Tuesday, 31 May 2022: 12:00
West Meeting Room 115 (Vancouver Convention Center)
As FinFET scaling down to sub-14 nm technology nodes, Self-aligned Quadruple Patterning (SaQP) scheme is widely deployed for Fin formation, where two mandrels (MD1 and MD2) and corresponding mandrel spacers (MD1SP and MD2SP) are patterned for accurate CD transferring. The Fin-cut etching process of the MD2SP Cut is very critical for the patterning of the Standard Cell and the SRAM patterns. This work studies the application of Front End of Line (FEoL) MD2SP Cut process in both inductive coupled plasma (ICP) and capacitive coupled plasma (CCP) etchers. The mismatch between the two tools are observed and discussed in details. For CCP tools, a degradation of line width roughness (LWR) and increase of critical dimension (CD) loading between dense and isolated patterns are observed. Compared with the ICP etchers, the CCP etchers have lower plasma dissociation and stronger physical bombardment of ions. Furthermore, it is harder to control the plasma density and directionality separately in conventional CCP etching condition than in ICP tools. To increase CCP tool applications in FEOL processes, we introduce a Silicon coating process to modify the photoresist (PR) during the CCP etching to harden the surface of the PR and enhance the LWR performance (Fig. 1). Furthermore, the application of atomic layer etching (ALE) technology ensures the CD loading between the dense and isolated patterns (Fig 1.). With the application of our study, we are able to broaden the application of CCP tools in FEoL for FinFET mass production.
