examkey - Fundamentals of Microfabrication Midterm Exam...

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Fundamentals of Microfabrication Name ______________________________ Midterm Exam March 14, 2010 Page 1 of 6 T F The most promising next generation lithography is X-ray lithography T F When mixing chemicals you should always add the water to the acid T F It is a common practice to have positive pressure in cleanroom and negative pressure inside fume hoods T F Aligned patterns cannot be placed on both sides of a wafer due to the difficulty associated with seeing through a wafer T F Silicon-based MEMS (NOT semi conductor) devices enjoys more market share than non-silicon based MEMS devices T F The wavelength of excitation light in photolithography is important in determining the resolution that can be achieved T F The term bulk micromachining is referred to subtractive processes for the substrate. T F The anisotropy of a dry etch increases with pressure in the chamber T F Using diffusion techniques, a layer of the diffused species is added on to the surface of the wafer T F Uniform flux of depositing species is important in APCVD process T F At high volumes (~10 million/month), very complex MEMS devices can sell for less than $2 each T F A class 1000 cleanroom is cleaner than a class 100 cleanroom T F The faster you spin a photoresist the thinner it becomes T F Positive photoresists polymerize in the presence of UV radiation T F Wet and dry oxidation techniques consume silicon at the surface to generate silicon dioxide T F Wet etching requires more complex equipment setup than dry etching T F Wet etching is more common in semi conductor industry T F Wet and dry etching rates usually increase with temperature T F Mean free path does not depend on the type of gases/molecules in the deposition chamber Which of the following is NOT a reason for using silicon as the primary material in micromachining? (a) Silicon is well characterized physically and electronically (b) Silicon is relatively inexpensive (c) Many techniques for processing silicon already exist (d) Silicon allows for the fabrication of hybrid structures (e) The equipment for processing silicon is inexpensive and easily obtained You are using KOH etching to define a 50 μ m square membrane in a 100 wafer. What should the dimensions on your mask be if you are using a 500 μ m thick wafer (Assume you are etching through the full 500 μ m). (a) 500 μ m (b) 832 μ m (c) 721 μ m (d) 708 μ m (e) 758 μ m (f) 354 μ m Which of the following is an advantage of wet etching methods when compared to dry etching? (a) No expensive equipment required (b) Eliminates handling of dangerous acids and solvents (c) Uses small amounts of chemicals (d) Isotropic or anisotropic etch profiles (e) Directional etching without using the crystal orientation of Si (f) Faithfully transfer lithographically defined photoresist patterns into underlying layers (g) No unintentional prolongation of etching (h) Ease of automation (e.g., cassette loading) Which of the following is NOT a general advantage of MEMS type devices? (a)
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This note was uploaded on 09/02/2010 for the course MEEN 5050 taught by Professor Himanshuj.sant during the Spring '10 term at Utah.

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examkey - Fundamentals of Microfabrication Midterm Exam...

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