Abstract:
A polishing pad, platen, method of monitoring, method of manufacturing, and method of detecting using a pseudo window area, where the pseudo window area has a thickness less than a thickness of a polishing layer and a thickness greater than zero.

Description:
CROSS-REFERENCE TO RELATED APPLICATION  
         [0001]    This application claims the benefit of priority of Korean Patent Application No. 2003-38740, filed on 16 Jun. 2003, in the Korean Intellectual Property Office, the contents of which are herein incorporated by reference in their entirety.  
         BACKGROUND OF THE INVENTION  
         [0002]    Polishing pads, such as chemical mechanical polishing (CMP) pads are widely used in a semiconductor manufacturing field to horizontally planarize various types of layers, such as oxide layers, nitride layers, metal layers, etc. In one conventional arrangement, a CMP pad is provided with a hole H. A chuck including a wafer to be planarized is placed in contact with the CMP pad including the hole H. A slurry is provided on the polishing pad to facilitate the CMP process and a light reflectance measurement unit is used to determine when the wafer has been sufficiently planarized. The end point of the polishing process is determined by the light reflectance measurement unit by measuring the light reflected through the hole or window H. However, the ability of the slurry to fall through the hole in the CMP pad reduces the accuracy of the measurements made by the light reflectance measurement unit.  
           [0003]    In another conventional device, the CMP pad does not include a hole. In such an arrangement, the progress of the polishing cannot be monitored in-situ and a manufacturing delay is introduced when the wafer must be removed from the CMP process to check the progress of the polish. In such a system, the end point of the polishing process may be determined utilizing a preset timing period. However, such systems are inherently inaccurate.  
           [0004]    In yet another conventional device, a pad window is inserted in the hole of a top polishing pad. The pad window is made of a transparent material, which allows transmission of the laser beam. However, in the conventional device, the pad window sags in downwardly and/or an interface gap occurs between the top polishing pad and the window due to mechanical polishing pressure. As a result, slurry may accumulate on the top surface of the sagging pad window or slurry may leak through gaps in the side. Each of these causes scattering of the laser beam and degrades the transmission.  
         SUMMARY OF THE INVENTION  
         [0005]    In exemplary embodiments, the present invention is directed to a chemical mechanical polishing (CMP) pad for in situ monitoring which includes a polishing layer including a pseudo window area, where the pseudo window area has a thickness less than a thickness of the polishing layer and a thickness greater than zero.  
           [0006]    In exemplary embodiments, the present invention is directed to a chemical mechanical polishing (CMP) pad for in situ monitoring which includes a polishing layer having a recessed region, thereby forming a pseudo window area adjacent to the recessed region.  
           [0007]    In exemplary embodiments, the present invention is directed to a chemical mechanical polishing (CMP) pad for in situ monitoring, which includes a polishing layer including a transparent supporting layer, thereby forming a pseudo window area adjacent to the transparent supporting layer.  
           [0008]    In an exemplary embodiment, the present invention is directed to a chemical mechanical polishing (CMP) platen for in situ monitoring, comprising a platen layer including a platen window, the platen window recessed within the platen layer.  
           [0009]    In exemplary embodiments, the present invention is directed to a chemical mechanical polishing (CMP) platen for in situ monitoring, which includes a platen layer including a platen window, the platen window protruding higher than a height of the platen layer.  
           [0010]    In exemplary embodiments, the present invention is directed to a method of monitoring a chemical mechanical polishing (CMP) process in situ, which includes providing a chemical mechanical polishing (CMP) pad on a platen, the chemical mechanical polishing (CMP) pad including a polishing layer and a pseudo window area, the pseudo window area having a thickness less than a thickness of the polishing layer and a thickness greater than zero and monitoring light passed through the pseudo window area to control the chemical mechanical polishing (CMP) process.  
           [0011]    In exemplary embodiments, the present invention is directed to a method of monitoring a chemical mechanical polishing (CMP) process in situ, which includes providing a chemical mechanical polishing (CMP) pad on a platen, the chemical mechanical polishing (CMP) pad including a polishing layer having a recessed region, thereby forming a pseudo window area adjacent to the recessed region, the pseudo window area having a thickness less than a thickness of the polishing layer and a thickness greater than zero and monitoring light passed through the pseudo window area to control the chemical mechanical polishing (CMP) process.  
