Case study: Doping profile analysis for 30nm DRAM devices using SCM and SSRM

This paper is to evaluate the doping profile analysis capability of Scanning Capacitance Microscope (SCM) and Scanning Spreading Resistance Microscope (SSRM) on 30nm Dynamic Random Access Memory (DRAM) devices and apply the SSRM technique on a real case to verify the junction depths of different doping recipes for device performance tuning. The results show SCM can be used on periphery devices in a 30nm DRAM due to they have larger feature size (>90nm). For array devices with minimum feature size (∼30nm) in a 30nm DRAM, only SSRM is capable with sufficient spatial resolution and sensitivity to identify the structures and doping profiles. For the real case, SSRM analysis results clarified there is approximate 10nm difference on the junction depth between 2 different doping recipes of samples and the result is consistent with the Technology Computer Aided Design (TCAD) simulation data. In addition, both SCM and SSRM techniques showed the analysis quality does highly rely on the surface cleanness and flatness of samples.