Abrasive platen wafer surface optical monitoring system

Abstract

Flat-surfaced workpieces such as semiconductor wafers are held in flat-surfaced abrading contact with the abrasive surface of a flexible raised-island disk that is attached to a flat-surfaced rotating platen. There are recessed areas between the abrasive-coated raised islands where light can transmitted through the transparent backings. Platens are constructed with open passageways that extend radially from the outer periphery of the platen to the area that is under the abraded wafer. Stationary light sources are directed radially to the platen edge where they enter the open passageways to impinge on mirrors that direct the light to contact the surface of the wafer. The light beams reflected from the wafer surface are directed with mirrors back to a stationary light-receiver positioned at the outer periphery of the platen. The light-receiver device allows abraded condition of the flat surface of the wafer to be monitored during the abrasive lapping or polishing procedure.

What is claimed: 
     
         1 . A rotatable platen abrading machine apparatus comprising a stationary light source that provides a light beam used to monitor an abraded condition of a surface of a workpiece abraded by an abrasive coating on the platen, the apparatus further comprising:
 a) a rotatable circular abrading platen having a horizontal flat annular abrading surface, a platen center of rotation, a platen outer circumference, a platen outer circumference vertical wall, a platen sealed internal chamber, a transparent window that is attached to the platen flat horizontal annular abrading surface, a transparent window that is attached to the platen outer circumference vertical wall, at least one i) reflective mirror device or ii) a light capture and transmission device that is enclosed in the platen sealed internal chamber and is attached to the platen, a platen radial line that extends from the platen center of rotation to the platen outer circumference   
       wherein the platen sealed internal chamber, the transparent window that is attached to the platen flat horizontal annular abrading surface, the transparent window that is attached to the platen outer circumference vertical wall and the at least one reflective mirror device are nominally aligned along the platen radial line that extends from the platen center of rotation to the platen outer circumference;
 b) the platen flat annular abrading surface has an abrasive coating or an attached abrasive coated disk with non-abrasive areas in the platen annular surface abrasive coating or in the attached abrasive coated disk wherein the non-abrasive areas are aligned to be coincident with the transparent window that is attached to the platen flat horizontal annular abrading surface and where light or radiant energy can be transmitted through the platen abrasive coating non-abrasive areas or light or radiant energy can be transmitted through the non-abrasive areas of the abrasive coated disk that is attached to the platen; 
 c) at least one workpiece having a flat abraded surface and a workpiece radius wherein the at least one workpiece is in flat abrading contact with the platen abrasive coating or in flat abrading contact with the abrasive coating on the abrasive disk that is attached to the platen wherein the workpiece abraded surface is periodically in alignment with the transparent window that is attached to the platen flat horizontal annular abrading surface when the platen is rotated wherein the at least one reflective mirror device that is enclosed in the platen sealed internal chamber is periodically positioned in line-of-sight alignment with the workpiece abraded surface through the transparent window that is attached to the platen flat horizontal annular abrading surface and through the platen abrasive coating non-abrasive areas or the at least one reflective mirror device is in line-of-sight alignment through the transparent window that is attached to the platen flat horizontal annular abrading surface and through the non-abrasive areas attached to the platen; 
 d) the at least one stationary light source or radiation energy device is located adjacent to the outer periphery of the rotatable platen; 
 e) an at least one stationary light receiver or radiation energy receiver device located adjacent to the outer periphery of the rotatable platen; 
 f) wherein beams of light or radiation energy that are generated by the at least one stationary light source or radiation energy device is directed nominally horizontally through the transparent window that is attached to the platen outer circumference vertical wall where the beams of light or radiation energy impinges on the surface of the at least one reflective mirror device that is enclosed in the platen sealed internal chamber wherein the beams of light or radiation energy are reflected toward the abraded surface of the workpiece by the at least one mirror device in a near-vertical direction through the transparent window that is attached to the platen flat horizontal annular abrading surface and through the platen abrasive coating non-abrasive areas or through the non-abrasive areas of the abrasive coated disk that is attached to the platen to impinge on the abraded surface of the at least one workpiece that reflects the beams of light or radiation energy in a near-vertical direction through the platen non-abrasive areas attached to the platen and through the transparent window that is attached to the platen flat horizontal annular abrading surface to impinge on at least one reflective mirror device that reflects the beams of light or radiation energy in a near-horizontal direction through the transparent window that is attached to the platen outer circumference vertical wall wherein the beams of light or radiation energy are directed to contact the at least one stationary light receiver or radiation energy receiver device that is located adjacent to the outer periphery of the rotating platen; 
 g) wherein the at least one stationary light receiver or radiation energy receiver device that receives the beams of light or radiation energy determines the intensity of or other characteristics of the impinging light or radiation energy from the at least one workpiece abraded surface to provide measurements that allow determination of the state of completion of the abrading action, the existence of surface defects or the existence of undesirable surface features on the stationary or moving at least one workpiece's flat abraded surface that is in flat abrading contact with the platen abrasive coating. 
 
