Please answer these simple five questions on fabrication engineering at the micro and nanoscale.
1- Air pressure decreases as altitude increases. At 18,000 ft above mean sea level, the atmospheric pressure is about half of what it is at sea level (i.e.,760 torr). The temperature also decreases by about 70 C. Does this change the speed distribution of the air molecules? Does it change the mean free path? How much does each change?
2- Why are entrainment pumps generally not used in processing with toxic gases?
3- It is possible to determine the chemical composition of a plasma by measuring the optical emission spectrum (i.e., optical intensity as a function of wavelength). Explain why.
4- Referring to High Density Plasma, if a process relies on ion bombardment of the wafers, would you want to put the wafers on the electrode connected to the chamber walls or on the electrode that is isolated from the chamber walls?
5- For a certain process, the maximum allowable pressure is 0.20 torr. If a D65 rotary vane pump is used and conductance losses in the vacuum system can be ignored; what is the maximum permissible inlet flow in standard cubic centimeters per minute?