| 摘要 |
PROBLEM TO BE SOLVED: To optimize the bulk micro defect(BMD) density and improve the mechanical strength by heat treating so as to meet specified equation of the treating temp. and time. SOLUTION: The low temp. heat treatment is applied at a lower temp. for a long time or at a higher temp., for a short time. At esp. regions A, a stable control is possible over a wide range of 1×10<10> BMDs/cm<3> or less. BMD formed at the heat treated regions A is smaller than that at regions B and has a low probability of the punch-out dislocation or laminate defect. BMD formed at the heat treated regions A can be stably controlled and the substrate mechanical strength hardly reduces with taking account of the sec. defects such as punchout dislocation. The region A is defined by log10 t>=(4.091×10<-7> )T<3> -(6,573×10<-4> ) T<2> +0.3478T-59.72. The bolded line A is derived by approximating with polynomials contour-lines at an experimentally obtd. BMD density of 1×10<10> defects/cm<3> .
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