Abrading – Precision device or process - or with condition responsive... – With indicating
Reexamination Certificate
2001-08-27
2004-05-25
Hail, III, Joseph J. (Department: 3723)
Abrading
Precision device or process - or with condition responsive...
With indicating
C451S005000, C451S041000, C451S285000
Reexamination Certificate
active
06739947
ABSTRACT:
BACKGROUND OF INVENTION
Chemical mechanical polishing (CMP) is generally known in the art. For example U.S. Pat. No. 5,177,908 to Tuttle issued in 1993 describes a finishing element for semiconductor wafers, having a face shaped to provide a constant, or nearly constant, surface contact rate to a workpiece such as a semiconductor wafer in order to effect improved planarity of the workpiece. U.S. Pat. No. 5,234,867 to Schultz et. al. issued in 1993 describes an apparatus for planarizing semiconductor wafers which in a preferred form includes a rotatable platen for polishing a surface of the workpiece and a motor for rotating the platen and a non-circular pad is mounted atop the platen to engage and polish the surface of the semiconductor wafer. Fixed abrasive finishing elements are also known for polishing semiconductor layers. An example is WO 98/18159 PCT application by Minnesota Mining and Manufacturing.
Semiconductor wafer fabrication generally requires the formation of layers of material having particularly small thickness. A typical conductor layer, such as a metal layer, is generally 2,000 to 6,000 angstroms thick and a typical insulating layer, for example a an oxide layer, is generally 3,000 to 5,000 angstroms thick. The actual thickness is at least partially dependent on the function of the layer along with the function and design of the semiconductor wafer. A gate oxide layer can be less than 100 angstroms while a field oxide is in the thousands of angstroms in thickness. In higher density and higher value semiconductor wafers the layers can be below 500 angstroms in thickness. Generally during semiconductor fabrication, layers thicker than necessary are formed and then thinned down to the required tolerances with techniques needed such as Chemical Mechanical Polishing. Because of the strict tolerances, extreme care is given to attaining the required thinned down tolerances. As such, it is important to accurately determine just when enough of the layer has been removed to reach the required tolerances, this is the end point for the thinning or polishing operation. One method to remove selected amounts of material is to remove the semiconductor wafer periodically from polishing for measurements such as thickness layer measurements. Although this can be done it is time consuming and adds extra expense to the operation. Further the expensive wafers can be damaged during transfer to or from the measurement process further decreasing process yields and increasing costs.
BRIEF SUMMARY OF INVENTION
Confidential applicant evaluations also suggest that lubricants supplied to the interface between the workpiece surface being finished and the polishing pad polishing surface can improve finishing. Addition of lubricants to the interface between the workpiece surface being finished and the polishing pad polishing surface can improve finishing but also changes the friction at this interface. In situ process control where lubricants are added or changed during the finishing process can change finishing performance. A method to detect in process changes due to lubricant additions and/or changes is needed in the industry. A method which can also help improve the cost of manufacture of the semiconductor wafers during a finishing cycle time having real time friction changes would be generally desirable.
As discussed above, there is a need for in situ detector for CMP and other finishing techniques which will function with or without the addition lubrication to the finishing interface. There is a need for an in situ detector and control of CMP and other finishing control parameters which account for and adjust for the addition and/or control of lubrication at the finishing interface. There is a need for an in situ detector and control of CMP and other finishing control parameters which detect the endpoint and/or/stop the CMP and/or other finishing processes. There is a need to use cost of manufacture parameters for real time process control when using operative friction sensors. There is a need to use real time process control and current cost of manufacture with active lubrication of the interface to improve the finishing costs.
It is an advantage of this invention to develop an in situ friction sensor subsystem and finishing sensor subsystem for CMP and other finishing techniques and methods which function with or without the addition lubrication to the finishing interface. It is an advantage of this invention to develop an in situ friction sensor subsystem and finishing sensor subsystem for control of CMP and other finishing control parameters which account for and adjust for the addition and/or control of lubrication at the finishing interface. It is an advantage of this invention to develop an in situ friction sensor subsystem and finishing sensor subsystem CMP and other finishing control parameters which detect the endpoint and stop the CMP and/or other finishing processes. It is an advantage of this invention to use cost of manufacture parameters for real time process control when using operative friction sensors. It is an advantage of this invention to develop to use real time process control and current cost of manufacture with active lubrication of the interface to improve the finishing costs. It is an advantage of this invention to develop a method which can also help improve the cost of manufacture of the semiconductor wafers during a finishing cycle time having real time friction changes.
These and other advantages of the invention in preferred embodiments will become readily apparent to those of ordinary skill in the art after reading the following disclosure of the invention.
A preferred embodiment of this invention is directed to a finishing apparatus comprising a workpiece carrier for holding workpiece surface to finished; a finishing element finishing surface positioned proximate the workpiece surface to be finished; a mechanism for applying an operative finishing motion to the operative finishing interface comprising workpiece surface to be finished and finishing element finishing surface; and a friction control subsystem having at least one friction sensor probe having a friction sensor surface proximate to the finishing element finishing surface and free of contact with the workpiece surface and the friction sensor subsystem being capable of in situ control of a finishing control parameter.
A preferred embodiment of this invention is directed to a finishing apparatus comprising a workpiece carrier for holding workpiece surface to finished; a finishing element finishing surface positioned proximate the workpiece surface to be finished; a mechanism for applying an operative finishing motion to the operative finishing interface comprising workpiece surface to be finished and finishing element finishing surface; and a friction control subsystem having at least one friction sensor probe having a friction sensor surface proximate to the finishing element finishing surface and free of contact with the workpiece surface, the friction sensor probe capable of measuring a change in tangential force of friction and the friction sensor subsystem being capable of in situ control of a finishing control parameter responsive to a signal from the friction sensor probe.
A preferred embodiment of this invention is directed to a finishing apparatus comprising a semiconductor wafer carrier for holding semiconductor wafer surface to be finished; a finishing element finishing surface positioned proximate the semiconductor wafer surface to be finished; a mechanism for applying an operative finishing motion to the operative finishing interface comprising the semiconductor wafer surface to be finished and finishing element finishing surface; and a friction control subsystem having at least one friction sensor probe having a friction sensor surface proximate to the finishing element finishing surface and free of contact with the semiconductor wafer surface and the friction sensor subsystem being capable of in situ control of a finishing control parameter.
A preferred embodiment of this invent
Beaver Creek Concepts Inc
Hail III Joseph J.
Ojini Anthony
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