     
     
         2 . The abrasive coated disk of  claim 1  where an abrasive coated disk is present on the plten and the abrasive coated disk is a flexible abrasive disk, having an annular band of abrasive coated raised-island structures that are attached to a transparent backing, wherein the flexible abrasive disk is attached to the platen, wherein the flexible abrasive disk annular band of abrasive coated raised-island structures is coincident with the platen flat annular abrading surface and wherein there are recessed areas between the individual raised island structures that expose the transparent backing, wherein a selected recessed area having the exposed backing between the individual raised island structures is aligned to be coincident with the transparent window that is attached to the platen flat horizontal annular abrading surface, wherein light or radiant energy can be transmitted through the backing in the selected recessed area having the exposed backing between the individual raised island structures. 
     
     
         3 . The abrasive coated disk of  claim 1  wherein the abrasive coated disk is a flexible abrasive disk having a backing with a backing thickness, and an annular band of abrasive coating that has an abrasive coating thickness, wherein the annular band of abrasive coating is attached to the flexible abrasive disk backing, wherein the flexible abrasive disk is attached to the platen, wherein the flexible abrasive disk annular band of abrasive is coincident with the platen flat annular abrading surface and wherein there is at least one through-hole that extends through the thickness of the flexible abrasive disk abrasive coating and extends through the thickness of the flexible abrasive disk backing, wherein a selected through-hole is aligned to be coincident with the transparent window that is attached to the platen flat horizontal annular abrading surface, wherein light or radiant energy can be transmitted through the transparent window that is attached to the platen flat horizontal annular abrading surface and through the selected through-hole. 
     
     
         4 . The platen flat annular abrading surface abrasive coating of  claim 1  where the platen abrasive coating is an annular band of a rigid abrasive layer, having a rigid abrasive layer thickness, where there is at least one through-hole that extends through the thickness of the rigid abrasive layer wherein a selected through-hole is aligned to be coincident with the transparent window that is attached to the platen flat horizontal annular abrading surface wherein light or radiant energy can be transmitted through the transparent window that is attached to the platen flat horizontal annular abrading surface and through the selected through-hole. 
     
     
         5 . The abrasive coated disk of  claim 1  wherein the abrasive coated disk is a flexible chemical mechanical planarization pad having a chemical mechanical planarization pad thickness that is attached to the platen, wherein there is at least one through-hole that extends through the thickness of the chemical mechanical planarization pad, wherein a selected through-hole is aligned to be coincident with the transparent window that is attached to the platen flat horizontal annular abrading surface such that light or radiant energy can be transmitted through the transparent window that is attached to the platen flat horizontal annular abrading surface and through the selected through-hole. 
     
     
         6 . The platen of  claim 1  further comprising multiple sets of components comprised of a platen sealed internal chamber, a transparent window that is attached to the platen flat horizontal annular abrading surface, a transparent window that is attached to the platen outer circumference vertical wall, at least one reflective mirror device that is enclosed in the platen sealed internal chamber and is attached to the platen, a respective platen radial line that extends from the platen center of rotation to the platen outer circumference wherein the platen sealed internal chamber, the transparent window that is attached to the platen flat horizontal annular abrading surface, the transparent window that is attached to the platen outer circumference vertical wall and the at least one reflective mirror device are nominally aligned along the respective platen radial lines that extend from the platen center of rotation to the platen outer circumference and multiple sets of these components are positioned around the circumference of the platen. 
     
