JP5562370B2 - Chemical mechanical polishing (CMP) head, apparatus and method - Google Patents

Description

  The present invention relates to a system, apparatus and method for polishing and planarizing a substrate, and more particularly to a chemical mechanical planarization or polishing (CMP) apparatus and method.

  Chemical mechanical planarization or polishing, commonly referred to as CMP, is a method for planarizing or polishing a semiconductor or other type of substrate. By planarizing the surface of the semiconductor substrate or wafer during a given processing step, more circuit layers can be formed vertically on the device. As the size of individual features decreases, the density increases, and the size of semiconductor wafers increases, the requirements of the CMP process become more stringent. Uniformity of wafer-to-wafer processes and uniformity of wafer surface planarization are important problems from the viewpoint of manufacturing semiconductor products at low cost. As the size of structures on the semiconductor wafer surface decreases, problems associated with non-uniform planarization processes are increasing, although currently typically around 0.2 microns. This problem is sometimes referred to as a non-uniformity (WIWNU) problem within the wafer plane.

  Many reasons are known to contribute to the uniformity problem. These reasons include the lack of edge effects resulting from the manner in which the wafer backside pressure is applied to the wafer during the planarization process, and the interaction between the polishing pad and the wafer, which typically differs in the wafer center region and wafer edge. It includes uniformity and non-uniform deposition (deposition) of metal and / or oxide layers that may be preferably compensated for by planarizing or adjusting the removal profile of the material during the polishing process. Attempts to solve the above problems simultaneously have not been completely successful so far.

  With regard to the nature of the polishing pressure on the back side of the wafer, conventional machines typically have a hard back head (hard back head) to press the wafer against the polishing surface, ie a hard receiving that directly presses the back of the semiconductor wafer. A head having a surface is used. As a result, any variation in the receiving surface of the head, or the presence of any material trapped between the wafer and the receiving surface, will apply non-uniform pressure on the backside of the wafer. Therefore, the surface of the wafer will not conform to the polished surface, resulting in non-uniform planarization. In addition, such a hard back head design provides a relatively high polishing pressure (eg, a pressure in the range of about 6 psi to about 8 psi) to obtain a reasonable degree of flexibility between the wafer and the polishing surface. Must be used. Such a relatively high pressure effectively deforms the wafer, removing too much material from one area of the wafer and removing too little material from other parts. , Resulting in poor quality flattening.

  Attempts have been made to eliminate the above-mentioned problems associated with hard back heads and in an attempt to provide some softness in the hard back system, an insert is provided between the receiving surface and the wafer to be polished. This insert is often called a wafer insert. These inserts have the problem of often resulting in process variations that lead to wafer-to-wafer variations. This variation is not constant, i.e. it is not deterministic. One factor of variation is the absorption of other fluids such as water or slurry used in the polishing process. Since the amount of water absorbed by the insert increases during its lifetime, there are often process variations between wafers. These process variations can be controlled to a limited extent by pre-conditioning the insert in water prior to use and replacing the insert before its property change exceeds acceptable limits. This is like making the initial usage period a later usage period, but this will increase the maintenance cost of the device and reduce the throughput of the process. In addition, unacceptable process variations are still observed due to, for example, insert thickness variations, insert wrinkles, and material trapped between the hard back head and insert or between the insert and wafer.

  Moreover, when using an insert, the fine adjustment of the whole surface where an insert is stuck is needed. This is because any non-uniformity of the surface, surface imperfections, i.e. deviations from the flatness or parallelism of the head surface, appear as variations in flatness across the wafer surface. For example, in a conventional head, an alumina or ceramic plate is made and then lapped and polished before installing the head. According to such a manufacturing method, the cost of the head increases and the cost of the entire apparatus increases. In particular, in the case of a multi-head, the cost of the apparatus increases and the cost of the apparatus increases.

  On the other hand, when a soft back head (soft back head) is used, the wafer is pressed against the polishing pad, but the wafer does not deform due to the soft material of the insert. As a result, a low polishing pressure can be used, and the conformity of the wafer surface to the polishing pad (conformability) can be achieved without deformation, and thus both polishing uniformity and good planarization can be achieved. Since the polishing rate in similar features between dies on the wafer is the same, better planarization uniformity is obtained, at least in part.

  In recent years, attempts have been made to use a soft back head, but this attempt has not been completely satisfactory. One such soft back head is described in US Pat. No. 6,019,671 (inventor Shendon), which is hereby incorporated by reference. Shendon teaches forming a chamber or cavity that is pressurized to press the substrate against the polishing surface with a membrane or flexible member stretched on the underside of the head. While significant improvements have been made to hardback heads with or without inserts, this approach as a whole is not sufficient for a number of reasons. One problem with this approach is that non-uniformities due to material trapped between the membrane and wafer have not been reduced or eliminated. Another problem is that during the load or unload operation, the membrane cannot use a vacuum to hold the wafer to the head. In addition, the use of membranes increases non-uniformity by introducing new variables such as membrane wrinkles that can actually occur due to variations in membrane surface thickness and flexibility and improper placement. doing.

  Other softback head designs use a seal between the edge of the wafer and the head to form a cavity that is pressurized to directly press the wafer against the polishing surface during polishing and planarization. doing. One approach is described in US Pat. No. 5,635,083, inventor Breivogel et al., Which is hereby incorporated by reference. Bravogel teaches the use of a lip seal against the outer periphery of the backside of the wafer to form a seal through which pressurized air is introduced between the head and the wafer. Unfortunately, such an approach provides a soft back head that eliminates some of the problems associated with soft back heads with hard back heads and membranes, but it does not provide torque on the machine in which the head rotates during the polishing process. To provide sufficient engagement between the wafer and the receiving surface. Another problem with this approach is that a vacuum can be used to hold the wafer to the head, but because the wafer is supported only at the periphery, unacceptable warpage occurs, resulting in wafer damage or loss. Result.

  With regard to correcting or compensating for the edge polishing effect, attempts have been made to adjust the shape of the retainer ring and change the pressure of the retainer ring so that the amount of material removed from the wafer near the retainer ring is changed. Typically, more material is removed from the wafer edge, i.e., the wafer edge is overpolished. To correct this over-polishing, the pressure on the retainer ring is usually adjusted to be somewhat higher than the pressure on the backside of the wafer, which causes the polishing pad in the area of the retainer ring to be somewhat compressed by the retainer ring. Less material is removed from the wafer within a few millimeters of the retainer ring. However, these attempts have not been fully satisfactory since the planarization pressure at the outer periphery of the wafer can only be adjusted indirectly based on the retainer ring pressure. It is impossible to extend the effective distance of the compensation effect of the retainer ring to an arbitrary distance from the edge of the wafer. In order to obtain the desired result, the pressure of the retainer ring, the edge pressure, or the pressure across the backside of the wafer could not be adjusted independently.

  Another problem with retainer ring in conventional CMP heads is that a predetermined point on the lower surface of the retainer ring corresponds to a predetermined portion of the wafer held by the subcarrier throughout the polishing operation. Thus, high or low points on the lower surface of the retainer ring result in non-planar polishing of the wafer. Although it is possible to machine the lower surface of the retainer ring to have a high degree of flatness, this is an expensive choice, especially because the retainer ring is a consumable that wears as the wafer is polished. This is because it must be replaced.

  With regard to the degree of preference of the method of adjusting the material removal profile to adjust for non-uniform deposition of incoming wafers, attempts have been made to provide a method or machine that provides such compensation. But it is not satisfactory. Non-uniform deposition may result from the structure of the circuit formed on the wafer or from the properties of the deposited layer. For example, an increasingly common copper layer in high speed integrated circuits tends to form a convex layer that is thicker at the center of the wafer than at the edge. Therefore, it is preferable to have a polishing method and apparatus that provide a higher polishing rate near the center of the wafer than at the edge.

  A final problem with conventional CMP apparatus and methods is inefficient use and waste of the slurry. A slurry is a chemically active liquid that typically contains suspended abrasive grains that are used to increase the rate at which material is removed from the substrate surface. Since the slurry is fed to the polishing surface in front of the head, typically the surplus is used to ensure that the slurry covers the entire surface between the wafer and the polishing surface as the slurry flows to the polishing surface. Slurry must be supplied. The slurry is expensive because of the stringent requirements regarding the purity of the slurry and, in particular, the size of the abrasive grains suspended in the slurry. Furthermore, to avoid contamination and to obtain consistent results, the slurry is generally not recycled and not recycled. Therefore, an important factor in the operating cost of the conventional CMP apparatus is the cost of the slurry.

  Therefore, in order to compensate for non-uniform film formation on the wafer, an apparatus and method for performing an excellent planarization process, controlling the effect of edge planarization, and adjusting the material removal profile from the wafer The need remains. There is a further need for an apparatus and method that allows a wafer to be held by a vacuum on a soft back head while minimizing or eliminating stress on the wafer. There is a further need for a CMP apparatus that does not waste excessive amounts of slurry and supplies sufficient slurry to the polishing surface.

  The present invention generally relates to a CMP system, apparatus and method for polishing and planarizing a substrate that achieves a high degree of planarization uniformity across the entire surface of the substrate. The present invention includes many systems, apparatus, structures and methodological aspects relating to chemical mechanical polishing (CMP). In one aspect, the present invention provides a chemical mechanical polishing and method with a polishing surface having a non-uniform recess. In another aspect, the present invention provides a chemical mechanical polishing head and method with an integral slurry dispensing mechanism. In yet another aspect, the present invention provides a chemical mechanical polishing apparatus and method with a rotating retainer ring. In yet another aspect, the present invention provides a chemical mechanical polishing apparatus and method with a soft-back polishing head. In yet another aspect, the present invention provides an apparatus and method that provides for more efficient use of slurry in polishing and planarization processes.

