Methods and systems for improved boundary contrast
AssigneeMicronic Laser Systems AB
InventorTorbjorn Sandstrom
Life of this patent
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Abstract
The present invention relates to methods and systems that define feature boundaries in a radiation sensitive medium on a workpiece using a diffraction-type micromirror array, extending to production of patterns and structures on a semiconductor substrate. Workpieces include lithographic masks, integrated circuits and other electronic and optical devices. Particular aspects of the present invention are described in the claims, specification and drawings.
Claims15
A method of calibrating a two dimensional array of micromirrors, including:
- parallel to a first axis, generating at least one first line of contrast between bright and dark micromirrors, applying the first line of contrast across the array with gray valued micromirrors between the dark and bright micromirrors for at least some first line locations, and recording reflected output intensity corresponding to the micromirrors;
- parallel to a second axis that is not parallel to the first axis, generating at least one second line of contrast between bright and dark micromirrors, applying the second line of contrast across the array with gray valued micromirrors between the dark and bright micromirrors for at least some second line locations, and recording reflected output intensity corresponding to the micromirrors;
- and
- calculating corrections to individual micromirrors corresponding to the recorded reflected output intensities.
A method of calibrating a two dimensional array of micromirrors illuminated by a partially coherent source of electromagnetic radiation having a characteristic wavelength, including:
- generating a checkerboard pattern of micromirrors in the array, with alternating squares of the checkerboard set to bright and non-bright values;
- driving the non-bright micromirrors in a range between a quarter- and half-wavelength difference between a tilting axis and edges of the micromirrors and recording the intensity of output in an image plane;
- and
- determining one or more driving values for the non-bright micromirrors to use in setting a response curve that maps the driving values to the recorded output intensity.
A method of calibrating a two dimensional array of micromirrors illuminated by a partially coherent source of electromagnetic radiation, including:
- generating a pattern of micromirrors in the array, with most micromirrors set to a first output intensity value and other micromirrors varied through a range of output intensity values, the other micromirrors being substantially separated from one another;
- driving the other micromirrors through a range output intensity values and recording output intensity of the other micromirrors at various drive signals;
- determining drive signals for individual micromirrors to produce desired output intensity levels.
A method of calibrating a two dimensional array of exposing radiation sources, including:
- generating a pattern of sources in the array, with most of the sources set to a first output intensity value and other sources varied through a range of output intensity values, the other sources being sufficiently separated from one another to be individually resolved by a sensor;
- driving the other sources through a range output intensity values and recording output intensity of the other sources at various drive signals;
- determining drive signals for the sources to produce desired output intensity levels.
Dependencies are inferred from the claim text.