Leaking light through embedded shifter-type opaque ring for attenuated phase-shift mask
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説明
Critical dimension error on a wafer caused by leaking light through embedded shifter type opaque ring on an i-line attenuated phase-shift mask has been studied. We have produced the mask that includes small pinhole-array pattern as the opaque ring, and confirm that transmittance through the opaque ring depends on pinhole size in good agreement with coherent theory. Our experimental result shows that the leakage must be less than 0.125% in transmittance in order to control resist dimension error less than 0.01 micrometer on a wafer for 0.35 - 0.4 micrometer devices. We have also derived an analytical form to represent leaking light, which shows good fit to the transmittance measurements with the various pinhole size. Then we have estimated the allowable error in phase difference and transmittance of the shifter, and that in pinhole size, applying for this formula. We also discuss the process feasibility for embedded shifter type opaque ring.
収録刊行物
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- SPIE Proceedings
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SPIE Proceedings 3096 344-, 1997-07-28
SPIE