a question about vgs breakdown

[xerxer]

vgs breakdown voltage relates to tox,pray Gray 's book saysvgs breakdown voltage is 6~7v when tox thick is 10nm .IN current process tox is about 5nm .which is The vgs breakdown voltage lower or higer than 6~7v ???

 

[eecs4ever]

The break down voltage is lower.

The reason that oxide breaks is because the eletric field inside the oxide is too high. E = V/ tox

so if the thickness of the oxide (tox) becomes smaller, then the required voltage to reach a given eletric field strength will also be smaller.

 

[gevy]

Breakdown voltage equals 0.6...0.7 V / 1 nm of tox.
So breakdown voltage equals from 3 V to 3.5 V for tox = 5 nm