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Grenoble, France

Figueiro T.,CNRS Microelectronics Technology Laboratory | Tortai J.H.,CNRS Microelectronics Technology Laboratory | Schiavone P.,Aselta Nanographics
Microelectronic Engineering | Year: 2012

One possible candidate to address future nodes (below 16 nm) is electron beam lithography as sub 10 nm resolution was already demonstrated in PMMA or HSQ resists. If multiple electron beam systems significantly increase the throughput to meet industrial needs, it can be the tool of choice. Nevertheless using a chemically amplified resist (CAR) is mandatory even for systems with a large number of beams. Achieving dense sub 20 nm patterns with CAR is still a challenge as proximity effects degrade the contrast of the aerial image. Bridging, shape rounding or partial development are typical degradation in the desired final pattern shape. Proximity effect correction is needed in order to properly delineate dense features as well as meet the required CD uniformity. Proximity effect correction can only be accurate if a Point Spread Functions (PSF) is precisely determined. In this paper we demonstrate a strategy that allows accurate determination of Point Spread Function parameters. This strategy consists in using sensitivity analysis in order to define conditions where the calibration features and the measured quantities are sensitive enough to the PSF parameters and this without a correlation between the final results. © 2012 Elsevier B.V. All rights reserved. Source


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 and French Atomic Energy Commission | Date: 2013-12-13

Method for simulating shot-noise effects in a particle-beam lithography process, and especially an e-beam lithography process, the process including depositing particles on the surface of a sample in a preset pattern by a beam of the particles, the pattern being subdivided into pixels and a nominal dose of particles being associated with each of the pixels, wherein the process includes the calculation of a map


A method for preparing a pattern to be printed on a plate or mask by electron beam lithography comprising the following steps: modelling of the pattern by breaking down this pattern into a set of elementary geometric shapes intended to be printed individually in order to reproduce said pattern and, for each elementary geometric shape of the model; determination of an electrical charge dose to be applied to the electron beam during the individual printing of the elementary shape, this dose being chosen from a discrete set of doses including several non-zero predetermined doses recorded in memory. The set of elementary geometric shapes is a bidimensional paving of identical elementary geometric shapes covering the pattern to be printed. In addition, when the doses to be applied to the elementary geometric shapes are determined, a discretisation error correction is made by dithering.


Patent
Aselta Nanographics and French Atomic Energy Commission | Date: 2012-08-16

A method for projecting an electron beam, used notably in direct or indirect writing lithography and in electronic microscopy. Proximity effects created by the forward and backward scattering of the electrons of the beam in interaction with the target must be corrected. For this, the convolution of a point spread function with the geometry of the target is conventionally used. At least one of the components of the point spread function has its maximum value not located on the center of the beam. Preferably, the maximum value is instead located on the backward scattering peak. Advantageously, the point spread function uses gamma distribution laws.

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