9 questions
Q.1. (a) What is Gettering? Why surface cleaning is required before processing of Si wafer? Write the methods RCA and Piranha for wet processing terminology. [10]
(b) What are crystal defects? Explain various types of crystal defects in brief. [6]
Q.1. (a) What do you understand by resistivity? Explain a technique for irregular size sample resistivity measurement. [8]
(b) A thin film window de-icer resistor meanders over a length of 5m and is 1mm wide. It is designed to deliver a total power of 5W, employing a 12V power source. For a 5000A thick film, what sheet resistance is required? [8]
Q.2. (a) State the difference between diffusion and ion implantation. [6]
(b) What is the difference between dry and wet oxidation? Explain a process for SiO2 synthesis. [10]
Q.2. (a) Explain Fick's diffusion equation in one dimension. [8]
(b) What are the factors which affect the diffusion profile? Explain one of the diffusion profile measurement technique also. [8]
Q.3. (a) Explain the following with respect to epitaxy - (i) Homoepitaxy (ii) Hetroepitaxy (iii) Defects in epitaxial growth (iv) Auto doping. [10]
(b) Explain gas transport mechanism in CVD briefly. [6]
Q.3. (a) Discuss about the hot wall reactor and cold wall reactor of LPCVD system. [6]
(b) What are the differences between growth mechanism of MOCVD and MBE? [4]
(c) Explain a technique for synthesis of GaAs homoepitaxy layer. [6]
Q.4. Define following terms with respect to optical lithography - (a) Resolution (b) DOF (c) Modulation Transfer Function (MTF) (d) Optical proximity compensation. [16]
Q.4. (a) What is photoresist? Explain the difference between negative and positive photoresist with suitable example. [8]
(b) What are the applications of dry etching? [4]
(c) Distinguish between proximity, contact and projection printing. [4]
Q.5. Write short note on following - (Any two) (a) SOI (b) CMOS IC technology (c) Latch up problem (d) Fault diagnosis and characterization technique. [16]