HW#2-F2023

1 EECS 414 Introduction to MEMS Fall 2023 Reading Assignments • Class Handouts and Notes, “Review of Standard Microfabrication Technologies”, “Introduction to Semiconductors” Homework #2 Total: 140 Points Handed Out: Thursday Sept. 7, 2023 Due: Thursday Sept. 14, 2023 @ 9 pm 1. Thermal and e-beam evaporation techniques have been used to deposit thin films of different materials. However, e-beam is more commonly used. Why? Provide short answer. 5 points 2. Assume a transistor with its associated interconnect wires occupies an area the size of a small square that is 0.5µm on a side. Approximately how many of these transistors can be fabrictaed on an 8” diameter silicon wafer? 5 points . 3. It has been said that silicon dioxide cannot be grown to a thickness much larger than about 1- 2µm. Briefly explain why? 5 points 4. Briefly explain what is photoresist, how it can be deposited onto a silicon wafer, what is the typical thickness when deposited, and how it can be patterned after deposition? 10 points 5. Evaporation is used to deposit a variety of materials. This process is typically performed under low-pressure, or vacuum conditions. Briefly explain why? 5 points 6. Name two advantages of sputtering over e-beam evaporation? 5 points 7. Photolithography forms the foundation for IC manufacturing. Name three reasons why? 5 points 8. Introducing impurities into silicon can be done using a number of different techniques. Circle any of the following process steps that would be required in any of these techniques. Please circle all the answers that you think are correct: 5 points a) Ion implantation b) High temperature annealing c) LPCVD deposition d) Thermal evaporation e) Pre-deposition f) All of the above

2 9. Thin films can be formed on top of wafers using a number of techniques. Which one of the techniques listed below requires a deposition temperature for the device wafer of more than 200°C (circle all that apply): 5 points a) PECVD b) Ion Beam Deposition c) Impurity Diffusion d) LPCVD e) Thermal Evaporation f) Sputtering 10. Which of the following materials are electrically insulating (circle all that apply): 5 points a) Doped polysilicon b) Sputtered aluminum c) LPCVD silicon oxide d) Doped silicon nitride e) Undoped silicon 11. Aluminum can be easily deposited using which of the following techniques, (circle all that apply): 5 points a) Thermal evaporation b) E-beam evaporation c) Sputtering d) LPCVD e) PECVD f) Ion beam deposition 12. The cross section of a device designed for fabrication using standard semiconductor techniques is shown below. The different layers are labeled. Can this device be fabricated with the layers as shown? If not, specify all the problems and explain why these are problems? 20 points Si PECVD Oxide Photoresist Polysilicon Thermal Oxide Nitride Aluminum