On the mechanism underlying the elimination of nitrogen-oxygen shallow thermal donors in nitrogen-doped Czochralski silicon at elevated temperatures

Abstract

Nitrogen-doped Czochralski (NCZ) silicon has been a base material for integrated circuits. The interaction between nitrogen (N) and interstitial oxygen (Oi) atoms in the low temperature regime (300–650 °C), which leads to N–O complexes in the form of NOx (x = 1, 2, or 3), forms a series of shallow thermal donors (denoted as N–O STDs). Such N–O STDs are detrimental to the stability of electrical resistivity of NCZ silicon. In this work, we have experimentally investigated the elimination of N–O STDs in NCZ silicon by means of conventional furnace anneal (CFA) and rapid thermal anneal at elevated temperatures ranging from 900 to 1250 °C, aiming to explore the underlying mechanism. It is found that most of the N–O STDs formed in NCZ silicon can be eliminated by a very short period of anneal at the aforementioned temperatures, providing solid evidence for the viewpoint that the elimination of N–O STDs is ascribed to the decomposition of NOx complexes. Somewhat unexpectedly, the residual N–O STDs are much more after the 1250 °C/2 h CFA than after the 900 °C/2 h or 1000 °C/2 h counterpart, which is found to be due to the fact that more nitrogen pairs [(N2)s] are remaining after the 1250 °C/2 h CFA. It is proposed that most of the (N2) atoms are involved in the growth of grown-in oxide precipitates during the 900 or 1000 °C/2 h CFA. The first-principles calculations and molecular dynamics simulation indicate that the elimination of N–O STDs is essentially ascribed to the destruction of “NO ring” that is the core of NOx complexes. Furthermore, based on the experimental and theoretical results, we have made a thorough thermodynamic analysis to account for the details of elimination of N–O STDs as revealed in this work. It is believed that our experimental and theoretical studies have gained more insight into the N–O STDs in NCZ silicon.

Electroluminescence from Silicon-Based Light-Emitting Devices with Erbium-Doped ZnO Films: Strong Enhancement Effect of Titanium Codoping

“…To figure out the effect of Ti-codoping on the symmetry of the “ErO 6 ” cluster in the ZnO:Er film, one ZnO supercell containing an “ErO 6 ” cluster and the other containing an “ErO 6 ” cluster with an adjacent Ti atom were constructed for DFT calculations. The procedures and conditions for DFT calculations can be referred to our previous reports. , …”

Nitrogen-Related Defects in Crystalline Silicon

“…Thus, these complexes have been studied systematically both experimentally and theoretically. Experimentally, there have been a variety of techniques employed to study defects in semiconductors and, especially in this work, N-related defects in Si: a) those studying the electrical properties of defects [32][33][34][35] use, for instance, the deep-level transient spectroscopy (DLTS) technique which basically investigates the properties of deep levels in the forbidden gap of semiconductors; b) those studying the magnetic properties of defects [32,[36][37][38] use, for instance, the electron paramagnetic resonance technique (EPR) spectroscopy which is used to identify the electronic structure of defects and their charge states; and c) those studying the optical properties of defects use, for instance, infrared spectroscopy (IR) which mainly investigates using infrared absorption of the localized vibrational modes (LVMs) of the defects [39][40][41][42][43], as well as photoluminescence (PL) where light separates charge carries within the band or impurity structure of a semiconductor, and whose later recombination produce characteristic emissions [44][45][46].…”