| 摘要 |
PROBLEM TO BE SOLVED: To heat-treat a boron-added silicon wafer without causing any slipping dislocation by empirically finding in advance the dislocation anchoring force caused by boron and easily and surely grasping the optimum temperature dropping/raising rate without conducting any experimental heat treatment by calculating the rate from relational expressions. SOLUTION: The temperature differenceΔT which occurs in the surface of a semiconductor wafer when the wafer is heat-treated is expressed by formula I, where, R,ρ, and d respectively represent the temperature raising/dropping rate, specific heat, wafer diameter and T,σ, w, and (t) respectively represent the temperature, Stefan- Boltzmann constant, wafer interval, and wafer thickness. The decompositional shearing stress S of thermal stress when the temperature difference T occurs in the surface of the wafer is expressed by formula II and exceeds the anchoring forceτcaused by boron. From formulae II and III, formula IV about the temperature raising/dropping speed is derived. In formula IV,α, E, (r), and respectively represent the coefficient of linear expansion, Young's modulus, wafer radius, and dislocation anchoring force caused by boron. When formula V is derived by substituting formulae I and II for formulae IV and theτis empirically found, the critical temperature raising/dropping speed can be derived from formula III.
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