Method of forming semiconductor device with a buried junction

Abstract

A method is disclosed for forming a first region with conductivity of a first type and second, buried region with conductivity of a second type which forms a junction with the first region. By first and second doping steps, impurities of a first and a second type are successively introduced into a silicon chip. A high-temperature treatment causes the impurities thus introduced to diffuse and form said first and second regions. In order to provide a buried region whose concentration and/or depth are little dependent on process parameters, the second doping step comprises a first sub-step of low dosage and high energy implantation, and a second sub-step of low dosage and high energy implantation. The dosages and energies are such that they will not compensate or reverse the type of conductivity of the first region, and such that the concentration in the second region will be substantially due to the second implantation step only.