The polishing head of the present invention is a polishing head for positioning a substrate having a surface on the polishing surface of a polishing apparatus, and includes a carrier having a bottom surface, the bottom surface holding the substrate during the polishing process. The carrier includes a plurality of ports extending through the bottom surface around the lower surface to distribute the abrasive material to the polishing surface during the polishing process, the carrier during the polishing process A subcarrier having a receiving surface on which the substrate is held, and the retainer ring is rotatably arranged around the subcarrier and separated from the subcarrier by an annular space , said retainer ring, each of the individual drive mechanism is rotatably configured independently, the retainer ring, the substrate on the sub-carrier during the polishing process different It is characterized in that at Tsu speed it is possible to rotate.
According to a preferred aspect of the present invention, the plurality of ports distribute slurry containing an abrasive to the polishing surface.
According to a preferred aspect of the present invention, the plurality of ports are arranged in a retainer ring.

According to a preferred aspect of the present invention, the plurality of ports are arranged in an annular space between the retainer ring and the subcarrier.
According to a preferred aspect of the present invention, the plurality of ports are arranged at equal intervals around the annular space between the retainer ring and the subcarrier.
According to a preferred aspect of the present invention, the plurality of ports include 2 to 30 ports.
According to a preferred aspect of the present invention, the plurality of ports are further configured to wash an annular space between the retainer ring and the subcarrier during a maintenance operation.

The chemical mechanical polishing apparatus of the present invention includes a polishing surface and the polishing head for positioning a substrate on the polishing surface.
The polishing method of the present invention is a method for polishing a substrate having a surface using a polishing apparatus comprising a polishing surface and a carrier having a bottom surface including a lower surface adapted to hold the substrate during the polishing step. The method includes positioning the substrate on the lower surface of the carrier, urging the carrier against the polishing surface so as to press the surface of the substrate against the polishing surface, and polishing the polishing material through the bottom surface of the carrier. And the carrier includes a subcarrier having a receiving surface on which the substrate is held during the polishing process, and the retainer ring is rotatably disposed around the subcarrier and is subdivided by the annular space. being adapted to be separated from the carrier, said retainer ring and subcarrier, respectively by separate drive mechanisms, are configured to be rotatable independently, the retainer The nulling, is characterized in that rotated at different speeds than the substrate on the sub-carrier during the polishing process.
According to a preferred aspect of the present invention, the polishing apparatus includes a slurry supply unit capable of supplying a slurry containing an abrasive to a plurality of ports, and the step of distributing the polishing substance to the polishing surface includes the slurry on the polishing surface. It is characterized by comprising the step of distributing.
According to a preferred aspect of the present invention, the polishing apparatus includes a cleaning fluid supply unit that can supply a cleaning fluid to a plurality of ports, and a valve that switches between the slurry supply unit and the cleaning fluid supply unit. The method further includes the step of cleaning the plurality of ports after polishing the substrate.

A polishing head according to the present invention is a polishing head for positioning a substrate having a surface on a polishing surface of a polishing apparatus, and is suspended from a carrier that holds the substrate during a polishing process. A retainer ring and means for distributing chemicals from the polishing head to the polishing surface during the polishing process, the retainer ring being arranged around a substrate held by a carrier, said carrier being held by the substrate during the polishing process The retainer ring is rotatably arranged around the subcarrier and is separated from the subcarrier by an annular space, the subcarrier and the retainer ring being each by a separate drive mechanism, and configured to be rotatable independently of the retainer ring, on the sub-carrier during the polishing process It is characterized in that the substrate is capable of rotating at different speeds.
According to a preferred aspect of the present invention, the means for distributing the chemical substance from the polishing head comprises means for distributing a slurry containing an abrasive to the polishing surface.
According to a preferred aspect of the present invention, the means for distributing the chemical substance from the polishing head comprises a plurality of ports arranged in the retainer ring.
According to a preferred aspect of the present invention, the plurality of ports are arranged in an annular space between the retainer ring and the subcarrier.

  According to another aspect of the present invention, a polishing head is provided for positioning a substrate having a surface on a polishing surface of a polishing apparatus for performing a process of removing material from the substrate. The polishing head includes a carrier with a flexible member such as a membrane that is attached to the lower surface on which the substrate is held during the polishing operation. The flexible member (a member having flexibility) includes a receiving surface adapted to receive a substrate and a plurality of holes extending through the flexible member on the receiving surface. When the substrate is held on the receiving surface of the flexible member, a closed cavity or chamber is formed by the lower surface of the carrier, the flexible member, and the substrate. The cavity is adapted to press the substrate directly against the polishing surface during the polishing operation. Preferably, if the carrier comprises a drive mechanism for rotating the subcarrier during the polishing operation, the number and size of the holes is sufficient between the receiving surface of the flexible member and the substrate to impart rotational energy to the substrate. Selected to provide frictional force.

  In one embodiment, the lower surface of the subcarrier includes a port for introducing pressurized fluid into the cavity and a flow path that distributes the pressurized fluid throughout the cavity. The port can be used to evacuate the cavity to hold the substrate on the receiving surface during loading and unloading operations before and after the polishing process. The polishing apparatus further includes a vacuum switch connected to the port for detecting that the substrate is held on the receiving surface. The vacuum switch is configured to switch from open to closed or from closed to open when a predetermined degree of vacuum is reached. In the modification of this embodiment, the flexible member, the substrate and the port function as a valve for separating the port from the cavity when a predetermined degree of vacuum is reached. When a vacuum is formed in the cavity, the hole is sealed by the substrate and the flexible member is pulled inward until the flexible member contacts and seals a port on the lower surface of the subcarrier. The port may or may not have a protruding lip to facilitate sealing. This design can be controlled such that the degree of vacuum, and therefore the degree of deformation of the flexible member and the substrate, minimizes the stress applied to the substrate.

  According to another aspect of the present invention, a polishing head is provided for positioning a substrate having a surface on a polishing surface of a polishing apparatus for performing a process of removing material from the substrate. The polishing head includes a carrier, a subcarrier supported by the carrier and configured to hold the substrate during a polishing operation, and a retainer ring disposed rotatably about the subcarrier. The retainer ring has a lower surface that is substantially flush with the surface of the substrate held by the subcarrier during processing, and the lower surface of the retainer ring is in contact with the polishing surface. The retainer ring deforms the polishing surface and reduces the polishing rate of the material removed from the edge portion of the substrate. In conventional carriers, variations in the lower surface of the retainer ring or bumps cause a local polishing rate of the material from the edge of the substrate adjacent to the bumps. However, with the carrier of the present invention, the retainer ring can be rotated relative to the subcarrier and hence relative to the substrate during processing, so that the lower surface of the retainer ring with respect to the removal rate of material from the edge of the substrate. The effects of fluctuations are minimized.

  In one embodiment, the subcarrier is driven by a drive mechanism, and the retainer ring rotates relative to the subcarrier by the frictional force between the retainer ring and the polishing surface. The retainer ring can also be rotated relative to the subcarrier by a single drive mechanism connected to the retainer ring.

  In another embodiment, the carrier includes a backing ring facing the top surface of the retainer ring and separated from the retainer ring by a bearing. The backing ring is adapted to apply pressure to the retainer ring during the polishing operation. The bearing can comprise, for example, a ball bearing, a fluid bearing, a roller bearing, or a tapered bearing. The retainer ring may further include a first lip that engages the second lip of the backing ring to connect the retainer ring to the backing ring when the carrier is raised from the polishing surface.

  In another aspect, the invention relates to a polishing apparatus for removing material from a surface of a substrate. The polishing apparatus is configured to perform a chemical reaction between the polishing head designed to hold the substrate during the polishing process, and the substrate held by the polishing head and the polishing surface when there is relative movement between the substrate and the polishing surface. And a polishing surface having a number of recesses for dispensing the substance. A number of recesses are provided with non-uniform spacing on the polishing surface to provide a variable polishing rate for removing material from the polishing surface. The spacing of the recesses in the polishing surface varies from the first region to the second region so as to provide a polishing rate difference between the first region and the second region. In general, when the first region has more dense recesses per inch than in the second region, the first region has a lower polishing rate than the second region. In one embodiment, the multiple recesses comprise grooves of non-uniform size or non-uniform radial spacing on the polishing surface. The recess also has a number of open cavities or depressions in the polishing surface, and the size and / or density of the cavities or depressions varies on the polishing surface.

  One problem with the conventional CMP apparatus is that the slurry is distributed to the polishing surface in front of the polishing head, so that when the slurry flows over the polishing surface, the slurry covers the entire surface between the substrate and the polishing surface. This means that excess slurry must be dispensed to ensure The polishing head according to the present invention comprises a plurality of ports for distributing the polishing substance (slurry) to the polishing surface during the polishing process, thereby ensuring that the entire surface between the substrate and the polishing surface is covered, Slurry waste is reduced or eliminated.

