Ivan Pollentier

Chain scission resists for extreme ultraviolet lithography based on high performance polysulfone-containing polymers

A series of polymers with a comb architecture were prepared where the poly(olefin sulfone) backbone was designed to be highly sensitive to extreme ultraviolet (EUV) radiation, while the well-defined poly(methyl methacrylate) (PMMA) arms were incorporated with the aim of increasing structural stability. It is hypothesized that upon EUV radiation rapid degradation of the polysulfone backbone will occur leaving behind the well-defined PMMA arms. The synthesized polymers were characterised and have had their performance as chain-scission EUV photoresists evaluated. It was found that all materials possess high sensitivity towards degradation by EUV radiation (E0 in the range 4–6 mJ cm−2). Selective degradation of the poly(1-pentene sulfone) backbone relative to the PMMA arms was demonstrated by mass spectrometry headspace analysis during EUV irradiation and by grazing-angle ATR-FTIR. EUV interference patterning has shown that materials are capable of resolving 30 nm 1 : 1 line : space features. The incorporation of PMMA was found to increase the structural integrity of the patterned features. Thus, it has been shown that terpolymer materials possessing a highly sensitive poly(olefin sulfone) backbone and PMMA arms are able to provide a tuneable materials platform for chain scission EUV resists. These materials have the potential to benefit applications that require nanopattering, such as computer chip manufacture and nano-MEMS.

Integration of Cu and low- k dielectrics: effect of hard mask and dry etch on electrical performance of damascene structures

Abstract In this work we discuss the importance of selecting the hard mask material and choosing the optimum dry etch and post-CMP clean processes on the integration of Cu and organic low-k dielectrics. The hard mask material plays an important role in the interline capacitance and in the effective dielectric constant of the interconnects. One generation of effective k can be gained simply by replacing the hard mask material by one with a lower dielectric constant, instead of moving to a more advanced low-k material. Interline leakage is not affected by the hard mask material and low values (∼10−9 A/cm2) are obtained at electric fields of 1 MV/cm for structures with spacing down to 0.2 μm. A non-optimized dry etch process for trench definition can result in undercutting, which affects the Cu filling of the trenches. From our results it is clear that the process conditions (lithography, etch, CMP) affect the geometry of the structures, which has a big impact on the effective dielectric constant of the interconnects.

State-of-the-art of EUV materials for N5 logic and DRAM applications

In the last year, the continuous efforts on the development of extreme ultraviolet lithography (EUVL) has allowed to push the lithographic performance of the EUV photoresists on the ASML NXE:3300 full field exposure tool. However, EUVL materials are deemed as critical to enable and extend the EUV lithography technology in a cost-effective manner. In this work, we present the imec activity on EUV materials. We show the results of the best performing EUV photoresists for dense line-space pattern at 32nm pitch, dense contact holes at 36nm pitch and dense staggered pillars at Px70nm-Py40nm pitch, reporting the most critical patterning challenges for the investigated structures. We discuss manufacturing challenges as nano-failures, line-width roughness, local critical dimension (CD) uniformity, process window limitations and metal cross contamination of metal containing resist (MCR). Further, we discuss the role of the substrate underneath the EUV photoresist and alternative patterning solutions as the tone reversal process (TRP). Furthermore, we discuss novel EUV materials lain on the horizon and fundamental material aspects.