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Unformatted text preview: N.CHEUNG, Sp 2009 EECS243: ADVANCED IC PROCESSING AND LAYOUT Homework Assignment #4 (Due March 4 Wed) Reading Assignment : Start with Plummer Chap 3.5.4 (point defects) Plummer Chap 7 Plummer Chap 4.23,4.33,4.43,4.53 (on Gettering) EE243 Lecture Notes Problem 1 Ratio of lateral junction depth / vertical junction depth Let C max be the maximum concentration of the diffusion profile and N B be the substrate concentration.With diffusion mask covering half of the Si wafer, the 2-dimensional drive-in doping concentration is given by: C(x,y,t) = Q 2 Dt e -x 2 /4Dt [ 1 +erf ( y 2 Dt ) ] (a) Derive an expression for the ratio of lateral junction depth y j over the vertical junction depth x j in terms of N B /C max . Diffusion Mask (0,0) y x-y j x j Substrate (N /cm3) B (b) Calculate and plot the ratio y j / x j (linear scale) versus N B /C max from 10-5 to 10-2 (log 10 scale) (Hint: You can find the erf function properties in the appendix page of this HW) Problem 2 Oxidation enhanced diffusion The following simulation result is taken from your textbook (PDG) to explain OED for Boron and ORD for Sb. (i) What is the physical origin that...
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- Spring '03