International Business Machines Corporation

Ronald L Gordon

Alan Edward Rosenbluth

Lars W Liebmann

Gregg M Gallatin

Nakgeuon Seong

Kafai Lai

Christopher P Ausschnitt

Timothy A Brunner

Allen H Gabor

Ioana C Graur

Christopher J Progler

Frances Anne Houle

Alexey Y Lvov

William Dinan Hinsberg

John Allen Hoffnagle

Carlos A Fonseca

Martin Burkhardt

Martha Inez Sanchez

A method for determining an image of a patterned object formed by a polychromatic lithographic projection system having a laser radiation source of a finite spectral bandwidth and a lens for imaging the patterned object to an image plane within a resist layer. The method comprises providing patterns for the object, a spectrum of the radiation source to be used in the lithographic projection system, an intensity and polarization distribution of the radiation source, and a lens impulse response in the spatial domain or in the spatial frequency domain of the image. The method then includes forming a polychromatic 4D bilinear vector kernel comprising a partially coherent polychromatic joint response between pairs of points in the spatial domain or in the spatial frequency domain, determining the dominant polychromatic 2D kernels of the polychromatic 4D bilinear vector kernel, and determining the image of the patterned object from convolutions of the object patterns with the dominant polychromatic 2D kernels.

Fast method to model photoresist images using focus blur and resist blur

A method for increasing coverage of subresolution assist features (SRAFs) in a layout. A set of possible SRAF placement and sizing rules for a given pitch is provided, ranked according to some figure of merit. During SRAF placement, the fit of a plurality of different SRAF solutions is successively evaluated to find the SRAF solution, or combinations thereof, which most improves lithographic performance while avoiding manufacturability problems. In general, the method comprises: obtaining a plurality of SRAF configurations for the layout; ranking the SRAF configurations based on a figure of merit; applying a highest ranked SRAF configuration to the layout; applying a predetermined number of lower ranked SRAF configurations to the layout; and selecting SRAF features from at least one of the applied SRAF configurations to provide the optimal SRAF configuration for the layout.

Pliant SRAF for improved performance and manufacturability

A method and system is provided for computing lithographic images that may take into account non-scalar effects such as lens birefringence, resist stack effects, tailored source polarizations, and blur effects of the mask and the resist. A generalized bilinear kernel is formed, which is independent of the mask transmission function, and which may then be treated using a decomposition to allow rapid computation of an image that includes such non-scalar effects. Weighted pre-images may be formed from a coherent sum of pre-computed convolutions of the dominant eigenfunctions of the generalized bilinear kernel with the appropriate mask polygon sectors. The image at a point may be formed from the incoherent sum of the weighted pre-images over all of the dominant eigenfunctions of the generalized bilinear kernel. The resulting image can then be used to perform model-based optical proximity correction (MBOPC).

Fast model-based optical proximity correction

A method of designing a mask for imaging an integrated circuit (IC) design layout is provided to efficiently configure subresolution assist features (SRAFs) corresponding to an optimally configured annular illumination source of a lithographic projection system. A critical pitch is identified for the IC design, and optimal inner and outer radial coordinates of an annular illumination source are determined so that the resulting image projected through the mask will be optimized for the full range of pitches in the design layout. A relationship is provided for determining an optimal inner radius and outer radius for the annular illumination source. The number and placement of SRAFs are added to the mask design so that the resulting range of pitches substantially correspond to the critical pitch. The method of configuring SRAFs so that the image will have optimal characteristics, such as good contrast and good depth of focus, is fast.

Pitch-based subresolution assist feature design

A method of modeling dose and focus response in lithographic imaging to simulate an optical critical dimension (OCD) metrology system creates simulated aerial images of the object pattern to be transferred to a resist film on the substrate at different focus settings of the metrology imaging system. The method then successively creates simulated images, at different exposure dose and focus settings of the metrology imaging system, of the latent and developed image of the object pattern in the resist film on the substrate, and the etched image of the object pattern in the substrate. The method converts the simulated images into polygons having more than four sides and determines the Fourier spectrum of the polygons simulating the images of the object pattern. Using the spectrum of the polygons simulating the images of the object pattern, the method then creates simulated aerial images of the object pattern developed in the resist film, at different dose and focus settings, as viewed by the OCD metrology system.

Integrated lithographic print and detection model for optical CD

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Poughkeepsie, NY, United States of America

Ronald L Gordon