The enhancement in chemical gradients between the EUV exposed and unexposed areas can generate a wider process window, possibly, a smaller stochastic defectivity, and a lower local CD uniformity in EUV resists. This enhancement, in turn, helps to overcome the challenge of the small process window in high NA EUV lithography. In this work, a new concept resist, which is developed based on our chemical gradient enhancement technique model, is used to drive the chemical gradient upward chemically. The resist also has the capability of absorbing UV selectively at EUV exposed areas. Therefore, the UV flood exposure system, which has been discussed in Photosensitized Chemically Amplified ResistTM (PSCARTM), is used as another key part to further enhance the new resist. The new concept resist with UV lights was confirmed to give 15.1% improvement in its EUV sensitivity and, simultaneously, 25.0% improvement in local CD uniformity. This technique might be one of the solutions to bring CAR resist further into high-NA EUV lithography.
Photosensitized Chemically Amplified ResistTM (PSCARTM) has been demonstrated as a promising solution for a high sensitivity resist in EUV lithography mass production. This paper describes the successful calibration of a PSCAR resist model for deployment within rigorous lithography process simulation, capturing continuum as well as stochastic effects. Verification of the calibrated model parameters was performed with new patterns or with new resist formulations with good agreement. The reduction of required EUV dose of PSCAR resist while maintaining similar roughness levels have been achieved both from experimental result and from simulated result. The simulation of PSCAR continues to be a great tool for understanding, predicting, and optimizing the process of PSCAR.
Photosensitized Chemically Amplified ResistTM (PSCARTM) **2.0’s advantages and expectations are reviewed in this paper. Alpha PSCAR in-line UV exposure system (“Litho Enhancer”) was newly installed at imec in a Tokyo Electron Ltd. (TELTM)’s CLEAN TRACKTM LITHIUS ProTM Z connected to an ASML’s NXE:3300. Using the Litho Enhancer, PSCAR 2.0 sensitization preliminary results show that suppression of roughness enhancement may occur while sensitivity is increased. The calibrated PSCAR 2.0 simulator is used for prediction of resist formulation and process optimization. The simulation predicts that resist contrast enhancement could be realized by resist formulation and process optimization with UV flood exposure.
In order to lower the cost of ownership of EUV lithography, high sensitivity EUV resists , enabling higher throughput of EUV scanners are being explored. The concept that utilizes a Photosensitized Chemically Amplified ResistTM (PSCARTM) is a promising solution for achieving increased resist sensitivity, while maintaining other high performance characteristics of the material (i.e., resolution, line edge roughness (LER), exposure latitude). PSCAR uses a UV exposure after EUV exposure and selective absorption to meet these goals . Preliminary results have been discussed in previous papers 1-8.
PSCAR utilizes an area-selective photosensitization mechanism to generate more acid in the exposed areas during a UV exposure. PSCAR is an attempt to break the resolution, line-edge-roughness, and sensitivity trade-off (RLS trade-off) relationships that limit standard chemically amplified resists. The photosensitizer, which is generated in exposed area by a photoacid catalytic reaction, absorbs the UV exposure light selectively and generates additional acid in the exposed area only.
Material development and UV exposure uniformity are the key elements of PSCAR technology for semiconductor mass fabrication. This paper will review the approaches toward improvement of PSCAR resist process robustness. The chemistry’s EUV exposure cycle of learning results from experiments at imec will be discussed.
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
INSTITUTIONAL Select your institution to access the SPIE Digital Library.
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.