Various features and advantages of the present invention will become apparent from the following detailed description when read in conjunction with the accompanying drawings.
FIG. 1 is a schematic diagram showing a multi-head CMP polishing or planarizing apparatus as a specific example. FIG. 2 is a schematic view showing a side sectional view of the polishing head according to the embodiment of the present invention. FIG. 3 is a plan view showing a part of the polishing head of FIG. 2 taken along line 3-3 of FIG. 2 showing an embodiment of a flexible member (flexible member) according to the present invention. FIG. 4 is a plan view similar to FIG. 3 of another embodiment of a flexible member according to the present invention. FIG. 5 is a plan view similar to FIG. 3 of yet another embodiment of a flexible member according to the present invention. FIG. 6 is a plan view similar to FIG. 3 of still another embodiment of the flexible member according to the present invention. FIG. 7 is a plan view similar to FIG. 3 of yet another embodiment of a flexible member according to the present invention. 8 is a cross-sectional view of the polishing head of FIG. 2 taken along line 8-8 of FIG. 2 according to an embodiment of the present invention. FIG. 9 is a schematic view showing a plan view of the lower surface of a subcarrier having a grooved lower surface according to an embodiment of the present invention. FIG. 10 is a schematic view showing a partial cross-sectional view of a polishing head provided with a rotating retainer ring according to an embodiment of the present invention. FIG. 11 is a schematic diagram showing a partial cross-sectional view of a polishing head provided with an integral supply mechanism for supplying a chemical substance (chemical solution) to a polishing surface according to an embodiment of the present invention. FIG. 12 is a schematic diagram showing a partial cross-sectional view of a polishing head having an integral supply mechanism for supplying a chemical substance to a polishing surface through an annular space between a retainer ring and a subcarrier according to another embodiment of the present invention. is there. FIG. 13A is a schematic diagram illustrating a plan view of a polishing surface having a plurality of grooves with non-uniform spacing according to an embodiment of the present invention. 13B is a schematic diagram illustrating a partial cross-sectional side view of the polished surface of FIG. 13A. FIG. 14 is a schematic diagram showing a plan view of another embodiment of a polishing surface with non-uniformly spaced helical grooves. FIG. 15 is a schematic diagram showing a plan view of another embodiment of a polishing surface with a number of non-uniformly spaced helical grooves. FIG. 16 is a schematic diagram showing a plan view of another embodiment of a polishing surface with concentric elliptical grooves with non-uniform spacing. FIG. 17 is a schematic diagram showing a top view of an embodiment of a linear polishing surface with parallel grooves with non-uniform spacing. FIG. 18 is a schematic diagram illustrating a partial cross-sectional view of a polished surface having a plurality of uniformly spaced grooves having a non-uniform depth according to an embodiment of the present invention. FIG. 19 is a schematic diagram showing a partial cross-sectional view of a polished surface having a plurality of uniformly spaced grooves having a non-uniform width according to an embodiment of the present invention. FIG. 20 is a schematic view showing a plan view of a polishing surface provided with non-uniformly spaced cavities according to an embodiment of the present invention. FIG. 21 is a flowchart illustrating an embodiment of a process for polishing or planarizing a substrate according to an embodiment of the present invention.

  An improved method and apparatus for polishing or planarizing a substrate is provided. In the following description of embodiments, numerous embodiments are disclosed that include specific details such as specific structure, arrangement, material, shape, and the like. However, it will be apparent to those skilled in the art that the present invention may be practiced without these specific details, and that the method and apparatus of the present invention are not so limited. FIG. 1 shows a chemical mechanical polishing or planarization (CMP) apparatus 100 for polishing a substrate 105. As used herein, the term “polishing” means polishing or planarization of the substrate 105, and the substrate includes a substrate used in a liquid crystal monitor and a solar cell, and particularly includes a semiconductor substrate or wafer on which an electric circuit element is formed. It is out. The semiconductor wafer is typically a thin and fragile disc having a diameter of 100 mm to 300 mm. Currently, 100 mm, 200 mm, and 300 mm semiconductor wafers are widely used in industry. The method and apparatus 100 of the present invention is applicable to semiconductor wafers and other substrates 105 up to a diameter of at least 300 mm, and is also applicable to larger diameter substrates.

  For clarity, many of the detailed structures of the CMP apparatus 100 that are widely known and not relevant to the present invention have been omitted. CMP apparatus 100 is described, for example, in US patent application Ser. No. 09 / 570,370, filed May 12, 2000, “System and Method for Pneumatic Diaphragm Heads With Independent Retainer Rings and Multi-Regional Pressure Control”, Application No. 09 / 570,369, filed May 12, 2000, “System and Method for CMP with Multi-Pressure Region Load for Improved Edge and Annular Region Material Removal Control”, and May 2000 US Provisional Application No. 60 / 204,212, filed 12 days, "System and Method for CMP with Multi-Pressure Annular Subcarrier Material Removal Control". These applications are hereby incorporated herein by reference in their entirety.

  The CMP apparatus 100 includes a base 110 that rotatably supports a large rotatable platen 115 having a polishing pad 120 and a polishing pad having a polishing surface 125 on which a substrate 105 is polished. The polishing pad 120 is typically made of a polyurethane material, such as that obtained from RODEL of Newark Delaware, Delaware. In addition, a number of recesses (not shown in FIG. 1) such as grooves or cavities are provided on the polishing surface to distribute chemicals or slurries between the polishing surface and the surface of the substrate 105 disposed on the polishing surface. 125 can be provided. A slurry is a chemically active liquid that contains suspended abrasive grains that are used to increase the rate at which material is removed from the substrate surface. Typically, the slurry is chemically active with at least one material of the substrate 105 and has a pH of about 4-11. For example, one suitable slurry is one containing about 12% abrasive grains and 1% oxidizer on a water base and having a particle size of about 100 nanometers (nm). Contains colloidal silica or alumina. Alternatively or in addition to the slurry, the polishing surface 125 of the polishing pad 120 may be fixed abrasive grains embedded in the pad as obtained from Minnesota Mining and Manufacturing Company. . In the embodiment of the CMP apparatus 100 having the polishing surface 125 with fixed abrasive grains, the chemical (abrasive) supplied to the polishing surface during the polishing process may be water.

  The base 110 also supports a bridge 130 that supports a carousel 135 with one or more polishing heads 140 on which the substrate 105 is held during the polishing operation. The bridge 130 raises and lowers the carousel 135 to bring the surface of the substrate 105 held by the polishing head 140 into contact with the polishing surface 125 during the polishing process. This particular embodiment of the CMP apparatus 100 shown in FIG. 1 is a multi-head design, which means that there are multiple polishing heads 140 for each carousel 135. However, a single head CMP apparatus 100 is known, and the polishing head 140, polishing surface 125 and polishing method of the present invention can be used with a multi-head type polishing apparatus or a single head type polishing apparatus. is there. Further, in this particular CMP design, each of the polishing heads 140 is driven by a single motor 142 that drives a chain 145, which drives each polishing head through a chain and sprocket mechanism (not shown). To drive. However, the present invention is also used in embodiments where each polishing head 140 is rotated by a separate motor and / or by something other than a chain and sprocket type drive. In addition to the rotation of the polishing pad 120 and the polishing head 140, the carousel 135 can orbit about a fixed central axis of the polishing platen 115 to provide orbital motion to the polishing head. Further, the polishing head 140 of the present invention can be used in the CMP apparatus 100 of all modes including a machine using a linear motion, that is, a reciprocating motion as is well known in the art.

  As described above, the CMP apparatus 100 also includes a chemical substance supply mechanism (not shown in FIG. 1) for supplying a chemical substance or slurry to the polishing surface 125 during the polishing process, and supply of the slurry to the polishing surface. A controller (not shown) that controls the movement of the polishing head 140 and a pressurized fluid such as air, water, and vacuum are communicated between a fixed source outside the polishing head and a position on or in the polishing head. And a rotary union (not shown) that provides a number of different flow paths.

  An embodiment of a polishing head 140 according to the present invention will be described with reference to FIG. In FIG. 2, the polishing head 140 includes a head mounting assembly 150 for attaching the polishing head to the carousel 135 and a carrier 155 that holds the substrate 105 during the polishing operation and positions the substrate on the polishing surface 125. . The carrier typically includes a subcarrier 160 having a lower surface 165 on which the substrate is held, and a retainer ring 170 disposed circumferentially around the subcarrier portion.

  The subcarrier 160 and the retainer ring 170 are suspended from the carrier 155 so that the subcarrier 160 and the retainer ring 170 can move up and down with almost no friction and no binding. The subcarrier 160 and the retainer ring 170 may be connected between the subcarrier 160 and the retainer ring 170 so that the subcarrier 160 and the retainer ring 170 can float on the polishing surface 125 in a manner that allows small angular variations during the polishing process. Small mechanical tolerances are provided between and between adjacent elements. In FIG. 2, the flange 162 is attached to the inner lower surface 164 of the carrier 155 by screws 163 or other fasteners. The flange 162 is coupled to the inner support ring 167 and the outer support ring 168 via a flexible membrane or gasket 166, and supports the subcarrier 160 flexibly and is closed above the subcarrier 160. A chamber or cavity 175 is formed. The retainer ring 170 is supported by a second flexible membrane or gasket 176 that extends between the subcarrier 160 and the skirt 177 of the carrier 155. As shown in FIG. 2, the retainer ring 170 is connected to the second gasket 176 via an adhesive (not shown) or screws 179 or other fasteners attached to the backing plate 178 on the opposite side of the gasket. ing. The flange 162, the lower skirt 177, the inner and outer support rings 167, 168, and the second gasket form a second closed cavity 180 above the retainer ring 170.

