Method of correcting electron proximity effects using Voigt type scattering functions
US9934336B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Apr 11, 2013 |
| Grant date | Apr 3, 2018 |
| Priority date | — |
| Expiry date | Apr 11, 2033 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH01J2237/31769
- WIPO fieldElectrical machinery, apparatus, energy
- WIPO sectorElectrical engineering
Abstract
A method for projecting an electron beam used notably in lithography by direct or indirect writing as well as in electron microscopy, is provided. Notably for critical dimensions or resolutions of less than 50 nm, the proximity effects created by the forward and backward scattering of the electrons of the beam in interaction with the target must be corrected. This is traditionally done using the convolution of a point spread function with the geometry of the target. In the prior art, said point spread function uses Gaussian distribution laws. At least one of the components of the point spread function is a linear combination of Voigt functions and/or of functions approximating Voigt functions, such as the Pearson VII functions. In certain embodiments, some of the functions are centered on the backward scattering peaks of the radiation.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.