Other

Keltech Engineering, Inc.

Fishair Incorporated

Twin City Surgical, Inc.

University of Minnesota

Wayne O Duescher

Cameron M Duescher

Clarence I Steinback

Louis R Amundsen

Gary W Schukar

Glenn N Scudder

Tanya L Baxter

Gary A Staus

Robert P Patterson

Mark J Luedtke

Willis E Dahlman

Embodiments of a high-speed rotatable workpiece abrasive polishing head are disclosed that allow flat surfaced hard material workpieces or sapphire or semiconductor wafers to be polished at high abrading speeds that can use water-mist cooled quick-change fixed abrasive island-type discs. Workpieces can be quickly attached with vacuum to a rotatable workpiece plate having a curved (e.g., spherical) bearing with an offset spherical center of rotation located at the workpiece abraded surface. Abrading contact there prevents lateral abrading friction forces from tilting workpieces and causing non-flat workpiece surfaces. The workpiece carrier plate can be rotationally driven by a floating drive shaft having a spherical spline head that contacts the workpiece carrier plate at a position close to the workpiece abraded surface to avoid tilting of the workpiece due to the shaft-applied workpiece rotation forces. The workpiece head can allow the workpieces to either float in contact with the abrasive or be held in rigid contact with the abrasive.

Abrasive lapping head with floating and rigid workpiece carrier

Abrasive disk sheet articles having raised islands coated with abrasive have a flexible disk polymer backing. The top flat surfaces of the raised islands are coated with a liquid controlled-thickness slurry mixture of abrasive particles and a polymeric adhesive by use of a magnetic precision-thickness coating-control font sheet having individual open holes that are slightly smaller than the respective raised islands. The magnetic coater font sheet is placed in flat-surfaced contact with the raised island surfaces where each individual font sheet open hole is aligned with a respective island surface. A magnet placed on the non-island surface of the disk polymer backing urges the magnetic coater font sheet into conformal contact with the island surfaces. A squeegee device moved along the font sheet fills and level coats the island tops with a uniform-thickness abrasive slurry mixture. After coating, the font sheet is removed and the abrasive slurry is solidified.

Abrasive coated disk islands using magnetic font sheet

Hard-material, flat-surfaced workpieces such as semiconductor wafers or sapphire disks are attached with vacuum to the flexible elastomeric membrane of a rotatable wafer carrier that allows one surface of the workpiece to be in conformal abrading contact with a moving flat-surfaced abrasive. The elastomeric membrane external wafer attachment surface has a pattern of recessed vacuum grooves where vacuum supplied to the grooves firmly attach the rigid-material silicon wafer in flat-surfaced contact with the membrane. The attached wafer seals the vacuum grooves. A flexible thin metal annular membrane support disk is attached to the membrane within an abrading-pressure chamber where attached drive pins engage matching holes in the wafer carrier provide rotational torque to the wafer and restrain it laterally against abrading forces. Wafer polishing pressure is applied uniformly over the wafer surface. The rotating wafer peripheral edge does not contact a rigid retaining ring during a wafer polishing procedure.

Vacuum-grooved membrane wafer polishing workholder

Hard-material, flat-surfaced workpieces such as semiconductor wafers or sapphire disks are attached with vacuum to the flexible elastomeric membrane of a wafer carrier that allows one surface of the workpiece to be in conformal abrading contact with a moving flat-surfaced abrasive. The elastomeric membrane external wafer attachment surface has a pattern of recessed vacuum grooves and vacuum is supplied to the grooves to firmly attach the rigid-material silicon wafer in flat-surfaced contact with the membrane. The attached wafer seals the vacuum grooves and also provides lateral stiffness to the center portion of the membrane. An outer annular extension of the flexible elastomer membrane maintains the wafer at its original membrane-centered location when abrading forces are applied to the rotating wafer. The rotating wafer peripheral edge does not contact a rigid retaining ring during a wafer polishing procedure. Fixed-abrasive disks or raised-island abrasive disks are attached to a rotatable flat-surfaced platen.

