Gradient assisted image resampling in micro-lithographic printing

Abstract

The present disclosure relates to the re-sampling of pixel data, with one application being micro-lithography. In particular, it relates to the extraction of modulator pixels from a rasterized image, as a function of how the modulator moves across the rasterized image.

1 . A method of enhancing accuracy of a rasterized pattern representation with reduced memory requirements of an intermediate pixel representation that can be resampled to produce a printable pixels, the method including:
 storing in computer readable memory a plurality of intermediate pixels produced from rasterizing vector data as white, black and grey scale pixels; and   calculating from the vector data and storing in the memory edge geometry data for at least some of the grey scale pixels, wherein the edge geometry data defines pattern edge placement within the grey scale pixels.   
     
     
         2 . The method of  claim 1 , further including resampling the intermediate pixels to produce printable pixels using the edge geometry data. 
     
     
         3 . The method of  claim 1 , wherein the edge geometry data is stored in a separate channel from coding data that identifies the intermediate pixels as white, black and grey scale. 
     
     
         4 . The method of  claim 1 , wherein a reference to the edge geometry data is stored with coding data that identifies the intermediate pixels as white, black and grey scale. 
     
     
         5 . The method of  claim 1 , wherein the edge geometry data that defines the pattern edge placement within the grey scale pixel includes a gradient that, when combined with a grey scale value of the grey scale pixel, allows estimation of an edge position and angle. 
     
     
         6 . The method of  claim 5 , further including calculating the gradient for a corner that falls within a grey scale pixel and representing the corner by an edge placement that defines an area of the pixel equal to the corner's area. 
     
     
         7 . The method of  claim 6 , wherein calculating the gradient for the corner further includes using information from at least two intermediate pixels adjoining the pixel in which the corner falls. 
     
     
         8 . The method of  claim 1 , wherein the intermediate pixels further distinguish between grey scale pixels that represent an edge and those that represent a corner. 
     
     
         9 . The method of  claim 1 , further including storing the edge geometry data with at least one black or white pixel that has an edge placement coincident with an edge of the black or white pixel. 
     
     
         10 . The method of  claim 1 , further including:
 using the intermediate pixels, without regeneration, for resampling to produce printable pixels in multiple printing passes on a particular workpiece, the multiple printing passes using pixel grids offset from one another.   
     
     
         11 . The method of  claim 1 , further including:
 using the intermediate pixels, without regeneration, for resampling to produce printable pixels in single printing pass on a particular workpiece.   
     
     
         12 . The method of  claim 1 , further including:
 using the intermediate pixels, without regeneration, for multiple workpieces that require varying transforms to compensate for differences between the workpieces.   
     
     
         13 . The method of  claim 1 , wherein the intermediate pixel representation requires about 5 to 10 times as much storage of as the printable pixels, while providing at least 64 times the resolution of the printable pixels when storing a pattern for a two-dimensional microlithographic pattern. 
     
     
         14 . A method of preparing an intermediate pixel representation from rasterization of vector data, including:
 supplementing hierarchically represented design data elements using a processor to create spatial index data elements that that identify parts of a two dimensional area represented by the elements of the hierarchically represented design data elements;   for a particular area within a tile, selecting relevant hierarchically represented design data elements using the spatial index data elements and unfolding the selected hierarchically represented design data elements; and   processing the unfolded hierarchically represented design data elements to produce white, black and grey scale pixels; and   storing the white, black and grey scale pixels as intermediate pixels.   
     
     
         15 . The method of  claim 14 , further including deriving the spatial index information from cell and cell boundary information and stored at a design cell level. 
     
     
         16 . The method of  claim 15 , further including using a data language format extension to store the spatial index data elements. 
     
     
         17 . The method of  claims 14 , further including processing multiple tiles to produce the intermediate pixel representation in parallel, each one of the multiple tiles processed by respective processors in a set of processors.