Nitrogen Doped 300 mm Czochralski Silicon Wafers Optimized with Respect to Voids with Laterally Homogeneous Internal Getter Capabilities

An internally gettering bulk defect zone and a defect denuded zone of at least 5 µm below the wafer surface were generated by out-diffusion of interstitial oxygen during annealing at temperatures in the range 1075-1100 °C in argon atmosphere. The CZ silicon material used was optimized with respect to voids and contained a central OSF region and an outer Pv region. Due to co-doping of at least 3×1013cm-3nitrogen, a laterally homogeneous bulk microdefect density was obtained which is independent of the temperature of the out-diffusion anneal. The internal getter created in this way efficiently getters nickel impurities as demonstrated in a getter test with 6.6×1011cm-3of intentional Ni contamination. In the central OSF region of the as-grown nitrogen co-doped wafers, the nuclei capable of generating OSFs also degrade the gate oxide integrity. Out-diffusion annealing at 1075-1100°C dissolves most of the defects capable of generating OSFs and it strongly improves the integrity of 5 nm gate oxides.

Interfacial Characterization of Mosi2+ X Sic Composite Thin Films on Molybdenum Substrates

ABSTRACTA novel coating architecture is being examined for enhancing the high temperature, oxidation resistance of molybdenum. The coating incorporates a thin, composite film of MoSi2+1.96 mole fraction SiC in order to match the coefficients of thermal expansion between the molybdenum substrate and the coating. Since the as-deposited composite film is amorphous in nature, a diffusion anneal treatment is carried out at 1000°C to achieve crystallization of the film. In this paper, a detailed examination of the Mo-MoSi2+1.96 SiC interface will be presented. The microstructural features of the composite films will be discussed based on electron microscopy, auger electron spectroscopy (AES), and X-ray diffraction analysis. Finally, a novel diffusion barrier layer for minimizing silicon and carbon diffusion from the coating to the substrate will be discussed.

Theoretical Investigation of Implanted Dopant Diffusion From a Silicide Layer to the Silicon Wafer for Ultra Shallow P-N Junction Formation

ABSTRACTIn this work a theoretical model is presented to analyze the technique recently suggested to form shallow p-n junction. According to this technique a silicide acts as a source of a dopant and it is followed by controlled diffusion anneal to accomplish the dopant penetration into a silicon wafer.In our analysis the dependence of the p-n junction depth on process parameters is discussed. The model considers two cases, namely, with and without dopant evaporation.Experimental data for B diffusion from CoSi2 acting as the source are used to evaluate our theoretical model. The agreement between theoretical and experimental results is satisfactory.

Interface Structure, Grain Morphology, and Kinetics of Growth of the Superconducting Intermetallic Compound Nb3Sn Doped with ZrO2 and Copper

One method for the fabrication of the superconducting compound Nb3Sn involves interdiffusion of a surface coating of Sn alloyed with Cu on Nb containing Zr and O. In this study, the kinetics and microstructure associated with this reaction have been studied in detail. The results show that small Nb3Sn grains nucleate at the Nb3Sn/Nb interface, and that the Nb3Sn grains experience grain growth immediately after they are formed. ZrO2 precipitates are observed in the Nb3Sn at the Nb3Sn/Nb interface and throughout the Nb3Sn. The ZrO2 precipitates occur in the form of small partially-coherent spheres in the Nb3Sn. No ZrO2 precipitates are observed by TEM in the unreacted Nb. The grain boundaries in the Nb3Sn region are coated with a Sn-Nb-Cu alloy which would have been liquid at the diffusion/reaction temperature. The thickness of the Nb3Sn reaction layer formed during the isothermal diffusion anneal is proportional to time to the first power, indicating “reaction”-controlled rather than “diffusion”-controlled kinetics. The absence of diffusion-controlled kinetics can be explained by the presence of the liquid coating on the Nb3Sn grains. Diffusion of Sn in this liquid layer is apparently fast enough to not be the limiting kinetic step.

Bevelled plan-view TEM specimen preparation and an artifact due to dimpling

The microstructure and metallic impurity gettering efficiency of misfit dislocation (MD) networks generated in Si/Si-2%Ge epitaxial films has been examined using TEM. Metallic elements were evaporated onto the top surface where alternating open windows and oxide masks were defined. The subsequent annealing permitted metal (i.e., gold in the present discussion) to diffuse through open windows into the wafer. The details of the sample structure and results can be found elsewhere in this proceedings. It is desirable to make microscopic observations in both cross-section and in plan-view. This contribution briefly outlines our procedure for making bevelled plan-view TEM specimens and describes a novel specimen preparation artifact.The top surface was treated with aqua regia (75% HCI, 25% HNO3) for a few seconds in order to remove the gold after the diffusion anneal. 2 mm square sections were cut from a gold diffused wafer and half of the top surface was polished at 2° angle with 6 μm and 1 μm diamond paste followed by final polishing with cyton using a vibrating lapping machine