VLSI_Class_Notes_9_2010 - EEL 5322 W.R.Eisenstadt-1 VLSI...

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EEL 5322 W.R.Eisenstadt - 1 - VLSI Class Fall 2010, Notes 9 Reading 6.1, 6.2 and 6.3 Jaeger Homework #8 Problems 6.3 and 6.7 from Jaeger: Due Sept 20, 2010. Lecture discussion : Deposition techniques a way of coating a wafer with different conductive and insulating materials. CVD: Chemical Vapor Deposition PVD: Physical Vapor Deposition Spin on Techniques: a solution of material you want to deposit on the wafer surface is dropped in the center of the wafer and spun with centrifugal force. The material uniformly distributes over the wafer. Thicknesses are controlled by the centrifugal force during the spinning. Example: Photo-resists use spin on techniques in patterning wafers during photolithography. CVD: Chemical Vapor Deposition is performed in a system similar to a diffusion system. However, the reactor needs a high vacuum and good pumping system. Deposition pressure is often lower than atmospheric pressure, the gasses are typically toxic, explosive, and flammable. Good CVD researchers are also good vacuum system plumbers. Wafer surface reactions: Reactant gasses are introduced in a deposition system and the gasses react at the surface of the heated wafer. The wafer temperature is held sufficiently high to form deposited thin films. This temperature is often way below the temperatures necessary to perform diffusion or oxidation. The wafer provides the energy required for reaction or to catalyze the reaction.
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VLSI_Class_Notes_9_2010 - EEL 5322 W.R.Eisenstadt-1 VLSI...

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