Line edge roughness evolutions in EUV resist patterns are investigated. Three dimensional scanning electron microscopy
images show the pattern sidewall roughness to be highly anisotropic and the roughness to be propagating from the resistsubstrate
interface up the resist pattern sidewall. In ultrathin resist films, (film thickness ca. 100 nm and below)
roughness is found to be fully correlated from the resist-substrate interface to the resist-air interface. This behavior is
seen regardless of the resist platforms being used.
Underlayer stack roughness contributions to the pattern sidewall roughness leading to resist LER were examined and no
correlations between the two were found. At the same time, the chemical properties of the underlayer stacks are shown
to have strong influences on the resist roughness and process performance. Exact mechanisms behind this are not clearly
understood at present.
This work discusses the development and characterization of Honeywell's middle layer material, UVAS, for trilayer
patterning. The UVAS polymer contains high Si content constructed by polymerizing multiple monomers selected to
produce a film that meets the requirements as a middle layer for trilayer patterning. Results of ArF photoresist patterning
evaluations, plasma and wet etch studies, and photoresist and full stack rework tests will be presented and discussed. ArF
photoresist patterning tests show that UVAS exhibits organic BARC like performance with respect to MEEF (Mask
Error Enhancement Factor), DOF (Depth of Focus) and EL (Exposure Latitude). Shelf life data shows that UVAS
maintains very stable properties even after 6 months storage at room temperature. We will also briefly discuss
investigation of amine or nitrogen-based contaminant blocking by the UVAS middle layer.
Negative tone chemically amplified i-line resists possess several advantages compared to conventional DNQ-Novolak resist. These advantages include excellent lithographic performance at a fast, tunable photospeed, high transparency, high thermal flow stability and improved etch resistance. An additional advantage of using negative resist of logic applications is that the difference in CD for various features at a fixed dose is small relative to conventional positive resists, allowing the maximum potential for printing these features simultaneously. ULTRA- i 300/310 are negative acting i-line photoresist with excellent lithographic performance optimized for 90 degrees C PAB/110 degrees C PEB processing. These materials offer extremely high resolution capability without microbridging, fast photospeed, and a robust post exposure delay process window with minimal film loss over a period of hours. these resists exhibit extremely low PEB temperature sensitivity which is expected to reduce across chip linewidth variation. Low optical density permits thick film applications producing high aspect ratio relief images with vertical profiles. Furthermore, addition of appropriate dyes permits resists to be designed for lift-off applications with controlled retrograde profiles.