硅酸盐学报2025，Vol.53Issue(12)：3506-3519,14.DOI:10.14062/j.issn.0454-5648.20250221
大直径直拉硅单晶中的氧关缺陷
Oxygen-Related Defects in Large-Diameter Czochralski Silicon
摘要
Abstract
Large-diameter Czochralski silicon(Cz-Si),particularly 300 mm wafer,becomes a dominant substrate material for integrated circuits(ICs)and replacs smaller diameters in the photovoltaic(PV)industry.Oxygen,introduced primarily through quartz crucible erosion during crystal growth,is one of the most inevitable and technologically critical impurity in Cz-Si.During crystal growth cooling and subsequent device processing,interstitial oxygen(Oi)atoms aggregate to form various electrically active oxygen-related defects,significantly degrading device performance.Oxygen precipitates contribute to a crucial role of internal gettering(IG)in IC industry.Understanding and controlling these defects are paramount for advancing both microelectronic and solar cell technologies.This review comprehensively analyzes the formation mechanisms,electrical properties,and control strategies for major oxygen-related defects in large-diameter Cz-Si. This review firstly represents the fundamental properties of oxygen impurities in Cz-Si,including the equilibrium solubility and the diffusion coefficient derived from plenty of works.Enhanced diffusion phenomenon was reported at 500-700℃.Some models like the dioxygen(O2i),oxygen-vacancy(O-V),and oxygen-self-interstitial(O-I)complexes were proposed to explain this phenomenon. Thermal donors(TDs)generate at 400-500℃via oxygen clustering.The formation kinetics are comprehensively investigated.TDs exhibit double donor properties and have an impact on the carrier concentration of Cz-Si.TDs can be annealed out at 650℃,while prolonged annealing can originate new donors(NDs). The agglomeration of oxygen can generate oxygen precipitates(OPs).Some nucleation peaks at 650-750℃appear in high[Oi]and crystal head regions.The growth(at 850-1050℃)is diffusion-limited.The morphology depends critically on annealing temperature and supersaturation.For the electrical properties,OPs serve as strong recombination centers,drastically reducing minority carrier lifetime and increasing reverse leakage current in devices.In IC industry,OPs and their secondary defects serve as internal gettering sites,which play a crucial role on the formation of denude zone. Oxygen-related complexes consist of oxygen atoms and other impurity atoms.For the acceptor-oxygen complexes,the Boron-Oxygen(B-O)complex is a primary cause of light-induced degradation(LID)in p-type Cz-Si solar cells.It requires both B and O,which exhibits a metastable degradation(i.e.,activated by excess carriers,activation energy of 0.2-0.4 eV)and a stable recovery(i.e.,activation energy of 1.3 eV).The widely accepted BsO2i model features bistable configurations("Annealed"and"Degraded"states).A"Third State"(fully recovered,immune to further degradation)is also identified.AlsO2i,GasO2i and InsO2i are identified,exhibiting no obvious degradation.Thus,Ga doping is widely adopted as impurities in engineering to suppress LID. For the intrinsic point defect-oxygen complexes,oxygen effectively traps vacancies and forms vacancy-oxygen(VOn,n=1-6)complexes.VO(A-center,EC-0.17 eV)and VO2 are significant recombination centers.VO4 dominates after high-temperature RTA(at 1250-1400℃).VO complexes,especially VO2,act as potent heterogeneous nucleation sites for oxygen precipitates,which are crucial for internal gettering in ICs.Isoelectronic dopants(Ge,Sn,Pb)and nitrogen affect VOn formation and stability. Light impurities-oxygen complexes mainly focus on Nitrogen—Oxygen(N—O)and Carbon—Oxygen(C—O)complexes.Nitrogen forms electrically inactive complexes like N2O and N2O2.N also forms a shallow donor NOx(i.e.,ionization energy 34-37 meV,IR peaks 190-270 cm⁻¹).Carbon enhances oxygen precipitate,which can originate from the formation of C-O complexes. Summary and Prospects The key formation mechanisms and electrical properties of oxygen-related defects remain some challenges.The crystal growth for 300 mm wafers involves complex multi-physics(i.e.,thermal,flow,electromagnetic fields)in large systems(i.e.,34-37 in crucibles,300-450 kg charge).Maintaining radial uniformity is difficult due to the V/G criterion(where V is pull rate,and G is axial temperature gradient).Deviations lead to vacancy-rich(V)or interstitial-rich(I)regions,with a transition zone prone to forming a ring of"P-band"native oxygen-related defects.This causes a radial non-uniformity in oxygen clustering during device processing,concerning the radial defect non-uniformity and nucleation anomalies in 300 mm crystals.We should also focus on the interaction between oxygen-related defects and metallic impurities in Cz-Si used for solar cells. We can benefit from effective control of oxygen-related defect in Large-diameter Cz-Si.The effective control requires a multi-pronged approach,i.e.,sophisticated crystal growth optimization(thermal/flow fields,magnetic fields,doping),strategic impurity engineering(nitrogen,isovalent dopants),and tailored thermal processing.A further research into defect interactions,advanced characterization,and multi-scale modeling is essential for pushing the performance limits of next-generation silicon devices.关键词
大直径直拉单晶硅/氧关复合体/氧热施主/氧沉淀/电学性质Key words
large-diameter Czochralski silicon/oxygen-related complex/thermal donor/oxygen precipitate/electrical properties分类
信息技术与安全科学引用本文复制引用
WU Ruokai,YU Xuegong,YANG Deren..大直径直拉硅单晶中的氧关缺陷[J].硅酸盐学报,2025,53(12):3506-3519,14.基金项目
国家自然科学基金(62025403). （62025403）
