Subquarter-Micrometer PMOSFET's with 50-nm Source and Drain Formed by Rapid Vapor-Phase Doping (RVD) (Special Issue on Quarter Micron Si Device and Process Technologies)

概要

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Single-drain PMOSFET's with a very shallow source and drain were fabricated using a new doping method called rapid vapor-phase doping (RVD). This process is carried out in hydrogen atmosphere using B_2H_6 as a source gas. By varying flow rate of B_2H_6 and the doping time, shallow boron doped layers which are suitable for source and drain regions of MOSFET's are formed. The fabricated RVD-PMOSFET's have -nm source and drain regions with peak concentration of 4 × ^<20> cm^<-3> which were formed under the condition of 800℃, B_2H_6 flow rate of 50 ml/min. The junction depth was one third of those formed by conventional low-energy BF_2 ion implantation. RVD-PMOSFET's showed normal operation down to poly-Si gate length L_g of 0.18 μm. The advantage of shallow junction was clearly shown by the threshold voltage roll-off chracteristics, that is, it was suppressed down to 0.18 μm, whereas in conventional device, roll-off occurred below 0.6 μm. This better short channel behavior suggests that RVD forms shallow source and drain regions with weaker lateral diffusion. This result confirms that RVD is an effective method for forming shallow junctions for MOSFET's.
社団法人電子情報通信学会の論文
1994-03-25