Investigation Of Oxygen Precipitates And Induced Defects In Heavily Doped Czochralski Silicon

Interstitial oxygen in Czochralski silicon(Cz-si) is a very important undoped impuity, the intrinsic gettering (IG) of oxygen precipitates and induced defects in lightly doped Cz-si has been investigated systematically. In recent years, the N/N+ and P/P+ epitaxial structures have been adopted by the developing CMOS technologies, and combined with IG technique to manufacture products of Latch-up free very large-scale integrated circuits. Therefore, it is significant to investigate the IG in heavily doped Cz-si. Many investigators have indicated that the precipitation behavior of oxygen in Cz-silion depends on the species and the density of dopants. It was retarded in n-type heavily antimony-doped Cz-si but enhanced in p-type heavily boron-doped Cz-si. Because the quantitative analysis of oxygen can't be done by general equipment, it is still lack of systematically investigation of precipitates and induced defects in heavily doped Cz-si.In this paper, the oxygen concentration in heavily doped Cz-si was determined by RO-416 Oxygen Determination which is widespread applied to determine the oxygen concentration in steel. By GFA combined with FTIR to determine oxygen concentration in lightly doped Cz-si, we obtained the calibration curve to guarantee the reliability of GFA method , and the test result of GFA also could be converted to the equivalent result of FTIR. GFA applied to determine the oxygen concentration in heavily doped Cz-si is not limited by the concentration of dopant in Cz-si. With the quantitative analysis of oxygen by GFA, the following results were obtained from the study of oxygen precipitation behavior in heavily doped Cz-si after heat treatment and the application of RTP to IG in n-type heavily doped Cz-si.1. By choosing a series of heavily doped Cz-si wafers with the distribution of oxygen concentration determined by GFA, we systematically investigated the effect of dopants (B, P, As, Sb) on oxygen precipitates and induced defects in heavily doped Cz-si after two step Lo-Hi temperature annealing by preferential etching. The experimental results show that (1) There were different influence on oxygen precipitation in heavily doped Cz-si between p-type dopant and n-type dopant. Dopant of p-type B enhanced oxygen precipitation, and the density of oxygen precipitates and induced defects was high. On the contrary, dopants of n-type P (As, Sb) retarded oxygen precipitation, and the density of oxygen precipitates and induced defects was low. (2) The degree of retardation of oxygen precipitation was different by n-type heavily dopants. On the condition of the same concentration of dopants and oxygen in heavily doped Cz-si, dopant of As had stronger retardation-3-than dopant of P. (3) The morphology of induced defects by oxygen precipitate in heavily doped Cz-si was affected by n-type dopants. Stacking faults were observed in heavily P (Sb)-doped Cz-siliocn, but dislocation loops were observed in heavily As-doped Cz-si. Because of that the nucleation critical radius of oxygen precipitate in heavily doped Cz-si is affected by dopants , combined with free-electron effect and dopant-intrinsic point defect interaction, there are reverse influence on oxygen precipitation in heavily doped Cz-si between p-type and n-type dopants. Owing to the covalent radii effect of dopant, the degree of retardation of oxygen pricipitation and the morphology of induced defects by oxygen precipitates are not same among n-type heavily P( As,Sb)-doped Cz-si.2. With different nucleation annealing, the behavior of oxygen precipitates and induced defcts in heavily As ( Sb)-doped Cz-si after two step Lo-Hi temperature annealing was investigated. It was found that (1) Heavily dopant of Sb only retarded the nucleation of oxygen precipitates and had no influence on the growth of oxygen precipitates, and stacking faults was observed . Heavily dopant of As retarded not only the nucleation but also the growth of oxygen precipitation, and dislocation loops was observed. (2) oxygen precipitation behavior in heavily doped Cz-si wafers wer...