(Invited) Plasma-Enhanced Quasi-ALE and ALD Processing for Leading-Edge Microfabrication

Abstract

In recent years, the progression of very large scale integration of semiconductor devices and miniaturization require extension of ultra-high selectivity process and CD control technique exhibiting atomic-layer-level control. We introduce herein a state-of-the-art self-aligned contact (SAC) etching process and multilayer patterning process developed by a new patterning technology using Atomic Layer Etch (ALE) and Atomic Layer Deposition (ALD) towards the 5/7nm generation. SAC etch processes are known to require SiO2 etching capability with ultra-high selectivity to SiN. We developed a modified ALE process [Quasi-ALE] to make it more suitable for SiO2 etch. By adopting this technology to the SAC process, conventional trade-offs between SiO2 etch through capability and SiO2selectivity to SiN in the fine slit pattern is significantly improved. This achievement is enabled by Quasi-ALE’s independent controllability of the radical flux and ion flux, which precisely controls the reaction layer thickness on the surface, allowing etch process at lower ion energy region which is most effective to improve etch selectivity. The advancement of EUV lithography toward manufacturability has accelerated the need for innovation in multilayer lithography stack etches. The patterning of high quality sub lithographic patterns is becoming more challenging, especially in regards to line-roughness (LER/LWR) reduction, and selectivity enhancement of thin EUV-resist. Furthermore, patterning with universal CD shrinkage independent of the pattern types (hole, oval, L/S) is also being required. As a result of various techniques were studied for enhancement of fine pattern formation, “fusion of ALD technology and etching” was confirmed to be very beneficial for its capability of atomic-level formation of surface protection film during the etch process. This technology enabled line-roughness reduction with CD shrink control independent of the pattern-size, since the ALD step is used according to the optimum timing during the etch process, which forms uniform deposition on any type of patterns. As described, precise control of the microfabrication at atomic layer level utilizing Quasi-ALE and ALD technology is becoming mandatory in the generation of 5/7nm.