Linjie Liu

Ultrathin highly uniform Ni(Al) germanosilicide layer with modulated B8 type Ni5(SiGe)3 phase formed on strained Si1−xGex layers

We present a method to form ultrathin highly uniform Ni(Al) germanosilicide layers on compressively strained Si1−xGex substrates and their structural characteristics. The uniform Ni(Al) germanosilicide film is formed with Ni/Al alloy at an optimized temperature of 400 °C with an optimized Al atomic content of 20 at. %. We find only two kinds of grains in the layer. Both grains show orthogonal relationship with modified B8 type phase. The growth plane is identified to be {10-10}-type plane. After germanosilicidation the strain in the rest Si1−xGex layer is conserved, which provides a great advantage for device application.

Analog and RF analysis of gate all around silicon nanowire MOSFETs

Gate all around (GAA) nanowire MOSFETs with gate length of 130 nm were fabricated on SOI wafers. The analog performance was analyzed in terms of transconductance, output conductance, voltage gain, Early voltage and transconductance efficiency. The RF characterization showed relatively low cutoff frequency and maximum oscillation frequency. Small-signal parameters are extracted using cold FET method combined with an optimization procedure called Artificial Bee Colony (ABC) method. It proves that large parasitic capacitance and high RF output conductance are the main reasons for the degraded RF performance.

Improved NiSi contacts on Si by CF4 plasma immersion ion implantation for 14nm node MOSFETs

We present in this paper high quality thin NiSi contacts on Si for the 16nm node using pre-silicidation CF4 Plasma Immersion Ion Implantation (PIII) The thermal stability, the layer uniformity and the interface roughness of thin NiSi layers are improved by CF4 PIII, which is assumed to be caused by segregation of C, F atoms at the grain boundaries and at the NiSi/Si interface. The Schottky barrier height of NiSi/p-Si is also lowered by CF4 plasma, thus a lower contact resistance on p+ doped Si is expected.

Ultrathin Ni silicide contacts on Si and SiGe formed with multi thin Ni/Al layers

We present the formation of very thin and uniform Ni silicide contacts on Si and strained SiGe using multi thin Ni/Al layers. Epitaxial Ni(Al1-xSi x)2 layers are achieved on Si with a layer thickness from 14 nm to 33 nm. The contacts show a lower Schottky barrier than NiSi. The incorporation of a small amount of Al slightly changes the Schottky barrier compared to pure NiSi2. Using Ni/Al multilayers allows formation of very thin and uniform Ni(Al)SiGe layers on SiGe. Best results Ni(Al)SiGe layers were obtained at 400°C with 20% Al. These layers show a Ni5(SiGe)3 phase. After silicidation the compressive strain in the remaining SiGe layer is still conserved, providing uniform contacts on high hole mobility SiGe layers.

Multi-gates SOI LDMOS for improved on-state performance

SOI LDMOS with multi-gates structure is proposed and fabricated. In this structure, the long gate of the conventional LDMOS (C-LDMOS) is split into four short gates. There is an n+ doped region between two adjacent short gates. The multi-gates structure enhances electric field in the channel region, leading to a higher electron velocity which will induce a larger channel current. The experimental results demonstrate that the proposed four gates LDMOS (FG-LDMOS) shows 4.5% increase in breakdown voltage, 19.2% reduction in on-state resistance and 30.5% improvement in peak transconductance compared with the C-LDMOS.