JP2009255292A - Carrier head and system for chemical mechanical polishing of substrate - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve productive efficiency of a die by reducing excessive local polishing and polishing a large number of substrates on a single polishing pad. <P>SOLUTION: This carrier head 200 to polish the substrate 12 is furnished with: a body 204 having a wall extending downward and to partition a cavity 210; a sleeve 220 provided on a lower end of the wall extending downward; and a member 214 with elasticity to form a pressure chamber in the cavity 210. The member 214 with elasticity has: an inner surface to make contact with fluid in the chamber; a part to make a substrate reception surface to make contact with a back surface of the substrate 12; and a part to make contact with an internal wall of the cavity 210. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to the field of semiconductor processing. In particular, the present invention relates to a method and apparatus for chemical mechanical polishing a substrate with high uniformity and reduced cost. The present invention provides an apparatus for improving the uniformity of the rate at which material is removed from different locations on a substrate, thereby increasing the number of useful dies ultimately recovered from the substrate. Furthermore, the present invention provides an apparatus and method for simultaneously polishing multiple substrates on a single polishing pad, thereby increasing the productivity of chemical mechanical polishing apparatus.

  Chemical mechanical polishing, commonly referred to as CMP, is a method of planarizing or polishing a substrate. CMP can be used as a final preparatory step in building a semiconductor slice on a substrate, providing a substantially flat front and back surface. CMP is also used to remove elevations or other non-continuous portions that are created on the outermost surface of the substrate in creating a microelectronic circuit on the substrate.

  In a typical prior art CMP process, a large rotating polishing pad that receives a chemically reactive slurry is used to polish the outermost surface of the substrate. In order to position the substrate on the polishing pad, the substrate is placed in a carrier. The carrier is received on or directly above the polishing pad, which maintains the biasing force between the surface of the substrate and the rotating polishing pad. The carrier may also swing, vibrate or rotate the substrate over the polishing pad. The material is chemically and physically polished from the surface of the substrate by the movement of the slurry-polished polishing pad across the flat surface of the substrate.

  One problem that occurs repeatedly in the CMP process is the difference in flat surface polishing of the substrate, which tends to over-polish or under-polish areas depending on the location on the substrate. Usually, one area on the surface of the substrate where the difference in polishing occurs is the portion adjacent to the edge of the substrate. When such edge over-polishing occurs, the polished substrate assumes a convex shape. That is, it is thick at the center and thin along the edge. When the substrate is further processed, for example, by photolithography or etching, this difference in thickness makes it extremely difficult to print high resolution lines on the substrate. Similarly, when CMP is used to remove the elevations that result from forming circuits on the working surface of the substrate, the difference in polishing will physically destroy the die formed in the over-polished area. Resulting in.

  Edge over-polishing is caused by several factors. The uneven distribution of the advanced polishing slurry on the surface of the substrate is one factor that causes over-polishing of the edges. The substrate is polished more quickly where the slurry is replenished more quickly, such as at locations along the edge of the substrate. The relative pressure between the substrate and the polishing pad at different locations on the substrate also affects the polishing rate. This is because higher pressure results in higher polishing rates. One relatively high pressure region occurs where the substrate edge is pressed against the polishing pad, which causes the substrate edge to be polished more quickly than the substrate center. Furthermore, when both the polishing pad and the substrate rotate, the cumulative motion distance between the substrate and the polishing pad is higher than the center of the substrate near the edge of the substrate. The greater the cumulative moving distance between the polishing pad and the substrate, the greater the amount of material removed from the substrate. As a result of these and other factors, the substrate edge portion is typically polished faster than the substrate center.

  Substrate overpolishing also occurs in non-contact areas of the substrate. This over-polishing is usually caused by a distorted or otherwise improperly prepared substrate and is exacerbated by the mounting system that attaches the substrate to the carrier. Usually, the carrier includes a substantially flat substrate receiving surface. A compatible material is placed on this lower surface and receives the substrate therein. The compatible material may be a polymer sheet or a wax mound against which the substrate is pressed to form a compatible receiving surface. These compatible materials and the lower surface of the carrier may not be as flat as the desired flatness of the substrate. Therefore, the conformable back material and the flat lower surface include ridges that place different loads on the back side of the substrate when the substrate is placed on the polishing pad. This different loading creates an overload region on the surface of the substrate that engages the polishing pad corresponding to the location of the flat surface and the raised region of conformable material. In the local region of the substrate where this overload occurs, the substrate is over-polished and the production yield of dies from the substrate is reduced.

  In addition to the reduction in die production yield that results from the creation of over-polished areas on the substrate, it is inherently inefficient to use large rotating polishing pads to sequentially process the substrate. The surface area of the substrate is usually not greater than 20% of the surface area of the polishing pad. Therefore, at any point in time, most of the polishing pad material is not in contact with the substrate. One way to increase the surface area utilization of a rotating polishing pad is to process multiple substrates simultaneously on the polishing pad. However, users of CMP equipment are hesitant to do so. It may cause the substrate to crack or cause other defects, and fragments and other contaminants may be transferred by the rotating polishing pad to all substrates being processed simultaneously on the polishing pad. This is because that.

