Chemistry: electrical and wave energy – Processes and products – Coating – forming or etching by sputtering
Reexamination Certificate
2000-12-04
2002-12-24
VerSteeg, Steven H. (Department: 1753)
Chemistry: electrical and wave energy
Processes and products
Coating, forming or etching by sputtering
C216S038000, C427S008000, C427S355000, C451S004000, C451S007000, C073S432100
Reexamination Certificate
active
06497798
ABSTRACT:
FIELD OF THE INVENTION
This invention relates generally to a method of polishing and more specifically to a method for the simultaneous, automatic, and precise, polishing of objects.
BACKGROUND OF THE INVENTION
Precise polishing is usually performed using rotary type polishing machines, where the polishing surface and the surface to be polished are placed in mechanical contact and rapidly moved relative to each other. Typically, the process is a time-consuming, multi-step task that requires constant monitoring. For example, if polishing to a predefined mark is required indicating the desired polishing “stop” or “end” point with an accuracy of a few microns or better relative to the mark line, then a mechanical micrometer indicator cannot be used for measuring the polishing progress due to vibration. Accordingly, precisely monitoring the approach to the mark-line often involves stopping the polishing, de-assembling the object being polished, using a microscope to view the polishing progress, re-assembling the object, and continuing with the polishing procedure. This expensive and time-consuming procedure is continued until the mark-line is reached.
Unfortunately, this method suffers from imprecision related to vibrations produced in the polishing procedure, variability in mounting the object, and in general, the skill of the polisher. Obviously, this method is not easily automated.
It is an object of this invention to provide a precise, vibration insensitive method of polishing an object that does not involve the de-assembling and re-assembling of the object to measure the progress of the polishing.
It is a further object of this invention to provide a method of polishing an object that is easily automated and that is more precise than prior art methods.
SUMMARY OF THE INVENTION
The instant invention provides a method for precisely polishing a non-electrical current conductive object (alternatively, if the object conducts electric current, the object should be coated with a thin layer of non-electric current conductive material using methods known to those skilled in the art). The method includes applying a conductive layer to the object in a manner such that when the object is polished an electric current flowing through the conductive layer changes in dependence upon a progress of the polishing. In a preferred embodiment, the conductive layer is applied in a predetermined pattern such that a measured resistance across the conductive layer is indicative of a predetermined stop-line for polishing.
In accordance with the invention there is provided a method of polishing comprising the steps of: providing an object having a first surface to be polished; applying a conductive material in a predetermined pattern to a second surface of the object; applying an electric current across the conductive material; polishing the first surface such that a portion of the conductive material on the second surface is removed; and measuring one of resistance and electric current across the conductive material for monitoring a progress of the polishing, the one of resistance and electric current being dependent on the predetermined pattern and the portion of the conductive material removed.
In accordance with the invention there is provided a method of polishing as defined in claim 5, further comprising the step of: providing at least one other object having a first surface to be polished; applying a conductive material in a predetermined pattern to a second surface of the at least one other object; simultaneously polishing the first surface of each of the object and the at least one other object; and measuring one of resistance and electric current across the conductive material applied to each of the objects.
In accordance with the invention there is further provided an apparatus for polishing a monolithic object having a conductive pattern coated thereon, the apparatus comprising: a mount for supporting the monolithic object during polishing; a polisher for polishing at least a portion of the monolithic object and the conductive pattern away; a meter having at least two contacts for coupling to the conductive pattern for measuring one of an electric current and a resistance across the conductive pattern; and a processor coupled to the polisher and the meter for receiving data from the meter and providing a signal to the polisher indicative of a progress of the polishing.
In accordance with the invention there is further provided a monolithic object comprising an electrically conductive region coated thereon for indicating when the object is polished to a desired length, at least a portion of said electrically conductive region designed to be polished away, said electrically conductive region having at least two terminals electrically coupled thereto for monitoring one of conductivity and resistance.
Advantageously, the method does not require the use of a microscope to measure the mark line. The approach to the mark line is measured as a function of resistance/electrical current—thus providing a more accurate and more precise measurement. Since the electrical current conductive bridge becomes thinner and thinner as the mark line is approached, the accuracy is high enough to measure changes in the progress of polishing for each individual turn of a fine polishing pad. Furthermore, the instant method is advantageously vibration insensitive.
REFERENCES:
patent: 5213655 (1993-05-01), Leach et al.
patent: 5624300 (1997-04-01), Kishii et al.
patent: 5877088 (1999-03-01), Samitsu et al.
patent: 6170149 (2001-01-01), Oshiki et al.
Rabinski Guenadi
Saulnier Eric
JDS Uniphase Inc.
Teitelbaum Neil
VerSteeg Steven H.
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