Abrading – Precision device or process - or with condition responsive... – With indicating
Reexamination Certificate
1999-05-28
2001-07-24
Banks, Derris H. (Department: 3723)
Abrading
Precision device or process - or with condition responsive...
With indicating
C451S296000
Reexamination Certificate
active
06264533
ABSTRACT:
FIELD OF THE INVENTION
This invention relates generally to abrasive processing of articles, and more particularly, to an apparatus and method for abrasively processing articles using an abrasive product encoded with a machine readable pattern representative of product identification information, indexing information, servo information, and the like.
BACKGROUND OF THE INVENTION
Various types of automated abrasion and polishing machinery have been developed to abrasively process articles of varying composition and configuration. In the semiconductor industry, for example, conventional chemical-mechanical planarization (CMP) machinery provides for automated planarization and polishing of semiconductor wafers. An example of an automatic wafer polishing apparatus is described in U.S. Pat. Nos. 5,643,044 and 5,791,969 issued to Lund, each of which is incorporated herein by reference in its entirety.
Conventional automated polishing machinery, such as that described in the above-identified patents, typically employs a computer-based control system to control the general polishing process. The servo control process used in such machinery is typically based on the shaft speed of a drive motor that drives a roll of abrasive material through the machinery. The shaft speed is compared to a programmed value, and a voltage or current supplied to the motor is adjusted by the servo control mechanism to equilibrate the sensed shaft speed with the programmed speed value.
Using this approach, only a indirect measure of abrasive roll speed may be obtained. Such an approach fails to account for a number of factors that can significantly affect the computation of the actual speed of the abrasive material relative to the wafer or article subject to polishing. Moreover, such conventional servoing approaches provide for only a limited degree of precision when attempting to position a particular region of abrasive material into contact with a given article during the polishing process. These and other limitations inherent in conventional automated polishing systems may have a profound negative impact on the ability to process and finish certain articles, such as semiconductor wafers, with a high level of precision.
Although conventional polishing approaches provide for some degree of automation, many of these approaches require human intervention at various steps. For example, an operator must typically verify, through manual means, that a particular type of abrasive product is appropriate for processing a particular type of article. An error made by the operator in this context will generally have deleterious results, typically resulting in damage to, or destruction of, costly articles and undesirable processing down-time. Other aspects of conventional polishing and abrasion processing methodologies are similarly limited in terms of automation, such as the use of partially automated or non-automated inventory systems, machine performance diagnostic systems, abrasive product/article tracking systems, and the like.
There exists a need for a system and method for abrasively processing articles that provide enhanced automation and data processing capabilities. There exists a particular need for an improved approach to controlling movement of an abrasive product relative to one or more articles during abrasion processing. There exists a further need for an integrated information system that provides for a variety of data acquisition and manipulation capabilities presently unavailable using conventional abrasion or polishing machinery. The present invention fulfills these and other needs.
SUMMARY OF THE INVENTION
The present invention is directed to an apparatus and method for abrasively processing an article. An abrasive product is provided with a machine discernable pattern representative of information which may vary in terms of type and content. The machine discernable pattern is read while the abrasive product moves relative to the article, and is used to initiate a machine operation, such as an operation associated with controlling the movement of the abrasive product relative to the article. The machine discernable pattern may include one or more of a machine discernable electrical characteristic, optical characteristic, topographic characteristic or magnetic characteristic. Reading the machine discernable pattern may involve one or more of electrically, optically, mechanically or magnetically reading the machine discernable pattern provided on the abrasive product.
The machine discernable pattern may include one or more of indicia, protrusions, depressions, holes, voids, color or pigment variations, bar codes, magnetic transitions or periodic markings. The machine discernable pattern may include a first pattern portion and a second pattern portion, wherein the first pattern portion exhibits a machine discernable characteristic different from a machine discernable characteristic exhibited by the second pattern portion.
The machine discernable pattern may include one or more of indexing information, servo information, alignment information or abrasive product identification information. Indexing information may be included in the pattern and used to compute one or more locations of the abrasive product at which the abrasive product contacts a given article. Servo information may also be included as part of the machine discernable pattern, alone or in combination with indexing information, and may be used to control abrasive product movement, such as a rate or direction at which the abrasive product moves relative to the article. The machine discernable pattern may further include alignment information from which changes in abrasive product alignment relative to the article may be effected.
Abrasive product identification information included in the machine discernable pattern may be used to verify that a particular abrasive product is appropriate for abrasively processing a given article. Movement of the abrasive product may be halted in response to a failure to verify that the abrasive product is appropriate for abrasively processing the subject article. The machine discernable pattern may include information identifying a location of one or more defective regions of the abrasive product. The defect location information may be used to control abrasive product movement so as to avoid contact between the defective regions and the article.
The abrasive product may constitute a web having a fixed length or, alternatively, may be a continuous web. The web may, for example, constitute a three dimensional, composite, fixed web suitable for planarizing a semiconductor wafer. The abrasive product may also constitute a movable pad and an abrasive slurry. The pad may be moved in a controlled manner relative to the article such that the pad and the abrasive slurry abrasively contact the article. The machine discernable pattern provided on the pad may be read subsequent to a cleaning operation. Depending on the configuration of the abrasive processing apparatus, the machine discernable pattern may be read at a first reading location prior to the abrasive product (e.g., pad and abrasive slurry) contacting the article and read at a second reading location subsequent to the abrasive product contacting the article, such as following a cleaning procedure. The article subject to abrasive processing may comprise a silicon article, a glass article, a ceramic article, a composite article, a wood article or a metallic article. The article may, for example, comprise a silicon wafer, geranium wafer or gallium arsenide wafer, and associated structures related to the fabrication of semiconductor devices.
Another embodiment of the present invention concerns an abrasive product for abrasively processing an article. The abrasive product includes a base layer having a first surface and a second surface. An abrasive material is disposed on the first surface. A machine discernable pattern is provided on either one or both of the first and second surfaces for use in generating a control signal for controlling movement of the abrasiv
Forsberg Gary B.
Kummeth Charles R.
Muilenburg Michael J.
Pendergrass, Jr. Daniel B.
Streifel Robert J.
3M Innovative Properties Company
Banks Derris H.
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