Heavily arsenic‐doped Czochralski (HAs‐CZ) silicon is an important substrate material for manufacturing power electronic devices. The arsenic impurities may be in a supersaturated status in a certain temperature range during the HAs‐CZ silicon crystal growth or the device fabrication. Then, whether and how the arsenic impurities can precipitate in HAs‐CZ silicon is an intriguing and practically significant issue that has never been addressed. Herein, it is first found that arsenic precipitation can occur in HAs‐CZ silicon when subjected to appropriately prolonged anneals at 550–950 °C. The resulting second‐phase precipitates are confirmed to be of orthorhombic SiAs phase, with the lattice parameters of a = 7.12 Å, b = 9.11 Å, and c = 9.00 Å, through systematic transmission electron microscopy characterizations. Moreover, it is discovered that the presence of vacancies/interstitial silicon atoms in HAs‐CZ silicon promotes/inhibits arsenic precipitation.
Improving the mechanical strength of Czochralski (CZ) silicon is of significance for increasing the manufacturing yield of integrated circuits. In this work, we have comparatively investigated the dislocation gliding behaviors in the conventional CZ silicon, nitrogen (N)-doped CZ silicon, germanium (Ge)-doped CZ silicon as well as Ge and N co-doped CZ silicon subjected to the indentations for 30 min at different temperatures in the range of 850–1050 °C with an interval of 50 °C. It is found that the suppressing effect of N-doping on the dislocation gliding is strongest at 950 °C and becomes slightly weakened at higher temperatures, while Ge-doping does not exert a remarkable suppressing effect on the dislocation gliding until the temperature exceeds 950 °C. The co-doping of N and Ge impurities takes both advantages of N- and Ge-doping to suppress the dislocation gliding in CZ silicon at the aforementioned temperatures. More importantly, at 1000 and 1050 °C that are the typical processing temperatures for integrated circuits, the N and Ge co-doping exhibits a stronger suppressing effect on the dislocation gliding in CZ silicon than the single Ge- or N-doping. This indicates that the mechanical strength of CZ silicon in terms of the resistance of dislocation gliding at a high temperature can be further improved by co-doping Ge and N impurities. It is believed that the N-doping can result in the formation of larger grown-in oxygen precipitates and N–O complex-related pinning agents within the dislocations to suppress the dislocation gliding at 850–1050 °C with the strongest suppressing effect at 950 °C, while the suppressing effect of Ge-doping on the dislocation gliding at the temperatures exceeding 950 °C is tentatively ascribed to the formation of Ge–O complexes near the front of the dislocation lines.
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.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.