Process for improving uniform thickness of semiconductor substrates using plasma assisted chemical etching
First Claim
1. A process for improving the uniformity of the thickness of a semiconductor substrate having a front surface and a back surface using plasma assisted chemical etching, the process comprising:
- measuring the thickness of the substrate at discrete positions on the front surface of the substrate using the back surface as a reference surface;
processing the thickness measurements and computing a dwell time versus position map for the front surface of the substrate to determine the length of time a plasma electrode must etch the surface;
inverting mathematically the dwell time versus position map and;
removing material selectively from the back surface of the substrate based on the inverted dwell time versus position map by plasma assisted chemical etching to improve the uniformity of the thickness of the substrate.
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Abstract
A process for improving the uniformity of the thickness of a semiconductor substrate utilizing plasma assisted chemical etching is disclosed. The process includes measuring the thickness of a semiconductor substrate at discrete points on the front surface, computing a dwell time versus position map based on the measured thickness data, mathematically inverting the position map to allow material to be removed from the back surface, and selectively removing material from the back surface of the substrate by plasma assisted chemical etching to improve the thickness uniformity of the substrate.
24 Citations
11 Claims
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1. A process for improving the uniformity of the thickness of a semiconductor substrate having a front surface and a back surface using plasma assisted chemical etching, the process comprising:
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measuring the thickness of the substrate at discrete positions on the front surface of the substrate using the back surface as a reference surface; processing the thickness measurements and computing a dwell time versus position map for the front surface of the substrate to determine the length of time a plasma electrode must etch the surface; inverting mathematically the dwell time versus position map and; removing material selectively from the back surface of the substrate based on the inverted dwell time versus position map by plasma assisted chemical etching to improve the uniformity of the thickness of the substrate. - View Dependent Claims (2, 3)
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4. A process for improving the uniformity of the thickness of a semiconductor substrate having a front surface and a back surface using plasma assisted chemical etching, the process comprising:
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polishing the front surface of the substrate to remove between about 20 and about 30 micrometers of material from the front surface; measuring the thickness of the polished substrate at discrete positions on the front surface of the substrate using the back surface as a reference surface; processing the thickness measurements and computing a dwell time versus position map for the front surface of the polished substrate to determine the length of time a plasma electrode must etch the surface; inverting mathematically the dwell time versus position map; removing material selectively from the back surface of the polished substrate based on the inverted dwell time versus position map by plasma assisted chemical etching to improve the uniformity of the thickness of the substrate; and re-polishing the front surface of the polished substrate to remove between about 100 and about 5000 angstroms of material from the front surface. - View Dependent Claims (5, 6, 7, 8, 9)
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10. A process for reducing the non-uniformity of a semiconductor substrate having a front surface and a back surface by about 90% using plasma assisted chemical etching, the process comprising:
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polishing the front surface of the substrate to remove between about 20 and about 30 micrometers of material from the front surface; measuring the thickness of the polished substrate at discrete positions on the front surface of the substrate using the back surface as a reference surface; processing the thickness measurements and computing a dwell time versus position map for the front surface of the polished substrate to determine the length of time a plasma electrode must etch the surface; inverting mathematically the dwell time versus position map; removing material selectively from the back surface of the polished substrate based on the inverted dwell time versus position map by plasma assisted chemical etching to improve the uniformity of the thickness of the substrate; and re-polishing the front surface of the polished substrate to remove between about 100 and about 5000 angstroms of material from the front surface. - View Dependent Claims (11)
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Specification