Research On Analog And RF Characteristics Of Novel Dual-k FinFET Devices

With the development and advancement of semiconductor industry in the past half century,FinFET structure has become the core device of 14nm technology development because of its strong gate control ability and good chip integration.With the introduction of hig-k gate dielectric layer,combined with the source and drain epitaxy region and the optimal structural parameters,the dual-k layer symmetric FinFET(Dual-k FinFET)structure can effectively enhance the gate control ability and restrain the deterioration of short channel effect.However,the increase of the high-k layer leads to the enhancement of the coupling effect between the two planes and the serious parasitic effect.The high parasitic gate capacitance and low cut-off frequency restrict the development of RF analog characteristics of the device.In order to solve these problems,an asymmetric dual-k layer drain epitaxial FinFET structure,AsymD-kDE FinFET,is proposed in this paper.And its RF simulation characteristics are studied.The main contents are as follows:1)Based on the FinFET structure of Dual-k layer,the geometric parameter model of RF simulation is studied and analyzed.The simulation results show that the optimal structure parameters can increase the internal gain(Av)of the device to 25 dB,which is in line with the prediction goal of ITRS technology.However,the increase of high k layer affects the parasitic effect of devices,the parasitic gate capacitance is too high and the cutoff frequency is low,which restricts the development of RF analog characteristics.2)Based on the FinFET structure of Dual-k layer,an asymmetric dual-k layer structure is proposed,in which different k values are used in the high k layer at the source and drain edges,to optimize the parasitic effect of the device.Compared with the dual-k layer symmetric FinFET(Dual-k FinFET)structure,the asymmetric dual-k layer structure can further improve the cutoff frequency(fT?13.47%)of the device,and reduce the total gate capacitance(Cgg?4.28%).Thus the RF analog performance of the device is greatly improved,but the gain(Av)of the device is sacrificed by about 14.50%.3)Based on the FinFET device structure of Dual-k layer,an asymmetric drain epitaxial structure with longer drain edge epitaxy region is proposed,which reduces the influence of drain on the channel region and improves the gain of the device.The increase of drain epitaxial region leads to significant reduction in inner fringe capacitance towards drain side due to shifting of drain extension's doping concentration away from the gate edge.Compared with the dual-k layer symmetric FinFET(Dual-k FinFET)structure,the asymmetric drain epitaxial structure can significantly increase the Av?25.78%and reduce the Cgg?38.57%of the device.However,due to the low doping concentration of gate ions near the leakage edge,the transconductance(gm)decreases and the initial current(Ion)decreases by about 1/4.Finally,by combining the characteristics of asymmetric dual-k layer structure and asymmetric drain epitaxial structure,an asymmetric dual-k layer drain epitaxial FinFET structure,AsymD-kkDE FinFET,is proposed in this paper.The simulation results show that,compared with the dual-k layer symmetric FinFET(Dual-k FinFET)structure,the introduction of asymmetric dual-k and asymmetric drain epitaxial makes the Av of the device increase 24.19%,the fT increases 14.82%,and the Cgg decreases 40.41%.To some extent,it makes up for the decrease of gm and the decrease of Ion due to the increase of drain epitaxial region.Finally,the results show that the structure of AsymD-kkDE FinFET can improve the RF analog performance of the device,which is an important research direction for the development of the next generation of FinFETs.