- 期刊
接觸孔蝕刻停止層之伸張應力對nMOSFET特性探討
Influence of Tensile Stress from CESL on Strained-Si and Strained-SiGe CMOSFET Characteristics
摘要
用覆蓋氮化矽接觸孔蝕刻停止層(Contact Etch Stop Layer, CESL)對CMOSFET通道方向施與單軸伸張應，藉此探討CESL會對nMOSFET特性的提升；由於CESL層會對元件通道產生局部性的伸張應，因此文中用測應變矽元件之衝擊子化效(ImpactIonization Efficiency, IIE)去觀察出應變矽元件會因通道的縮短所受到的伸張應增加，當元件通道縮短時IIE也隨之增加，因此在受CESL伸張應力所影響的MOSFET元件利用進長時間高閘極偏壓加速測試驗證出其IIE的增強其原因可歸於通道能隙的改變，並非載子平均自由徑的變化。
並列摘要
Influence of tensile stress from contact etch stop layer (CESL) on strained-Si CMOSFET characteristics has been investigated. The tensile CESL can improve nMOSFETs performance, whereas it can degrade I-V characteristics of pMOSFETs.In the thesis, we utilize the measurement of impact ionization efficiency (IIE) to observe the effect of the tensile CESL on strained-Si nMOSFET and verify whether the local strain depends on the channel length or not. From the experiment, the IIE can be enhanced when the channel length is reduced. This result can be attributed to the cause of reduced energy bandgap, regardless of the modification of mean free path. Therefore, a decrease in channel length can increase the tensile CESL stress and further change the magnitude of the energy bandgap.