As one of the main sources of instability in p-MOSFETs, interface state (Nit) generation has become an important reliability issue for over three decades.Interface state can be generated gradually under device operational conditions or generated rapidly under accelerated stress such as negative bias temperature instability(NBTI)In this letter,by charge pumping method,it can be seen interface traps are improved after fluorine implant, hence,drain current increases due to VT reduces.NBTI is improved as the dose of fluorine increases.
According to Power Law,the slope (n) of are almost 0.25, and the result is consistent with R-D model.Therefore,the physical mechanism is dominated by Si-H during NBTI stress.In addition,in order to eliminate process issue, an external mechanical uniaxial tensile stress applied on p type metal oxide semiconductor field effect transistors(pMOSFETs) is used for the study of negative bias temperature instability (NBTI)characteristics.Drain current and hole mobility decreases under uniaxial tensile strain,and the NBTI characteristics also become more serious simultaneously.The NBTI degradation mechanism and activation energy are consistent with R-D model before and after applying mechanical stress.
Temperature-dependent biaxial strain effect on p-MOSFETs.The fabrication of devices adopted a commercial 65 nm process on industry standard 12 in.Si wafers, in which the channel direction is parallel to Si¡Õ110¡Ö.Additionally,a selective epitaxial Si1-x Gex source/drain structure was also introduced to form the uniaxial compressive stress.The external mechanical stress was performed by a bending silicon substrate, and the preparation of the bending device is described as follows,the thickness of silicon substrate was reduced from 800 to 50 um by using a Struers RotoPol-21 polisher.
The influence of biaxial compressive stress on p type metal oxide semiconductor field effect transistors MOSFETs was investigated.It was found that drain current and hole mobility of p-type MOSFET with Si1-xGex raised source/drain and external applied mechanical stress significantly decreased due to the increase of effective conductive mass at room temperature.
However,this phenomenon was inverted above 333K.Because the hole can gain enough thermal energy to transmit to a higher energy level by intervalley scattering,its transport mechanism was dominated by lower effective mass at higher energy level.Using strained-silicon this method,we can study the temperature-dependent strain effects and the relationship between strain and electrical characteristics can be also investigated without any process effects.In order to strain the channel,silicon substrate is bent by applying external mechanical stress,the lattice of channel will be strained after applying uniaxial tensile stress.
Therefore,we successfully improve drain current and carrier mobility of SOI NMOSFET,and the increasing rates are 22% and 30% respectively.In addition,we can understand the influence of hot carrier effect on strain silicon by bending silicon substrate with external mechanical stress.With the increase of curvature,substrate current goes up.
| Identifer | oai:union.ndltd.org:NSYSU/oai:NSYSU:etd-0726109-140139 |
| Date | 26 July 2009 |
| Creators | Jheng, Bao-tang |
| Contributors | Yao-Tsung Tsai, Ting-Chang Chang, James B. Kuo, Jyi-Tsong Lin, Chun-Hsing shih, Wen-Kuan Yeh |
| Publisher | NSYSU |
| Source Sets | NSYSU Electronic Thesis and Dissertation Archive |
| Language | Cholon |
| Detected Language | English |
| Type | text |
| Format | application/pdf |
| Source | http://etd.lib.nsysu.edu.tw/ETD-db/ETD-search/view_etd?URN=etd-0726109-140139 |
| Rights | not_available, Copyright information available at source archive |
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