Abstract
Gettering is defined as a process by which metal impurities in the device region are reduced by localizing them in predetermined, passive regions of the silicon wafer. Internal or intrinsic gettering is an effective way to reduce the contamination in active regions. The generation of internal getters is based on the decomposition of the supersaturated oxygen solid solution in silicon, which favours the formation of a complex defect system in silicon that consists of various precipitate/dislocation agglomerates. Regularities of microdefect formation during oxygen solid solution decomposition in silicon have been studied. We show that actual solid solution supersaturation, temperature and heat treatment duration determine the structure of the solid solution. Combining these factors, including heat treatment parameters, one can control solid solution decomposition rate and SiOx precipitate sizes and quantity. The methods of X-ray diffuse scattering and transmission electron microscopy have shown high efficiency for studying the effect of heat treatment in crystals. For annealing at 450 °C, solid solution decomposition occurs at high supersaturation degrees, and concentration inhomogeneity regions may form at an early decomposition stage over the actual annealing time (up to 40 h). With an increase in the temperature of subsequent annealing to 650 °C, local regions with above-average oxygen supersaturation degrees increase the efficiency of oxygen solid solution decomposition. Further, an increase in annealing temperature to T > 1000 °С results in a more intense generation of the largest precipitates at the expense of the smaller ones. Once the precipitate sizes become sufficiently large, the elastic stresses start to relax, leading to partial incoherence and the generation of dislocations around the particles. This type of defect structure seems to be the most efficient getter.
Highlights
Heat treatments for internal getter synthesis through the decomposition of a supersaturated oxygen solid solution in silicon matrix require combining temperature and duration so as to produce an efficient gettering environment providing for reliable trapping of detrimental impurities during further treatments [1–4].A theoretical analysis of the thermodynamic and kinetic conditions controlling the formation of microdefects, i.e., oxygen-containing precipitates in silicon, was Bublik VT et al.: Regularities of microdefect formation in silicon reported earlier [5–8]
Selection of the optimum internal getter synthesis mode should take into account the abovementioned factors which may control the oxygen solid solution decomposition rate and the size and quantity of precipitates which determine the gettering properties of the structure
Given similar initial supersaturation degree and high-temperature heat treatment duration the decomposition rate of oxygen solid solution in silicon and the resultant crystal structure will mostly depend on the processes occurring during low-temperature heat treatments
Summary
Heat treatments for internal getter synthesis through the decomposition of a supersaturated oxygen solid solution in silicon matrix require combining temperature and duration so as to produce an efficient gettering environment (sizes and quantity of microdefects) providing for reliable trapping of detrimental impurities during further treatments [1–4]. Given similar initial supersaturation degree and high-temperature heat treatment duration the decomposition rate of oxygen solid solution in silicon and the resultant crystal structure will mostly depend on the processes occurring during low-temperature heat treatments. The structure of crystals after the complete heat treatment cycle for internal getter synthesis is of great interest since the decomposition of an oxygen solid solution in silicon leads to the formation of various microdefect complexes: SiOx precipitates, precipitate/dislocation associations and ~2–3 μm stacking faults. The density of the precipitates per unit volume depends on the supersaturation degree and the critical-size precipitate formation energy, and the results of the secondary processes during which dislocations and point defects form [9] are controlled by kinetic factors. This work continues our study of structure formation during decomposition of oxygen solid solution in silicon for different heat treatment combinations
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
