| 摘要 |
<p>PURPOSE:To obtain a high performance P-I-N diode with small frequency dispersion with a high yield by a method wherein one conductivity type impurity atoms are diffused into one of trenches formed in specific Si by anisotropic chemical etching and the other conductivity type impurity atoms are diffused into the other trenches. CONSTITUTION:One conductivity type impurity atoms are diffused into one of trenches 3 surrounded by (111) faces which are so formed by anisotropic chemical etching as to be parallel to each other and to make right angles with a ma.in surface of Si in the Si which has a resistivity not less than 50OMEGA-cm and (110) face as a main surface and the other conductivity type impllrity atoms are diffused into the other trench. For instance, a protective film 2 sv!ch as a silicon oxide film is formed on the Si substrate 1 and a rectangular part of the protective film 2 is removed and the exposed substrate is etched by anisotropic chemical solution of caustic alkali system or the like to form a rectangular parallelepiped trench 3 whose side walls are surrounded by (111) faces and N-type impurity is diffused into the trench. After that, etching resistant films are provided on the inner walls of the trench and another trench of the same shape is formed with its longer side being parallel to the longer side the trench 3 and with a distance corresponding to the thickness of a required high resistance wall 5 leaving between the two trenches and P-type impurity is diffused into the other trench.</p> |
