Surface Stress Modulation Structure Applied To Si-based Devices

When the characteristic size of the chip enters deep submicron,some special small size manufacturing processes will introduce stress into the channel area of the device,which will affect the performance of the device.This stress is contrary to the stress introduced by strained silicon technology to enhance carrier mobility,which will adversely affect device performance.Therefore,how to effectively modulate the channel stress of the device in small size will be particularly important,which can make the device performance more flexible to be regulated to meet specific needs.In this paper,combined with the trench stress modulation technology,it is applied to two different types of devices,and its effects on the mechanical and electrical characteristics of devices are studied.Firstly,in order to reduce the source-drain contact resistance of small size devices,NiSi is usually used as the source-drain electrode.Because NiSi leads to uniaxial tensile stress in PMOSFET channel region,its electrical characteristics will be reduced.To solve this problem,a NiSi electrode PMOSFET device based on trench structure is proposed.Through Sentaurus simulation analysis,it is found that the trench structure can effectively relax the stress in the channel region of the device introduced by NiSi electrode,and the relaxation amplitude is related to the size of the trench structure.When the groove structure size is adjusted to the optimum value,the uniaxial tensile stress relaxation in PMOSFET channel area along the channel direction is greater than 50%.Compared with the non-trench stress modulation structure,the transfer and output characteristics of the device are effectively improved by using the trench stress modulation structure.Secondly,for the most important uniaxial strain CESL technology at present,when the compressive strain CESL is used to improve the electrical characteristics of PMOSFET,the compressive strain CESL will reduce the electrical characteristics of NMOSFET,so it is necessary to remove the compressive strain CESL on the surface of NMOSFET,which will increase the process complexity.In addition,when the device channel size is further reduced,the boundary between NMOSFET and PMOSFET becomes difficult to distinguish,which increases the complexity of etching the surface compressive strain CESL of NMOSFET.To solve this problem,a strained NMOSFET with surface stress modulation structure is proposed.Through Sentaurus simulation analysis,it is concluded that the surface stress modulation structure can effectively relax the compressive stress in the channel region of NMOSFET devices introduced by compressive strain CESL,and the relaxation amplitude is related to the size of the surface stress modulation structure.By setting the geometrical parameters of the surface stress modulation structure to a specific value,the uniaxial compressive stress along the channel direction of NMOSFET can be effectively relaxed,and its transfer and output characteristics can be effectively improved.