           [0012]    In exemplary embodiments, the present invention is directed to a method of monitoring a chemical mechanical polishing (CMP) process in situ, which includes providing a chemical mechanical polishing (CMP) pad on a platen, the chemical mechanical polishing (CMP) pad including a polishing layer and a transparent supporting layer, thereby forming a pseudo window area adjacent to the transparent supporting layer and monitoring light passed through the pseudo window area to control the chemical mechanical polishing (CMP) process.  
           [0013]    In exemplary embodiments, the present invention is directed to a method of monitoring a chemical mechanical polishing (CMP) process in situ, which includes providing a chemical mechanical polishing (CMP) pad on a platen, the chemical mechanical polishing (CMP) pad including a polishing layer and a pseudo window area and the platen including a platen layer and a platen window, the platen window protruding higher than a height of the platen layer and monitoring light passed through the pseudo window area to control the chemical mechanical polishing (CMP) process.  
           [0014]    In exemplary embodiments, the present invention is directed to a method of manufacturing a chemical mechanical polishing (CMP) pad for in situ monitoring of a chemical mechanical polishing (CMP) process, which includes providing a polishing layer and forming a pseudo window area in the polishing layer, the pseudo window area having a thickness less than a thickness of the polishing layer and a thickness greater than zero.  
           [0015]    In exemplary embodiments, the present invention is directed to a method of manufacturing a chemical mechanical polishing (CMP) pad for in situ monitoring of a chemical mechanical polishing (CMP) process, which includes providing a polishing layer and forming a recessed region in the polishing layer to form a pseudo window area adjacent to the recessed region.  
           [0016]    In exemplary embodiments, the present invention is directed to a method of manufacturing a chemical mechanical polishing (CMP) pad for in situ monitoring of a chemical mechanical polishing (CMP) process, which includes providing a polishing layer, forming a recessed region in the polishing layer, and arranging a transparent supporting layer in the recessed region, thereby forming a pseudo window area adjacent to the transparent supporting layer.  
           [0017]    In exemplary embodiments, the present invention is directed to a method of manufacturing a platen for in situ monitoring of a chemical mechanical polishing (CMP) process, which includes providing a platen layer, forming a hole in the platen layer, and arranging a platen window in the hole, the platen window protruding higher than a height of the platen layer.  
           [0018]    In exemplary embodiments, the present invention is directed to a method of detecting an end point in situ, which includes providing a pad on a platen, the pad including a polishing layer and a pseudo window area, the pseudo window area having a thickness less than a thickness of the polishing layer and a thickness greater than zero and monitoring light passed through the pseudo window area to detect the end point.  
           [0019]    In exemplary embodiments, the present invention is directed to a method of detecting an end point in situ, which includes providing a pad on a platen, the pad including a polishing layer having a recessed region, thereby forming a pseudo window area adjacent to the recessed region, the pseudo window area having a thickness less than a thickness of the polishing layer and a thickness greater than zero and monitoring light passed through the pseudo window area to detect the end point.  
           [0020]    In exemplary embodiments, the present invention is directed to a method of detecting an end point in situ, which includes providing a pad on a platen, the pad including a polishing layer and a transparent supporting layer, thereby forming a pseudo window area adjacent to the transparent supporting layer and monitoring light passed through the pseudo window area to detect the end point.  
           [0021]    In exemplary embodiments, the present invention is directed to a method of detecting an end point in situ, which includes providing a pad on a platen, the pad including a polishing layer and a pseudo window area and the platen including a platen layer and a platen window, the platen window protruding higher than a height of the platen layer and monitoring light passed through the pseudo window area to detect the end point. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0022]    The present invention will become more fully understood from the detailed description given below and the accompanying drawings, which are given for purposes of illustration only, and thus do not limit the invention.  
         [0023]    [0023]FIG. 1 illustrates a polishing table in accordance with an exemplary embodiment of the present invention.  
