Process for diffusing boron into semiconductor wafers
AssigneeShin-Etsu Handotai Co., Ltd.
InventorsYoshiyuki Mori, Yukiharu Kitazawa, Masahide Kojima, Tomoyuki Sakai, Eiichi Nishijo, Nobuhiro Tsuda, Tadayuki Ebe
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Abstract
In a boron diffusion process, a multiplicity of semiconductor wafers and pyrolytic boron nitride dopant disks are placed in a diffusion tube kept in an inert atmosphere at a high temperature, and boron diffusion is performed with hydrogen injection, the initial concentration of hydrogen in the diffusion tube being a very low range of 0.05% by volume at maximum. The result is that it is possible to improve dispersion of sheet resistivity (.rho.s) of the silicon wafer surface remarkably and to suppress occurrence of lattice defects.
Claims11
In the process of diffusing boron into a semiconductor wafer which comprises:
- at least partially oxidizing a disk of pyrolytic boron nitride to a disk comprising boron oxide;
- assembling such wafer and said oxidized disk adjacent thereto;
- subjecting said wafer and disk to conditions, including high temperature and an inert atmosphere comprising hydrogen, which are conducive to the diffusion of boron from said disk into said wafer;
- thereby diffusing said boron into said wafer;
- the improvement which comprises limiting the initial proportion of hydrogen in said inert atmosphere to the range of 0.01-0.05% by volume, whereby reducing the number of lattice defects in said boron diffused wafer, as compared to the number of lattice defects which would exist in substantially the same wafer having boron diffused thereinto from substantially the same source under substantially the same conditions, except at a higher effective concentration of hydrogen than that present in said inert atmosphere.
Dependencies are inferred from the claim text.