A method of manufacturing a semiconductor device includes providing a silicon substrate with multiple layers formed on a front side and a backside, wherein at least a dielectric layer is formed on the backside of the silicon substrate; defining isolation regions and active regions at the front side of the silicon substrate, wherein the active regions are separated by the isolation regions; treating the multiple layers formed at the front side and the backside of the silicon substrate, so as to remain the dielectric layer as an outermost layer exposed at the backside of the silicon substrate; and depositing a polysilicon layer on the isolation regions and the active regions at the front side of the silicon substrate.