Optics: measuring and testing – Angle measuring or angular axial alignment
Patent
1999-06-10
2000-05-16
Kim, Robert H.
Optics: measuring and testing
Angle measuring or angular axial alignment
356394, 356426, 414936, G01C 100
Patent
active
060644753
ABSTRACT:
An apparatus and method for determining local de-focus problems on a real time basis in a wafer exposure system. The distance of a wafer from an objective lens and rotation of the wafer about two orthogonal axis at each field position is adjusted to achieve optimum focus for each field of the wafer. The rotational data is fed to a computer and analyzed to determine if any of the rotational angles or if the difference between individual rotational angle and the mean rotational angle exceed critical angles. If any of the critical angles are exceeded local de-focus will occur and the exposure system must be checked for defects. If none of the critical angles are exceeded processing continues with the next wafer. The comparison of the rotational angles to the critical angles is performed for each wafer before continuing with the next wafer so that problems are discovered on a real time basis.
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Chen Hung-Chih
Chu Yao-Chanet
Hung Chih-Chien
Lin Tzu-Yu
Ackerman Stephen B.
Kim Robert H.
Natividad Philip S.
Prescott Larry J.
Saile George O.
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