Diffusion of impurities to semiconductor substrate

Abstract

Abstract PURPOSE:To thermally diffuse impurities at a lower heat treatment temperature and in a short time by a method wherein a substance with a small thermal diffusion constant of the impurities is implanted deep into the bottom of an impurity region by a high-energy ion implantation method to form an impurity-diffusion stopper region. CONSTITUTION:A polysilicon electrode 3 is deposited on a gate insulating film 2 which is formed on a surface part of a semiconductor substrate 1. Then, phosphorus is implanted into the semiconductor substrate by an ion implantation method in a self- aligned manner with the polysilicon electrode (this becomes an n<-> region 5 later on). Then, ion seeds with a small thermal diffusion constant of the phosphorus are implanted into a deep part of the semiconductor substrate by a high-energy ion implantation method to form an impurity-diffusion stopper region 4. In addition, an annealing operation is executed in an atmosphere of nitrogen in order to anneal and diffuse a phosphorous implanted region to form the n<-> region 5. However, since the previously formed impurity-diffusion stopper region exists, an impurity thermal diffusion operation which is more anisotropic in a horizontal direction than in a depth direction can be executed; impurities can be thermally diffused at a lower heat treatment temperature and in a short time.

Inventors

• 👤 Akishige Nakanishi
• 👤 章滋 中西

Bibliographic Details