IUVSTA 15th International Vacuum Congress (IVC-15), AVS 48th International Symposium (AVS-48), 11th International Conference on Solid Surfaces (ICSS-11)
    Thin Films Tuesday Sessions
       Session TF-TuP

Paper TF-TuP9
Composite Tantalum Nitride-Silicon Nitride Thin Films for 193nm Embedded Attenuated Phase Shift Masks

Tuesday, October 30, 2001, 5:30 pm, Room 134/135

Session: Microstructure, Oxides, and Optical Properties Poster Session
Presenter: M.G. Lassiter, Photronics Corporation
Authors: M.G. Lassiter, Photronics Corporation
M. Cangemi, Photronics Corporation
P.D. Rack, Rochester Institute of Technology
B.W. Smith, Rochester Institute of Technology
Correspondent: Click to Email
As semiconductor device dimensions continually decrease in size, the ability to print these dimensions using 248nm light from a KrF excimer laser is becoming increasingly more difficult. According to Lord Rayleigh's resolution criteria the minimum resolution on the wafer is proportional the exposure wavelength divided by the numerical aperture of the objective lens. Thus resolution can be improved by using smaller wavelengths, which has brought about the development of exposure systems that use the 193nm ArF excimer laser. The use of a new exposure wavelength requires the development of new materials for the photomasks used in such an imaging system. Image contrast has been significantly improved in the past due to the use of embedded attenuated phase shift masks (EAPSM). An EAPSM induces a 180-degree phase shift and limited transmission in the regions that are traditionally opaque in a binary mask. The result is a phase induced contrast enhancement at image edges at the expense of higher background intensity compared to a binary mask. New materials are needed to construct such a mask for 193nm wavelength. This paper explores the use of a composite TaN-Si3N4 for the purpose of providing both the radiation attenuation and the relative phase shift on an EAPSM for use at 193nm wavelength. The TaN and Si3N4 were each reactively rf sputter deposited and their respective optical constant spectra were determined using a Woollam VUV-Variable Angle Spectroscopic Ellipsometer. An effective media approximation (EMA) was used to combine the constituents to tune the optical properties to the desired values for an EAPSM film. Finally, a matrix of composite thin films of varying the TaN-Si3N4 composition were co-deposited and the optical constants of the composites were determined using the ellipsometer to verify the EMA. The composition was iteratively tuned to provide the optimum optical constants at 193nm for a 20% transmission EAPSM.