Vacuum-grooved membrane abrasive polishing wafer workholder

Hard-material, flat-surfaced workpieces such as semiconductor wafers or sapphire disks are quickly attached with vacuum to a rotatable floating workpiece carrier. Fluid pressure in a sealed chamber applies uniform abrading pressure over the full abraded surface of the workpieces. A flexible diaphragm is used to form the sealed chamber and the carrier is rotationally driven by a lug-pin device. The floating carrier is horizontally restrained by a center-post device that provides rigid lateral support against abrading forces. Tilting of the floating carrier is provided by a spherical bearing. The abrading system can be operated at the very high abrading speeds used in high speed flat lapping with raised-island abrasive disks. Vacuum can also be applied to the sealed chamber to quickly move the workpiece away from the abrading surface. A mode of providing rigid parallel-surface abrading of a workpiece can be activated by simply applying vacuum to the sealed chamber.

Flexible diaphragm post-type floating and rigid abrading workholder

Flat-surfaced workpieces such as semiconductor wafers or sapphire disks are attached to a rotatable floating workpiece holder carrier that is supported by a pressurized-air flexible elastomer sealed air-chamber device and is rotationally driven by a lug-pin device. The rotating wafer carrier rotor is restrained by a set of idlers that are attached to a stationary housing to provide rigid support against abrading forces. The abrading system can be operated at the very high abrading speeds used in high speed flat lapping with raised-island abrasive disks. The range of abrading pressures is large and the device can provide a wide range of torque to rotate the workholder. Vacuum can also be applied to the elastomer chamber to quickly move the wafer away from the abrading surface. Internal constraints limit the axial, lateral and circumferential motion of the workholder. Wafers can be quickly attached to the workpiece carrier with vacuum.

Pin driven flexible chamber abrading workholder

Flat-surfaced workpieces such as semiconductor wafers or sapphire disks are attached to a rotatable floating or rigid workpiece holder carrier that is supported by a pressurized-air flexible elastomer disk sealed air-chamber device and is rotationally driven by a flexible arm or a lug-pin device. The rotating wafer carrier rotor is horizontally restrained by a set of idlers that are attached to a stationary housing to provide rigid support against abrading forces. The abrading system can be operated at the very high abrading speeds used in high speed flat lapping with raised-island abrasive disks. A wide range of abrading pressures are applied uniformly across the surface of the workpiece. Vacuum can also be applied to the elastomer chamber to quickly move the wafer away from the abrading surface. Internal constraints limit the axial, lateral and circumferential motion of the workholder. Wafers can be quickly attached to the workpiece carrier with vacuum.

Flexible diaphragm combination floating and rigid abrading workholder

Flat-surfaced workpieces such as semiconductor wafers are attached to a rotatable floating workpiece holder carrier rotor that is supported by and rotationally driven by a bellows. The rotating wafer carrier rotor is restrained by a set of idlers that are attached to a stationary housing to provide rigid support against abrading forces. The idlers allow low-friction operation of the abrading system to be provided at the very high abrading speeds used in high speed flat lapping with raised-island abrasive disks. The carrier rotor is also restrained by a rigid rotating housing to allow a limited lateral motion and also a limited angular motion. Air pressure within a sealed bellows chamber provides controlled abrading pressure for wafers or other workpieces. Vacuum can also be applied to the bellows chamber to quickly move the wafer away from the abrading surface. Wafers can be quickly attached to the workpiece carrier with vacuum.

Bellows driven floatation-type abrading workholder

Flat-surfaced workpieces such as semiconductor wafers or sapphire disks are attached to a rotatable floating workpiece holder carrier that is supported by a pressurized-air flexible elastomer sealed air-chamber device and is rotationally driven by a circular flexible-arm device. The rotating wafer carrier rotor is restrained by a set of idlers that are attached to a stationary housing to provide rigid support against abrading forces. The abrading system can be operated at the very high abrading speeds used in high speed flat lapping with raised-island abrasive disks. The range of abrading pressures is large and the device can provide a wide range of torque to rotate the workholder. Vacuum can also be applied to the elastomer chamber to quickly move the wafer away from the abrading surface. Internal constraints limit the axial and lateral motion of the workholder. Wafers can be quickly attached to the workpiece carrier with vacuum.

Spider arm driven flexible chamber abrading workholder

Flat-surfaced workpieces such as semiconductor wafers are attached to a rotatable floating workpiece holder carrier rotor that is supported by and rotationally driven by a bellows. The wafer carrier rotor is contained by a set of idlers that are attached to a stationary rotor housing to provide support against abrading forces that are imposed on the wafer by the moving abrasive coating on a rotary platen. The idlers allow low-friction operation of the abrading system to be provided at the very high abrading speeds used in high speed flat lapping with raised-island abrasive disks. The system is also well suited for lapping optical devices and rotary seals and for chemical mechanical planarization (CMP) polishing of wafers using resilient pads. Pressurized air is injected into the bellows device to provide uniform abrading pressure across the full surface of the wafer. Wafers can be attached to the workpiece carrier with vacuum.