  Therefore, a CMP polishing apparatus capable of (1) increasing the uniformity of the material removal rate between different positions or regions on the surface of the substrate, and (2) increasing the utilization of the polishing pad. There is a need.

  The present invention is a chemical mechanical polishing apparatus and method that includes numerous examples useful for increasing the uniformity or utilization of the material removal rate of a chemical mechanical polishing apparatus. In a first embodiment, the apparatus includes a substrate carrier that applies different loads to selected portions of the outer surface of the substrate relative to the polishing pad. When edge over-polishing occurs, the carrier is shaped to increase the pressure between the polishing pad and the substrate in the center of the substrate, otherwise it would have occurred near the edge of the substrate Compensates for high material removal rate. In a second embodiment of the invention, the carrier is configured to equally load all portions of the outermost surface of the substrate relative to the polishing pad. By equally loading the substrate against the polishing pad, the occurrence of localized over-polishing caused by compliant material or ridges on the carrier lower surface is reduced or completely prevented. In addition, the substrate may be placed on the polishing pad while the polishing pad is rotating slowly in order to suppress edge over-polishing that occurs as a result of the greater cumulative movement distance between the substrate and the polishing pad at the substrate edge. Orbital motion may be used. The carrier may be controlled to orbit the substrate without rotating, or to rotate the substrate at a desired speed while it is orbiting. By precisely controlling the rotation speed of the substrate compared to the rotation speed of the polishing pad, the difference in the amount of substrate polishing caused by different cumulative movement distances at different locations or regions of the substrate is reduced. Or it is prevented.

  In a third embodiment of the present invention, multiple substrate carriers are provided to place and load multiple substrates simultaneously on a single polishing pad. In one sub-embodiment of the majority carrier embodiment, the polishing pad is rocked rotationally. By rotating the polishing pad in a rotational manner, areas of the polishing pad that are in contact with any one of a number of substrates are isolated from areas of the polishing pad that are in contact with other substrates. In another sub-embodiment of the present invention, the polishing pad includes a single groove or multiple grooves, which are formed to collect fragments of the substrate that may occur during processing. In yet another sub-embodiment of the majority carrier embodiment of the present invention, the polishing pad is maintained in a stationary position and the multi-lobed groove is within the polishing pad and the substrate is received on the polishing pad. Located just below the position. The multi-lobed grooves provide contact and non-contact areas between the substrate and the polishing pad such that slurry is replenished in the non-contact areas between the substrate and the polishing pad.

FIG. 1 is a partial cross-sectional perspective view of the polishing apparatus of the present invention. FIG. 2 is a cross-sectional view of the substrate carrier and drive assembly of the polishing apparatus of FIG. FIG. 3 is a cross-sectional view of another embodiment of the substrate carrier of FIG. FIG. 4 is a perspective view of another embodiment of the polishing apparatus of FIG. 1, showing two polishing heads operating on the polishing pad. 5 is a partial cross-sectional view of the device of FIG. 4 taken along line 5-5. FIG. 6 is a top view of another embodiment of the polishing pad of the present invention showing details of another polishing pad configuration.

  First, the outline of the present invention will be described.

  The present invention provides a number of embodiments for polishing a substrate on a large polishing pad with improved uniformity and yield. In each of the embodiments of the invention described herein, the substrate 12 is pressed against a polishing pad 22 on a polishing apparatus, such as the polishing apparatus 10 of FIG. 1, and preferably traverses the orbital path with controlled rotation. exercise. The polishing pad 22 preferably rotates, but may remain stationary while the substrate 12 is moved relative thereto.

  In the embodiment of the invention shown in FIGS. 1 and 2, a substrate carrier 24 is provided to receive the substrate 12 and position the substrate 12 on the rotating polishing pad 22. The carrier 24 is coupled to a transfer case 54 that moves the carrier 24 and the substrate 12 received therein along the track path on the polishing pad 22 and the base 14 of the polishing apparatus 10. The rotation direction of the carrier 24 and the substrate 12 is controlled simultaneously with respect to the fixed point. The carrier 24 is formed so as to selectively and differentially apply the load to the central portion of the substrate 12 as compared with the load on the substrate applied adjacent to the edge of the substrate 12. By differentially loading the central portion of the substrate 12, the material removal rate at the central portion of the substrate 12 is adjusted to match the material removal rate of the portion adjacent to the edge of the substrate 12.

  In the embodiment of the invention shown in FIG. 3, the substrate carrier is formed as a front referencing carrier 200 that equally loads all positions or regions of the substrate 12 relative to the polishing pad 22. This reduces the occurrence of non-contact over-polished areas on the substrate 12 resulting from the non-contact and differentially loaded areas of the substrate 12.

