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Integrated Circuit Devices

This resource delves into the evolution of MOSFET technology, beginning with the invention of the first transistor and culminating in the advanced gate oxides manufactured today. The basics of MOSFET structure, including n-MOSFET and p-MOSFET operations, threshold voltage concepts, and key characteristics such as ID-VDS relationships are explored. Readers will gain insights into complementary MOSFETs (CMOS), current saturation, and the impact of oxide thickness on performance, providing a comprehensive overview of MOSFET functionality and its significance in modern electronic devices.

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Integrated Circuit Devices

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  1. Integrated Circuit Devices Professor Ali Javey Summer 2009 MOSFETs Reading: Chapters 17 & 18

  2. The First Transistor

  3. 1956 Physics Nobel Prize

  4. Invention of the Field-Effect Transistor In 1935, a British patent was issued to Oskar Heil. A working MOSFET was not demonstrated until 1955.

  5. Today’s MOSFET Technology Gate oxides as thin as 1.2 nm can be manufactured reproducibly. Large tunneling current through the oxide limits oxide-thickness reduction.

  6. Introduction to the MOSFET Basic MOSFET structure and IV characteristics

  7. Introduction to the MOSFET Two ways of representing a MOSFET:

  8. Complementary MOSFETs (CMOS) NFET PFET When Vg = Vdd , the NFET is on and the PFET is off. When Vg = 0, the PFET is on and the NFET is off.

  9. Qualitative discussion: n-MOSFET VG > VT ; VDS 0 ID increases with VDS VG > VT; VDS small, > 0 ID increases with VDS , but rate of increase decreases. VG > VT; VDS pinch-off ID reaches a saturation value, ID,sat The VDS value is called VDS,sat VG > VT; VDS > VDS,sat ID does not increase further, saturation region.

  10. Threshold voltage for NMOS and PMOS When VG = VT, s = 2 F; we get expression for VT. Ideal n-channel (p-silicon) device both terms positive Ideal p-channel (n-silicon) device both terms negative Si / ox = = 11.9 / 3.9  3 F > 0 means p-type F < 0 means n-type

  11. I ds V = 10mV ds V gs V t How to Measure the VT of a MOSFET Vt is measured by extrapolating the Ids versus Vgs (at low Vds) curve to Ids = 0.

  12. Quantitative ID-VDS Relationships “Square Law” ; ID will increase as VDS is increased, but when VG – VDS = VT, pinch-off occurs, and current saturates when VDS is increased further. This value of VDS is called VDS,sat. i.e., VDS,sat = VG – VT and the current when VDS= VDS,sat is called IDS,sat. ; Here, Cox is the oxide capacitance per unit area, Cox = ox / xox

  13. ID-VDS characteristics expected from a long channel (L << L) MOSFET (n-channel), for various values of VG

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