MATE/EE 129 Midterm Examination Fall 2003 1. Surface Preparation Question • Explain surface affinity issues • List and explain the 3 major types of contamination • Discuss the potential impact of contamination of the wafer • List and discuss the FEOL cleaning process. i. SC-1, SC-2, BOE, Piranha ii. Be able to discuss what type of contaminate each clean removes 2. Oxidation • List and discuss the application of SiO2 • Describe the crystal structure of SiO2 • Compare the two types of SiO2 (single crystalline and amorphous) • Describe the thermal oxidation process a. Mass transport fluxes b. Differences between wet and dry oxidation c. Issues with the consumption of Si during oxidation • Apply the Deal Grove Model for thermal oxidation a. Discuss the limiting regimes for the Deal Grove Model b. Discuss the variables that effect growth rate 3. Diffusion. • Describe the mechanisms for solid state diffusion • Discuss the application(s) of diffusion related to integrated circuits • Discuss the types of dopants that are used in IC processes (include the characteristics of each type of dopant) • Identify each variable/term in Fick’s Law of diffusion • Describe the Pre-Dep process. Explain the purpose of the Pre-Dep • Describe the Drive-In process. Explain the purpose of the Drive-In. • Apply Fick’s Law of diffusion • Calculate the junction depth for Pre-Dep and Drive-In • Calculate the dose • Determine the concentration profile for Pre-Dep and Drive-In Page 1 of 3MATE/EE 129 Midterm Examination Fall 2003 List of Equations • ()τ+=+ t B A x ox2oxx • +=h1k1 2D sA • 1*2DC NB = • Bi2iA x x +=τ • ),( txCDJ ∇−= • xtxCDJx∂∂−=),( • 22xCDtC∂∂=∂∂ • ()=DtxerfcCtxCs2, • πDtCQso4= • ()=−ssubjCCerfcDtx12 • ()−=DtxDtQtxCo4exp,2π • ()DtQtCosπ= • =DtCQDtxsubojπln4 Page 2 of 3MATE/EE 129 Midterm Examination Fall 2003 Page 3 of