Product Information SOI (Silicon-on-Insulator) is a “sandwich” structure wafer consisting of three layers: the top silicon layer, also known as the Top Si / Device Layer, is used to fabricate transistors; the middle layer is the Buried Oxide (BOX), which provides electrical isolation; and the bottom layer is the silicon support substrate (Handle/Substrate Wafer). Compared with conventional Bulk Si wafers, SOI wafers feature complete dielectric isolation, enabling lower