Radiant energy – Photocells; circuits and apparatus – Photocell controls its own optical systems
Patent
1992-10-28
1994-04-05
Nelms, David C.
Radiant energy
Photocells; circuits and apparatus
Photocell controls its own optical systems
356401, G01N 2186
Patent
active
053007867
ABSTRACT:
A photolithography mask structure having a novel optical focus test pattern is described. The mask structure has a non-phase-shifted, transparent substrate and includes a phase shifter of other than 180.degree. disposed between spaced, parallel opposing lines such that an alternating pattern of non-phase-shifted material and phase-shifted material is defined transverse said parallel lines. When projected onto the surface of an object measurable shifts of the test pattern corresponds in direction and magnitude with the extent of system defocus. Various alternating test pattern embodiments are presented, all of which include at least one phase shift window of other than 180.degree. in relation to the mask substrate. Further, a monitoring system and a monitoring process are discussed employing the presented mask structures.
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Brunner Timothy A.
Hibbs Michael S.
Peck Barbara B.
Spence Chrisopher A.
Davenport T.
International Business Machines - Corporation
Nelms David C.
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