     
         7 . The platen of  claim 1  wherein a light capture and transmission device is present as at least one flexible optic fiber cable that is enclosed in the platen sealed internal chamber, wherein the at least one optic fiber cable has optic fiber cable entry and optic fiber cable exit surfaces, wherein beams of light or radiation energy generated by the at least one stationary light source or radiation energy device are directed nominally horizontally through the transparent window that is attached to the platen outer circumference vertical wall where the beams of light or radiation energy impinge on the optic fiber cable entry surface of the at least one optic fiber cable where the beams of light or radiation energy are transmitted toward the abraded surface of the workpiece by the at least one optic fiber cable and exit the at least one optic fiber cable at the optic fiber cable exit surface in a near-vertical direction through the transparent window that is attached to the platen flat horizontal annular abrading surface and through the platen abrasive coating non-abrasive areas or through the non-abrasive areas of the abrasive coated disk that is attached to the platen to impinge on the abraded surface of the at least one workpiece that reflects the beams of light or radiation energy in a near-vertical direction through the platen abrasive coating non-abrasive areas or through the non-abrasive areas of the abrasive coated disk that is attached to the platen and through the transparent window that is attached to the platen flat horizontal annular abrading surface to impinge on the optic fiber cable entry surface of the at least one optic fiber cable that transmits the beams of light or radiation energy through the at least one optic fiber cable to exit at least one optic fiber cable at the optic fiber cable exit surface in a near-horizontal direction and are directed through the transparent window that is attached to the platen outer circumference vertical wall where the beams of light or radiation energy are directed to contact the at least one stationary light receiver or radiation energy receiver device that is located adjacent to the outer periphery of the rotating platen. 
     
     
         8 . The platen of  claim 1  having a set of selected components where the set of selected components comprise a platen sealed internal chamber, at least one transparent window that is attached to the platen flat horizontal annular abrading surface, a transparent window that is attached to the platen outer circumference vertical wall, multiple reflective mirror devices that are enclosed in the platen sealed internal chamber and are attached to the platen, a respective platen radial line that extends from the platen center of rotation to the platen outer circumference wherein the platen sealed internal chamber, the at least one transparent window that is attached to the platen flat horizontal annular abrading surface, the transparent window that is attached to the platen outer circumference vertical wall and the multiple reflective mirror devices are nominally aligned along the respective platen radial line that extends from the platen center of rotation to the platen outer circumference wherein multiple reflective mirror devices are located sequentially along the platen radial line that extends from the platen center of rotation to the platen outer circumference wherein the multiple reflective mirror devices receive beams of light or radiation energy generated by the at least one stationary light source or radiation energy device, wherein the multiple reflective mirror devices reflect them to impinge the beams of light or radiation energy on individual selected areas at multiple radii locations on the abraded surfaces of the at least one workpieces and the multiple reflective mirror devices reflect beams of light or radiation energy that are reflected from individual selected areas at multiple radii locations on the abraded surfaces of the at least one workpiece in a near-horizontal direction to at least one stationary light receiver or radiation energy receiver device. 
     
     
         9 . The platen of  claim 7  having a set of selected components where the set of selected components is comprised of a platen sealed internal chamber, at least one transparent window that is attached to the platen flat horizontal annular abrading surface, a transparent window that is attached to the platen outer circumference vertical wall, multiple flexible optic fiber cables that are enclosed in the platen sealed internal chamber and are attached to the platen, a respective platen radial line that extends from the platen center of rotation to the platen outer circumference, wherein the platen sealed internal chamber, the at least one transparent window that is attached to the platen flat horizontal annular abrading surface, the transparent window that is attached to the platen outer circumference vertical wall and the multiple flexible optic fiber cables are nominally aligned along the respective platen radial line that extends from the platen center of rotation to the platen outer circumference, wherein multiple flexible optic fiber cables are located along the platen radial line that extends from the platen center of rotation to the platen outer circumference, wherein the multiple flexible optic fiber cables receive beams of light or radiation energy that are generated by the at least one stationary light source or radiation energy device, wherein the multiple flexible optic fiber cables impinge the beams of light or radiation energy on individual selected areas at multiple radii locations on the abraded surfaces of the at least one workpieces and the multiple flexible optic fiber cables transmit beams of light or radiation energy that are reflected from individual selected areas at multiple radii locations on the abraded surfaces of the at least one workpieces to at least one stationary light receiver or radiation energy receiver device. 
     
     
         10 . The at least one reflective mirror devices of  claim 1  wherein an individual reflective mirror device is used to reflect a first horizontal beam of light or radiation energy to a near-vertical direction and the same at least one reflective mirror device can reflect a second near-vertical direction beam of light or radiation energy to a horizontal direction. 
     
     
         11 . The stationary light source or radiation energy devices of  claim 1  wherein the light or radiation energy sources emits white light including light having wavelengths of 200 to 800 nanometers and/or the light or radiation energy sources emit light or radiation energy having wavelengths that extend to about 1550 nm or more. 
     
