International Business Machines Corporation

Porter Dean Gerber

Raman Gobichettipalayam Viswanathan

Stephen A Rishton

Samuel Jonas Wind

Dieter P Kern

Michael G Rosenfield

Walter W Molzen, Jr

Christopher J Ashton

A method for formulating an exposure dose for an electron beam on a resist film for a pattern of geometric shapes which compensates for electron scattering effects utilizing hierarchial design data which is preserved to as great as an extent as possible in the computation of the exposure dose. The exposure dose is corrected for both the forward scatter and backscatter effects of the electron beam in which the design data is modified for interactions of shapes which are affected only over the forward scatter range. In another version of the method, a multiple Gaussian approximation is used where the short term Gaussian terms are treated as the forward scatter terms and the long term Gaussian terms are treated as the back scatter terms.

Electron beam proximity correction method for hierarchical design data

A proximity effect correction method for electron beam lithography suitable for high voltages and/or very dense patterns applies both backscatter and forward scatter dose corrections. Backscatter dose corrections are determined by computing two matrices, a 'Proximity Matrix' P and a 'Fractional Density Matrix' F. The Proximity Matrix P is computed using known algorithms. The elements of the Fractional Density Matrix are the fractional shape coverage in a mesh of square cells which is superimposed on a pattern of interest. Then, a Dose Correction Matrix D is computed by convolving the P and F matrices. The final backscatter dose corrections are assigned to each shape either as area-weighted averages of the D matrix elements for all cells spanned by the shape, or by polynomial or other interpolation of the dose correction field defined by the D matrix. The D matrix also provides a basis for automatic shape fracturing for optimal proximity correction. Optionally, forward scattering correction may be included in the correction process. Forward scattering correction consists of boosting the dose applied to shape i by a factor b.sub.i. These boost factors are computed in a separate and independent step which considers only forward scattering. They are combined with those resulting from the backscatter correction scheme either by simple multiplication to form the final correction factors, or by inputting them to the backscatter correction scheme as numerical weights for each shape.

Method for correcting proximity effects in electron beam lithography

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White Plains, NY, United States of America

Porter Dean Gerber