Paper 15: Pure Silicon

Abstract

The requirements of the semi-conductor industry for manufacturing devices such as transistors and rectifiers have resulted in new standards of purity for certain materials. Ultra-pure silicon is now produced commercially, with impurity levels lower than 1 part in 10¹⁰, in single crystal form of high structural perfection. This paper describes such a material, laying particular emphasis on the electrical properties, and describes methods by which it is manufactured commercially. The importance of electrically active impurities, such as boron and phosphorus, is discussed with reference to the p-type and n-type conductivities which are thereby introduced.

The necessity for strict control of physical parameters during manufacture is emphasized, and methods used for the evaluation of the essential physical properties such as electrical resistivity and crystal structure are described.

Some of the applications of pure silicon are introduced in this paper and the physical basis underlying the use of pure silicon in semi-conductor device manufacture is briefly reviewed.