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Proceedings Paper

Novel photoresist thin films with in-situ photoacid generator by molecular layer deposition
Author(s): Han Zhou; Stacey F. Bent
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Paper Abstract

Current photoresist materials are facing many challenges introduced by advanced lithographies, particularly the need for excellent compositional homogeneity and ultrathin film thickness. Traditional spin-on polymeric resists have inherent limitations in achieving a high level of control over the chemical composition, leading to interest in development of alternative methods for making photoresists. In this work, we demonstrate that molecular layer deposition (MLD) is a potential method for synthesizing photoresists because it allows for precise control over organic film thickness and composition. MLD utilizes sequential, self-limiting reactions of organic precursors to build a thin film directly on a substrate surface and grows organic films by depositing only one molecular layer at each precursor dose, which in turn allows for fine-tuning of the position and concentration of various functionalities in the deposited film. In this study, we use bifunctional precursors, diamine and diisocyanate, to build polyurea resist films via urea coupling reaction between the amine and isocyanate groups. Acid-labile groups and photoacid generators (PAGs) are embedded in the backbone of the resist films with a highly uniform distribution. The resist films were successfully deposited and characterized for both materials properties and resist response. E-beam patterning was achieved with the resist films. Cross-linking behavior of the resist films was observed, likely due to the aromatic rings in the films, which is undesirable for application as a positive-tone photoresist. Moreover, the in-situ polymer-bound PAGs had low sensitivity. It is suggested that this effect may arise because the PAG is cation-bound, leading to lower efficiency of sulfur-carbon bond cleavage in the sulfonium cation, which is needed to produce the photoacid, and consequently a lower photoacid yield. Further work is needed to improve the performance of the MLD resist films.

Paper Details

Date Published: 29 March 2013
PDF: 7 pages
Proc. SPIE 8682, Advances in Resist Materials and Processing Technology XXX, 86820U (29 March 2013); doi: 10.1117/12.2011572
Show Author Affiliations
Han Zhou, Stanford Univ. (United States)
Stacey F. Bent, Stanford Univ. (United States)

Published in SPIE Proceedings Vol. 8682:
Advances in Resist Materials and Processing Technology XXX
Mark H. Somervell, Editor(s)

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