Patent ID: 8110449

Claim:
A method of manufacturing a semiconductor device comprising: a dielectric layer formed in a surface of a first semiconductor substrate; a first semiconductor layer formed in a surface of said dielectric layer; a semiconductor element formed in a surface of said first semiconductor layer; and a ring-shaped trench isolation region formed surrounding said semiconductor element, said dielectric layer including a first buried oxide film formed in the surface of said first semiconductor substrate, a shield layer formed below said first buried oxide film and opposite said semiconductor element and receiving a predetermined potential, a ring-shaped second buried oxide film formed below said first buried oxide film and surrounding said shield layer, and a third buried oxide film formed below said shield layer and said second buried oxide film; wherein said trench isolation region includes: ring-shaped first to third trenches successively formed surrounding said semiconductor element; said first and second trenches are provided above said shield layer and said third trench is provided above said second buried oxide film, and each of said first and third trenches penetrates said first semiconductor layer and reaches said first buried oxide film, said second trench penetrates said first semiconductor layer and said first buried oxide film and reaches said shield layer; said dielectric layer further includes one or not less than two fourth buried oxide films formed on said first buried oxide film; and each fourth buried oxide film is formed in a shape of a ring surrounding a central line of said semiconductor device, the method comprising the steps of: forming said dielectric layer on a surface of said first semiconductor substrate; forming a light shielding mask having a pore shaped corresponding to said fourth buried oxide film on a surface of a second semiconductor substrate, forming said fourth buried oxide film by irradiating said second semiconductor substrate with an excitation light through the pore of said mask while flowing an anodization current from a front side to a rear side of said second semiconductor substrate; and affixing surfaces of said first and second semiconductor substrates to use said second semiconductor substrate as said first semiconductor layer.