Effect of Channel Concentration and Boron Penetration on Poly-Si Junctionless Accumulation Mode FinFETs

• Main Authors: Chan, Yi-De, 詹宜得
• Other Authors: Chao, Tien-Sheng
• Format: Others
• Language: en_US
• Published: 2017
• Online Access: http://ndltd.ncl.edu.tw/handle/u49wnr

碩士 === 國立交通大學 === 電子物理系所 === 105 === In this thesis, we used the double patterning to successfully fabricate devices, which with sub-30 nm channel dimension without the use of advanced lithography tools, implantation processes, and plasma treatments. The Pi gate (PG) poly-Si junctionless accumulation mode (JAM) FinFETs with different channel concentration (Nch) have been successfully fabricated and demonstrated. Through the material analysis, we found the devices with lower Nch have lower activation rate due to grain boundary, so the interface state easily affected the carriers and degraded the performance. As the channel dimension (Hfin × Wfin) of 35.5 nm × 26.5 nm and Nch of 5 × 1018 cm-3, the PG JAM FinFETs show the excellent electrical performance, such as steep S.S. ~ 114 mV/dec., small DIBL ~ 29 mV/V and Ion/Ioff ratio > 1×108 (VD = 1V)。 In addition to the effects of Nch, the issue of boron penetration was found on the PG JAM FinFETs by different S/D activation condition: It caused the obvious degradation and positive shift for S.S. and VTH, respectively. It can be mitigated by reducing thermal budget of the additional S/D activation. Our PG JAM FinFETs show the best S.S. ~ 92 mV/dec., DIBL ~ 20 mV/V. But this lowers the Ion due to the higher source/drain resistance. Moreover, we successfully separated and systematically quantitated these effects of charges, which resulted from boron penetration. The performance and reliability will be improved by scaling down channel dimension (sub-10 nm), rapid thermal annealing (RTA) and microwave annealing (MWA) in the future. Therefore, these devices are promising candidates for future multi-functional 3-D integrated circuit (IC) applications.