1 Analysis of Strained-Si Device including Quantum Effect Fujitsu Laboratories Ltd. Ryo Tanabe Takahiro Yamasaki Yoshio Ashizawa Hideki Oka IWCE-10 October 24-27, 2004, Indiana USA

2 Si Substrate SiGe buffer layer Gate Source Drain Strained Si tensile strain x y z compressive strain Background Strained Si is studied and used aggressively as one of “Technology Booster” Is the merit of strain kept with scaling ? ・ Quantum Effect ・ Ballistic Transport The necessity of Strained-Si Monte Carlo simulation including quantum effect.

3 The Implementation of Strained Band kyky kxkx kzkz We linked the first principle band calculation program to the FUJITSU ensemble full band Monte Carlo simulator FALCON directly Full band Monte Carlo simulator :FALCON The first principle band calculation program :PHASE Full band structure of Strained Si Monte Carlo Analysis Band structure of conduction band near X point with 50% expansion of k y, k z direction k Energy (eV) k y,k z direction k x direction

4 Evaluated Structure ・ We calculated below Lg=50nm. ・ We used Double Gate structure. Lg=40nm T soi =10nm T ox =1nm Phonon, Impurity and Surface Roughness scattering

5 I d -V d =0.05V ・ V d =0.05V ・ Drain current is saturated at Ge=20%

6 I d -V d =0.8V ・ Vd=0.8V ・ Drain current is not saturated.

7 Valley Distribution 2fold 4fold ① 4fold ②

8 The Introduction of Quantum Effect ・・・ (1) ・・・ (2) t < t max Scattering V(r) V * (r) E(r ) Eq. (1) Eq. (2) V(r) ： Potential V*(r) ： Quantum Corrected Potential E(r) ： Electric Field ・ We implemented quantum effect by Bohm Potential method

9 The Comparison with Schr ö dinger-Poisson Gate Oxide L=40nm V g =0.8V, V d =0V

10 I d -V g =0.8V

11 The Comparison of Scattering Including quantum effect Strain Effect Quantum Effect

12 Ballistic Rate and I on Improvement ・ Ballistic particles exceed 50% at L=10nm. ・ Both ballistic rate and I on improvement with quantum effect are larger than with classical.

13 The Comparison of Electron Velocity Source region x=0.3 x=0 L=40nm L=20nm L=10nm L=5nm V g =V d =0.8 V 0.0E E E E Position along the channel (nm) Electron Velocity (cm/sec)

14 Summary We linked the first principle band calculation program to full-band MC simulator directly. We implemented Bohm Potential Quantum correction model and analyzed Strained-Si device including quantum effect. As gate length is scaled down, I on improvement by strain effect will decrease, but In the regime that ballistic transport is dominant (about below 10nm), strain effect will increase again due to increasing injection velocity from source region.