Page 36 - Sami Franssila Introduction to Microfabrication

Introduction 15

4. Silicon is etched in plasma according to reaction Comments, hints and answers to selected problems are
Si (s) + 2Cl 2 (g) → SiCl 4 (g). What is the theoretical presented in appendix A.
maximum etch rate of a 200 mm diameter silicon
wafers when chlorine flow is 100 sccm (standard
cubic centimetres per minute)? REFERENCES AND RELATED READINGS
5. Accelerated tests for chips are run at elevated Blomberg, M. et al: Electrically tunable micromachined Fabry-
temperatures in order to find out failures faster. Perot interferometer in gas analysis, Physica Scripta, T69
Acceleration factor temperature (AFT) is given by (1997), 119.
Arrhenius formula AFT = exp(E a /(1/kT operation − Bouwstra, S. et al: Resonating microbridge mass flow sensor,
1/kT test ). Use activation energy, 0.7 eV. What accel- Sensors Actuators, A21–A23 (1990), 332.
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eration factor does 175 C present? Temperatures Green, A.M.: Silicon Solar Cells, University of New South
are junction temperatures, and typical values are Wales, Sydney, 1995.
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55 C for consumer and 85 C for industrial elec- Lin, C.-C. et al: Fabrication and characterization of a micro
turbine/bearing rig, Proc. MEMS ’99 (1999), p. 529.
tronics. Whyte, W.: (ed.): Cleanroom Design, 2 nd ed., Wiley, 1999.
6. Aluminium wires do not tolerate current densities Yilmaz, H. et al: 2.5 million cell/in , low voltage DMOS FET
2
2
higher than 1 MA/cm . What are maximum currents technology, Proc. IEEE APEC (1991), p. 513.
that can run in micrometre aluminium wiring? Solid State Technology Magazine: http://sst.pennwellnet.com/
7. CMOS linewidths have been scaled down steadily by home.cfm
30% every three years. In the year 2000, linewidths Semiconductor International Magazine:
were in the range of 0.18 µm. When will linewidth http://www.reed-electronics.com/semiconductor/
equal atomic dimensions? Materials database at http://www.memsnet.org/material/