fluid passage 422 is formed in the intermediate bladder clamp 420 to connect to the intermediate bladder fluid passage 412.
Referring to FIG. 34, when a pressure P3 is applied to the edge bladder fluid passage 312, the edge bladder 300 expands and contacts the inner surface 610 of the substrate receiving member 600 while forming an edge bladder chamber 350 with the pressure P3. The inner surface 610 contacted by the edge bladder 300 may be an edge area of the inner surface 610 defined by the edge wall structure 740 and the intermediate wall structure 750. The applied pressure to the inner surface 610 may be the pressure P3 in the edge bladder chamber 350. Again, this pressure is applied to an edge area of a substrate 50 through the plate portion 602 of substrate receiving member 600. Similarly, the intermediate bladder 400 where a pressure P4 is applied forms an intermediate bladder chamber 450 with the pressure P4 and contacts an intermediate area of the inner surface 610 thereby the pressure P4 is transferred to an intermediate area of the substrate 50. Likewise, the center bladder 500 where a pressure P5 is applied forms a center bladder chamber 550 with the pressure P5 and contacts a center area of the inner surface 610 thereby the pressure P5 is transferred to a center area of the substrate 50. Here, an atmospheric pressure or a positive pressure smaller than P3, P4 and P5 can be applied to the substrate receiving member fluid passage 612. Therefore, by adjusting pressure P3, P4 and P5 independently, polishing rates on the center, intermediate and edge areas of the substrate 50 can be controlled.
Referring to FIG. 35, the edge bladder 300 with a pressure P3 expands and contacts an edge area of the inner surface 610, but the intermediate bladder 400 where a pressure P4 is applied and the center bladder 500 where a pressure P5 is applied contract. The center and intermediate areas of the substrate 50 receive pressure directly from the substrate receiving member chamber 650 where a pressure P1 is applied. In this case, P1 has a higher value than P4 and P5 but a smaller value than P3. Such a combination is feasible when a same pressure is necessary for the center and intermediate areas and a higher pressure is necessary for the edge area. Also in the case in which the center bladder 500 and the intermediate bladder 400 expand and contact the inner surface 610 like in FIG. 34, a similar pressure distribution can be obtained by adjusting P1, P3, P4 and P5.
Referring to FIG. 36, the center bladder 500 with a pressure P5 expands and contacts a center area of the inner surface 610 but the intermediate bladder 400 where a pressure P4 is applied and the edge bladder 300 where a pressure P3 is applied contract. The intermediate and edge areas of the substrate 50 receive pressure directly from the substrate receiving member chamber 650 where pressure P1 is applied. In this case, P1 has a higher value than P3 and P4 but a smaller value than P5. Such a combination is feasible when a same pressure is necessary for the intermediate and edge areas and a higher pressure is necessary for the center area.
Therefore, referring to FIG. 34, the carrier head 940 according to another exemplary embodiment of the present invention comprises: the base 100; the substrate receiving member 600 connected to the lower part of the base 100, having the outer surface 608 against which the substrate 50 can be mounted; the three bladders 300, 400, 500 positioned inside of the substrate receiving member 600 and connected to the lower part of the base 100, wherein the three bladders 300, 400, 500 can apply pressure independently to the predetermined areas of the inner surface 610 of the substrate receiving member 600 by expanding and contacting the inner surface 610; and the three wall structures 740, 750, 760 connected to the lower part of the base 100, wherein the three wall structures 740, 750, 760 can limit lateral expansions of the three bladders 300, 400, 500.
Above examples showed how the three bladders 300, 400, 500 can control the polishing rate in the edge, intermediate and center areas of a substrate. However, the number of bladders is not limited to 3. Instead the number can be increased as long as the space of the base 100 permits. For example, a carrier head for 450 mm silicon wafers can have up to 12 bladders while a carrier head for 300 mm silicon wafers can have up to 8 bladders.
