Electron beam proximity effect correction by reverse field pattern exposure
AssigneeHewlett-Packard Company
InventorsGeraint Owen, Paul Rissman
Life of this patent
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Abstract
In electron beam lithography, a beam of incident electrons exposes a preselected circuit pattern in a thin resist layer deposited on top of a substrate to be etched. Some of the electrons scatter from the substrate back into the resist layer producing an undesired exposure which produces variable resolution of features. In accordance with the disclosed technique, the region of the resist which is complementary to the desired circuit pattern is also exposed by an electron beam which has been adjusted to produce an exposure approximating that due to backscattering. This additional exposure removes the spatial variability in resolution attainable by the electron beam lithography.
Claims8
An improved lithography method of the type in which particles are directed to impinge on preselected regions of a surface of a workpiece to expose in the workpiece a preselected pattern, said particles producing in the workpiece a total exposure which is the sum of a desired forward exposure to generate the preselected pattern and an undesired backscattered exposure, wherein the improvement comprises the additional step of exposing each pixel in the reverse field pattern with a flux of particles which produces in each of these pixels a total exposure that approximates the backscattered exposure produced in each pixel in the preselected regions, whereby a total exposure is produced that is the sum of the exposure due to the particles incident on the preselected regions and the exposure due to the particles incident on the reverse field pixels, said total exposure being the sum of a first component which is the ideal exposure which would result if there were no proximity effect and only the preselected regions were exposed and a second component which is essentially constant over the workpiece.
Dependencies are inferred from the claim text.