  In the embodiment of the present invention shown in FIGS. 4-6, an apparatus for polishing multiple substrates 12 simultaneously on a single polishing pad 302 or 400 is shown. 4 and 5, a number of substrates 12 are pressed against a separate polishing pad 302, which is the region of the separate polishing pad 302 that is in contact with any one substrate 12. In order not to come into contact with other substrates 12 to be used, it is preferable to perform a rocking motion in a rotational manner. In FIG. 6, a foliate polishing pad 400 is shown having lobes 404 or recesses in its surface. The lobes are densely grouped so that the substrate 12 is orbital, rotational, oscillating, oscillating, or other relative to a single group of lobes 404. It can be moved by a bear. The foliate polishing pad 400 preferably remains stationary, and all relative movement between the substrate 12 and the foliate polishing pad 400 is preferably provided by moving the substrate 12.

  Next, the polishing apparatus of the present invention will be described.

  FIG. 1 shows a polishing apparatus 10 useful for polishing a substrate 12 using any of the embodiments of the invention described herein. The apparatus 10 is useful for the embodiments of the present invention described herein, but is depicted in association with a carrier 24 and a polishing pad 22 for ease of illustration. The polishing apparatus 10 generally includes a base 14 that supports a rotatable platen 16 and a polishing pad 22 thereon, a carrier 24 that receives the substrate 12 and positions the substrate 12 on the polishing pad 22, and the polishing pad 22. And a transfer case 54 connected to the carrier 24 so as to load and move the substrate 12. When it is desired to rotate the polishing pad 22, a motor and gear assembly (not shown) is disposed on the lower side of the base 14 and connected to the center of the lower side of the platen 16 to rotate the platen 16. The platen 16 may be supported from the base 14 by bearings or may be supported at the same time as the motor and gear assembly rotates the platen 16. The polishing pad 22 is placed on the top surface of the platen 16 and is thereby rotated by the motor and gear assembly.

  Slurry is provided on the polishing pad 22 to enhance the polishing characteristics of the polishing pad 22. The slurry may be supplied to the polishing pad 22 through a slurry port 23 where the slurry is dripped onto the polishing pad 22 or otherwise metered, or supplied through the underside of the platen 16 and the polishing pad 22. Alternatively, it may flow up to the substrate 12 through the polishing pad 22. The polishing pad 22 and the slurry are selected so that the substrate 12 can be polished as desired. The composition of the polishing pad 22 is preferably a woven polyurethane material. For example, IC1000 or SubaIV, available from Rodel, Newark, PA. One slurry composition that enhances the selective etching of the material deposited on the substrate is an aqueous solution with 5% NaOH, 5% KOH and colloidal silica having a size of approximately 200 nm. Those skilled in the art will readily be able to modify the material and slurry composition of the polishing pad 22 to provide the desired polishing to the substrate 12.

  In order to properly position the carrier 24 with respect to the polishing pad 22, the transfer case 54 is connected to a crossbar 36 that extends above the polishing pad 22. The cross bar 36 is positioned above the polishing pad 22 by a pair of opposed vertical members 38 and 39 and a biasing piston 40. The crossbar 36 is preferably hingedly connected to the vertical member 38 at its first end 44 and is preferably connected to the biasing piston 40 at its second end 46. The second vertical member 39 is provided adjacent to the biasing piston 40 and provides a vertical stop to limit the downward movement of the second end 46 of the crossbar 36. In order to replace the substrate 12 on the carrier 24, the crossbar 36 can be removed from the biasing piston 40 and the second end 46 of the crossbar 36 connects the carrier 24 connected to the crossbar 36. To be lifted from the polishing pad 22, it is pulled up. The substrate 12 is then replaced and the carrier 24 is lowered to place the surface 26 of the substrate 12 against the polishing pad 22.

  The transfer case of the polishing apparatus of the present invention will be described.

  Referring to FIGS. 1 and 2, the configuration form and details of the transfer case 54 necessary to provide the preferred orbital and controlled rotational movement of the substrate 12 on the polishing pad 22 are shown. Again, for convenience of illustration, the transfer case 54 is depicted in relation to the carrier 24. However, the transfer case 54 is specifically configured to interchangeably drive any orbiting carrier, including the front reference carrier 200. The transfer case 54 is suspended below the cross bar 36 and couples the carrier 24 to the cross bar 36. Generally, the transfer case 54 includes a drive shaft 56 and a housing 58. The drive shaft 56 extends upwardly through the crossbar 36, is connected to a motor and drive assembly 50 that is securely connected to the crossbar 36, and extends downwardly through the housing 58. The rotary motion of the motor and drive assembly 50 is converted into an orbital and controlled rotational motion of the carrier 24. A drive belt 52 connects the drive shaft 56 to the motor and gear assembly 50 to rotate the drive shaft 56. In addition, a drive sprocket 88 is placed on the outer surface of the housing 58. The drive sprocket 88 is connected to a housing drive motor 90 placed on the cross arm 36 by a drive belt 61. Although the housing 58 is shown as having a sprocket 88 thereon, the sprocket 88 can be easily replaced with other forms for transferring rotational motion, such as pulleys or pulleys.

