Apply the maximum reverse bias to both diffusions and find the minimum distance that these diffusions can be spaced. Hint: use eq$.15\mathrm{.}1$ for a one$-$sided step junction and assume that Vbi $=0\mathrm{.}7$ V $[10$ points$]$

$($b$)$ If the field oxide is $600$ nm thick and the oxide is ideal $($i$.$e$.$ no work function difference, no oxide charges, no interface states$)$ what is the threshold voltage of the parasitic inversion layer formed under the field oxide?$-$ see Section $15\mathrm{.}1[10$ points$]$