MatE/ EE 129: Homework Fall 2002 1Problem Solving Exercises 5 Due: 21 OCT 2002 1.) Calculate how much wider the S/D hole we etched are from the etch process we carried out. Use the traveler for etch rates and thicknesses. Use the class notes fro selectivities. Assume a 60o Side wall angle of the PR. If in doubt, assume realistic worst case values. 2.) Draw the 2 cross sections of the FAT team wafers based on: a. PR Removal b. Spin on of SOG. Drain SourceGateBodyABFigure 1: Top View of TransistorMatE/ EE 129: Homework Fall 2002 2 So the width of the hole would be 2*W or .73u. Not a big deal for our Process. P+ Si (100) 500 micronsP Si (100) 200 micronsSiO2 about .4 micronsSiO2 about .4 micronsSiO2 about .4 micronsSiO2 about .4 microns Figure 2: After PR Strip. Mean Thincknesshf.4352104−cm⋅:=Varation δ .1:=10%Mean Etch Rateνf.033360104−⋅cms:=Variation φf.1:=Maximum line width loss occurs where material is thicknest, etch rate is slowest, and thus the time is longest.Fraction of ever etch time∆ .2:=tchf1 δ+()⋅ 1 ∆+()⋅νf1 φf−( )⋅:= tc1.15 103× s=tc60s19.168=The mask has a horizontal and vertical etch rateνmlνf5.5:= νmvνf5.5:=Assume a 60 degree sidwall Total line width lossθ60180π⋅:= θ 1.047=W 2 νmv⋅ hf⋅ 1 δ+( )⋅1 ∆+( )νf1 φf−( )⋅⋅ cot θ( )νmlνmv+⋅:= W 3.661 105−×cm=MatE/ EE 129: Homework Fall 2002 3P+ Si (100) 500 micronsP Si (100) 200 micronsSiO2 about .4 micronsSiO2 about .4 micronsSiO2 about .4 micronsSiO2 about .4 micronsSOG Figure 3: After SOG (T=.3x10-4