  Referring now to FIG. 2, the detailed internal structure of the transfer case 54 is shown. The housing 58 has an inner fixed hub 57 and an outer rotating hub 59. The fixed hub 57 inside the housing 58 is securely attached to the underside of the crossbar 36, preferably by a plurality of bolts or other removable members (not shown). The outer rotating hub 59 is bearing connected to the inner fixed hub 57, preferably by upper and lower tapered bearings. These bearings support the outer rotating hub 59 in a vertical direction, while allowing the outer rotating hub 59 to rotate relative to the inner fixed hub 57. The drive shaft 56 extends through a fixed hub 57 on the inside of the housing 58 and is tapered to support the drive shaft 56 in a vertical direction and to allow the drive shaft 56 to rotate with respect to the internal fixed hub 57. Supported by bearings in it as well. In order to rotate the outer rotating hub 59, a sprocket 88 is mounted directly thereon.

  The orbital motion drive unit of the transfer case will be described.

  A cross arm 60 is provided at the lower end of the drive shaft 56 in order to give orbital motion so that the carrier 24 is orbited. The cross arm 60 includes a first end and a second end. The first end of the cross arm 60 receives the lower end of the drive shaft 56 therein, and the second end of the cross arm 60 supports a second shaft 64 extending downwardly therefrom. ing. The lower end of the second shaft 64 has its end located at the center of the carrier plate 80, and the carrier plate forms the upper end of the carrier 24. A bearing assembly 79 is provided on the carrier plate 80 and receives the lower end of the second shaft 64. As the drive shaft 56 rotates, it sweeps the second end of the cross arm 60, and thus the shaft 64 extending downward therefrom, onto an arc. The radius of this arc is the distance between the drive shaft 56 and the second shaft 64, but defines the radius of the track on which the carrier 24 moves. The second shaft 64 is connected to the bearing 79 so that the carrier 24 can rotate about the second shaft 64 when the second shaft 64 pushes the carrier 24 along the track. . The lower end of the second shaft 64 also forms a solid bearing point on which the carrier 24 is supported when the substrate 12 is pressed against the polishing pad 22.

  The rotation compensation unit of the transfer case will be described.

  The connection of the shaft 64 to the carrier 24 is formed so that the rotational force transmitted to the carrier 24 is minimized, and the rotation of the substrate 12 and the carrier 24 is performed when the substrate 12 orbits on the polishing pad 22. Shaped to minimize. However, due to the dynamic interaction between the substrate 12 and the polishing pad 22 and between the carrier 24 and the second shaft 64, the substrate 12 rotates slowly as it orbits. ) In order to suppress or prevent rotation when the substrate 12 is orbited, a rotation compensation assembly 62 is provided on the underside of the housing 58 to position it positively when the substrate 12 is orbited. It has become. In order to achieve this firm positioning, the compensation assembly 62 is attached to an internal ring gear 70 disposed on the lower side of the outer rotating hub 59 of the housing 58 and a second shaft 64 just below the cross arm 60. And a pinion gear 74 formed. Pinion gear 74 includes an outwardly toothed surface that meshes with the teeth of ring gear 70 and an inner diameter that is received in bearing 77 on second shaft 64. The pinion gear 74 is rotationally fixed with respect to the carrier plate 80 by a pair of pins 73 extending from the pinion gear 74 into a pair of mating recesses 75 in the carrier plate 80. Therefore, when the second shaft 64 orbits, the orbital motion of the shaft 64 is transmitted to the carrier plate 80 at the bearing 79, and the rotational motion of the pinion gear 74 is transmitted to the carrier plate 80 through the pin 73.

Because of the compensation assembly 62, a CMP apparatus user can change the rotational component of the movement of the carrier 24, thereby preventing or accurately controlling the rotation of the carrier 24 as the carrier 24 orbits. be able to. As the cross arm 60 rotates about the drive shaft 54, it sweeps the pinion gear 74 around the inner circumference of the ring gear 70. Since the teeth of the pinion gear 74 and the teeth of the ring gear 70 are in mesh, the pinion gear 74 rotates with respect to the ring gear 70 as long as the teeth of the ring gear 70 are not moving at the same speed as the teeth of the pinion gear 74. By rotating the rotating hub 59 outside the housing 58 while simultaneously rotating the drive shaft 56, the effective rotational motion of the pinion gear 74 around the second shaft 64 and of the carrier 24 attached thereto is controlled. Can do. For example, if the ring gear 70 rotates at a speed sufficient to cause the pinion gear 74 to make one full revolution as the carrier 24 moves in one orbit, the pinion gear 74 and thus the orbiting carrier 74 attached thereto. Does not rotate with respect to a fixed reference point such as the base 10. Further, the rotational speed of the carrier 24 can be matched to the rotational speed of the polishing pad 22 by simply changing the relative rotational speed of the drive shaft 56 and the external rotary hub 59 of the housing 58, or can be changed accordingly. it can. This physical phenomenon is used to control the rotational speed of the carrier 24 when it orbits by changing the relative speed of the ring gear 70 and the pinion gear 74.

