The crystalline structure, thermal stability, and electrical properties of TaN and TaSiN thin films formed by reactive RF-sputtering with a broad range of N and Si composition ratios were investigated. TaSiN with a Si/(Si+Ta) ratio less than 25% were crystalline, whereas that with a ratio more than 25% was amorphous, regardless of the N2 partial pressure. The amorphous films exhibited excellent thermal stability with no crystallization up to 900°C. Crystalline films consisted of columnar grains with sizes ranging from 20–30 nm. Electrical resistivity showed a strong dependence on the Si and N composition ratios. However, amorphous films deposited at low N2 partial pressure exhibited constant resistivity, regardless of the Si/Ta ratio. These results clarify that the crystalline structure and electrical resistivity of TaSiN films can be controlled by varying the Si and N composition ratios.

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The lithography challenges posed by the 22 nm node continue to place stringent requirements on photomasks. The dimensions of the mask features continue to shrink more deeply into the sub-wavelength scale. In this regime residual mask electromagnetic field (EMF) effects due to mask topography can degrade the imaging performance of critical mask patterns by degrading the common lithography process window and by magnifying the impact of mask errors or MEEF. Based on this, an effort to reduce the mask topography effect by decreasing the thickness of the mask absorber was conducted. In this paper, we will describe the results of our effort to develop and characterize a binary mask substrate with an absorber that is approximately 20-25% thinner than the absorber on the current Opaque MoSi on Glass (OMOG) binary mask substrate.For expediency, the thin absorber development effort focused on using existing absorber materials and deposition methods. It was found that significant changes in film composition and structure were needed to obtain a substantially thinner blank while maintaining an optical density of 3.0 at 193 nm.Consequently, numerous studies to assess the mask making performance of the thinner absorber material were required and will be described. During these studies several significant mask making advantages of the thin absorber were discovered. The lower film stress and thickness of the new absorber resulted in improved mask flatness and up to a 60% reduction in process-induced mask pattern placement change. Improved cleaning durability was another benefit. Furthermore, the improved EMF performance of the thinner absorber [1] was found to have the potential to relieve mask manufacturing constraints on minimum opaque assist feature size and opaque corner to corner gap.Based on the results of evaluations performed to date, the thinner absorber has been found to be suitable for use for fabricating masks for the 22 nm node and beyond.

Three types of high transmission attenuated phase shift masks were evaluated. The attenuating materials were obtained from commercial and non-commercial sources. Various key performance metrics were investigated. Blanket film transmission and reflection was measured at various wavelengths. Laser durability and cleaning durability were measured. Standard dry etch processes were used for each film and the profile and surface properties were compared. Final mask transmission and phase were also measured. The summarized results show clear benefits of using some high transmission materials relative to others.