Particle beams with collimated discrete charged carriers such as electrons have been employed to lithographically
transfer design patterns onto the photoresist for fabrication of devices, such as photomasks. In this paper, we use a
single standard deviation σ of total blur based on Gaussian convolution kernel to address the limit of ebeam lithography,
where the total blur is constituted of several mechanisms, including space charge effect within the ebeam, shot noise,
resist diffusion, and photoacid fluctuation, etc. Based on the Gaussian blur imaging formalism including both electron
forward scattering and backward scattering, we derive a fundamental principle based analysis to address the patterning
resolution limit, local pattern density (LPD) dependent critical dimension (CD) proximity bias, CD non-linearity, image
edge-slope, 2D corner pull back and 2D touch corner structures. Assuming a minimum normalized image log slope of
NILS >= 1 across all LPD is required for high volume manufacturability, the requirement of maximum total blur can be
derived as σ≤CD/2.4 for a given exposed feature size targeted to pattern.
The objective of this paper is to establish a predictive model with simplicity for fundamental limit of ebeam lithography,
and accordingly to define the requirement of blur reduction for meeting technology roadmap spec. The key emphasis of
this paper is to highlight that mask patterning capability is becoming resolution limited with equipment and material
available today. This is an inflection point! An integrated plan for total blur reduction is urgently needed for ebeam
lithography to continue enabling technologies moving beyond 45nm and 32nm nodes.