Lecture 8 - MIT

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Spring 2007Lecture 81Lecture 8MOSFET(I)MOSFET I-V : cross -section, layout, characteristicsReading Assignment:Howe and Sodini, Chapter 4, Sections :Quiz#1, March 14, 7:30-9:30PM, Walker Memorial; covers Lectures #1-9; open book; must have Spring 2007Lecture 821. MOSFET: layout, cross -section, symbols Inversion layer under gate(depending on gate voltage) Heavily doped regions reach underneath gate inversion layer to electrically connect sourceand drain 4-terminal device: bodyvoltage importantKey elements: deposited oxidefieldoxiden+ drain diffusiondraininterconnect p+[ p-type ]bulkinterconnectLdiffgate contact(a) Adraincontactsbulkcontactn+ polysilicon gate active area (thinoxide area)polysilicon gatecontactmetalinterconnectn+ source diffusionedge ofactive area sourceinterconnect(b)Ln+ polysilicon gate gate oxidegateinterconnectsource Spring 2007Lecture 83Circuit symbolsTwo complementary devices.

1. MOSFET: layout, cross-section, symbols • Inversion layer under gate (depending on gate voltage) • Heavily doped regions reach underneath gate ⇒ – inversion layer to electrically connect source and drain • 4-terminal device: – body voltage important Key elements: deposited oxide field oxide n+ drain diffusion drain interconnect p+ ...

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