  Thanks to its shape of the transfer case 54, the user of the CMP apparatus can achieve a uniform polishing rate across the surface 26 of the substrate 12 by controlling the relative speed at different locations on the surface 26 when polishing the substrate 12. Gender can be strictly controlled. As the substrate 12 is moved by the carrier 24 in the track on the polishing pad 22, the platen 16 and the polishing pad 22 are rotated by a motor and gear assembly (not shown). Together, the orbital speed of the substrate 12 and the rotational speed of the polishing pad 22 provide a nominal speed at the substrate surface 26 of 1800 to 4800 cm / min. Its orbital radius is less than 1 inch, and the polishing pad 22 preferably rotates at a relatively low speed, less than 10 rpm, and most preferably less than 5 rpm.

  The orbiting substrate 12 may or may not be rotated by selectively rotating the housing 58 by means of a motor 91 through the belt 61. By rotating the orbiting substrate 12 at the same speed as the polishing pad 22, the cumulative movement distance between the polishing pad 22 and each point on the substrate 12 can be kept uniform. Therefore, over-polishing due to different cumulative motion distances in different areas of the substrate is prevented. In addition, if desired, the rotational speed of the substrate can be increased by increasing the rotational speed of the polishing pad 22 to increase the relative motion distance between the edge portion of the substrate and the polishing pad 22 relative to the center point of the substrate. It may be changed. If desired, the substrate 12 may be moved in a direction of rotation opposite to the direction of the polishing pad 22.

  The substrate carrier of the polishing apparatus of the present invention will be described.

  Referring to FIG. 2, the structure of one preferred embodiment of the carrier 24 is shown in detail. The carrier 24 includes an internal biasing member 30 therein that selectively controls the application of primary and secondary forces used to load the substrate 12 on the polishing pad 22. It includes an outer sleeve portion 130 that conveys orbital motion to the substrate 12. The inner biasing portion 30 includes an upper biasing portion 102 and a lower body portion 104.

  The upper biasing portion 102 of the carrier is configured to control the primary pressure applied to load the substrate 12 against the polishing pad 22. To control the primary load pressure, the upper biasing portion 102 of the carrier 24 is formed as a cavity 112 that is selectively pressurized to load the substrate 12 against the polishing pad 22. The cavity 112 is defined by a carrier plate 80 that forms the upper end thereof, an upper surface of the lower body portion, and a bellows 110 that extends downward from the carrier plate 80 and ends at the lower body portion 104. Bellows 110 is preferably made of approximately 8/1000 inch thick stainless steel that provides sufficient rigidity to prevent substantial twisting of carrier 24. Bellows 110 serves as the outer wall of cavity 114 and it also serves to transmit rotational motion from carrier plate 80 to substrate 12.

  The lower body portion 104 of the carrier 24 is used to finely adjust the load pressure between the substrate 12 and the polishing pad 22 at different locations on the substrate 12. The lower body portion 104 is generally a right circular hollow member that is received within the sleeve portion 130 and forms a connection between the lower end of the bellows 110 and the lower body portion 104. Having a generally circular top wall 138. An outer circular wall 140 extends downward from the circular member 132 and terminates at the lower contour wall 142. Circular member 132, outer wall 140 and lower contour wall 142 form the outer boundary of chamber 144. The lower contour wall 142 has a substantially flat outer surface 152 and a contoured inner surface. Preferably, the contour of the inner surface of the lower contour wall 142 has a first tapered portion 146 extending from the outer periphery of the wall 142 to a position approximately one third of its radius, and any portion of the tapered portion 146. And a flat portion 148 that forms a thin film 150 having a constant thickness at the center of the wall 142. The outer or lower surface 152 of the wall 142 is flat and preferably receives a film 154 thereon, preferably a layer of closed cell film. The lower end of the sleeve 130 extends downward beyond the outer surface 152 of the wall 142 and the overlying film 154 and together with the wall 142 forms a lower substrate receiving recess 28.

  The sleeve portion 130 is configured to receive the components of the inner biasing portion 30 therein and to guide these components and the substrate 12 in the track. The sleeve portion 130 includes an upper generally right annular member 132 having an upper end connected to the lower end of the carrier plate 80 and a lower generally right annular ring 134. Including. The annular ring 134 is connected to the lower side of the annular member 132, and is pressed downward by a circular leaf spring 128 disposed at a connection portion between the annular member 132 and the ring 134, to the polishing pad 22. It can be engaged. The sleeve portion 130 provides a strong, substantially rigid member that receives the lower body portion 104 therein and guides the lower body portion 104 through the track. The circular ring 134 is preferably a conformable member that conforms slightly as the substrate 12 loads it.

