1. Spring 2007EE130 Lecture 43, Slide 1 Lecture #43 OUTLINE Short-channel MOSFET (reprise) SOI technology Reading: Finish Chapter 19.2

2. Spring 2007EE130 Lecture 43, Slide 2 Short-Channel MOSFET I DS does not saturate with increasing V DS due to DIBL, and also channel-length modulation for V DS >V GS -V T OUTPUT CHARACTERISTICSTRANSFER CHARACTERISTICS

3. Spring 2007EE130 Lecture 43, Slide 3 Silicon on Insulator (SOI) Technology Transistors are fabricated in a thin single-crystal Si layer on top of an electrically insulating layer of SiO 2 Simpler device isolation  savings in circuit layout area Low junction capacitances  faster circuit operation Better soft-error immunity No body effect  Higher cost T SOI

4. Spring 2007EE130 Lecture 43, Slide 4 Partially Depleted SOI (PD-SOI) Floating body effect (history dependent): 1.When a PD-SOI NMOSFET is in the ON state, at moderate-to-high V DS, holes are generated via impact ionization near the drain 2.Holes are swept into the neutral body, collecting at the source junction 3.The body-source pn junction is forward biased 4.  V T is lowered  I Dsat increases  “kink” in output I D vs. V DS curve

5. Spring 2007EE130 Lecture 43, Slide 5 Fully Depleted SOI (FD-SOI) No floating body effect! V T 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 R S, R D Silicon Substrate SourceDrain SiO 2 SOI Gate