Method and apparatus for printing patterns with improved cd uniformity
AssigneeMicronic Laser Systems AB
InventorTorbjorn Sandstrom
Life of this patent
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Abstract
An aspect of the present invention includes a method to pattern a workpiece with improved CD uniformity using a partially coherent electromagnetic radiation source. Said method including the actions of: determining, for a plurality of layers in said workpiece, CD uniformity as a function of a number of exposure flashes, determining, for the plurality of layers in said workpiece, the cost of patterning as a function of the number of exposure flashes, and selecting the number of exposure flashes on a layer by layer basis, which gives a predetermined CD uniformity corresponding to a preferred cost. Other aspects of the present invention are reflected in the detailed description, figures and claims.
Claims29
A method to pattern a workpiece with improved CD uniformity using a partially coherent electromagnetic radiation source having a speckle pattern which is a fine grained random variation in illumination different from mode to mode and/or flash to flash, including the actions of:
- determining, for a plurality of layers in said workpiece, CD uniformity due to said speckle as a function of a number of exposure flashes,
- determining, for a plurality of layers in said workpiece, the cost of patterning as a function of the number of exposure flashes,
- selecting the number of exposure flashes on a layer by layer basis, which gives a predetermined CD uniformity corresponding to a preferred cost.
A computer assisted apparatus for printing a workpiece with improved CD uniformity by using a partially coherent radiation source having a speckle pattern which is a fine grained random variation in illumination different from mode to mode and/or flash to flash, comprising:
- logic and resources that determine, for a plurality of layers in said workpiece, CD uniformity due to said speckle as a function of the number of exposure flashes,
- logic and resources that determine, for the plurality of layers in said workpiece, a cost of patterning as a function of the number of exposure flashes,
- logic and resources that select the number of exposure flashes on a layer by layer basis, which gives a predetermined CD uniformity at a minimum of patterning cost.
A method for printing a workpiece with improved CD-uniformity by using a partially coherent radiation source having a speckle pattern which is a fine grained random variation in illumination different from mode to mode and/or flash to flash, including the action of:
- changing a number of exposure flashes per surface element on a layer by layer basis.
A method for printing a workpiece with improved CD-uniformity by using a partially coherent radiation source having a speckle pattern which is a fine grained random variation in illumination different from mode to mode and/or flash to flash, including the action of:
- changing a pulse length of exposure flashes per surface element on a layer by layer basis.
A method for printing a workpiece with improved CD-uniformity by using a partially coherent radiation source having a speckle pattern which is a fine grained random variation in illumination different from mode to mode and/or flash to flash, including the action of:
- changing a radiation bandwidth of exposure flashes per surface element on a layer by layer basis.
A method for printing a workpiece with improved CD-uniformity by using a partially coherent radiation source having a speckle pattern which is a fine grained random variation in illumination different from mode to mode and/or flash to flash, including the action of:
- changing a slit width of exposure flashes per surface element on a layer by layer basis.
A procedure to improve CD uniformity of a layer exposed in a scanner or stepper using partially coherent light having a speckle pattern, which speckle pattern is a fine grained random variation in illumination different from mode to mode and/or flash to flash, including the actions of:
- providing a scanner system with an optical field larger than 10 mm,
- increasing one or more of the following parameters
- a. slit width,
- b. laser bandwidth,
- c. pulse length,
- d. laser flash frequency,
- e. number of flashes,
- f. number of flashes per field,
- g. number of scan cycles per field
- until the calculated illumination non-uniformity (3 sigma) from said speckle amounts to less than 0.5%.
A procedure to improve CD uniformity of a layer exposed in a maskless scanner using partially coherent light having a speckle pattern which is a fine grained random variation in illumination different from mode to mode and/or flash to flash comprising the steps of:
- providing a maskless scanner systems with an optical field larger than 0.5 mm,
- increasing one or more of the following parameters:
- a. laser bandwidth,
- b. pulse length,
- c. number of overlayed flashes,
- until the calculated illumination non-uniformity (3 sigma) from said speckle amounts to less than 0.5%.
An apparatus for printing a workpiece with improved CD uniformity including:
- logic and resources to calculate speckle, which speckle is a fine grained random variation in illumination different from mode to mode and/or flash to flash,
- logic and resources that change the number of pulses per surface element on a layer to layer basis.
A procedure for optimizing speckle, which is a fine grained random variation in illumination different from mode to mode and/or flash to flash, during microlithographic printing including the actions of:
- providing a model for the value of improved CD uniformity,
- calculating the CD uniformity as a function of the number of flashes,
- providing a model for the cost of printing with a particular number of pulses,
- providing logic and resources that select a number of flashes that corresponds to a preferred result,
- providing a control adapted to change the number of flashes, and
- setting said approximately optimized number of flashes.
An electronic device with improved CD uniformity printed with speckle, which speckle is amounting from fine grained random variation in illumination different from mode to mode and/or flash to flash, less than 1% (3 sigma).
Dependencies are inferred from the claim text.