This is a phase test I want from you to solve it in details please
Q1. (a) Explain why there is a trade-off between minimum resolution and depth of focus when using shorter wavelength photons for projection lithography
(b) A mask set for a simple rectangular pn junction diode is shown below. The diode is formed on a p-type substrate. What type of photoresist must be used with each of the three mask levels used to fabricate the diode. Assume the areas shown on the mask are dark.
Q2 A <100> silicon wafer has 400 nm of oxide on its surface. How long will it take to grow an additional 1pm of oxide in wet oxygen at 1100 °C? Show results from the graphical Deal-Grove methods.
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Wet 02 (Xi = Onm)
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Dry )2 (Xi, = 25nm)
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Do
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EAG
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Do
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EA
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<100>
Silicon
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Linear
(B/A)
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9.70 x 107 um/hr
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2.05 eV
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3.71 x 106 um/hr
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2.00 eV
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Parabolic
(B)
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386 um2/hr
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0.78 eV
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772 um2/hr
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1.23eV
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<111>
Silicon
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Linear
(B/A)
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1.63 x 108 um/hr
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2.05 eV
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6.23 x 106 um/hr
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2.00 eV
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Parabolic
(B)
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386 um2/hr
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0.78 eV
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772um2/hr
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1.23eV
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Q3 (a) Why is sputtering preferable to evaporation for the deposition of compound thin films?
(b) You are asked to deposit a Ti layer by sputtering onto a glass substrate prior to evaporation of Au. If Ar flow rates are kept constant , which RF nower would result in the least dense film: 5W or 500W? Explain your reasoning.
Q4 Describe how the boundary layer forms in a CVD reactor, its effect and how this can be compensated for.
Q5 (a) Draw schematics showing the step coverage of a thin film deposited over the structure shown in the figure below using (i) evaporation and (ii) CVD.
(b) List 2 advantages and 2 disadvantages of chemical vapour deposition over physical vapour deposition