13-Brandon Dyer-Silicon on Insulator

13-Brandon Dyer-Silicon on Insulator - Silicon on Insulator...

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Unformatted text preview: Silicon on Insulator Silicon Brandon Dyer ECE3080 Background Background Research started in 60s for NASA First put into commercial use by IBM Now used by IBM, AMD, Freescale and Chartered Semiconductor now use Intel still insistent on use of bulk silicon Advantages Advantages Resistant to punch through Lower junction capacitances Better low voltage operation Electrical Isolation Functions better in Extreme Conditions Disadvantages Disadvantages COST!!! 10 – 15% more expensive per wafer Self heating – insulating layer worsens heat dissapation Yield issues – added complexity of Wafer Manufacturing Wafer SIMOX – Seperation by Implantation of Oxygen Eltran – uses porous silicon and water Smart Cut – Ion implantation to determine controlled breaks Types of SOI Types Partially Depleted Fully Depleted Si film thickness Si film thickness greater than twice smaller than depletion depletion width width Floating body issues No floating body issues Easier to manufacture Up to 9 modes of Much like bulk operation transistors Junction Capacitances Junction Source/drain-substrate capacitance lowered Higher switching speed Less dynamic power dissapation P = .5*f*C*V^2 Floating Body Effects Floating Present mostly in PDSOI Impact Ionization creates holes Holes flow to undepleted region Kink Effect – Charge lower VT creating creating kinks in I-V curve Electrical Isolation Electrical Presence of insulating layer helps to reduce latchup - Latchup: presence of PNPN structure can cause current to flow until power off Allows for tighter packing of transistors Reduces soft errors due to cross talk between transistors Soft Errors Soft Changing of signal or memory state based on out side influences Most often caused by radiation Insulating layer prevents alpha particles from entering channel Other Applications Other ZRAM - Uses the Floating Body Effect to store data Mixed Mode circuits - SOI advantages allow better integration of RF, analog, and digital circuitry High Temperature Circuits – absence of wells allows better high temp behavior Sources Sources Silicon-On-Insulator Technology: Materials to VLSI, 3rd Edition by Jean-Pierre Colinge Fabrication of SOI and sSOI Wafers Using Ion Implantation by Devendra K. Sadana SOI Technology for the GHz Era by G.G. Shahidi ...
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