Bellows driven air floatation abrading workholder

The rotary platens used here for high speed lapping are light in weight and low in mass inertia to allow fast acceleration and deceleration of the platens. The use of cast aluminum materials that are adhesively bonded together provides very rigid platens that have precision-flat surfaces that are dimensionally stable over long periods of time. Use of hardened spherical bead coatings on the surfaces of the platens provides wear-resistant coatings that are easy to apply and to maintain. The platens are constructed using ribs that provide very substantial stiffness and yet are light in weight which allows relatively small motors to be used to drive the platens. Platens are also constructed where the platen mass center is offset a very small distance from the center of rotation of the spherical-action bearings that support the platens to prevent dynamic distortion of the platen abrasive surface due to platen out-of-balance forces.

Floating abrading platen configuration

A method and apparatus for releasbly attaching flexible abrasive disks to a flat-surfaced platen that floats in three-point abrading contact with three rigid equal-height flat-surfaced rotable fixed-position workpiece spindles that are mounted on a precision-flat abrading machine base where the spindle surfaces are in a common plane that is co-planar with the base surface. The three spindles are positioned to form a triangle of platen supports where the rotational-centers of each of the spindles are positioned at the center of the annular width of the platen abrading surface. Flat surfaced workpieces are attached to the spindles and the rotating floating-platen abrasive surface contacts all three rotating workpieces to perform single-sided abrading. The platen abrasive can be re-reflattened by attaching equal-thickness abrasive disks to the three spindles that are rotated while in abrading contact with the rotating platen abrasive. There is no wear of the abrasive-disk protected platen surface.

Three-point spindle-supported floating abrasive platen

A low friction flat-lapping abrading apparatus and method for releasably attaching flexible abrasive disks to a flat-surfaced platen that floats in three-point abrading contact with flat-surfaced workpieces that are attached to three rotary spindles. The rigid equal-height flat-surfaced rotatable fixed-position workpiece spindles are mounted on a flat abrading machine base. They are positioned to form a triangle to provide stable support of the floating platen. All three spindle-tops are co-planar aligned to provide a precision-flat reference plane for mounting of the workpieces. The lapping operation has very high abrading speeds and very low abrading forces. The lightweight but strong lapping machine employs a pivot-balance structure where the weight of the drive motor is used to balance the weight of the abrading platen. Use of low-friction air bearings provides the capability for precision control of the abrading forces. The lapping machine is robust and well suited for a harsh abrading environment.

Pivot-balanced floating platen lapping machine

A method and apparatus for robotic devices that can be used to load and remove workpieces and abrasive disks for an abrading system having a floating, rotatable abrading platen that is three-point supported by annular, flat abrading-surface of the floating platen. The rotary spindles are mounted on the flat horizontal surface of a machine base and the spindle-top flat surfaces are aligned to be precisely co-planar with each other where the rotational-centers of each of the spindles fixed-position rotary flat-surfaced spindles. The flexible abrasive disks are releasably attached to the are positioned at the center of the annular radial-width of the platen abrading-surface. Flat-surfaced workpieces are attached to the spindle-top flat surfaces and the abrasive surface of the abrasive disk that is attached to the rotating floating-platen abrading surface contacts the workpieces to perform single-sided abrading on the workpieces. Workpieces can be flat-lapped to provide precision-flat and smoothly-polished surfaces.

Fixed-spindle floating-platen workpiece loader apparatus

There are three flat-surfaced rotary workpiece abrasive lapping spindles that are spaced apart from each other in a circle and are attached to the flat surface of a granite lapping machine base. Flat-surfaced workpieces are attached to the flat rotary surfaces of the workpiece spindles. Flexible abrasive disks are attached to the annular abrading surface of a rotary platen that is positioned to be concentric with the three spaced workpiece spindles. The platen is moved where the disk abrasive surface contacts the workpieces that are attached to the workpiece spindles. Both the platen and the workpieces spindles are rotated at high speeds to flat lap the exposed surfaces of the workpieces. Laser alignment devices are attached to an alignment rotary spindle that is positioned at the center of the workpiece spindle circle. These laser alignment distance sensors are used to co-planar align the top flat surfaces of the workpiece spindles.

Growing community of inventors

Roseville, MN, United States of America

Wayne O Duescher