Reading: Finish Chapter 19.2 Lecture #43 OUTLINE Short-channel MOSFET (reprise) SOI technology Reading: Finish Chapter 19.2 EE130 Lecture 43, Slide 1

OUTPUT CHARACTERISTICS TRANSFER CHARACTERISTICS Short-Channel MOSFET OUTPUT CHARACTERISTICS TRANSFER CHARACTERISTICS IDS does not saturate with increasing VDS due to DIBL, and also channel-length modulation for VDS>VGS-VT EE130 Lecture 43, Slide 2

Silicon on Insulator (SOI) Technology TSOI Transistors are fabricated in a thin single-crystal Si layer on top of an electrically insulating layer of SiO2 Simpler device isolation  savings in circuit layout area Low junction capacitances  faster circuit operation Better soft-error immunity No body effect Higher cost EE130 Lecture 43, Slide 3

Partially Depleted SOI (PD-SOI) Floating body effect (history dependent): When a PD-SOI NMOSFET is in the ON state, at moderate-to-high VDS, holes are generated via impact ionization near the drain Holes are swept into the neutral body, collecting at the source junction The body-source pn junction is forward biased  VT is lowered  IDsat increases  “kink” in output ID vs. VDS curve EE130 Lecture 43, Slide 4

Fully Depleted SOI (FD-SOI) No floating body effect! VT is sensitive to SOI film thickness Poorer control of short-channel effects due to fringing electric field from drain Elevated S/D contact structure needed to reduce RS, RD Silicon Substrate Source Drain SiO2 SOI Gate EE130 Lecture 43, Slide 5