ARC stack development for hyper-NA imaging

The merits of hyper NA imaging using 193 nm exposure wavelength with water immersion for 45 nm and 32 nm nodes is clear. However, the challenge remains CD control at hyper NA and the development of ARC stacks to support not only lithographic response but also device integrations. Extreme off-axis illumination, polarization, and dense pitches of the C045 and C032 nodes show a significant degradation of reflection and CD control and a significant loss of resolution. Consequently, hyper NA patterning requires the development of a new ARC to improve the overall CD control. Thus, a single ARC layer could not ensure the reflectivity condition, and ARC stacks must now be decomposed into two or three components in order to suppress reflectivity through a wide range of incidence angle. In a previous work, we presented the advantage of using an antireflective based on CVD organic - inorganic stacks. This paper presents an upgrade of this type of stack, applied to 1.2NA imaging. We will show stack reflectivity simulations based on S-matrix approach. The capabilities of the CVD tools have been taken into account in the simulations in order to define a reflectivity process window. We will present 1.2NA lithography with different optimized ARC stacks, comparing potential capability and CD control in conjunction with the immersion lithography for 45 nm and 32 nm nodes.