摘要 |
PURPOSE:To reduce costs, by a method wherein etching is previously applied to insular regions for low dielectric strength and high hFE element and then insular crystal for low dielectric strength element is simultaneously provided with isolation grooves are etched to form insular regions for high dielectric strength element. CONSTITUTION:An SiO2 2 on an Si substrate 1 is opened 5, and etching is applied by the depth (a). Furthermore, opening is provided in new SiO2 6, and patterning is simultaneously applied to isolation regions, 7, 8 for high dielectric strength element, and low dielectric strength and high hFE element, and isolation grooves 9 with a depth of (b) and those 10 with a depth (c) are formed by anisotropic etching to constitute b=c+a, and groove width b'=2<1/2>b, c'=2<1/2>c are formed at a substrate surface <100>. Next, the SiO2 6 is removed to pile up an N<+> layer 11, SiO2 12, poly Si 13, and high dielectric strength element islands 14, and low-dielectric strength and high hFE element islands 15 are simultaneously formed by grinding the substrate 1 as far as line beta-beta'. By said constitution, a dielectric isolation substrate having different thick single cyrstal regions can be obtained by just adding an etching process and an IC incorporating in built-in manner elements having various characteristics can easily be obtained. |