Method for manufacturing double-faced semiconductor circuits

A method for processing front and rear surfaces of a semiconductor substrate, including the steps of:

• depositing on the front surface a photosensitive material of negative type;
• annealing the substrate at a relatively high temperature;
• turning over the substrate;
• depositing the photosensitive material on the rear surface;
• drying said material so that it adheres to the substrate while keeping some flexibility;
• exposing, according to a desired pattern, regions of the photosensitive material on the rear surface;
• annealing to solidify the photosensitive material;
• turning over the substrate and realigning it using rear surface deformations defining the first pattern in the photosensitive material, obtained by the preceding steps of drying, rear surface exposing and annealing;
• exposing the front surface, according to a second etch pattern;
• simultaneously developing the two surfaces;
• and
• simultaneously processing on both surfaces the substrate portions exposed by the openings in the photosensitive material performed at the preceding step of simultaneously developing the two surfaces.