MANUFACTURE OF PHOTODETECTOR

PURPOSE:To enable annealing without bringing about deterioration of properties thereby reducing dark currents by forming a photoabsorptive layer and a one conductivity type doubling layer in order on a semiconductor substrate, and forming an opposite conductivity type region and a reflection preventive film, and then forming a lower electrode layer in the opening for electrode formation where this is removed selectively, and applying heat treatment to the reflection preventive film so as to form an upper electrode layer above the lower electrode layer. CONSTITUTION:First, a photoabsorptive layer 10 and a doubling layer 11 are formed in order on an N-type of INP substrate 1, and then an SiN film 3a is formed. Next, an opening 4 is provided at a specified position, and a photoreceptive layer 2 is formed, and a reflection preventive film 36 is formed at the whole exposed face. Next, photoresist 6 is applied, and a hole opened at a specified position, and the reflection preventive film 3b is partially removed by etching so as to form an opening for electrode. Next, a Ti layer is formed at the whole face, and the photoresist 6 is removed by solvent, whereby it is made into the shape that the Ti layer 5 is buried in the opening 9. After this, annealing is done to the reflection preventive film 3b, and Ti, Pt, and Au are deposited in order to form an electrode 7, and further to lower the contact resistance, annealing is done.