Due Sep. $17($Tuesday$)$

Problem $1($Lithography$)$

The linear expansion coefficient of a glass mask plate is $9\frac{{10}^{-6}}{}C$ and that of Silicon is $2\mathrm{.}3{10}^{-6}$

$1C.$ The maximum allowable error due to thermal run in$/$out is $+-0\mathrm{.}5m$ across a $100$ mm

diameter Si wafer. Calculate the required ambient temperature tolerance for:

$($a$)$ Contact printing $-$ assuming mask and wafer are at room temperature

$($b$)$ Projection printing $-$ the mask temperature is controlled to be fixed but the Si wafer will

follow the ambient temperature.

Problem $2($Lithography$)$

The mask set for a simple rectangular pn junction diode is shown. The diode is formed in a p$-$

type substrate. Please draw both top view and cross sectional view for the diode that result when

a worst$-$case alignment of $3m$ in both the $x-$ and $y-$direction on each mask level.

$($a$)$ if both the contact and metal levels are aligned to the diffusion level

$($b$)$ if the contact level is aligned to the diffusion level and the metal level is aligned to the

contact level

Fig. Problem $2$

Fig. Problem $3$

Problem $3($Surface Micromachining$)$

Read over the mumps process $($chapter $1$ only$)$ in the internet $($Class#$3$ webpage link$)-$

$(1)$ please determine the figures $($Fig$.1\mathrm{.}1$ to Fig. $1\mathrm{.}16)$ where an optical mask has been used

for the process and what is the total number of masks?

$(2)$ draw the top view of the masks and indicate "bright" or "dark" for each mask to make an

electro$-$static wobble micromotor $($hand drawing is fine$)-$ the top view in Fig. Problem $3.$