  In order to apply a load pressure between the substrate 12 and the polishing pad 22, the cavity 112 and the chamber 144 must be supplied with fluid in a pressurized state. Further, the fluid supplied to the cavity 112 must be able to be maintained independently at a different pressure than the fluid supplied to the chamber 144. In order to supply these fluids, the drive shaft 56 includes a pair of channels 160, 162 extending longitudinally therein. Similarly, the second shaft 64 includes a pair of flow passages 160 ', 162' extending longitudinally therein. A rotating union 164 is provided at the upper end of the drive shaft 54 and supplies fluid to the flow paths 160 and 162. The rotating union is also located at the connection of the cross arm 60 to both the drive shaft 54 and the second shaft 64, and the cross arm 60 includes a pair of through passages (not shown). The passage cooperates with the rotating union to allow fluid to flow from the flow path 160 to the flow path 160 ′ and from the flow path 162 to the flow path 162 ′. The channel 160 ′ supplies fluid in a pressurized state and selectively pressurizes the cavity 112. A hose 124 is connected to the lower end of the flow path 162 ′ by rotational fitting, extends from the flow path 162 ′ to an opening 126 in the lower body portion, and supplies fluid to the chamber 144 of the lower body portion 104. It is like that. The fluid is preferably supplied from a variable pressure source, such as a pump with multiple regulated gas supplies with a regulated output, a regulated pressurized liquid source or other pressurized fluid supply.

  To load the substrate 12 against the polishing pad 22, fluid is supplied in a pressurized state to the bellows cavity 112 and the chamber 144. The pressure exerted by the fluid on the bellows cavity 112, together with the weight of the component that is loaded against the carrier 24 and the weight of the carrier 24 itself, is the primary load pressure 0.3 of the substrate 12 against the polishing pad 22. 0.7kg / cm2 is created. If no over-polishing of the edge portion occurs when the substrate 12 is polished, the chamber 144 is maintained at atmospheric pressure. However, if over-polishing occurs at the edge portion of the substrate 12, the contoured lower wall 144 is a distance sufficient to additionally press the center of the substrate 12 downward against the polishing pad 22. In particular, chamber 144 is pressurized with sufficient pressure to deflect its central flat portion 148 outward. The pressure supplied to the chamber 144 may be varied to control the deflection of the flat portion 148 to increase the polishing rate at the center of the substrate 12 in order to equalize the polishing rate at the edge of the substrate 12. . The desired amount of deflection for a given semiconductor polishing operation will be determined during manufacturing once a history of polishing and edge over-polishing is established.

  Although the carrier 24 has been described as providing a compensating force to increase the loading force between the polishing pad 22 and the substrate 12 near the center of the substrate 12, it also reduces the pressure at the center of the substrate 12 and reduces the center. It may be used to deal with excessive polishing. This can be accomplished by draining the fluid in chamber 144. In addition, the form of the carrier 24 may be changed to provide more force to the edge portion of the substrate 12, or more force may be applied to different radial locations on the substrate 12 by changing the contour of the lower contour wall 142. You may change it to hang.

  Another substrate carrier of the polishing apparatus of the present invention will be described.

  FIG. 3 shows another embodiment of the carrier, which is preferably used with the transfer case 54. In this alternative embodiment, the substrate carrier is formed as a front referencing carrier 200 so as to load the surface 26 of the substrate 12 equally to the polishing pad 22. The front reference carrier 200 applies an even load to the back side of the wafer, and this causes the front surface of the substrate 12 to be equally loaded. That is, it becomes a front reference with respect to the polishing pad 22. The front reference carrier 200 includes a correct circular body 204 having an upper shaft receiving portion 206 and an outer peripheral wall 208 extending downwardly from the upper shaft receiving portion 206, which together form a bladder. ) The boundary of the cavity 210 is formed. The lower end of the second shaft 64 of the transfer case 54 is received by a bearing in the center of the shaft receiving portion 206 so as to transmit the orbital motion to the front reference carrier 200. The second shaft 64 also provides a vertical rigid bearing point on which the carrier 200 rides when loading the substrate 12 on the polishing pad 22. In order to control the rotation of the front reference carrier 200, a pin 73 of the transfer case 54 extends downward from the pinion gear 74 and is received in a mating aperture 75 in the receiving portion 206 of the shaft of the carrier 200. Has been.

  The bladder cavity 210 is formed to receive a resilient rubbery bladder 214 therein. The lower end 212 of the bladder cavity 210 is open and sized to receive the substrate 12 therein. When the substrate 12 is received in the lower end 212 of the carrier, it contacts the bladder 214 that extends across the open end 212 of the carrier. The lower end of the bladder cavity 210 to limit the inward placement of the substrate 12 into the bladder cavity 210 and to prevent the bladder 214 from shrinking into the bladder cavity when the bladder 214 is not pressurized. A limiting plate 216 is placed inside 212 and within the outer jacket of the bladder 214. The restrictor plate is securely connected to the inner wall of the bladder cavity 210 so that the portion of the bladder 214 that extends beyond it will shrink between the inner wall of the bladder cavity 210 and the edge of the restrictor plate 216. Yes. Alternatively, the inner wall of the bladder cavity 210 includes a number of recessed grooves therein and the limiting plate 216 includes a plurality of tabs received in the recess. The bladder 214 may also extend beyond the tab into the recess, or the tab may extend past the bladder 214 and the area around the tab is sealed and the bladder 214 Maintaining the integrity of A sleeve 220 is provided at the lower end of the downwardly extending wall 208 to hold the substrate 12 at the open end 212 of the bladder cavity. The sleeve 220 is preferably made of a compatible material, such as a plastic material, such that the compatible material slightly adapts when the substrate is loaded against it. The sleeve 220 is pressed downward and engages the polishing pad 22 by a circular leaf spring or other pressing member (not shown) placed at the interface between the sleeve 220 and the downwardly extending wall 208. It is preferred that

