Chapter29MEMS-MechanicalEngineering.ppt

Chapters 28 and 29 April 10, 2006 Group 5 Michael Linley Matt Sallee Bryan Estvanko Patrick Pace Clean Rooms Typical integrated circuits are a few millimeters in length and transistor on the circuit can be only a few nanometers. Clean Room - a room where contaminants (dust, smoke, perfume, and bacteria) are reduced to a very low level by special procedures so that operations can be performed effectively. Clean Rooms There are many different level or classes of clean rooms. The system of classification refers to the number of .5 micrometers (10^-6) or larger particles in within a cubic foot of air. The controlled atmosphere in a clean room is done with ventilation which passes all the air through high-performance particulate air (HEPA) filters. Most clean rooms for microelectronics manufacturing are from class 10 to class 1. Clean Rooms Clean Rooms The greatest source of contaminants in clean rooms, comes from the people who work in them. Skin particles, hair, makeup, clothing and bacteria are given off by humans constantly, due to this fact special covering are required such as lab coats, gloves, hair nets and avoidance of perfume and makeup. Clean Rooms The more stringent clean rooms require people to wear bunny suits. Semiconductors and Silicon Semiconductors are the foundation for electronic devices because their properties can be control by adding impurity atoms. Silicon has become the industry standard in the fabrication of these devices because it’s the second most abundant atom and it can operate at higher temperatures than the alternative germanium. Crystal Growing and Wafer Preparation Single-crystal material is needed for semiconductor device production. Single-crystal silicon is usually obtained through the Czochralski or CZ process. Crystal Growing and Wafer Preparation A seed crystal is dipped into melted silicon, then is pulled out slowly while being rotated . Controlled amounts of impurities can be added to obtain a uniformly doped crystal