FIG. 37 is schematic a cross-sectional view illustrating gaps between the wall structures 740, 750, 760 and the inner surface 610 for the carrier head 940 shown above. Here, the gaps h1, h2, and h3 may be adjusted so that the de-chucking of a substrate from a polishing pad can be securely performed. It is advantageous that the gap becomes larger as it goes toward the center area of the substrate receiving member 600, say h1<h2<h3. This is to let the plate portion 602 have a form of suction cup when the vacuum is applied to the inside of the substrate receiving member 600 to de-chuck a substrate.
FIGS. 38 and 39 are schematic cross-sectional views illustrating carrier heads 942, 944 according to still other exemplary embodiments of the present invention. Referring to FIG. 38, bladder clamps 320, 420, 520 are clamped first to a connecting member 172 in which wall structures 740′, 750′, 760′ are integrally formed in one body. The connecting member, or integrated wall structure, 172 is fastened to a base 170 by screws (not shown) or the like to connect the bladders 300, 400, 500 to the lower part of the base 170. The connecting member 172 may have fluid passing holes 173 to connect the bladder fluid passages 312, 412, 512 to clamp fluid passages 322, 422, 522 respectively, and the substrate receiving member fluid passage 612 to fluid passages (not shown) formed in the wall structure 740′, 750′, 760′. FIG. 39 represents an example of plural connecting members 174, 176 which are each integrally formed with wall structures 740″, 750″, 760″. After the edge bladder 300 is clamped to a first connecting member 174, where an edge wall structure 740″ and an intermediate wall structure 750″ are integrally formed, the first connecting member 174 is fastened to a second connecting member 176 where a center wall structure 760″ is integrally formed. After the intermediate and center bladders 400, 500 are clamped to the second connecting member 176, the second connecting member is fastened to the base 170 by screws (not shown) or the like to connect the bladders 300, 400, 500 and the wall structures 740″, 750″, 760″ to the lower part of the base 170. The first and second connecting members 174, 176 may have fluid passing holes 175, 177 to connect the bladder fluid passages 312, 412, 512 to the clamp fluid passages 322, 422, 522 respectively, and the substrate receiving member fluid passage 612 to fluid passages (not shown) formed in the wall structure 740″, 750″, 760″.
FIGS. 40 and 41 are schematic cross-sectional views illustrating carrier heads 946, 948 where a bladder is removed. First, FIG. 40 shows the carrier head 946 in which the above mentioned center bladder 500 and members needed to operate the center bladder are removed. Here, a pressure in the substrate receiving member chamber 650 is applied to a center area of the inner surface 610. At this time, if a pressure is about to be applied to an intermediate area of the inner surface 610 by an expansion of the intermediate bladder 400, the pressure in the substrate receiving member chamber 650 is required to be smaller than the pressure applied to the intermediate bladder 400. FIG. 41 shows the carrier head 948 in which the above mentioned intermediate bladder 400 and members needed to operate the intermediate bladder are removed. Here, a pressure in the substrate receiving member chamber 650 is applied to an intermediate area of the inner surface 610. At this time, if the center and edge bladders 500, 300 are about to expand and apply pressures to the inner surface 610, the pressure in the substrate receiving member chamber 650 is required to be smaller than the pressures applied to the center and edge bladders 500, 300.
As described above, the carrier heads according to the exemplary embodiments of the present invention include a plurality of bladders, but pressures from bladders does not have to be applied to entire areas of the inner surface of the substrate receiving member during CMP. Therefore, the bladder of the corresponding area may be contracted or removed.
FIGS. 42 to 47 are schematic cross-sectional views illustrating carrier heads 960, 962, 964, 966, 970, 972 including a single bladder. Here, terms for all members and materials of all members are the same as those of carrier heads including a plurality of bladders described above. Same components will be described as the same reference numerals, and an overlapped description will be omitted.
First, referring to FIG. 42, the carrier head 960 according to an embodiment of the present invention comprises: a base 100; a substrate receiving member 600 connected to a lower part of the base 100, having an outer surface 608 against which a substrate can be mounted; an edge bladder 300 positioned inside of the substrate receiving member 600 and connected to the lower part of the base 100, wherein the edge bladder 300 can apply pressure to an edge area of an inner surface 610 of the substrate receiving member 600 by expanding and contacting the inner surface 610; and a wall structure 70 connected to the lower part of the base 100, wherein the wall structure can limit an inward expansion of the edge bladder 300.