  The front reference carrier 200 is preferably positioned on the polishing pad 22 by a transfer case 54 that is configured to convey orbital motion and selective rotational motion to the front reference carrier 200. The bladder 214 is pressurized to provide a primary load on the substrate 12 against the polishing pad 22. To supply air into the bladder, a fluid such as air is preferably supplied through a route through the drive shaft 58 and the second shaft 64. When the bladder 214 is pressurized, it expands within the bladder cavity 210 and presses the substrate 12 downward against the polishing pad 22. At the same time, the expanding bladder 214 separates from the limiting plate 216 and raises the body 204 of the carrier 200 slightly upward with respect to the substrate 12. However, this movement is limited by the fixed lower end of the second shaft 64. Therefore, when the bladder 241 is further pressurized, the main body 204 of the carrier 200 rides on the lower end portion of the second shaft 64 and the load on the substrate 12 increases. The load applied to the substrate 12 by the front reference carrier 200 applies a load to the surface 26 of the substrate equally to the polishing pad 22. This is because the bladder 214 does not place an unequal load on the back side of the substrate 12. Thus, the polishing disparity that normally occurs when the substrate 12 is subjected to unequal forces by raised areas on the carrier or in compatible material is substantially eliminated.

  Next, the multi-substrate polishing mode of the present invention will be described.

  FIG. 4 shows another apparatus for polishing multiple semiconductors 12 on a single rotating platen 16. In this alternative embodiment, two polishing heads 300, 300 ′ are placed on a separate polishing pad 302. Each head 300, 300 ′ may be orbital, oscillating, oscillating, rotating, or otherwise with respect to the divided polishing pad 302. It may be arranged by the method. The heads 300, 300 ′ may be formed as the carrier 24, the front reference carrier 200, or other carrier configuration that can hold the substrate 12 against the divided polishing pad 302. The heads 300, 300 ′ are preferably orbited to move the substrate 12 with respect to the divided polishing pad 302 therein, but instead are vibrated to provide movement with respect to the divided polishing pad 302. Alternatively, it may be oscillated or rotated.

  One problem with polishing multiple substrates 12 on a single polishing pad is that the substrate 12 may be chipped or cracked, which is a concern for CMP equipment users. is there. If the substrate 12 is chipped, fragments of the damaged substrate 12 can move and come into contact with one or more other substrates 12 and damage it. The present invention overcomes this problem by rotationally oscillating the divided polishing pad 302. In that way, any part of the divided polishing pad 302 that is in contact with the substrate 12 in the head 300 cannot be in contact with the substrate 12 in the head 300 ′, and vice versa. It is. To cause this movement, the divided polishing pad 302 moves first in the first direction of rotation and then in the opposite direction of rotation. As shown in FIG. 5, a two-way motor 310 is provided on the lower side of the base 14 and selectively operates to sequentially rotate the divided polishing pads 22 in the reverse direction. It is not sufficient to move the divided polishing pad 302 in any direction, and any part of the divided polishing pad 302 comes into contact with two or more substrates 12. This ensures that approximately one-half of the divided polishing pad 302 moves only under the head 300, and approximately one-half of the divided polishing pad 302 moves only under the head 300 '. . In addition, in order to prevent contaminants from moving from one substrate 12 to another, grooves 304 for receiving and collecting any particulates generated from one substrate 12 are provided in the divided polishing pad 302. May be. Further, when the groove 304 is used, the polishing pad may be rotated continuously. This is because fragments and other particulate contaminants collect in the groove 304 and do not come into contact with another substrate 12.

  In order to rotationally swing the pteran 16 and the divided polishing pad 302, a triggering means is provided, and the two-way motor 310 is rotated backward after the desired rotational movement. One device for causing the reverse rotation of the motor is shown in FIG. The trigger means includes an electromagnetic pickup 306 connected to the base 14 under the platen 16. A pair of magnets 308 are attached to the underside of the platen 16 and are separated by an arc distance equal to the desired arcuate motion desired before the platen 16 rotates in reverse. When any magnet 308 enters the vicinity of the pickup 306, a signal is sent to the controller. This causes the controller to reverse rotate the bi-directional motor 310, thereby reversing the rotational motion of the motor and platen 16. In this way, the platen 16 oscillates rotationally between the magnets 308 until the motor is stopped or released.

  The lobe polishing pad of the present invention will be described.

