Negative Tone Metallic Organic Resists with Improved Sensitivity for Plasma Etching: Implications for Silicon Nanostructure Fabrication and Photomask Production

Ahmad Chaker; Hayden A Alty; Paul Winpenny; George F S Whitehead; Grigore A Timco; Scott M Lewis; Richard E P Winpenny

doi:10.1021/acsanm.2c02986

Negative Tone Metallic Organic Resists with Improved Sensitivity for Plasma Etching: Implications for Silicon Nanostructure Fabrication and Photomask Production

ACS Appl Nano Mater. 2022 Dec 23;5(12):17538-17543. doi: 10.1021/acsanm.2c02986. Epub 2022 Nov 30.

Authors

Ahmad Chaker¹, Hayden A Alty¹, Paul Winpenny², George F S Whitehead¹, Grigore A Timco¹, Scott M Lewis^{1

3

2}, Richard E P Winpenny^{1

2}

Affiliations

¹ Department of Chemistry, The University of Manchester, Oxford Road, Manchester M13 9PL, U.K.
² Sci-Tron Ltd, 34 High Street, Aldridge, Walsall WS9 8LZ, U.K.
³ The Kavli Nanoscience Institute, California Institute of Technology, 1200 East California Boulevard, 107-81, Pasadena, California 91125, United States.

Abstract

Metal-organic materials such as [NH₂(CH₂-CH=CH₂)₂][Cr₇NiF₈(Pivalate)₁₆] can act as negative tone resists for electron beam lithography (EBL) with high-resolution patterning of sub-40 nanometer pitch while exhibiting ultrahigh dry etch selectivities >100:1 and giving line dose exposures >11,000 pC/cm. It is clear that the resist sensitivity is too low to be used to manufacture the latest nanoscale photomasks that are suitable for extreme ultraviolet lithography. Therefore, the focus of this work here is to improve the sensitivity of this resist while maintaining its resolution and dry etch selectivity. Using our latest Monte Carlo simulation called Excalibur, we predict that the sensitivity would increase by a factor of 1.4 when the nickel atom is substituted by a cadmium atom. EBL studies showed an excellent agreement with the simulation, and plasma etching studies demonstrated that this did not affect the dry etch performance of the resist which remains very good with a selectively of ca. 99:1 for the etching of silicon at these resolutions with a low sensitivity of 7995 pC/cm.