Zhou Jianming, Fan Yongfa, Bourov Anatoly, Smith Bruce W
Microelectronic Engineering Department, Rochester Institute of Technology, New York 14623, USA.
Appl Opt. 2006 May 1;45(13):3077-82. doi: 10.1364/ao.45.003077.
Immersion lithography has become attractive since it can reduce critical dimensions by increasing numerical aperture (NA) beyond unity. Among all the candidates for immersion fluids, those with higher refractive indices and low absorbance are desired. Characterization of the refractive indices and absorbance of various inorganic fluid candidates has been performed. To measure the refractive indices of these fluids, a prism deviation angle method was developed. Several candidates have been identified for 193 nm application with refractive indices near 1.55, which is approximately 0.1 higher than that of water at this wavelength. Cauchy parameters of these fluids were generated and approaches were investigated to tailor the fluid absorption edges to be close to 193 nm. The effects of these fluids on photoresist performance were also examined with 193 nm immersion lithography exposure at various NAs. Half-pitch 32 nm lines were obtained with phosphoric acid as the immersion medium at 1.5 NA. These fluids are potential candidates for immersion lithography technology.
浸没式光刻技术因其能够通过将数值孔径（NA）增大到1以上来减小关键尺寸而变得颇具吸引力。在所有浸没液候选材料中，需要折射率较高且吸光度较低的材料。已经对各种无机流体候选材料的折射率和吸光度进行了表征。为了测量这些流体的折射率，开发了一种棱镜偏角法。已确定了几种适用于193nm的候选材料，其折射率接近1.55，比该波长下水的折射率高出约0.1。生成了这些流体的柯西参数，并研究了使流体吸收边接近193nm的方法。还通过在不同数值孔径下进行193nm浸没式光刻曝光，研究了这些流体对光刻胶性能的影响。以磷酸作为浸没介质，在1.5的数值孔径下获得了半间距为32nm的线条。这些流体是浸没式光刻技术的潜在候选材料。