     
         12 . The stationary light source or radiation energy devices of  claim 1  wherein the light or radiation energy sources can emit light or radiation energy continuously or at controlled intervals with a sampling frequency of at least between 2 to 200 milliseconds. 
     
     
         13 . The rotatable platen abrading machine apparatus of  claim 1  where the measurement outputs of the at least one stationary light receiver or radiation energy receiver devices is transmitted to a rotatable platen abrading machine abrading machine system control device that analyzes the stationary light receiver or radiation energy receiver devices measurement outputs and uses analytical algorithms to actively control the abrading system parameters comprising the duration of the workpiece abrading procedure, the workpiece abrading pressures and the workpiece abrading speeds and the platen abrading speeds during the abrading procedures. 
     
     
         14 . The rotatable platen abrading machine apparatus of  claim 1  has a semiconductor wafer substrates on the platen. 
     
     
         15 . A process of monitoring abraded conditions of the surface of a workpiece abraded by an abrasive coating on an abrading machine rotatable platen using light that is reflected off the workpiece comprising:
 a) providing a rotatable circular abrading platen having a horizontal flat annular abrading surface, a platen center of rotation, a platen outer circumference, a platen outer circumference vertical wall, a platen sealed internal chamber, a transparent window that is attached to the platen flat horizontal annular abrading surface, a transparent window that is attached to the platen outer circumference vertical wall, at least one reflective mirror device that is enclosed in the platen sealed internal chamber and is attached to the platen, a platen radial line that extends from the platen center of rotation to the platen outer circumference,   
       wherein the platen sealed internal chamber, the transparent window that is attached to the platen flat horizontal annular abrading surface, the transparent window that is attached to the platen outer circumference vertical wall and the at least one reflective mirror device are nominally aligned along the platen radial line that extends from the platen center of rotation to the platen outer circumference;
 b) providing the platen flat annular abrading surface with an abrasive coating or an attached abrasive coated disk wherein there are non-abrasive areas in the platen annular surface abrasive coating or in the attached abrasive coated disk where the non-abrasive areas are aligned to be coincident with the transparent window that is attached to the platen flat horizontal annular abrading surface and, wherein light or radiant energy can be transmitted through the platen abrasive coating non-abrasive areas or light or radiant energy can be transmitted through the non-abrasive areas of the abrasive coated disk that is attached to the platen; 
 c) providing at least one workpiece having a flat abraded surface and a workpiece radius wherein the at least one workpiece is in flat abrading contact with the platen abrasive coating or in flat abrading contact with the abrasive coating on the abrasive disk that is attached to the platen, wherein the workpiece abraded surface is periodically in alignment with the transparent window that is attached to the platen flat horizontal annular abrading surface when the platen is rotated, wherein the at least one reflective mirror device that is enclosed in the platen sealed internal chamber is periodically positioned in line-of-sight alignment with the workpiece abraded surface through the transparent window that is attached to the platen flat horizontal annular abrading surface and through the platen abrasive coating non-abrasive areas or the at least one reflective mirror device is in line-of-sight alignment through the transparent window that is attached to the platen flat horizontal annular abrading surface and through the non-abrasive areas of the abrasive coated disk that is attached to the platen; 
 d) providing at least one stationary light source or radiation energy device is located adjacent to the outer periphery of the rotatable platen; 
 e) providing at least one stationary light receiver or radiation energy receiver device is located adjacent to the outer periphery of the rotatable platen; 
 f) providing beams of light or radiation energy that are generated by the at least one stationary light source or radiation energy device and directed nominally horizontally through the transparent window that is attached to the platen outer circumference vertical wall where the beams of light or radiation energy impinges on the surface of the at least one reflective mirror device that is enclosed in the platen sealed internal chamber, wherein the beams of light or radiation energy are reflected toward the abraded surface of the workpiece by the at least one mirror device in a near-vertical direction through the transparent window that is attached to the platen flat horizontal annular abrading surface and through the platen abrasive coating non-abrasive areas or through the non-abrasive areas of the abrasive coated disk that is attached to the platen to impinge on the abraded surface of the at least one workpiece that reflects the beams of light or radiation energy toward the abraded surface of the workpiece in a near-vertical direction through the platen abrasive coating non-abrasive areas or through the non-abrasive areas of the abrasive coated disk that is attached to the platen and through the transparent window that is attached to the platen flat horizontal annular abrading surface to impinge on at least one reflective mirror device that reflects the beams of light or radiation energy in a near-horizontal direction through the transparent window that is attached to the platen outer circumference vertical wall, wherein the beams of light or radiation energy are directed to contact the at least one stationary light receiver or radiation energy receiver device that is located adjacent to the outer periphery of the rotating platen; 
 g) using the at least one stationary light receiver or radiation energy receiver device that receives the beams of light or radiation energy to determine the intensity of or other characteristics of the impinging light or radiation energy from the at least one workpiece abraded surface to provide measurements that allow determination by a processor of the state of completion of the abrading action, the existence of surface defects or the existence of undesirable surface features on the stationary or moving at least one workpiece's flat abraded surface that is in flat abrading contact with the platen abrasive coating. 
 
