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US 8,568,959 B2Granted
Techniques for reducing degradation and/or modifying feature size of photomasks
AssigneeInternational Business Machines Corporation
InventorsPeter H. Bartlau, Thomas B. Faure, Alfred Wagner
Life of this patent
Estimating the term…
Abstract
A photomask includes a light transmitting substrate and an absorber layer adjacent thereto. The absorber layer includes a silicide, such as molybdenum silicide, patterned into a plurality of features. The surrounding environment is controlled to prevent undesirable growth by oxidation of the absorber layer when the mask is exposed to light while being used to fabricate integrated circuits. In another aspect, the surrounding environment is controlled to encourage desirable growth by oxidation of the absorber layer when the mask is exposed to light.
Claims24
A method comprising the steps of:
- obtaining a photomask comprising a light transmitting substrate and an absorber layer adjacent thereto, said absorber layer comprising a silicide patterned into a plurality of features;
- mounting said photomask into a stepper apparatus for use in an integrated circuit fabrication process;
- and
- during said integrated circuit fabrication process, irradiating said photomask with radiation of less than about 240 nm in wavelength in an atmosphere comprising a substantially dry inert gas and a substantial absence of water vapor;
- whereby growth of said absorber layer by oxidation is substantially inhibited.
2 more elements
A method comprising the steps of:
- obtaining a photomask comprising a light transmitting substrate and an absorber layer adjacent thereto, said absorber layer comprising a silicide patterned into a plurality of features;
- mounting said photomask into a stepper apparatus for use in an integrated circuit fabrication process;
- during said integrated circuit fabrication process, irradiating said photomask with radiation of greater than about 100 nm and less than about 240 nm in wavelength in a vacuum environment having a substantial absence of water vapor;
- whereby growth of said absorber layer by photo-chemistry induced oxidation is substantially inhibited.
1 more element
A method comprising the steps of:
- obtaining a photomask for use in an integrated circuit fabrication process, said photomask comprising a light transmitting substrate and an absorber layer adjacent thereto, said absorber layer comprising a silicide patterned into a plurality of features, said photomask having a required lifetime;
- taking into account an effect of ambient humidity on oxidation of said absorber layer during said integrated circuit fabrication process over said required lifetime, to obtain a humidity value consistent with said required lifetime, wherein taking into account comprises irradiating a plurality of regions on at least one test photomask substantially similar to said photomask for use in said integrated circuit fabrication process with progressively larger doses of photons, and repeating the progressively larger doses at a plurality of test ambient humidity values;
- mounting said photomask into a stepper apparatus for use in said integrated circuit fabrication process;
- and
- during said integrated circuit fabrication process, irradiating said photomask with radiation of less than about 240 nm in wavelength in an environment consistent with said humidity value;
- whereby growth of said absorber layer by oxidation is substantially inhibited to aid in achieving said required lifetime.
3 more elements
A method comprising the steps of:
- determining that, for a photomask comprising a light transmitting substrate and an absorber layer adjacent thereto, said absorber layer comprising a silicide patterned into a plurality of features, it is desirable to cause growth of said absorber layer to change a size of at least one of said plurality of features to a target size;
- responsive to said determining, irradiating at least a portion of said photomask adjacent said at least one of said plurality of features with radiation of less than about 240 nm in wavelength in presence of an oxidizing environment from a laser beam of a broadband laser, to cause said growth of said absorber layer with concomitant change of said size of said at least one of said plurality of features to substantially conform to said target size.
Dependencies are inferred from the claim text.