Qualitative doping area characterization of SONOS transistor utilizing scanning capacitance microscopy (SCM) and scanning spread resistance microscopy (SSRM)

• Published in: Materials science & engineering. B, Solid-state materials for advanced technology Solid-state materials for advanced technology, 2005-12, Vol.124, p.301-304
• Main Authors: Heo, Jinhee, Kim, Deoksu, Kim, Chung woo, Chung, Ilsub
• Format: Article
• Language: English
• Subjects: Scanning capacitance microscopy; Scanning spread resistance microscopy; SONOS
• ISSN: 0921-5107; 1873-4944
• DOI: 10.1016/j.mseb.2005.08.097

Continuous shrinkage in the memory devices demands further understanding about the doping concentration variations at shallow junction and channel region. Scanning capacitance microscopy (SCM) and scanning spread resistance microscopy (SSRM) can provide reliable information about the electrical and physical junction structure simultaneously. In this work, we attempt to visualize the doping concentration variations of split-gate structure silicon–oxide–nitride–oxide–silicon (SONOS) transistor with thin oxide–nitride–oxide (ONO; 4/7/11 nm). From SCM image, we could identify the source and drain region, which have different doping concentrations from that at channel region. In addition, a gate oxide layer and a depletion region were also identified. Similar results were obtained using SSRM. However, SSRM shows a better resolution, in particular, for highly doped region. For this experiment, the cross-sectional sample has been prepared using focused ion beam (FIB) and hand-polishing method. The results show that SCM and SSRM are very useful methods to analyze the doping profile near the junction as well as the channel.