Novel method to find the best process point in e-beam mask making

Ulrich Hofmann; Holger Sailer; Stephan Martens; Nezih Unal

doi:10.1117/12.2604372

23 August 2021 Novel method to find the best process point in e-beam mask making

Ulrich Hofmann, Holger Sailer, Stephan Martens, Nezih Unal

Proceedings Volume 11908, Photomask Japan 2021: XXVII Symposium on Photomask and Next-Generation Lithography Mask Technology; 119080M (2021) https://doi.org/10.1117/12.2604372
Event: Photomask Japan 2021, 2021, Online Only

Abstract

To this day there is no established practical method available to identify the “optimal” base dose in e-Beam lithography for mask making. Methods range from choosing the “zero-bias” exposure dose that yields CDmeasured = CDtarget to real isofocal calibrations that require to print the structures at different blurs/focus settings. While the latter yields an optimal base dose, it requires a significant experimental procedure, whereas the former uses a pretty simple experiment but will likely yield a non-optimal base dose due to process effects (e.g., lateral resist development). Here we present a novel method to find the optimum base dose for e-Beam mask exposures that requires only a simple experiment. Surprisingly, the exposure doses required to print features with different densities at the same CD does depend on the process point, adding an error term to the proximity effect correction in case the correction is not aligned to this. This is due to the fact that for a given stack and acceleration voltage, a PEC method will deliver one fixed dose range, whereas the experimentally required dose range depends on the process point chosen. This observation can be used to calibrate the base dose such that it matches the dose range obtained from PEC. Moreover, it can be used to add a new criterion to proximity effect correction – the iso-focal condition - to not only correct for line width (also called critical dimension, CD) linearity and density dependent effect, but to also add immunity to process variations such as focus and blur variations.

Citation Download Citation

Ulrich Hofmann, Holger Sailer, Stephan Martens, and Nezih Unal "Novel method to find the best process point in e-beam mask making", Proc. SPIE 11908, Photomask Japan 2021: XXVII Symposium on Photomask and Next-Generation Lithography Mask Technology, 119080M (23 August 2021); https://doi.org/10.1117/12.2604372

ACCESS THE FULL ARTICLE

INSTITUTIONAL
Select your institution to access the SPIE Digital Library.

SELECT YOUR INSTITUTION

PERSONAL
Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.

PERSONAL SIGN IN

No SPIE Account? Create one

PURCHASE THIS CONTENT

SUBSCRIBE TO DIGITAL LIBRARY

50 downloads per 1-year subscription

Members: $195

Non-members: $335 ADD TO CART

25 downloads per 1 - year subscription

Members: $145

Non-members: $250 ADD TO CART

PURCHASE SINGLE ARTICLE

Includes PDF, HTML & Video, when available

Members: $17.00

Non-members: $21.00 ADD TO CART

PROCEEDINGS
10 PAGES

DOWNLOAD PAPER SAVE TO MY LIBRARY

GET CITATION

RIGHTS & PERMISSIONS

Get copyright permission Get copyright permission on Copyright Marketplace

KEYWORDS

Calibration

Etching

Data modeling

Point spread functions

Backscatter

Electron beam lithography

Photomasks

Show All Keywords

Keywords/Phrases

Search In:

Publication Years