Abrading – Abrading process – Glass or stone abrading
Reexamination Certificate
2001-09-20
2003-12-02
Hail, III, Joseph J. (Department: 3723)
Abrading
Abrading process
Glass or stone abrading
Reexamination Certificate
active
06656023
ABSTRACT:
Provisional Applications and Regular Patent Applications which this patent claims benefit of are included herein by reference in their entirety.
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 semiconductor wafer 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 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 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 targeted tolerances with techniques needed such as Chemical Mechanical Polishing. Because of the strict tolerances, extreme care is given to attaining the targeted thinned down tolerances. As such, it is particularly preferred to accurately determine just when enough of the layer has been removed to reach the targeted 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
An objective of polishing of semiconductor layers is to make the semiconductor layers as nearly perfect as possible. Abrasive finishing of sensitive microelectronic surfaces can suffer from overly harsh finishing on a workpiece causing unwanted scratching or other unwanted surface damage thus reducing the perfection of the surface. Further, finishing pad finishing surface can suffer from having a higher than necessary coefficient of friction when finishing a workpiece causing higher than desired coefficient(s) of friction in the operative finishing interface. This higher than necessary coefficient of friction can lead to other unwanted surface damage. Further, fixed abrasive finishing pads can have abrasive particles unexpectedly break away from their surface during finishing and these broken away abrasive particles can scratch or damage the workpiece surface. Still further, during finishing a particle can break away from the workpiece surface forming a workpiece abrasive particle which can scratch or damage the workpiece surface. These unwanted effects are particularly important and deleterious to yield when manufacturing electronic wafers which require extremely close tolerances in required planarity and feature sizes.
It is an advantage of this invention to reduce the harshness of abrasive finishing on the workpiece surface during finishing. It is an advantage of this invention to reduce unwanted scratching or other unwanted surface damage on the workpiece surface during finishing. It is further an advantage of this invention to reduce the coefficient(s) of friction during finishing a workpiece to help reduce unwanted surface damage. It is an advantage of this invention to reduce unwanted damage to the workpiece surface when during finishing with a fixed abrasive finishing element an abrasive particle unexpectedly breaks away from their surface. It is an advantage of the invention to reduce unwanted damage to the workpiece surface when an abrasive workpiece particle breaks away workpiece surface during finishing. It is further an advantage of this invention to help improve yield for workpieces having extremely close tolerances such as semiconductor wafers.
Addition of lubricants to the interface between the workpiece surface being finished and the finishing pad finishing 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. Friction can change due to real time changes to the workpiece surface, the finishing element finishing surface, lubricant changes, and changes to process control parameter set points. A method which use a plurality of process sensors to gain information about finishing progress and uses this information for improved finishing control is preferred. Further, the preferred real time tangential force of friction and/or coefficient of friction control can change due to the specific structure and/or topography to the workpiece being finished. By tracking the workpiece during manufacture, improved information for in real time (in situ) control of lubricant changes, tangential force of friction, and/or coefficient of friction can be effected. A method to further improve control in situ process changes due to lubricant additions and/or changes is needed in the industry. A method to track a workpiece during manufacture and to use tracking information during finishing is needed. 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.
These and other advantages of the invention 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 method of finishing a semiconductor wafer surface having a uniform region and a finishing cycle time comprising a step 1) of providing a tracked semiconductor having tracked information; a step 2) of providing a finishing element finishing surface; a step 3) of providing an organic lubricant to the operative finishing interface comprising the interface formed between the finishing element finishing surface and the semiconductor wafer surface being finished; a step 4) of providing a finishing control subsystem having at least three operative process sensors which include at least two operative friction sensors for sensing in situ process information, access to the tracked information, and a processor to evaluate the in situ process information and tracked information; a step 5) of applying an operative finishing motion in the operative finishing interface forming in the operative finishing interface a uniform region having the organic lubrication and wherein the uniform region has a coefficient of friction; and a step 6) of changing a plurality of control parameters in response to an evaluation of both the in situ process information and the tracked information, wherein changing the control parameters changes the coefficient of friction in the uniform region having organic lubrication during at least a portion of the finishing cycle time.
A preferred embodiment of this invention is directed to a method of finishing a semiconductor wafer surface having a uniform region and a finishing cyc
Beaver Creek Concepts Inc
Ojini Anthony
LandOfFree
In situ control with lubricant and tracking does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with In situ control with lubricant and tracking, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and In situ control with lubricant and tracking will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3105019