| 摘要 |
PURPOSE:To enable to form a guard ring for an extremely effective semiconductor photo detector by a method wherein an insulation film is formed on the surface of an N type semiconductor, and the thermal diffusion of a P type impurity is performed into the N type semiconductor via this insulation film. CONSTITUTION:An SiO2 film is deposited on the surface of the N type InP substrate 11 to the thickness of 500-1,000Angstrom as the insulation film by using RF sputtering method and sealed in vacuum into a quartz ampul, thermal diffusion is performed for a fixed time at a fixed temperature by using Cd3P2 sealed at the same time, thus a P type impurity diffused layer 13 is formed, and the SiO2 film 12 is removed; thereafter a P electrode 14 and an N electrode 15 are formed, then etching is performed to a mesa structure by using photo resist, resulting in the completion of the element. The hole impurity concentration at this case has the concentration gradient very gentle in the level of 10<15>-10<16> cm<-3>, and further the hole impurity concentration in the InP diffused surface is also low. The surface concentration and the concentration gradient can be controlled by varying film thickness and diffusion temperature, and accordingly an inclination junction type guard ring of excellent characteristics can be formed. |