  During operation, the subcarrier 160 and the retainer ring 170 are independently urged or pressed against the polishing surface 125 while slurry is supplied to the polishing surface 125 and relative movement between the substrate 105 and the polishing surface occurs. And the substrate is polished. The biasing force is generated by the weight of a spring (not shown) or subcarrier 160 and retainer ring 170. Preferably, as shown in FIG. 2, the subcarrier 160 and the retainer ring 170 are each by a pressurized fluid introduced into a sealed cavity or chamber 175, 180 above the subcarrier 160 and the retainer ring 170. Pressed against the polishing surface 125. The use of pressurized fluid is preferred because the application of force can change more uniformly and more quickly to adjust the polishing rate or removal rate. In general, the applied pressure ranges between about 4.5 and 5.5 psi, more typically about 5 psi. However, these ranges are merely exemplary because the pressure can be adjusted in the range of about 2 psi to about 8 psi to obtain the desired polishing or planarization effect. More preferably, the biasing force or pressure applied to the retainer ring 170 is greater than the biasing force or pressure applied to the subcarrier 160 to slightly deform the polishing surface 125, thereby reducing the so-called edge effect and reducing the substrate 105 A more uniform polishing rate or planarization rate of the surface of the substrate can be obtained. The edge effect is that the polishing rate at the edge portion of the substrate tends to be larger than the polishing rate at the center portion of the substrate due to the interaction between the edge portion of the substrate and the polishing surface 125. By pressing and slightly deforming the polishing surface 125 near the edge of the substrate 105, the retainer ring 170 reduces the force with which the edge of the substrate is pressed against the polishing surface, thereby local polishing. Reduce the speed to a level approximately equal to the polishing rate of other areas of the substrate surface.

  In accordance with the present invention, the subcarrier 160 can include a flexible insert 185 having a receiving surface 190 on which the substrate 105 is received on the lower surface 165 or a soft insert such as a membrane. The flexible member 185 applies a pressurized fluid at least partially directly to the back surface of the substrate 105 to press the substrate directly against the polishing surface 125, and therefore the receiving surface through the thickness of the flexible member. It has a predetermined thickness with a plurality of openings or holes 195 extending to 190. In general, the applied pressure ranges between about 2-8 psi, more typically about 5 pi. Preferably, during the polishing process, it is directly exposed to the pressurized fluid while ensuring sufficient area of the receiving surface 190 that engages or contacts the substrate 105 that provides torque or rotational energy from the polishing head 140 to the substrate. The area of the substrate 105 is selected to be maximized. The flexible member 185 of the present invention has the following advantages. (I) The ability to reduce or eliminate the impact on the polishing uniformity of particles or impurities trapped between the receiving surface 190 and the substrate 105 by reducing the area where the particles are trapped. (Ii) Ability to reduce or eliminate non-uniformities in polishing due to substrate wrinkling. (Iii) Ability to reduce or eliminate polishing non-uniformity by variation in the thickness of the flexible member 185. The flexible member 185 and the hole 195 or opening formed in the flexible member will be described in detail later.

  In addition, the retainer ring 170 is suspended rotatably from the backing ring 200 on the carrier 155, allowing the retainer ring 170 to rotate at a different speed than the substrate 105 on the subcarrier 160 during the polishing process. ing. The backing ring 200 applies pressure to the retainer ring 170 during the polishing process. There are two advantages of providing a retainer ring 170 that is rotatably disposed about the substrate 105. First, since the substrate 105 and the retainer ring 170 rotate at different speeds, during the polishing process, it corresponds to closely follow a point on the edge portion of the substrate as a point on the lower surface 205 of the retainer ring. There is no point. Therefore, the effect of high or low points on the lower surface 205 of the retainer ring 170 on the polishing rate at the edge of the substrate is reduced if not removed, thereby suppressing uneven polishing of the surface of the substrate 105. . Second, since the influence of the high and low points on the lower surface 205 of the retainer ring 170 is minimized, the lower surface 205 of the retainer ring does not need to be finished to a high degree of flatness, and therefore Manufacturing cost can be reduced. Furthermore, since the retainer ring 170 is a consumable that wears as the substrate 105 is polished, a reduction in the cost of the retainer ring can greatly reduce the operating cost of the CMP apparatus 100. The rotating retainer ring 170 is described in detail below.

  The flexible member 185 will be described with reference to FIGS. 2 and 3 to 7. 3-7 illustrate various embodiments of the receiving surface 190 and the hole 195 provided in the receiving surface. In FIG. 2, the flexible member 185 is typically made from a polymeric material such as EPDM, EPR, silicon, or rubber that does not react with the substrate 105 and does not react with chemicals used during the polishing process. ing. The flexible member 185 is spread and separated on the lower surface 165 of the subcarrier 160 by an annular or ring-shaped edge or cornering piece 210, and the lower surface 165 of the subcarrier 160, the cornering piece 210, the flexible member 185. A lower cavity 215 formed by the back surface of the substrate 105 held on the receiving surface 190 of the flexible member 185 is formed. Pressurized fluid is introduced into the lower cavity 215 via a passage 220 connected to a port 225 on the lower surface 165 of the subcarrier 160. The lower ring piece 210 can be formed from an incompressible or substantially incompressible material, such as a metal or a hard polymeric material, and can be made of a compressible or soft material such as soft plastic, rubber, silicon or similar material. When formed from an elastic material, the edge effect can be further reduced.

  FIG. 3 shows a plan view of the receiving surface 190 of the flexible member 185 according to the embodiment of the present invention. In this figure, a number of holes 195 are shown regularly and symmetrically spaced on the receiving surface 190. As described above, the number and size of the holes 195 is sufficient to provide a receiving surface 190 with sufficient area to contact the substrate 105 to apply torque or rotational energy from the polishing head 140 to the substrate to rotate the substrate during the polishing process. Have been selected to get. It has been found that sufficient engagement is obtained when the total area of the holes 195 is from about 50% to about 90%, more preferably from about 66 to about 75% of the surface area of the receiving surface. In a preferred embodiment, the hole 195 can have an edge that is angled with respect to the direction of rotation of the polishing head 140, thereby increasing the rigidity of the flexible member 185, and the flexible member and substrate. The engagement with 105 can be increased, thereby increasing the torque. For example, in the hole 195 having the shape shown in FIG. 3, the engagement force increases when the polishing head rotates in the clockwise direction.

Alternative designs and patterns for the holes 195 in the receiving surface 190 of the flexible member 185 are shown in FIGS.
FIG. 4 is a schematic diagram illustrating a top view of another embodiment of a flexible member 185 having smaller and larger holes 195 rather than more regularly spaced and angled edges. FIG. 5 is a schematic diagram illustrating a top view of another embodiment of a flexible member 185 having a number of circular holes 195. In the illustrated embodiment, the holes 195 all have the same diameter, but it will be understood that the size and number of holes may vary on the receiving surface 190 without departing from the scope of the present invention. I can do it. FIG. 6 shows another embodiment of the flexible member 185 having a plurality of chevron or arrow-shaped holes 195 arranged circumferentially around the receiving surface 190 of the flexible member 185. It is the schematic which shows the top view of embodiment. Although not shown, the flexible member 185 can have a second ring-shaped hole 195 inside and concentrically with the first hole. The chevron holes 195 in the second ring can point in the same or opposite direction as the holes in the first ring. However, directing the chevron in the opposite direction to the rotation of the polishing head 140 increases the engagement between the flexible member 185 and the substrate 105, thereby increasing torque. A plan view of another embodiment of the flexible member 185 is shown in FIG. In FIG. 7, hole 195 consists of two relatively large openings or holes. Also, although shown as circular, the holes 195 may be regular or irregular shapes including polygons and ellipses, and each hole need not be the same shape or size as the other holes.

  In FIG. 8, in another aspect of the present invention, a flexible member 185 having a raised lip 230 on the port 225 and the substrate 105 on the lower surface 165 of the subcarrier 160, the port 225 is vacuumed into the lower cavity. When used to form the, the isolation valve 235 functions to isolate the port 225 from the lower cavity 215. During the polishing operation, when the substrate 105 is not in contact with the polishing surface 125, a vacuum is introduced into the lower cavity 215 to hold the substrate 105 on the receiving surface 190. For example, during loading and unloading operations before and after the polishing process. The problem with conventional polishing heads that have soft inserts and hold the substrate to the head using vacuum is that the deformation of the insert causes stress on the substrate, especially from the flat surface of the insert to the concave shape. The stress is generated near the edge of the substrate where the deformation of the substrate is the largest, thereby leading to damage or loss of the entire substrate. Depending on the process in which the loss occurs, the loss of the semiconductor substrate can be in the thousands of dollars. Accordingly, an advantage of the present invention is that by selecting a separation between the flexible member 185 and the lip 230 of the port 225, the port separates (isolates) from the lower cavity 215 when a predetermined vacuum level is reached. ). The predetermined degree of vacuum provides sufficient force to hold the substrate 105 on the receiving surface 190 while reducing deformation of the flexible member 185 and thereby reducing stress on the substrate. Selected. The CMP apparatus 100 can further include a vacuum switch 240 or transducer, as schematically shown in FIG. 8, which is connected to the port 225 and at a predetermined degree of vacuum. It is used to detect the presence of the substrate 105 on the receiving surface 190 by switching or changing state when it arrives.

  The hole 195 in the flexible member can be sized and positioned as shown in FIG. 8, so that the hole 195A opposite the port 225 has a smaller diameter than the lip 230 around the port. And the edge of the hole seals the port against the substrate 105. This embodiment has the advantage that a vacuum can act directly on the substrate 105 and evacuates and removes the air pockets between the substrate and the receiving surface 190. Also, in another embodiment (not shown), the size and arrangement of the holes 195 can be selected such that a substantially unbroken region of the flexible member 185 faces the port 225. This embodiment has the advantage of reducing or eliminating possible failures (malfunctions) of the isolation valve 235 due to misalignment of the holes 195 and ports 225.

