Advanced transistors (FinFET and GAA)
Which correctly describes the "scale length (natural length) λ" used to estimate the severity of short-channel effects?
- AThe length of the gate wiring
- BA measure of how far the drain potential's influence extends into the channel; if the gate length is much longer than λ, short-channel effects are small
- CExactly the same value as the fin height
Show answer and explanation
Answer: B. A measure of how far the drain potential's influence extends into the channel; if the gate length is much longer than λ, short-channel effects are small
The scale length λ is a measure of the distance over which the drain potential's influence decays in the channel, determined by insulator thickness, channel thickness, permittivities and gate structure. If the gate length is several times λ or more, short-channel effects stay small. Structures where the gate surrounds more surfaces have smaller λ, allowing scaling to shorter gate lengths.
- A. It does not represent a wiring length.
- B. Correct. It measures how far the drain's influence reaches.
- C. It is a different quantity from the fin height.