Port-Saint-Louis-du-Rhône, France
Port-Saint-Louis-du-Rhône, France

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A method to easily determine the parameters of a second process for manufacturing from the parameters of a first process is provided. Metrics representative of the differences between the two processes are computed from a number of values of the parameters, which can be measured for the two processes on a calibration layout, or which can be determined from pre-existing values for layouts or reference data for the two processes by an interpolation/extrapolation procedure. The number of metrics is selected so that their combination gives a precise representation of the differences between the two processes in all areas of a design. Advantageously, the metrics are calculated as a product of convolution of the target design and a compound of a kernel function and a deformation function.


A method for transferring a pattern onto a substrate by direct writing by means of a particle or photon beam, the method comprising:- a step of producing a dose map, associating a dose to each of a plurality of elementary features of said pattern; and- a step of exposing the substrate according to the pattern with a spatially-dependent dose depending on said dose map;characterized in that said step of producing a dose map includes:- computing at least two metrics for each of said elementary features of the pattern; and- determining the emitted dose associated to each of said elementary features of the pattern as a function of said metrics. A computer program product for carrying out such a method or at least said step of producing a dose map.


Patent
French Atomic Energy Commission and Aselta Nanographics | Date: 2015-12-09

The invention discloses a method for calculating the parameters of a resist model of an IC manufacturing process. According to an embodiment of the method of the invention, a function representative of the target design convoluted throughout the whole target design with a kernel function compounded with a deformation function with a shift angle. Advantageously, the deformation function is replaced by its Fourier series development, the order of which is selected so that the product of convolution is invariant through rotations within a tolerance of the corrections to be applied to the target design. Alternatively, the product of convolution may be decomposed into basic kernel functions selected varying by angles determined so that a deformation function for a value of the shift angle can be projected onto a couple of basic kernel functions the angles of which are proximate to the shift angle.


The invention discloses a computer implemented method of fracturing a free form target design into elementary shots to get a minimum number of shots for a defined roughness of the contour. The method includes determining a first set of shots which pave the target design, except for gaps, and then determining a second set of shots to fill or cover the gaps. The dose levels of the overlapping shots in the first or second sets of shots are determined so that the compounded dose is adequate in view of the resist threshold, taking into account the proximity effect which affects the actual imprint of the shots on the insulated target. Advantageously, a dose geometry modulation is applied. Advantageously, rounded shot prints are produced by shots which are not circular. Shots and rounded shot prints may or may not overlap. The degree of overlap may be determined as a function of a desired optimization of a fit criteria between a printed contour and the contour of the desired pattern. Placements and dimensions of the shots may be determined by a plurality of fit criteria between said printed contour and said contour of the desired pattern.


According to the invention, an IC manufacturing model is disclosed, wherein input variables and an output variable are measured using a calibration set of patterns. The model can or not include a PSF. The output variable may be a dimensional bias between printed patterns and target patterns or simulated patterns. It can also be a Threshold To Meet Experiments (TTME). The input variables may be defined by a metric which uses kernel functions, preferably with a deformation function which includes a shift angle and a convolution procedure. A functional or associative relationship between the input variables and the output variable is defined. Preferably this definition includes normalization steps and interpolation steps. Advantageously, the interpolation step is of the kriging type. The invention achieves a much more accurate modeling of IC manufacturing, simulation or inspection processes.


A computer implemented method of fracturing free form target design into elementary shots for defined roughness of the contour comprises determining a first set of shots which pave the target design and determining a second set of shots to fill the gaps. The dose levels of overlapping shots in the first or second sets of shots are determined so the compounded dose is adequate to the resist threshold, considering the proximity effect of the actual imprint of shots on the insulated target. A dose geometry modulation is applied and rounded shot prints are produced by shots not circular that may overlap. The degree of overlap is determined as a function of desired optimization of fit criteria between a printed contour and the contour of the desired pattern. Placements and dimensions of the shots are determined by a plurality of fit criteria between printed contour and contour of the desired pattern.


Patent
Aselta Nanographics | Date: 2016-06-29

The invention discloses an improved method of geometry corrections to be applied to properly transfer semiconductor designs on a wafer or a mask in nanometer scale processes. In contrast with some prior art techniques, geometry corrections and possibly dose corrections are applied before fracturing. Unlike edge based corrections, where the edges are displaced in parallel, the displacements applied to generated geometry corrections according to the invention do not preserve parallelism of the edges, which is specifically well suited for free form designs. A seed design is generated from the target design. Vertices connecting segments are placed along the seed design contour. Correction sites are placed on the segments. Displacement vectors are applied to the vertices. A simulated contour is generated and compared to the contour of the target design. The process is iterated until a match criteria between simulated and target design (or another stop criteria) is reached.


Patent
Aselta Nanographics | Date: 2015-02-06

The invention discloses a computer implemented method of fracturing a surface into elementary features wherein the desired pattern has a rectilinear or curvilinear form. Depending upon the desired pattern, a first fracturing will be performed of a non-overlapping or an overlapping type. If the desired pattern is resolution critical, it will be advantageous to perform a second fracturing step using eRIFs. These eRIFs will be positioned either on the edges or on the medial axis or skeleton of the desired pattern. The invention further discloses method steps to define the position and shape of the elementary features used for the first and second fracturing steps.


Patent
Aselta Nanographics | Date: 2014-08-28

A method for projecting an electron beam onto a target includes correction of the scattering effects of the electrons in the target. This correction is made possible by a calculation step of a point spread function having a radial variation according to a piecewise polynomial function.


The invention discloses a method to easily determine the parameters of a second process for manufacturing from the parameters of a first process. Metrics representative of the differences between the two processes are computed from a number of values of the parameters, which can be measured for the two processes on a calibration layout, or which can be determined from pre-existing values for layouts or reference data for the two processes by an interpolation/extrapolation procedure. The number of metrics is selected so that their combination gives a precise representation of the differences between the two processes in all areas of a design. Advantageously, the metrics are calculated as a product of convolution of the target design and a compound of a kernel function and a deformation function.

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