rapid growth. ii) Find the time required to perform the oxidation, taking rapid growth into account. Do not use oxide growth curves. b) A <100> silicon wafer is oxidised using the following sequence i) 40 mins @ 1000°C in dry O₂. ii) 60 mins @ 1000°C in steam. iii) Etch 0.3 microns of oxide. iv) 20 mins @ 1100°C in dry O₂. Use growth curves to calculate the oxide thickness after each step. Nitride- Silicon Wafer Oxidation: Pad Oxide Oxide Nitride removal: "Bird's beak" [10 1/3 marks] [10 marks] Figure 1. LOCOS process c) The diagram above, Figure 1, shows a fully recessed LOCOS (Local Oxidation of Silicon) process. Explain, with reference to the diagram, how the process is used to produce areas of oxide on a wafer without a subsequent lithography and etch step. [5 marks] d) Discuss five of the features of SiO₂ which account for its widespread use in microelectronics. [5 marks]/n
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