  FIG. 6 illustrates yet another embodiment of a foliate polishing pad 400 useful for polishing one or more substrates 12 simultaneously. In this embodiment, the leaf-shaped polishing pad 400 includes one or more multi-leaf groove members 402 therein that are on the polishing pad 400 in a position to receive the substrate 12 thereon. Each groove member 402 includes a plurality of lobes 404 extending radially from a central recessed area 406. Each leaf 404 is preferably substantially triangular, with oppositely extending sides 408 ending at the arc end 410. Although leaf 404 is shown as having flat sides, other configurations are specifically contemplated. For example, the leaf 404 may be curved, or the leaf 404 defines a plurality of depressions having a linear or curved profile formed in a dense region of the pad 400. Also good. Further, the leaves 404 are preferably interconnected at the central recessed area 406 so that slurry is fed through the polishing pad 22 to the central recessed area 406 and to the leaves 404. Although one leaf can be used, it is preferred that at least two leaves 404 are provided. The dimensions of the leaf 404, along with the material of the polishing pad 400 between the leaves 404, is the region where the leaf 404 is equal to the full path of the orbital, oscillating, oscillating or rotating motion of the substrate 12 on the polishing pad 400. Decided to spread upward. The leaf groove member 402 is preferably used with a track carrier driven by a track motion drive member with rotational position control, such as the transfer case 54 shown in FIGS. Held in a stationary position. In addition, the leaf-shaped polishing pad 400 swings, swings or orbits under the stationary or moving substrate 12, and gives a relative motion between the substrate 12 and the leaf-shaped polishing pad 400. May be. The leaves 404 provide a slurry replenishment reservoir on the surface of the substrate that engages the leaf-like polishing pad 400 and continuously replenishes the surface with the slurry as the substrate 12 is polished on the leaf-like polishing pad 400. In FIG. 6, the leaf-shaped groove member 402 is shown in a configuration for polishing multiple substrates 12 on a single leaf-shaped polishing pad 400, but the leaf-shaped polishing pad 400 is dimensioned slightly larger than the substrate 12. A single substrate 12 may be processed sequentially on it.

  Although the leaf-like groove member 402 has been described here, other groove forms can be used to supply the slurry to the lower side of the substrate 12. For example, if the polishing pad 22 is rotating, the pad may include one or more grooves in the surface of the polishing pad 22 that extend radially and preferably radially and circumferentially. Thus, as the polishing pad 22 passes under the substrate 12, the groove sweeps under the substrate and replenishes the substrate with slurry. Such grooves are discussed in detail in a US patent application entitled Taleeh's improved chemical mechanical polishing apparatus filed concurrently herewith.

  In conclusion, the embodiment described above reduces the occurrence of local over-polishing and also provides chemical mechanical polishing by providing an apparatus that simultaneously polishes multiple substrates on a single polishing pad. An apparatus is provided that can be used to increase the number of useful dies produced from processed substrates. The improvements disclosed herein reduce the number of defective dies created on the substrate that would otherwise result from the limitations inherent in chemical mechanical polishing processes. Although specific materials and dimensions have been described herein, one of ordinary skill in the art will understand that the dimensions and materials disclosed herein may be changed without departing from the scope of the present invention.

  As described above, according to the present invention, local excessive polishing is prevented and the production yield of the die is increased.

  These and other features and advantages of the present invention will become apparent upon reading the description of the embodiments in conjunction with the following drawings.

DESCRIPTION OF SYMBOLS 10 ... Polishing apparatus, 12 ... Substrate, 16 ... Platen, 22 ... Polishing pad, 23 ... Slurry port, 24 ... Substrate carrier, 36 ... Cross bar, 38, 39 ... Vertical member, 40 ... Biasing piston, 54 ... Transfer case .

Claims (6)

A carrier head for polishing a substrate,
A body having a wall extending downward and defining a cavity;
A sleeve provided at the lower end of the wall extending downward;
A resilient member forming a pressurized chamber in the cavity,
The elastic member has a carrier head having an inner surface that contacts a fluid in the chamber, a portion that forms a substrate receiving surface that contacts a back surface of the substrate, and a portion that contacts the inner wall of the cavity. A system for chemical mechanical polishing of a substrate,
A body having a wall extending downwardly defining a cavity and a resilient member forming a pressurized chamber in the cavity, wherein the resilient member contacts fluid within the chamber A carrier head having an inner surface, a portion forming a substrate receiving surface in contact with the back surface of the substrate, and a portion in contact with the inner wall of the cavity;
A platen that supports the polishing pad,
The carrier head is arranged so that the substrate faces the polishing pad, and applies a load between the substrate and the polishing pad,
A system configured to cause relative motion between the substrate and the polishing pad.   The system of claim 2, wherein the relative movement is performed by moving the substrate with the carrier head.   The system of claim 2, wherein the carrier head further comprises a sleeve provided at a lower end of the wall extending downward.   5. During polishing, the load is provided by pressurizing the resilient member, the sleeve engages the polishing pad, and the sleeve holds the substrate at the lower end of the cavity. The system described in. Further comprising a rigid member disposed within the chamber;
The system of claim 2, wherein the rigid member is arranged to prevent the elastic member from moving inwardly.

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