         [0024]    [0024]FIG. 2 illustrates a polishing table in accordance with another exemplary embodiment of the present invention.  
         [0025]    [0025]FIG. 3 illustrates a polishing table in accordance with another exemplary embodiment of the present invention.  
         [0026]    [0026]FIG. 4 illustrates a polishing table in accordance with another exemplary embodiment of the present invention.  
         [0027]    [0027]FIG. 5 illustrates a polishing table in accordance with another exemplary embodiment of the present invention.  
         [0028]    [0028]FIG. 6 illustrates a method of monitoring a chemical mechanical polishing (CMP) process in situ in accordance with another exemplary embodiment of the present invention.  
         [0029]    [0029]FIG. 7 illustrates a method of manufacturing a chemical mechanical polishing (CMP) pad for in situ monitoring of a chemical mechanical polishing (CMP) process in accordance with another exemplary embodiment of the present invention.  
         [0030]    [0030]FIG. 8 illustrates a method of manufacturing a platen for in situ monitoring of a chemical mechanical polishing (CMP) process in accordance with another exemplary embodiment of the present invention.  
         [0031]    [0031]FIG. 9 illustrates a method of detecting an end point in situ in accordance with another exemplary embodiment of the present invention. 
     
    
     DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS  
       [0032]    [0032]FIG. 1 illustrates a polishing table  4   a  in accordance with an exemplary embodiment of the present invention. As illustrated, the polishing table  4   a  includes a platen  1  and a polishing pad  3 . The polishing pad  3  includes an in-situ window area  3   a  which may be semi-transparent. The platen  1  may include a platen window la. The geometries of the platen  1  and the polishing pad  3  shown in FIG. 1 form a hole H and a void V. The void V may be filled with air or another gas. As illustrated in FIG. 1, the polishing pad  3  does not contain a through hole. A top surface of the platen  1  and a stepped bottom surface of the polishing pad  3  define the void V. In an exemplary embodiment, the polishing pad  3  is made of syndiotatic 1,2-polybutadiene, polyurethane, or polybutadiene (PBD) which are semi-transparent materials. In an exemplary embodiment, the in-situ window area  3   a  has a thickness in the range of between 1.0 mm and 2.0 mm or 1.5 mm and 2.0 mm to allow light transmission.  
         [0033]    In an exemplary embodiment, the platen  1  is made of a metal material, such as stainless steel. As illustrated in FIG. 1, an upper surface of the platen window  1   a  is at the same or substantially the same level as the upper surface of the platen  1 . In an exemplary embodiment, the platen window  1   a  is made of a transparent material, such as polycarbonate, polyethylene terephthalate glycol, polypropylene, 2-aryl glycol carbonate, quartz or glass. In an exemplary embodiment, the void V is positioned above the hole H of the platen  1 . In an exemplary embodiment, the void V is formed by the recessed region between the pseudo window  3   a  and the platen window  1   a.    
         [0034]    [0034]FIG. 2 illustrates another exemplary embodiment of the present invention. As shown in FIG. 2, the polishing table  4   b  includes a platen  51  and a polishing pad  53 . In the exemplary embodiment illustrated in FIG. 2, the platen  51  and the polishing pad  53  are essentially the same as the platen  1  and polishing pad  3  of FIG. 1; however, in the exemplary embodiment of FIG. 2, the top surface level of the platen window  51   a  is above the top level of the platen  51 . In an exemplary embodiment, this configuration may allow for easier self-alignment.  
         [0035]    In an exemplary embodiment, the top surface level of the platen window  51   a  is sufficiently higher above the top level of the platen  51 , that no void V is formed. In an exemplary embodiment, the void V′ in FIG. 2 is smaller than the void V of FIG. 1 due to the top surface level of the platen window  51   a  being above the level of the top level of the platen  51 . In an exemplary embodiment, the platen window  51   a  protrudes from the platen  51  in a direction closer to the polishing pad, to thereby reduce the size of or eliminate altogether, the void V′.  
