Diffusion-Temperature-Dependent Formation of Cu Centers in Cu-Saturated Silicon Crystals Studied by Photoluminescence and Deep-Level Transient Spectroscopy

Abstract

Using photoluminescence (PL) and deep-level transient spectroscopy (DLTS) we observed the concentration changes of Curelated centers in silicon crystals saturated with Cu at various temperatures (600 -1000 C), in which each sample was measured at the same location for both methods. The DLTS peak assigned to have the same origin as the 1.014 eV PL center (Cu PL center) was by far the strongest component among the DLTS peaks, and no DLTS peak due to isolated substitutional Cu (Cu s ) was observed for any of the diffusion temperatures used. The PL and DLTS intensities of the Cu PL center increased with increasing diffusion temperature of Cu from 600 to 700 C, reached a maximum between 700 and 800 C, then sharply decreased at higher temperatures than 800 C. This behavior was reasonably explained by considering the outdiffusion and precipitation of Cu in addition to the solubility of Cu. The maximum DLTS concentration of the Cu PL center ($10 14 cm À3 ) observed in the present study far exceeded the estimated concentration of Cu s formed through a vacancy-mediated reaction. From this finding we concluded that a model containing Cu s was invalid for the Cu PL center and that another model containing unique Cu atom at the center of the Si-Si bond was realistic.

Depth profiles of the nickel donor center in p-type silicon diffused with dilute nickel measured by deep-level transient spectroscopy

“…However, the equilibrium vacancy concentration of intrinsic silicon is estimated to be lower than 5 © 10 11 /cm 3 at 800 °C and the pre-existence of such a high unstable-vacancy concentration of FZ silicon is unrealistic, as discussed in a previous report. 33) The unexpectedly high concentration of nickel center measured in this study is accordingly formed by a mechanism (or mechanisms) differed from the dissociative mechanism. We surveyed possible origins to explain the data obtained in this study.…”

Deep-Level Transient Spectroscopy and Photoluminescence Studies of Formation and Depth Profiles of Copper Centers in Silicon Crystals Diffused with Dilute Copper

“…We can also identify the species H(175) to be due to Cu precipitates present in the bulk. Since the peak H(175) was not observed in the rapidly cooled samples reported previously, 12) we consider that this species was produced by slow cooling. Since we did not observe any PL peaks related to dislocations, such as D1 and D2 peaks, 19) in all the studied samples, we consider that both species H(185) and H(175) are not directly related to the dislocations.…”

“…The position of the peak at 95 K is near that of the peak at 85 K due to an intermediate Cu center 14) between the Cu DLA and Cu DLB centers. The peak at 150 K observed in the samples diffused between 450 and 600 C was also observed in the sample diffused with saturated Cu at 600 C. 12) Changes in the concentrations of the main DLTS peaks H(50) and H(185) with diffusion temperature are plotted in Fig. 2.…”

“…For Si crystals saturated with Cu, the formation of the Cu centers in the bulk was studied for a wide range of diffusion temperatures, and the Cu DLB center was the main species throughout the diffusion temperature range studied. 5,12) However, these data do not seem fully useful for the analysis of the behavior of Cu in the ULSIC devices, because the failures in the devices are often caused by the contamination of dilute Cu during the manufacturing processes. 2,3) For the samples diffused with dilute Cu at 700 C, the depth profile of the Cu DLB center measured by PL was almost uniform throughout the depth direction.…”

Four-copper complexes in Si and the Cu-photoluminescence defect: A first-principles study

“…32 However, the gap levels of the complex and its vibrational spectrum have not been calculated. Nakamura et al 33 proposed instead that the core of the defect is copper at the bond-centered (BC) site (Cu BC ), 34,35 and that Cu PL is a trigonal Cu BC Cu i3 complex. No theoretical support for this structure based on its electrical or optical properties was provided.…”