EEL%205225%20F10%20Exam1%20Solutions - EEL5225 Principles...

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Page 1 of 8 EEL5225 Principles of MEMS Transducers Exam 1 Fall 2010 Semester Monday, 10/11 Name: _____________________________ Honor Code: We, the members of the University of Florida community, pledge to hold ourselves and our peers to the highest standards of honesty and integrity. __________________________ Signature Part I – Short Answer 50 pts. 10 questions Part II – Process Flow 50 pts. 1 multi-part question Total : 100 pts. Instructions: Sign the Honor Code statement above. Be sure you have all 8 pages before starting the exam. Read and follow the directions for each section carefully. Use only the paper provided in the exam. Write on the backside of the paper if necessary. Only one 3” x 5” index card with notes and a calculator is permitted during the exam.
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Page 2 of 8 Part I – Short Answer (50 points total, 5 points per question) Answer each question briefly . Sketches can be used where appropriate. 1. List two material properties of silicon and explain how each are advantageous for use in MEMS microsystems. High modulus / high yield strength / low density – excellent mechanical properties Low TCE – fairly stable with temperature High piezoresistivity – can make strain-based sensors Semiconductor nature – doping can be used to affect conductivity High thermal conductivity – can conduct large heat flows 2. Many interesting MEMS technologies aren’t commercially viable because of cost. List two reasons why costs of MEMS are often higher. Not big enough market, so not many devices needed, so lose “economies of scale” Custom process flows Custom or complex packaging requirements Testing costs can be high 3. Consider a crystalline material with a cubic unit cell of cell size a . The lattice for the (100) plane is shown. Draw and label the lattice (i.e. atomic arrangement) for the (110) plane. 4. Regarding a chemical process, what is meant by the “rate limiting step”? Provide a specific example. The rate limiting step refers to the slowest “link in the chain” of a complex physical process. For example, in etching Si with HNA etch, if an excess of HF is used, the rate limiting step is the nitric acid oxidation of the silicon.
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EEL%205225%20F10%20Exam1%20Solutions - EEL5225 Principles...

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