28 August 2003 Current developments of a high-performance CA resist for mask-making application
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Proceedings Volume 5130, Photomask and Next-Generation Lithography Mask Technology X; (2003) https://doi.org/10.1117/12.504049
Event: Photomask and Next Generation Lithography Mask Technology X, 2003, Yokohama, Japan
The mask fabrication industry is slowly migrating to chemically amplified (CA) resists to take the advantages of their high contrast, resolution, and sensitivity. During this migration process, the industry has encountered several problems associated with CA resists such as baking homogeneity of thick mask plates on hot plates, footing on Cr masks, and storage stability of mask blanks. In addressing these issues, we have adopted a low Ea CA resist platform to overcome the bake latitude issue. The resist formulation has been reformulated to reduce the footing and a new package method has been introduced to extend the storage of the blanks. In addition, we will also discuss our studies on two major areas, such as sensitivity and etch resistance, which we think is extremely important for E-beam resists in the future. The mask industry started with 248nm DUV CA resist systems and then found out that there was a need for even higher sensitivity resist systems to address the throughput issue. In our early study, we have observed that by simply increasing photoacid generator loading in the resist formulation we were able to increase the sensitivity, but there was a significant reduction in the dose latitude. After studying the dissolution and inhibition properties of different PAGs, we have been able to optimize PAG and base loading in combination with proper choice of PAGs to achieve high sensitivity and large dose latitude. The new resist formulation exhibits a large dose latitude of 38% for 100 nm l/s images with high sensitivity of 4.4μC/cm2 at 100 kV. Due to the electron scattering effect and the image collapse issues with thicker resists, thinner imaging layer is desirable. Sufficient etch selectivity is needed to compensate the insufficient resist thickness. Therefore, there is a need to develop a high Cl2/O2 RIE (used in Cr etch process) etch resistant resist system for mask making. We have reported earlier that a resist formulation based on blending KRS-XE with SSQ polymer has resolved 50nm l/s resist images with etch rate 20% better than conventional novolak I-line resist systems. Since then, we have investigated a few new SSQ polymers and found some lithographic improvement in this new blending systems due to better compatibility of the SSQ polymer to the KRS-XE.
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Wu-Song Huang, Wu-Song Huang, Wei He, Wei He, Wenjie Li, Wenjie Li, Wayne M. Moreau, Wayne M. Moreau, Robert Lang, Robert Lang, David R. Medeiros, David R. Medeiros, Karen E. Petrillo, Karen E. Petrillo, Arpan P. Mahorowala, Arpan P. Mahorowala, Marie Angelopoulos, Marie Angelopoulos, Christina Deverich, Christina Deverich, Chester Huang, Chester Huang, Paul A. Rabidoux, Paul A. Rabidoux, } "Current developments of a high-performance CA resist for mask-making application", Proc. SPIE 5130, Photomask and Next-Generation Lithography Mask Technology X, (28 August 2003); doi: 10.1117/12.504049; https://doi.org/10.1117/12.504049

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