Improvements in resist performance towards EUV HVM

Abstract

Extreme ultraviolet (EUV) lithography with 13.5 nm wavelength is the main option for sub-10nm patterning in the semiconductor industry. We report improvements in resist performance towards EUV high volume manufacturing. A local CD uniformity (LCDU) model is introduced and validated with experimental contact hole (CH) data. Resist performance is analyzed in terms of ultimate printing resolution (R), line width roughness (LWR), sensitivity (S), exposure latitude (EL) and depth of focus (DOF). Resist performance of dense lines at 13 nm half-pitch and beyond is shown by chemical amplified resist (CAR) and non-CAR (Inpria YA Series) on NXE scanner. Resolution down to 10nm half pitch (hp) is shown by Inpria YA Series resist exposed on interference lithography at the Paul Sherrer Institute. Contact holes contrast and consequent LCDU improvement is achieved on a NXE:3400 scanner by decreasing the pupil fill ratio. State-of-the-art imaging meets 5nm node requirements for CHs. A dynamic gas lock (DGL) membrane is introduced between projection optics box (POB) and wafer stage. The DGL membrane will suppress the negative impact of resist outgassing on the projection optics by 100%, enabling a wider range of resist materials to be used. The validated LCDU model indicates that the imaging requirements of the 3nm node can be met with single exposure using a high-NA EUV scanner. The current status, trends, and potential roadblocks for EUV resists are discussed. Our results mark the progress and the improvement points in EUV resist materials to support EUV ecosystem.

Stability studies on a sensitive EUV photoresist based on zinc metal oxoclusters

“…This is close to the reported values for tinbased resists, where the α ranges from 15 and 19 μm −1 , whereas for organic photoresists is typically 4.8 μm −1 . 17,30,31 As a reference value, the theoretical linear absorptivity was calculated for this material. To do so, we considered that the material was consisting of Zn-tetrameric clusters with 5 MA and 1 TFA ligands (molecular formula C 22 H 25 O 13 Zn 4 F 3 ), and we approximated its density (2.4 g∕cm 3 ) assuming that the molecular packing was the same as for an analogous tetrameric cluster consisting of six acetate ligands, Zn 4 ðOAcÞ 6 (1.9 g∕cm 3 ) 40 and correcting for the different molecular weights (ρ 1 ∕MW 1 ¼ ρ 2 ∕MW 2 ).…”

“…16 Furthermore, increasing EUV light absorption by the resist material is now one of the most important design criteria toward optimizing resist performance. 17 These performance targets require research on new materials that incorporate elements with high EUV photon absorption cross-sections and, at the same time, are composed of small units consistent with future resolutions targets. 13,[18][19][20] Metal oxoclusters are hybrid molecular compounds 10,21 and hold great potential as resist platforms for EUV lithography applications.…”

Stochastics in extreme ultraviolet lithography: investigating the role of microscopic resist properties for metal-oxide-based resists

“…However, the approach lacks an intuitive explanation. To provide more insight, we modified an existing analytical model that described LCDU for CAR 22,23 to also apply to the non-CAR resist platform. The core of this analytical LCDU model lies in counting the number of absorbed photons 16,24 in a relevant volume based on the feature edge and the resist blur.…”

Mechanistic insights in Zr- and Hf-based molecular hybrid EUV photoresists

“…With extreme ultraviolet (EUV) lithography technology almost ready to be launched for high-volume manufacturing, there are still only few photoresists with the required performance for an optimal industrial throughput at the targeted 10-nm feature size. [1][2][3][4] Ideally, a photoresist should render patterns with line width roughness (LWR) below 20%. [4][5][6] Reaching this LWR limit, however, usually requires a dose high enough to keep the shot noise at an acceptable level.…”

“…[1][2][3][4] Ideally, a photoresist should render patterns with line width roughness (LWR) below 20%. [4][5][6] Reaching this LWR limit, however, usually requires a dose high enough to keep the shot noise at an acceptable level. At the same time, the dose should be low enough (typically defined below 20 mJ∕cm 2 ) 4-6 so that the exposure times allow for a high volume throughput.…”