     
     
         16 . The process of  claim 15  wherein the measurement outputs of the at least one stationary light receiver or radiation energy receiver devices are transmitted to a rotatable platen abrading machine abrading machine system control device comprising a processor that analyzes the stationary light receiver or radiation energy receiver devices measurement outputs and executes code that performs analytical algorithms to actively control the abrading system parameters comprising the duration of the workpiece abrading procedure, the workpiece abrading pressures and the workpiece abrading speeds and the platen abrading speeds during the abrading procedures. 
     
     
         17 . The process of  claim 15  wherein the abrasive coated disk is a flexible abrasive disk, having an annular band of abrasive coated raised-island structures attached to a transparent backing, wherein the flexible abrasive disk is attached to the platen, wherein the flexible abrasive disk annular band of abrasive coated raised-island structures is coincident with the platen flat annular abrading surface and wherein there are recessed areas between the individual raised island structures that expose the transparent backing, wherein a selected recessed area having the exposed backing between the individual raised island structures is aligned to be coincident with the transparent window that is attached to the platen flat horizontal annular abrading surface and wherein light or radiant energy is transmitted through the backing in the selected recessed area having the exposed backing between the individual raised island structures. 
     
     
         18 . The process of  claim 15  wherein a set of selected components is provided, wherein the set of selected components comprises a platen sealed internal chamber, at least one transparent window that is attached to the platen flat horizontal annular abrading surface, a transparent window that is attached to the platen outer circumference vertical wall, multiple reflective mirror devices that are enclosed in the platen sealed internal chamber and are attached to the platen, a respective platen radial line that extends from the platen center of rotation to the platen outer circumference, wherein the platen sealed internal chamber, the at least one transparent window that is attached to the platen flat horizontal annular abrading surface, the transparent window that is attached to the platen outer circumference vertical wall and the multiple reflective mirror devices are nominally aligned along the respective platen radial line that extends from the platen center of rotation to the platen outer circumference where multiple reflective mirror devices are located sequentially along the platen radial line that extends from the platen center of rotation to the platen outer circumference,
 wherein the multiple reflective mirror devices receive beams of light or radiation energy generated by the at least one stationary light source or radiation energy device to reflect them to impinge on individual selected areas at multiple radii locations on the abraded surfaces of the at least one workpieces and the multiple reflective mirror devices reflect beams of light or radiation energy that are reflected from individual selected areas at multiple radii locations on the abraded surfaces of the at least one workpieces in a near-horizontal direction to at least one stationary light receiver or radiation energy receiver device. 
 
     
     
         19 . The rotatable platen abrading machine apparatus of  claim 1  wherein the abrasive-coated platen is a floating-platen in abrading contact simultaneously with at least one flat-surfaced workpiece that is attached to one of three individual rotatable workpiece spindles that are mounted on a rigid abrading machine base, wherein the rotatable circular abrading platen apparatus has the components to optically measure the surface condition of the abraded surface of the at least one workpiece during an abrading procedure using the stationary at least one stationary light source or radiation energy device and the at least one stationary light receiver or radiation energy receiver device. 
     
     
         20 . The rotatable platen abrading machine apparatus of  claim 1  wherein two of the rotatable circular abrading platens are used on a doubled-sided abrading system having an upper rotatable circular abrading platen and a lower rotatable circular abrading platen, wherein the at least one workpiece that has two opposed flat surfaces are positioned between the upper rotatable circular abrading platen and the lower rotatable circular abrading platen, wherein both of the two opposed flat surfaces of the at least one workpieces are abraded simultaneously by the abrading coatings on the upper rotatable circular abrading platen and on the lower rotatable circular abrading platen, wherein either or both the upper rotatable circular abrading platen apparatus and the lower rotatable circular abrading platen apparatus has the components to optically measure the surface condition of one or both abraded surfaces of the at least one workpieces during the abrading procedure using the stationary at least one stationary light source or radiation energy device and the at least one stationary light receiver or radiation energy receiver device.