  In another embodiment shown in FIGS. 2 and 9, the lower surface 165 of the subcarrier 160 facilitates evacuation of the lower cavity and facilitates introduction of pressurized fluid into the lower cavity during the polishing process. For this purpose, a spacer 243 having one or more grooves or passages 245 disposed between the port 225 and the outer portion of the lower cavity 215 is provided. The spacer 243 may be composed of another member located on the lower surface 165 of the subcarrier 160 or attached by an adhesive or a mechanical fastener. Further, as shown in FIG. 9, the passage 245 is directly processed on the lower surface 165 of the subcarrier 160 to form the spacer 243. FIG. 9 is a schematic diagram illustrating a plan view of a lower surface 165 of a subcarrier 160 having a number of symmetrically spaced radial passages 245 according to an embodiment of the present invention. In a further improvement of this embodiment, the separation between the flexible member 185 and the raised or flat portion between the passages 245 on the lower surface 165 is such that when a vacuum is formed in the lower cavity 215, It is selected to further reduce the deformation of the flexible member 185, thereby supporting the substrate 105, preventing excessive warping of the substrate, and reducing stress on the substrate. The exact separation depends on a number of factors including the size or diameter of the substrate 105 and the receiving surface 190. For a semiconductor substrate 105 having a diameter of about 200, it has been found that a suitable separation is about 100 microns (μ) or less.

  The rotating retainer ring 170 will be described with reference to FIGS. 2 and 10 show different embodiments of rotating retainer rings. In FIG. 2, the retainer ring 170 has an upper surface 255 in a relationship facing the lower surface 260 of the backing ring 200 and is separated from the backing ring by a bearing 260. The bearing 260 includes a ball bearing, a fluid bearing, a roller bearing, or a taper bearing. In the embodiment shown in FIGS. 2 and 10, the bearing 260 is a roller bearing that includes an inner race or housing 265, a number of balls 270, and an outer race 275 formed on the retainer ring 170. In addition, a small annular space 280 is provided between the retainer ring 170 and the subcarrier 160 so that the retainer ring 170 and the subcarrier 160 can rotate relative to each other during the polishing operation. It has become.

  Preferably, the retainer ring 170 includes a mechanism for connecting the retainer ring to the carrier 155 when the polishing head 140 is raised from the polishing surface 125. In the embodiment shown in FIG. 2, the connection is made by a first lip 285 of the retainer ring 170 that engages a second lip 290 of the backing ring 200 when the polishing head 140 is raised from the polishing surface 125. In the embodiment shown in FIG. 10, the first lip 285 is formed using a number of bolts 295, each bolt being associated with the second lip 290 of the backing ring 200 as the carrier 155 is raised from the polishing surface 125. In order to match, a shaft portion 300 screwed to the retainer ring 170 or the bearing housing 265 and a head portion 305 having a surface 310 protruding radially outward from the shaft portion are provided. Preferably, there are at least three bolts 295 that are evenly spaced around the retainer ring 170 to securely connect the retainer ring to the backing ring 200.

  As described above, even if the influence of the high point or the low point on the lower surface 205 of the retainer ring 170 is not lost, the rotating retainer ring 170 is rotated to reduce the polishing rate (removal rate) of the material on the surface of the substrate 105. ) And the uniformity of the flatness of the substrate. The retainer ring 170 is rotatable relative to the subcarrier 160 by a frictional force between the retainer ring and the polishing surface 125 during the polishing process, and this frictional force is slower than the subcarrier 160 rotated by the driving mechanism. Rotate the ring. In addition, the retainer ring 170 can be rotated by a second drive mechanism connected to the retainer ring 170. This second drive mechanism may be a gear or chain and sprocket drive mechanism coupled to another motor 315 or a polishing head drive mechanism (not shown) as shown in FIG. The advantage of the embodiment due to the frictional force rotating the retainer ring 170 is the simplicity and durability of the design. An advantage of the embodiment using the second drive mechanism is the ability to control the difference in rotational speed between the substrate 105 held on the subcarrier 160 and the retainer ring 170, and the direction of the subcarrier. The ability to rotate the retainer ring in the opposite direction.

  In another aspect of the invention, a polishing head 140 with an integral dispensing mechanism 320 is provided to distribute chemicals or slurries to the polishing surface 125 during the polishing process. In order to avoid contamination and obtain a consistent effect, the slurry is generally not recycled or recycled. In addition, due to the stringent conditions regarding the purity of the slurry and in particular the size of the abrasive grains suspended in the slurry, the cost factor of the conventional CMP apparatus 100 is the cost of the slurry. One of the problems of the conventional CMP apparatus 100 is that the slurry is distributed to the polishing surface 125 in front of the polishing head 140, so that when the slurry flows on the polishing surface 125, the slurry is separated between the substrate 105 and the polishing surface 125. In order to ensure that the entire surface is covered, excess slurry must be dispensed. The polishing head 140 according to the present invention includes a number of ports 325 positioned in the circumferential direction of the retainer ring 170 surrounding the carrier 155 or the substrate 105, thereby covering the entire surface between the substrate and the polishing surface 125. To ensure that the waste of the slurry is reduced or eliminated. The size and number of ports 325 are selected to obtain sufficient coverage and depend directly on the size of the substrate 105 being polished. In addition, the size of the port 325 is selected to match the viscosity and particle size of the particular slurry used. For example, to polish a 200 mm substrate 105 with a slurry having a viscosity of 1.5 centipoise and a particle size of 100 nanometers (nm), about 2 to 20 having a diameter of about 3 mm to about 1 mm. It turns out that there are enough ports. In the embodiment shown in FIG. 11, the slurry is distributed from ports 325 that are evenly spaced on the lower surface 205 of the retainer ring 170. In another embodiment shown in FIG. 12, the port 325 is disposed in the annular space 280 between the retainer ring 170 and the subcarrier 160. Preferably, the ports 325 are equally spaced in the annular space 280 between the retainer ring 170 and the subcarrier 160. More preferably, the CMP apparatus 100 further includes a cleaning fluid supply unit 330, a slurry supply unit 335, and a valve 340 for switching between the cleaning fluid supply unit 330 and the slurry supply unit 335, and the port 325 is maintained. During operation, the annular space 280 between the retainer ring 170 and the subcarrier 160 is cleaned.

  In yet another aspect, the present invention is directed to a polishing surface 125 having a number of indentations or recesses that are unevenly concentrated on the polishing surface to control the polishing rate of the surface of the substrate 105. As described above, the concave portion of the polishing surface 125 has a function of distributing a chemical substance or slurry between the polishing surface and the surface of the substrate 105 placed on the polishing surface. In general, the recesses may or may not have the same dimensions, and a number of grooves that may or may not be evenly spaced on the polishing surface 125. 345 or multiple indentations or cavities 350. That is, the concave portion is composed of grooves 345 or cavities 350 having a non-uniform spacing in the radial direction on the polishing surface, or is composed of grooves 345 or cavities 350 having a non-uniform cut surface.

  In FIG. 13A, in one embodiment where the polishing surface 125 is a disc-shaped rotatable surface, the recesses have a uniform depth and width and a number of concentricity provided at non-uniform intervals in the polishing surface. Shaped groove 345 is included. In FIGS. 13A, 14, 15, 16, and 17, the groove is shown as a single solid line because the width of the groove 345 is small relative to the polishing surface 125. These lines are used to illustrate the placement of the grooves 345 on the polishing surface 125 and should not be construed to convey any information regarding the dimensions of the grooves. As shown in FIG. 13B, in general, in a region where the gaps of the grooves 345 are further spaced, the surface of the polishing surface 125 where the polishing surface 125 is in contact with the substrate 105 is large. Greater than polishing rate. Therefore, the positioning of the polishing head 140 indicated by the phantom lines 355 in FIGS. 13A and 13B provides a higher polishing rate at the center than at the edge of the substrate 105, which has a greater density of grooves 345. Periodically pass through the region (or the lower surface region between the grooves). This is particularly preferred when processing a substrate having a layer of a material such as copper that tends to have a convex shape due to the properties of the material and the film formation process. As shown in FIG. 13A, for a polished surface 125 having grooves 345, grooves are formed at a density of grooves from about 20 grooves per inch in the radial direction in the first region to about one groove in the second region. The change causes a polishing rate difference of at least 5% between the first region and the second region, with the polishing rate of the first region being lower than the polishing rate of the second region.

  Another design and pattern of the polishing surface 125 having a plurality of non-uniformly spaced grooves 345 is shown in FIGS. FIG. 14 is a schematic diagram illustrating a top view of one embodiment of a polishing surface 125 having spiral grooves 345 disposed at a single non-uniform spacing. The groove 345 is spiraled or wound to provide a region having a lower surface area and a higher surface area between the groove near the center of the polishing surface 125 and the groove at the edge. FIG. 15 is a schematic diagram illustrating a top view of one embodiment of a polishing surface 125 having a number of non-uniformly spaced helical grooves 345. Also, the grooves 345 are wound at an interval to provide a lower surface area and a higher surface area between the groove near the center of the polishing surface 125 and the groove at the edge. FIG. 16 is a schematic diagram illustrating a top view of one embodiment of a polishing surface 125 having concentric elliptical grooves 345 arranged at non-uniform intervals. FIG. 17 is a schematic diagram illustrating a top view of one embodiment of an elongated polishing surface 125 having non-uniformly spaced parallel grooves 345. In this embodiment, the elongated polishing surface 125 comprises a fixed elongated surface on which the polishing head 145 moves or a rotating belt (not shown) (not shown).

  FIGS. 18-20 illustrate different designs and patterns of the polishing surface 125 that vary to provide different polishing rates from one area to another with relatively uniform spacing between the recesses and the dimensions of the recesses. Show. FIG. 18 is a partial cross-sectional side view of one embodiment of a polishing surface 125 having a number of uniformly spaced grooves 345 having a uniform width and a non-uniform depth. In this embodiment, the surface area of the polishing surface 125 in contact with the substrate 105 is constant from region to region, and varying the depth of the grooves 345 that control the difference in polishing rate can reduce the amount of slurry provided to that region. Change. This embodiment is beneficial for processes using slurries containing abrasives, particularly in processes where the chemical reactivity of the slurry is an important component of the polishing process.