         [0036]    [0036]FIG. 3 illustrates another exemplary embodiment of the present invention. As illustrated in FIG. 3, the polishing table  4   c  includes a platen  61  and a polishing pad  63 . In the exemplary embodiment illustrated in FIG. 3, the polishing pad  63  is essentially the same configuration as that of the polishing pad  3  of FIG. 1; however, a transparent supporting layer  63   b  is inserted in the recessed region of the polishing pad  63 . In an exemplary embodiment, the transparent supporting layer  63   b  helps prevent the pseudo window area  63   a  from being deformed due to mechanical pressure by a wafer chuck. In an exemplary embodiment, the transparent supporting layer  63   b  is made of the same material as that of the platen window  61 .  
         [0037]    In another exemplary embodiment illustrated in FIG. 4, the polishing table  4   d  includes a platen  61  and a polishing pad  63 . As illustrated in FIG. 4, the platen window  62   a  protrudes from the platen  61  (such as in shown in FIG. 2) and a transport parent supporting layer  64   a  is inserted between the in-situ window area and the platen window  62   a  (such as in shown in FIG. 3).  
         [0038]    In another exemplary embodiment illustrated in FIG. 5, the transparent supporting layer  64   b  protrudes from a bottom surface of the polishing pad  63  and its protrusion is inserted into the platen window  62   b  of the platen  61 .  
         [0039]    In other exemplary embodiments, the various pad and platen features of the present invention illustrated in FIGS. 1-5 may be utilized either singly or in any combination.  
         [0040]    In exemplary embodiments, the various pad and platen features of the present invention illustrated in FIGS. 1-5 may be utilized in an in-situ end point detection (EPD) system; such an exemplary optical system is illustrated in U.S. Pat. No. 5,433,651.  
         [0041]    [0041]FIG. 6 illustrates a method of monitoring a chemical mechanical polishing (CMP) process in situ in accordance with another exemplary embodiment of the present invention. As illustrated, the flowchart of FIG. 6 includes a step  60  of providing a pad with a pseudo window area and a step  62  of monitoring light passed through the pseudo window area to control the chemical mechanical polishing (CMP) process.  
         [0042]    [0042]FIG. 7 illustrates a method of manufacturing a chemical mechanical polishing (CMP) pad for in situ monitoring of a chemical mechanical polishing (CMP) process in accordance with another exemplary embodiment of the present invention. As illustrated, the flowchart of FIG. 7 includes a step  70  of providing a polishing layer and a step  72  of forming a pseudo window area in the polishing layer.  
         [0043]    In an exemplary embodiment of the present invention, the polishing layer is formed by one of molding, extruding, or grinding.  
         [0044]    [0044]FIG. 8 illustrates a method of manufacturing a platen for in situ monitoring of a chemical mechanical polishing (CMP) process in accordance with another exemplary embodiment of the present invention. As illustrated, the flowchart of FIG. 8 includes a step  80  of providing a platen layer, a step  82  of forming a hole in the platen layer, and a step  84  of arranging a platen window in the hole, the platen window protruding higher than a height of the platen layer.  
         [0045]    [0045]FIG. 9 illustrates a method of detecting an end point in situ in accordance with another exemplary embodiment of the present invention. As illustrated, the flowchart of FIG. 9 includes a step  90  of providing a pad with a pseudo window area and a step  92  of monitoring light passed through the pseudo window area to detect the end point.  
         [0046]    As described above, in other exemplary embodiments, the various pad and platen features of the present invention illustrated in FIGS. 1-5 may be utilized either singly or in any combination in any of the embodiments illustrated in FIGS. 6-9.  
         [0047]    As also described above, in exemplary embodiments, the various monitoring, manufacturing, and/or detecting features of the present invention illustrated in FIGS. 6-9 may be utilized in an in-situ end point detection (EPD) system; such an exemplary optical system is illustrated in U.S. Pat. No. 5,433,651.  
         [0048]    In exemplary embodiments of the present invention, the pad is described as a CMP pad, however the exemplary pads disclosed herein may also be used for other types of polishing as would be known to one of ordinary skill in the art.  
         [0049]    The invention being thus described, it will be obvious that the same may be varied in many ways. Such variations are not to be regarded as a departure from the spirit and scope of the invention, and all such modifications as would be obvious to one skilled in the art are intended to be included within the scope of the following claims.