The wall structure 70 of the present embodiment may have a same form as that of the wall structure 700 described above. However, the wall structure 70 may not have a fluid passage through which a fluid may pass as in the above described wall structure 700.
Referring to FIG. 43, the carrier head 962 further comprises an edge wall structure 72 connected to the lower part of the base 100 and located between the edge bladder 300 and the perimeter portion 604 of the substrate receiving member 600. The edge wall structure 72 may limit a lateral expansion of the edge bladder 300 toward outer direction and thus may limit a contact between the perimeter portion 604 and the edge bladder 300.
Referring to FIG. 44, the carrier head 964 comprises an edge bladder 370 clamped externally such that no clamp is needed in the internal portion thereof. Meanwhile, the edge bladder 370 is clamped by an outside clamp 76 and an inside clamp 74. Here, the inside clamp 74 may have a lower portion extended toward the inner surface 610 so that it may serve as a wall structure simultaneously. The edge bladder 370 forms a bladder chamber 340 isolated from the substrate receiving member chamber 650, and expands by a fluid supplied through the bladder fluid passage 312 and contracts by a vacuum. The bottom portion of the edge bladder 370 in FIG. 44 is spaced away from the inner surface 610. However, when the pressure applied to the edge bladder 370 is same as that applied to the substrate receiving member 600, the edge bladder 370 does not necessarily have to be spaced away from the inner surface 610, and may have a shape extending toward the inner surface 610 so as to contact the inner surface 610.
Referring to FIG. 45, the carrier head 966 includes a connecting member 180. Without direct connection to the base 100, the bladder clamp 320 may be clamped first to the connecting member 180 and then the connecting member 180 is fastened to the base 100 by screws (not shown), or the like, thereby making it possible to connect the edge bladder 300 to the lower part of the base 100. Here, as shown, a center portion of the connecting member 180 may extend toward the inner surface 610 to serve as a wall structure to limit an inward expansion of the edge bladder 300. The connecting member 180 may have fluid passing holes 182 to connect the substrate receiving member fluid passage 612 to the substrate receiving member chamber 650, and to connect the bladder fluid passage 312 to the clamp fluid passage 322.
Referring to FIG. 46, the carrier head 970 according to another embodiment of the present invention comprises: a base 100; a substrate receiving member 600 connected to a lower part of the base 100, having an outer surface 608 against which a substrate can be mounted; a center bladder 200 positioned inside of the substrate receiving member 600 and connected to the lower part of the base 100, wherein the center bladder 200 can apply pressure to a center area of an inner surface 610 of the substrate receiving member 600 by expanding and contacting the inner surface 610; and a wall structure 70 connected to the lower part of the base 100, wherein the wall structure can limit an outward expansion of the center bladder 200.
Referring to FIG. 47, the carrier head 972 includes a connecting member 184. Without direct connection to the base 100, the bladder clamp 220 may be clamped first to the connecting member 184 and then the connecting member 184 is fastened to the base 100 by screws (not shown), or the like, thereby making it possible to connect the center bladder 200 to the lower part of the base 100. Here, as shown, an edge portion of the connecting member 184 may extend toward the inner surface 610 to serve as a wall structure to limit an outward expansion of the center bladder 200. The connecting member 184 may have fluid passing holes 186 to connect the substrate receiving member fluid passage 612 to the substrate receiving member chamber 650, and to connect the bladder fluid passage 212 to the clamp fluid passage 222.
As set forth above, the carrier head for a chemical mechanical polishing system may independently control polishing pressure applied to each predetermined area of the substrate during CMP, thereby making it possible to control easily the uniformity of polishing rate.
Although the embodiments of the present invention have been disclosed for illustrative purposes, it will be appreciated that the present invention is not limited thereto, and those skilled in the art will appreciate that various modifications, additions and substitutions are possible, without departing from the scope and spirit of the invention.
Accordingly, any and all modifications, variations or equivalent arrangements should be considered to be within the scope of the invention, and the detailed scope of the invention will be disclosed by the accompanying claims.