  FIG. 19 is a schematic diagram illustrating a partial cross-sectional side view of a polishing surface 125 with a number of uniformly spaced grooves 345 having non-uniform widths in accordance with an embodiment of the present invention. As described above, variation in the surface area in contact with the substrate 105 results in variation in the polishing rate. FIG. 20 is a schematic diagram illustrating a top view of a polishing surface 125 with cavities 350 of uniform spacing but non-uniform size according to an embodiment of the present invention. The size and shape of the cavity 350 shown in FIG. 20 is shown for illustrative purposes only and should not be construed as limiting in any way with respect to the size or shape of the cavity; rather, the cavity is regular or irregular. It can be regular in shape and have dimensions as small as a fraction of a millimeter to a few millimeters. Further, the change in the surface area in contact with the substrate 105 causes a change in the polishing rate. Although not shown, the polishing rate variation is achieved by a non-uniformly spaced but uniformly sized cavity 350 on the polishing surface 125 or a uniformly spaced cavity whose depth varies with a uniform sized opening. Is quickly understood.

  A method of operating the CMP apparatus 100 according to the present invention will be described with reference to FIG. In the initial or loading process, the substrate 105 is received on the receiving surface 190 of the flexible member 185. (Step 360) A vacuum is introduced into the lower cavity 215 via the port 225 (Step 365), and a predetermined degree of vacuum is reached and the port is separated. (Step 370) The presence of the substrate 105 on the receiving surface 190 may be detected by switching the vacuum switch 240 connected to the port 225. (Step 375) The substrate 105 is positioned on the polishing surface 125 (Step 380), and a pressurized fluid is introduced into the lower cavity 215 to press the substrate against the polishing surface 125. (Step 385) A chemical substance such as water or slurry is distributed to the polishing surface 125 (Step 390), and distributed between the substrate 105 and the polishing surface via the recesses of the polishing surface. (Step 395) These recesses may be non-uniformly spaced and / or non-uniformly sized grooves 345 or cavities 350 to provide varying polishing rates to the polishing surface 125, as described above. There may be. A relative movement is made between the polishing surface 125 and the substrate 105 to polish the substrate. (Step 400) The retainer ring 170 is rotated at a speed different from that of the subcarrier 160 and the substrate 105 held by the subcarrier 160, thereby eliminating the influence on the polishing rate of the high point or the low point on the lower surface 205 of the retainer ring. If not, it may be reduced. (Step 405) After the polishing is finished and the rotation of the polishing head 140, the retainer ring 170 and the polishing platen 115 is stopped, a vacuum is again formed in the lower cavity 215 (Step 410), and after reaching a predetermined degree of vacuum ( Step 415), the substrate 105 is raised from the polishing surface 125. (Step 420)

Several important aspects of the invention are described repeatedly to further emphasize their structure, function and advantages.
The present invention relates to a polishing head for positioning a substrate having a surface on a polishing surface of a polishing apparatus. The polishing head includes a carrier, a subcarrier supported by the carrier and adapted to hold the substrate during the polishing operation, and a retainer ring disposed rotatably around the subcarrier. The retainer ring has a lower surface that is substantially flush with the surface of the substrate and is in contact with the polishing surface during the polishing operation. The retainer ring is rotatable with respect to the substrate held on the subcarrier, and suppresses uneven polishing of the surface of the substrate.

  In one embodiment, the subcarrier can rotate the substrate held therein during the polishing process, and the retainer ring can rotate at a different speed than the substrate held on the subcarrier.

  In another embodiment, the polishing head further comprises a backing ring that faces the upper surface of the retainer ring and is separated from the retainer ring by a bearing. The backing ring is adapted to apply pressure to the retainer ring during the polishing process. The bearing comprises a ball bearing or a fluid bearing, a roller bearing or a taper bearing. Preferably, the retainer ring comprises a first lip that engages the second lip of the backing ring when the carrier is raised from the polishing surface to connect the retainer ring to the backing ring. In a variation of this embodiment, the first lip comprises a number of bolts, each bolt having a shaft for engaging the shaft and the second lip of the backing ring when the carrier is raised from the polishing surface. And a head having a surface projecting radially outward from the portion.

  In another embodiment, the polishing head includes a drive mechanism coupled to the retainer ring that is adapted to rotate the retainer ring relative to the subcarrier during the polishing process. In addition, the retainer ring can be rotated relative to the subcarrier during the polishing process by the frictional force between the retainer ring and the polishing surface.

  The polishing head of the present invention is particularly useful in a polishing apparatus such as CMP. Typically, the apparatus comprises a polishing surface and a slurry distribution mechanism adapted to distribute slurry onto the polishing surface during the polishing process. The apparatus also includes a polishing surface having fixed abrasive grains and a chemical substance distribution mechanism adapted to distribute chemical substances to the polishing surface during the polishing process.

  In another aspect, a method uses a polishing apparatus comprising a polishing surface, a carrier with a subcarrier, and a retainer ring circumferentially disposed around the subcarrier and having a lower surface. Is provided for polishing a substrate having a surface. The method includes the steps of positioning the substrate on the subcarrier such that the surface of the substrate is substantially flush with the lower surface of the retainer ring, and pressing the substrate surface and the lower surface of the retainer ring against the polishing surface. Polishing the surface and rotating the retainer ring relative to the subcarrier to suppress uneven polishing of the surface of the substrate. The method further includes rotating the substrate held on the subcarrier during the polishing step and rotating the retainer ring, wherein the rotating the retainer ring includes a speed of the substrate held on the subcarrier. Rotates the retainer ring at different speeds.

  In one embodiment, the step of rotating the retainer ring includes the step of rotating the retainer ring by a frictional force applied to the lower surface of the retainer ring by the polishing surface. The polishing apparatus further includes a drive mechanism connected to the retainer ring, and the step of rotating the retainer ring includes a step of operating the drive mechanism to rotate the retainer ring.

  In yet another embodiment, the polishing head includes means for rotatably mounting the retainer ring to the carrier so that the retainer ring rotates relative to the subcarrier, and thus suppresses polishing of the substrate. In one embodiment, the means for allowing the retainer ring to rotate can cause the retainer ring to rotate at a different speed than the substrate held on the subcarrier.

  In another embodiment, the carrier includes a backing ring in a relationship facing the upper surface of the retainer ring to apply pressure to the retainer ring during the polishing process, and the means for allowing the retainer ring to rotate relative to the substrate comprises: A bearing is included that separates the backing ring from the retainer ring.

  In another embodiment, the polishing head further includes a drive mechanism coupled to the retainer ring that rotates the retainer ring relative to the substrate held on the subcarrier during the polishing process. Also, the retainer ring rotates relative to the subcarrier during the polishing process by the frictional force between the retainer ring and the polishing surface.

  The present invention relates to a polishing head for positioning a substrate having a surface on a polishing surface of a polishing apparatus. The polishing head includes a carrier adapted to hold the substrate during the polishing process. The carrier has a lower surface, a flexible member fixed to the carrier and extending to the lower surface, and a cornering disposed between the flexible member and the lower surface to form a cavity between the flexible member and the lower surface. With a piece. The carrier includes a passage that communicates with a lower surface that introduces pressurized fluid into the cavity. The flexible member has a receiving surface adapted to engage the substrate so as to press the substrate against the polishing surface during the polishing process. The flexible member has a predetermined thickness and includes a number of holes extending through the thickness to the receiving surface to apply pressure directly to the substrate. Preferably, the flexible member is adapted to be sealed by the substrate on the receiving surface to allow the cavity to be pressurized.

In one embodiment, the carrier further comprises a subcarrier supported by the carrier, and the flexible member is fixed to the subcarrier and extends to the lower surface of the subcarrier.
In another embodiment, the polishing apparatus further comprises a drive mechanism for rotating the carrier during the polishing process, wherein the number and size of the holes is the receiving surface of the flexible member for imparting rotational energy to the substrate. Selected to provide sufficient frictional force between the substrate and the substrate.

  In another embodiment, the lower surface of the carrier includes a port in communication with the passage. The port is adapted to receive pressurized fluid into the cavity during the polishing process. In a variation of this embodiment, the lower surface of the carrier comprises at least one groove adapted to distribute pressurized fluid from the port to the entire cavity. In another variation, the port creates a vacuum in the cavity, and the flexible member and the substrate function as a valve that separates the port from the cavity when a predetermined degree of vacuum is reached. Preferably, the predetermined degree of vacuum is selected to hold the substrate on the receiving surface during the loading and unloading steps before and after the polishing step. More preferably, the polishing apparatus further comprises a vacuum switch coupled to the port, and is selected such that the vacuum switch is switched according to a predetermined degree of vacuum when the substrate is held on the receiving surface.

  The polishing head of the present invention is particularly useful for polishing apparatuses such as CMP. Typically, the apparatus comprises a polishing surface and a slurry distribution mechanism adapted to distribute slurry to the polishing surface during the polishing process. The apparatus also includes a polishing surface having fixed abrasive grains and a chemical substance distribution mechanism adapted to distribute chemical substances to the polishing surface during the polishing process.

