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US 4,727,234 AGranted
Laser-based system for the total repair of photomasks
AssigneeGould Inc.
InventorsModest M. Oprysko, Peter L. Young, Mark W. Beranek
Life of this patent
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Abstract
An apparatus for repairing both clear and opaque defects in a photomask having a metal film pattern on a glass plate in which a visible laser light source is pulsed at selected frequencies to direct an optically focused laser beam into a gas sealed cell containing a mask. At one frequency, the laser pulses ablate opaque mask defects. At another frequency, and with the cell filled with a metal bearing gas, the laser beam causes thermal decomposition of the gas and deposition of metal to cure clear defects.
Claims8
A system for repairing clear and opaque defects in photomasks comprising:
- a cell for enclosing a photomask;
- a laser source for providing a low power laser light beam;
- means for focusing said laser light beam onto the photomask;
- means for positioning said laser light beam and said photomask relative to one another so as to vary the point of focus of the light beam on the photomask;
- and
- means for causing said laser source to emit laser light pulses of selected power and duration and at selectable frequency including a single pulse.
3 more elements
Dependencies are inferred from the claim text.