Enabling the 45nm node by hyper-NA polarized lithography

Abstract

The introduction of immersion step & scan systems has opened the road for hyper-NA lenses (NA > 1). At these NA's polarization control becomes a key parameter in imaging. Application of polarized illumination leads to an increase of contrast and exposure latitude. The resulting resolution enhancement offered by polarized illumination enables 45nm node lithography with an ArF, NA=1.2 system. Hyper-NA systems utilizing polarized illumination must be fully compatible with all requirements for a volume production tool: maintaining imaging performance at full throughput, overlay and focus control; flexibility and ease-of-use are essential features. Adequate polarization control is realized by employing polarization-preserving optics, and by automated in-line metrology to optimize the system for any selected polarization state. In this paper we address the improvements of polarization for the 65nm and 45nm imaging node applications. Experimental results describing the imaging effects while using polarized illumination on high-NA (NA=0.93) and hyper-NA (NA=1.2) exposure tools will be shown. These data will also be compared to simulations. In addition, this paper includes a short section that deals with the issues of reticle birefringence. Finally, system control and in-line metrology under high-volume production conditions will be discussed.

Impact of polarized illumination on high NA imaging in ArF immersion lithography at 45 nm node

“…The larger the DOF and EL, the larger the process latitude and the more robust the image. Our study is carried out by PROLITH simulation which is widely used in the semiconductor industry to study the lithographic process [11][12][13]. The full physics model is used in the PROLITH simulation, and the vector mode which is accurate in the case of high NA imaging is chosen.…”

Two-dimensional polarization distribution controller based on variable retarder array

“…Because solution set (7) is subset of solution set (5), the solution meeting the equation set (4) and the equation set (6) at the same time is solution set (7).…”

“…Radial and azimuthal polarization distributed beams propagating through turbulent atmosphere have been investigated for further applications [6]. Azimuthal polarization distributed beams are also utilized in the hyper numerical aperture immersion lithographic machines [7,8].…”

Immersion lithography with an ultrahigh-NA in-line catadioptric lens and a high-transmission flexible polarization illumination system

“…The IPS is measured over the full pupil as function for the field position. The effect of IPS on imaging performance has been investigated in Ref [5]. Variation of the IPS over the field may, result in a variation of the CDU uniformity.…”