  In another aspect, a method is provided for polishing a substrate having a surface using a polishing apparatus that includes a polishing surface, a carrier having a lower surface, and a flexible member extending to the lower surface. The The flexible member has a receiving surface, a predetermined thickness, and a number of holes extending through the predetermined thickness to the receiving surface. The method positions the substrate between the carrier and the polishing surface and applies pressure to the flexible member such that the flexible member engages the substrate and the surface of the substrate is placed on the polishing surface. Pressing the surface against the polishing surface to polish the surface of the substrate. The pressure is applied directly to the substrate through the holes.

  In one embodiment, the carrier further comprises a cornering piece disposed between the flexible member and the lower surface to form a cavity, the lower surface of the carrier so as to introduce pressurized fluid into the cavity. The step of applying a pressure to the flexible member having a configured port includes introducing pressurized fluid into the cavity through the port. Preferably, if the polishing apparatus includes a drive mechanism that rotates the carrier during the polishing process, the method further includes the step of applying torque to the substrate via the flexible member. More preferably, the number and size of the holes through the thickness of the flexible member is sufficient to provide sufficient friction between the receiving surface of the flexible member and the substrate to impart rotational energy to the substrate during the polishing process. Selected to provide power.

  In one embodiment, the port is adapted to draw a vacuum into the cavity, and the method further includes a loading step that draws the vacuum into the cavity to hold the substrate on the receiving surface. Preferably, the pulling loading step further includes the step of separating the port from the cavity when a predetermined degree of vacuum is reached using the flexible member and the substrate as a valve. More preferably, the polishing apparatus has a vacuum switch connected to the port, and the loading step detects the presence of the substrate on the receiving surface by switching the vacuum switch when a predetermined degree of vacuum is reached. Is included. The method further includes introducing a vacuum into the cavity during the unloading step after the polishing step to hold the substrate on the receiving surface before raising the carrier from the polishing surface.

  In another aspect, a polishing apparatus for polishing a substrate includes means for applying pressurized fluid directly to the substrate to press the substrate against the polishing surface, and rotational energy from the carrier during the polishing operation. Means for transmitting to the substrate. Preferably, the means for applying pressurized fluid directly to the substrate includes a flexible member attached to the underside of the carrier on which the substrate is held during the polishing process. The flexible member includes a receiving surface adapted to engage the substrate, a predetermined thickness, and a plurality of holes extending through the thickness to the receiving surface to directly apply pressure to the substrate. I have. More preferably, the means for transmitting rotational energy from the carrier to the substrate includes a receiving surface of the flexible member, and the number and size of the holes is between the receiving surface and the substrate to impart rotational energy to the substrate. It is chosen to provide sufficient frictional force in between.

  The present invention also relates to a polishing head for positioning a substrate having a surface on a polishing surface of a polishing apparatus having a carrier adapted to hold the substrate during a polishing process. The carrier includes a lower surface and a flexible member fixed to the carrier and extending to the lower surface. The flexible member has a receiving surface that engages the substrate. The carrier includes a port extending to the lower surface for supplying a suction force, and a cornering piece disposed between the flexible member and the lower surface in the vicinity of the port. The flexible member includes a predetermined thickness and at least one hole extending through the thickness to the receiving surface, the position of the hole being substantially aligned with the position of the port. The flexible member is in a first position spaced from the lower surface in the vicinity of the port, the flexible member engages the lower surface around the port, and the hole is at least partially aligned with the port. A suction force is applied to the port to hold the substrate on the receiving surface during at least a portion of the polishing process, so that the spacer is substantially attracted to the second position. Is limited to only a portion of the substrate, thus minimizing undesirable stress on the rest of the substrate. Preferably, the flexible member is sealed by a substrate on the receiving surface to allow drawing into a vacuum cavity.

  In one embodiment, the flexible member and the substrate function as a valve to isolate (isolate) the port from the cavity when a predetermined degree of vacuum is achieved, thereby deforming the flexible member. And stress on the substrate held on the receiving surface is reduced. In a variation of this embodiment, the spacer has a thickness that separates the flexible member from the lower surface of the carrier, and the thickness further increases the deformation of the flexible member when vacuum is drawn into the cavity. It is selected to reduce, thereby reducing the stress on the substrate held on the receiving surface. In another variation, the polishing apparatus further comprises a vacuum switch coupled to the port, and the presence of the substrate on the receiving surface is detected when a predetermined degree of vacuum is reached by switching the vacuum switch. .

  In another embodiment, the polishing apparatus includes a drive mechanism for rotating the carrier during the polishing process, and the size of the holes includes the receiving surface of the flexible member and the substrate to impart rotational energy to the substrate. To provide sufficient frictional force between the two.

  In another embodiment, the multiple holes extend through the thickness of the flexible member to the receiving surface. In a variation of this embodiment, the carrier further includes a passage that communicates with a port for introducing pressurized fluid into the cavity during the polishing process, and the multiple holes are provided during the polishing process. The pressurized fluid can be applied directly to the substrate through the holes to press the substrate against the polishing surface. In another variation, the polishing apparatus includes a drive mechanism for rotating the carrier during the polishing process, wherein the number and size of the holes provides the receiving surface of the flexible member and the substrate to provide rotational energy to the substrate. To provide sufficient frictional force between the two.

  In another embodiment, a method is provided for polishing a substrate having a surface using a polishing apparatus that includes a polishing surface and a carrier adapted to hold the substrate during a polishing operation. The The carrier includes a lower surface having a flexible member fixed to the carrier, and a cornering piece disposed between the flexible member and the lower surface to form a cavity between the flexible member and the lower surface. It has. The underside of the carrier has a port adapted to draw a vacuum into the cavity. The flexible member has a receiving surface adapted to receive the substrate. The flexible member has a predetermined thickness and at least one hole extending through the thickness to the receiving surface. The method includes the steps of receiving a substrate on a receiving surface, drawing a vacuum into the cavity to hold the substrate on a carrier, and positioning the surface of the substrate on the polishing surface. Preferably, the step of drawing the vacuum into the cavity includes the step of separating (isolating) the port from the cavity when a predetermined degree of vacuum is reached using the flexible member and the substrate as a valve. More preferably, the polishing apparatus further includes a vacuum switch coupled to the port, and the method detects the presence of a substrate on the receiving surface by switching the vacuum switch when a predetermined degree of vacuum is reached. Is included.

  The present invention also relates to a polishing head for positioning a substrate having a surface on a polishing surface of a polishing apparatus. The polishing head includes a carrier having a bottom surface. The bottom surface includes a lower surface adapted to hold the substrate during the polishing process. The carrier includes a number of ports extending through the bottom surface around the lower surface for dispensing abrasive material to the polishing surface during operation. In general, the port is adapted to distribute a slurry containing an abrasive to the polishing surface. Also, if the polishing surface contains fixed abrasive, the port distributes water to the polishing surface during the polishing process.

In one embodiment, the port is located in the retainer ring.
In another embodiment, the carrier comprises a subcarrier having a receiving surface on which the substrate is held during the polishing process, and the retainer ring is rotatably arranged around the subcarrier and is separated from the subcarrier by an annular space. It is separated. In a modification of the present embodiment, the port is arranged in an annular space between the retainer ring and the subcarrier. Preferably, the ports are evenly spaced around the annular space between the retainer ring and the subcarrier. More preferably, there are 2 to 30 ports. Most preferably, the port is further adapted to clean the annular space between the retainer ring and the subcarrier during maintenance operations.

  The polishing head of the present invention is particularly useful in a polishing apparatus such as CMP. Typically, the apparatus comprises a polishing surface and a port adapted to dispense a slurry containing an abrasive on the polishing surface during the polishing process. The polishing surface has fixed abrasive grains and the port distributes water to the polishing surface during the polishing process.

  In another aspect, a method for polishing a substrate having a surface using a polishing apparatus comprising a polishing surface and a carrier having a bottom surface adapted to hold the substrate during a polishing process. Is provided. The method includes positioning the substrate on the lower surface of the carrier, urging the carrier against the polishing surface so as to press the surface of the substrate against the polishing surface, and distributing abrasive material to the polishing surface through the lower surface of the carrier. It has.

  In one embodiment, the polishing surface has fixed abrasive grains and the step of distributing the chemical to the polishing surface includes the step of distributing water to the polishing surface. The chemical mechanical polishing apparatus includes a slurry supply unit that can supply the slurry to a number of ports, and the step of distributing the chemical substance to the polishing surface includes a step of distributing the slurry to the polishing surface. In a modification of this embodiment, the polishing apparatus includes a cleaning fluid supply unit that can supply a cleaning fluid to a number of ports, and a valve that switches between the slurry supply unit and the cleaning fluid supply unit. The method further includes the step of cleaning a number of ports after polishing of the substrate.

  In yet another aspect, a polishing head for positioning a substrate having a surface on a polishing surface of a polishing apparatus includes means for distributing chemicals from the polishing head to the polishing surface during the polishing process.

  In one embodiment, the means for dispensing chemicals from the polishing head includes means for dispensing a slurry containing an abrasive to the polishing surface. The polishing surface also has fixed abrasive grains and the means for distributing chemicals from the polishing head includes means for distributing water to the polishing surface during the polishing process.

  In another embodiment, the means for dispensing chemicals from the polishing head includes a number of ports disposed within the retainer ring. Preferably, the carrier further comprises a subcarrier having a receiving surface on which the substrate is held during the polishing process, and the retainer ring is rotatably arranged around the subcarrier and separated from the subcarrier by the annular space Has been. Most preferably, the port is disposed in an annular space between the retainer ring and the subcarrier.

