Mehrotra Prateek, Mack Chris A, Blaikie Richard J
The MacDiarmid Institute for Advanced Materials and Nanotechnology, Department of Electrical and Computer Engineering, University of Canterbury, Christchurch, New Zealand.
Opt Express. 2013 Jun 3;21(11):13710-25. doi: 10.1364/OE.21.013710.
Higher resolution demands for semiconductor lithography may be fulfilled by higher numerical aperture (NA) systems. However, NAs more than the photoresist refractive index (~1.7) cause surface confinement of the image. In this paper we describe how evanescent wave coupling to effective gain medium surface states beneath the imaging layer can counter this problem. We experimentally demonstrate this at λ = 405 nm using hafnium oxide on SiO2 to enhance the image depth of a 55-nm line and space pattern (numerical aperture of 1.824) from less than 40 nm to more than 90 nm. We provide a design example at λ = 193 nm, where a layer of sapphire on SiO2 counters image decay by an effective-gain-medium resonance phenomena allowing evanescent interferometric lithography to create high aspect ratio structures at NAs of 1.85 (26-nm resolution) and beyond.
更高的数值孔径（NA）系统可以满足对半导体光刻更高分辨率的要求。然而，数值孔径超过光刻胶折射率（约1.7）会导致图像的表面限制。在本文中，我们描述了倏逝波与成像层下方有效增益介质表面态的耦合如何能够解决这个问题。我们在λ = 405 nm处通过在SiO₂上使用氧化铪进行实验验证，将55 nm线宽和间距图案（数值孔径为1.824）的图像深度从小于40 nm提高到超过90 nm。我们提供了一个在λ = 193 nm处的设计示例，其中SiO₂上的一层蓝宝石通过有效增益介质共振现象对抗图像衰减，使得倏逝波干涉光刻能够在数值孔径为1.85（26 nm分辨率）及更高的情况下制造高深宽比结构。
