Quantitative Analysis of Phosphorus and Arsenic in Silcon by means of Ion Microanalyzer

Abstract

Experimental study on the analysis of phosphorus and arsenic in silicon has beencarried out with Hitachi IMA-2type ion microanalyzer. It was found that the interfere of ³⁰SiH⁺ and ²⁹Si³⁰SiO⁺ peaks were important problem for the analysis. The anal ytical conditions which minimize the production of silicon hydride ions have been studied. The intensity ratio31P+/28Si+on Si wafers(10¹⁷-10¹⁹ P atoms/cm³)was not propo rtional to the phosphorus concentration determined by wet chemical analysis. But in high concentration range, a normal caribration curve was obtained for P in Phospho silicate glasses with 0.5-7P²O⁵ mol %.
The intensity ratio⁷⁵As⁺/²⁸Si on Si wafers(10¹⁶-10²⁰As atoms/cm³)was not proportional to the arsenic concentration determined from the electric resistivities. But at higher concentration than 10²⁰ atoms/cm, the intensity ratio for polycrystalline silicon films was proportional to the arsenic concentration determined by activation analysis. The minimum detectable limit of phosphorus and arsenic in silicon have been esti mated to be nearly 10¹⁷-10¹⁸ atoms/cm³.