  The present invention also relates to a polishing apparatus for removing material from the surface of a substrate. The polishing apparatus is configured such that a polishing head configured to hold a substrate during the polishing process and a chemical between the substrate and the polishing surface held by the polishing head when there is a relative movement between the substrate and the polishing surface. And a polishing surface having a number of recesses for dispensing the substance. The multiple recesses are formed at non-uniform intervals on the polishing surface to provide a variable polishing rate for removing material on the polishing surface. The spacing of the recesses on the polishing surface varies from the first region to the second region to provide a difference in polishing rate between the first region and the second region.

In one embodiment, the multiple recesses include grooves with radially non-uniform spacing in the polishing surface. In the modification of this embodiment, the groove has a non-uniform cut surface. Preferably, the spacing of the recesses in the polishing surface varies from the first region to the second region, providing a polishing rate difference of at least 5% between the first region and the second region. Yes. More preferably, the multiple grooves are more dense in the first region than in the second region, and the first region provides a lower polishing rate than the second region. The groove spacing on the polishing surface varies from 20 grooves per inch in the first region to 2 grooves per inch in the second region. Preferably, the groove has a substantially uniform depth and a substantially uniform width. In general, there are more grooves per inch in the first region than grooves per inch in the second region, and the first region provides a lower polishing rate than the second region. The grooves may be parallel grooves, concentric circular grooves, concentric elliptical grooves, multiple pitched spiral grooves or a single spiral groove.
The recess can also consist of a number of open cavities or depressions in the polishing surface.

  When the polishing surface has fixed abrasive grains, the recess distributes water between the polishing surface and the substrate held by the polishing head during the polishing process. The concave portion distributes slurry containing an abrasive between the substrate held by the polishing head and the polishing surface during the polishing step.

  In yet another aspect, a polishing apparatus for removing material from a surface of a substrate is provided. A polishing apparatus is a chemical device between a polishing head adapted to hold a substrate during a polishing operation and the substrate held by the polishing head and the polishing surface when there is a relative movement between the substrate and the polishing surface. And a polishing surface having a number of recesses for dispensing the substance. The recess has a non-uniform size that varies from the first region to the second region on the polishing surface to provide a variable polishing rate for removing material from the first region to the second region on the polishing surface.

In one embodiment, the recess includes a number of cavities in the polishing surface, and the depth of the cavities provides a difference in polishing rate between the first region and the second region, so that the second region to the second region. It changes to the area.
In another embodiment, the recess includes a plurality of cavities in the polishing surface, each of the cavities having a cutting surface parallel to the polishing surface, and each cutting surface of the plurality of cavities includes the first region and the second region. In order to provide a polishing rate difference between the regions, the first region changes to the second region.

In yet another embodiment, the recess includes a number of grooves having a predetermined depth in the polishing surface, the groove depth providing a difference in polishing rate between the first region and the second region. Therefore, the first region changes to the second region.
In yet another embodiment, the recess includes a number of grooves in the polishing surface, each groove having a predetermined width. The width of each of the multiple grooves varies from the first region to the second region to provide a polishing rate difference between the first region and the second region.

  In another aspect, a method includes a polishing head adapted to hold a substrate during a polishing process, and a substrate and polishing surface held by the polishing head when there is relative motion between the substrate and the polishing surface. For removing material from the surface of the substrate using a polishing apparatus having a polishing surface with a number of recesses for distributing chemicals between the substrate and the substrate. The multiple recesses are formed at non-uniform intervals on the polishing surface to provide a variable polishing rate for removing material on the polishing surface. A method includes positioning a substrate on a polishing head, pressing the surface of the substrate against the polishing surface, dispensing a chemical on the polishing surface, and a material from the surface of the substrate at a polishing rate that varies across the polishing surface. Providing relative motion between the substrate and the polishing surface.

In one embodiment, the spacing of the recesses in the polishing surface varies from the first region to the second region, and providing the relative motion between the substrate and the polishing surface to remove material from the surface of the substrate comprises , Providing a polishing rate difference between the first region and the second region.
In another embodiment, the recess includes a number of grooves having a substantially uniform depth and a substantially uniform width.

In still other embodiments, the recess includes a number of cavities, each having a substantially uniform depth and a substantially uniform cut surface parallel to the polishing surface.
In yet another embodiment, the present invention provides a polishing object or substrate, such as a semiconductor wafer, manufactured by the apparatus of the present invention.
In yet another embodiment, the present invention provides a polishing object or substrate, such as a semiconductor wafer, manufactured by the above-described method or process of the present invention.

  While numerous features and advantages of embodiments of the present invention have been described in the foregoing description, together with details of the structure and function of the various embodiments of the present invention, this disclosure is illustrative only and modifications In particular, to the fullest extent indicated by the broad and general meaning of the terms expressed in the appended claims, it can be made as a matter of structure and arrangement of parts within the scope of the principles of the present invention.

100 CMP apparatus 105 substrate 110 base 115 platen 120 polishing pad 125 polishing surface 130 bridge 135 carousel 140 polishing head 142 motor 145 chain 150 head mounting assembly 155 carrier 160 subcarrier 162 flange 163 screw 164 lower surface 165 lower surface 166 gasket 167 support ring 168 support Ring 170 Retainer ring 175, 180 Cavity (chamber)
176 Gasket 177 Skirt portion 178 Backing plate 179 Screw 185 Flexible member 190 Receiving surface 195 Hole 200 Backing ring 205 Lower surface 210 Cornering piece 215 Lower cavity 220 Passage 225 Port 230 Lip 235 Separation valve 240 Vacuum switch 243 Spacer 245 Passage 260 Bearing 265 Housing 275 Outer race 280 Space 285 First lip 290 Second lip 295 Bolt 300 Shaft 305 Head 315 Motor 320 Distribution mechanism 325 Port 330 Cleaning fluid supply part 335 Slurry supply part 340 Valve 345 Groove 350 Cavity 355 Virtual line 360, 365, 370, 375, 380, 385, 390, 395, 400, 405, 410, 415, 420

Claims (15)

A polishing head for positioning a substrate having a surface on a polishing surface of a polishing apparatus,
A carrier having a bottom surface, the bottom surface including a lower surface adapted to hold the substrate during the polishing process, the carrier around the lower surface for distributing abrasive material to the polishing surface during the polishing process. With multiple ports extending through the bottom,
The carrier includes a subcarrier having a receiving surface on which a substrate is held during a polishing process, and the retainer ring is rotatably disposed around the subcarrier and separated from the subcarrier by an annular space. And
Each of the subcarrier and the retainer ring is configured to be independently rotatable by an individual drive mechanism,
A polishing head characterized in that the retainer ring can be rotated at a speed different from that of the substrate on the subcarrier during the polishing process.   2. The polishing head according to claim 1, wherein the plurality of ports distribute slurry containing an abrasive to the polishing surface.   The polishing head according to claim 1, wherein the plurality of ports are disposed in a retainer ring.   The polishing head according to claim 1, wherein the plurality of ports are arranged in an annular space between the retainer ring and the subcarrier.   The polishing head according to claim 4, wherein the plurality of ports are arranged at equal intervals around an annular space between the retainer ring and the subcarrier.   The polishing head according to claim 4, wherein the plurality of ports include 2 to 30 ports.   The polishing head according to claim 4, wherein the plurality of ports are further configured to clean an annular space between the retainer ring and the subcarrier during a maintenance operation.   A chemical mechanical polishing apparatus comprising: a polishing surface; and the polishing head according to claim 1 for positioning a substrate on the polishing surface. A method of polishing a substrate having a surface using a polishing apparatus comprising a polishing surface and a carrier having a bottom surface including a lower surface adapted to hold the substrate during a polishing step,
The method includes the steps of positioning the substrate on the lower surface of the carrier, urging the carrier against the polishing surface so as to press the surface of the substrate against the polishing surface, and distributing the polishing material to the polishing surface through the bottom surface of the carrier. And
The carrier includes a subcarrier having a receiving surface on which a substrate is held during a polishing process, and the retainer ring is rotatably disposed around the subcarrier and separated from the subcarrier by an annular space. And
Each of the subcarrier and the retainer ring is configured to be independently rotatable by an individual drive mechanism,
A polishing method, wherein the retainer ring is rotated at a speed different from that of the substrate on the subcarrier during the polishing step.   The polishing apparatus includes a slurry supply unit capable of supplying a slurry containing an abrasive to a plurality of ports, and the step of distributing the polishing substance to the polishing surface includes the step of distributing the slurry to the polishing surface. The polishing method according to claim 9.   The polishing apparatus includes a cleaning fluid supply unit that can supply a cleaning fluid to a plurality of ports, and a valve that switches between the slurry supply unit and the cleaning fluid supply unit, and the method includes: The polishing method according to claim 10, further comprising a step of cleaning the plurality of ports after polishing the substrate. A polishing head for positioning a substrate having a surface on a polishing surface of a polishing apparatus,
A carrier adapted to hold the substrate during the polishing process, a retainer ring suspended from the carrier, and means for distributing chemicals from the polishing head to the polishing surface during the polishing process; Placed around the substrate held by the carrier,
The carrier includes a subcarrier having a receiving surface on which a substrate is held during a polishing process, and the retainer ring is rotatably disposed around the subcarrier and separated from the subcarrier by an annular space. And
Each of the subcarrier and the retainer ring is configured to be independently rotatable by an individual drive mechanism,
A polishing head characterized in that the retainer ring can be rotated at a speed different from that of the substrate on the subcarrier during the polishing process.   13. The polishing head according to claim 12, wherein the means for distributing chemical substances from the polishing head comprises means for distributing a slurry containing an abrasive to the polishing surface.   13. The polishing head according to claim 12, wherein the means for distributing the chemical substance from the polishing head comprises a plurality of ports arranged in a retainer ring.   The polishing head according to claim 14, wherein the plurality of ports are disposed in an annular space between the retainer ring and the subcarrier.

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