Conversion of a Patterned Organic Resist Into a High Performance Inorganic Hard Mask for High Resolution Pattern Transfer

Jean-François de Marneffe, Boon Teik Chan, Martin Spieser, Guy Vereecke, Sergej Naumov, Danielle Vanhaeren, Heiko Wolf, Armin W Knoll

ACS Nano. 2018 Nov 27;12(11):11152-11160.

PMID: 30481961

Abstract:

Polyphthalaldehyde is a self-developing resist material for electron beam and thermal scanning probe lithography (t-SPL). Removing the resist in situ (during the lithography process itself) simplifies processing and enables direct pattern inspection, however, at the price of a low etch resistance of the resist. To convert the material into a etch resistant hard mask, we study the selective cyclic infiltration of trimethyl-aluminum (TMA)/water into polyphthalaldehyde. It is found that TMA diffuses homogeneously through the resist, leading to material expansion and formation of aluminum oxide concurrent to the exposure to water and the degradation of the polyphthalaldehyde polymer. The plasma etch resistance of the infiltrated resist is significantly improved, as well as its stability. Using a silicon substrate coated with 13 nm silicon nitride and 7 nm cross-linked polystyrene, high resolution polyphthalaldehyde patterning is performed using t-SPL. After TMA/H2O infiltration, it is demonstrated that pattern transfer into silicon can be achieved with good fidelity for structures as small as 10 nm, enabling >10× amplification and low surface roughness. The presented results demonstrate a simplified use of polyphthalaldehyde resist, targeting feature scales at nanometer range, and suggest that trimethyl-aluminum infiltration can be applied to other resist-based lithography techniques.

Chemicals Related in the Paper:

Catalog Number	Product Name	Structure	CAS Number	Price
LS777279	Polyphthalaldehyde			Price