Abrading – Precision device or process - or with condition responsive... – By optical sensor
Reexamination Certificate
1999-06-30
2001-04-17
Eley, Timothy V. (Department: 3723)
Abrading
Precision device or process - or with condition responsive...
By optical sensor
C451S008000, C451S011000, C451S067000, C451S288000
Reexamination Certificate
active
06217410
ABSTRACT:
TECHNICAL FIELD
The present invention relates, generally, to methods and apparatus for the in-situ endpoint detection of semiconductor layers during a planarization process and, more particularly, to methods and apparatus for the in-process cleaning of semiconductor workpieces and optical measurement probes utilized during endpoint detection processes.
BACKGROUND ART AND TECHNICAL PROBLEMS
The production of integrated circuits begins with the creation of high-quality semiconductor wafers. During the wafer fabrication process, the wafers may undergo multiple masking, etching, and dielectric and conductor deposition processes. Because of the high-precision required in the production of these integrated circuits, an extremely flat surface is generally needed on at least one side of the semiconductor wafer to ensure proper accuracy and performance of the microelectronic structures being created on the wafer surface. As the size of the integrated circuits continues to decrease and the density of microstructures on an integrated circuit increases, the need for precise wafer surfaces becomes more important. Therefore, between each processing step, it is usually necessary to polish or planarize the surface of the wafer to obtain the flattest surface possible.
For a discussion of chemical mechanical planarization (CMP) processes and apparatus, see, for example, Arai, et al., U.S. Pat. No. 4,805,348, issued February, 1989; Arai, et al., U.S. Pat. No. 5,099,614, issued March, 1992; Karlsrud et al., U.S. Pat. No. 5,329,732, issued July, 1994; Karlsrud, U.S. Pat. No. 5,498,196, issued March, 1996; and Karlsrud et al., U.S. Pat. No. 5,498,199, issued March, 1996. One typical CMP procedure involves the removal of one or more semiconductor layers originally present on a wafer. The removal of these layers (often formed of metallic materials such as tungsten, titanium, or the like) eventually exposes the oxide layer of the wafer. The endpoint of such a removal procedure may be indicated by the exposure of the oxide layer, the elimination of the metallic layers, the thickness of the oxide layer, the thickness of the wafer, or other measurable parameters of the wafer.
Methods and systems for performing endpoint detection are disclosed in U.S. patent application Ser. No. 08/798,803, filed Feb. 12, 1997, and entitled Methods and Apparatus for Detecting Removal of Thin Film Layers During Planarization, and U.S. patent application Ser. No. 08/687,710, filed Jul. 26, 1996, and entitled Methods and Apparatus for the In-process Measurement of Thin Film Layers, both of which are hereby incorporated by reference. The systems disclosed in these applications utilize an optical probe device that detects reflective characteristics of the semiconductor wafer surface during planarization. Unfortunately, water, slurries, and other processing materials present on the wafer surface and/or the optical probe may adversely affect the performance of such systems.
Previous attempts at cleaning the workpiece surfaces during such endpoint detection procedures have employed compressed air directed at the point where the optical interrogation signal contacts the workpiece surface. Unfortunately, the compressed air may dry the workpiece surface and/or the slurry, which can cause material build-up and scratching of the polished surface. Furthermore, the compressed air may blow loose particulate onto the surface of the workpiece; such particulate may damage the workpiece or alter the polishing characteristics of the slurry.
SUMMARY OF THE INVENTION
Accordingly, it is an advantage of the present invention that improved methods and apparatus for detecting the endpoint of a planarization procedure performed upon a workpiece are provided.
Another advantage of the present invention is that it provides methods and apparatus for cleaning a workpiece surface and for cleaning an optical endpoint detection probe during a planarization procedure performed upon the workpiece.
A further advantage is that the present invention employs water to clean a semiconductor wafer surface to provide a suitable area for optical interrogation during an endpoint detection process.
Another advantage of the present invention is that the present invention employs compressed gas to clean an optical endpoint detection probe to facilitate substantially consistent signal generation and detection during an endpoint detection process.
A further advantage is that the present invention provides a system that employs water and compressed gas to respectively clean a workpiece and an optical endpoint detection probe in a controlled manner in accordance with the operating protocol of a corresponding endpoint detection process.
The above and other advantages of the present invention may be carried out in one form by an apparatus for cleaning a surface of a workpiece during processing of the workpiece. The apparatus includes a support block having first and second fluid paths formed therein, a cavity for coupling an interrogation probe to the support block, a first fluid outlet for directing a first fluid proximate the tip of the probe during processing of the workpiece, and a second fluid outlet for applying a second fluid to the surface of the workpiece during a workpiece monitoring procedure. The probe is utilized to interrogate the surface of the workpiece during the monitoring procedure.
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Goudie Chad
Holzapfel Paul
Natalicio John
Yednak, III Andrew
Eley Timothy V.
Snell & Wilmer L.L.P.
SpeedFam-IPEC Corporation
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