PAM-XIAMEN is able to supply nitrogen (N) doped silicon wafers, specifications please refer to:
https://www.powerwaywafer.com/silicon-wafer.
The doping of nitrogen as an impurity into silicon crystals not only has a beneficial effect on the performance of silicon wafers, but also has an important impact on the physical and electrical properties of silicon wafers.
In Czochralski monocrystalline silicon, nitrogen doping is mainly achieved through methods such as nitrogen protection during crystal growth, adding silicon nitride powder or Si3N4 coating on quartz crucibles to the molten silicon. Nitrogen pairs mainly exist in nitrogen pairs, with only about 1% of nitrogen in substitution sites and exhibiting a donor effect, with an ionization energy of approximately 17 meV. This doping method has multiple impacts on the properties and performance of silicon wafers. The effect of nitrogen and oxygen forming N-O STDs (Nitrogen-Oxygen Shallow Thermal Donors) and other complexes on silicon crystal defects during heat treatment. In the process of nitrogen doped Czochralski silicon, N impurities exist in various forms, including N-O STDs, N dimers (N2), and possible configurations of other monomers N.
1. Influence of Nitrogen Dopingon Si Electrical Properties
The interaction between nitrogen and oxygen forms a nitrogen oxygen complex, exhibiting multiple absorption peaks. This composite has electrical activity, which can be eliminated by annealing, thereby changing the resistivity or carrier concentration of the silicon wafer. In addition, the formation of nitrogen oxygen complexes can promote oxygen deposition, improve the internal impurity absorption ability of silicon wafers, facilitate the intrinsic gettering (IG) process of silicon wafers, enhance the mechanical strength of silicon wafers, reduce the slip distance of dislocations, enhance the anti warping ability, and improve the yield of integrated circuits.
2. Impact of Nitrogen Dopant on Oxygen Precipitation and Defect Characteristics of Silicon
The introduction of tensile stress by nitrogen atoms in silicon crystals alters the diffusion of vacancies and vacancy oxygen complexes, promoting the conversion of VO to VO2. Under N doping, the precipitation density of crystalline originated particles (COPs) in monocrystalline silicon increases and the size decreases. N doping may promote oxygen precipitation and limit the growth of voids.
Nitrogen doping can suppress the generation of dislocation loops, vacancy clusters, and void defects in zone melted silicon single crystals and large-diameter Czochralski single crystals. Theoretical calculations indicate that nitrogen first combines with double vacancies to form a complex, and then combines with oxygen to promote the generation of primary oxygen deposition, leading to the production of high-density, small-sized hollow defects. The formation of these complexes can promote the nucleation of oxygen deposition, enhance the deposition of interstitial oxygen, and improve the internal impurity absorption ability of silicon wafers.
3. Effect of Intrinsic Gettering Process and Heat Treatment on N Doped Silicon
Nitrogen and oxygen can form N-O STDs under heat treatment conditions of 300-650 ℃, which affects the performance of electronic devices. High temperature treatment at 900-1200 ℃ and annealing at 650 ℃ will affect the formation of N-O STDs in NCZ silicon. During the pre annealing stage, oxide precipitation will capture more nitrogen atoms, inhibiting the formation of N-O STDs.
The conventional high low high three-step annealing IG process was used to study the effect of nitrogen doping on oxygen precipitation in NCZ silicon crystals. At low temperatures, nitrogen can combine with oxygen to form N2On complexes. The N-V and N-O complexes in nitrogen doped silicon compete with each other, and their concentration fractions vary with the interstitial oxygen concentration [OI]. Under low [OI] conditions, the concentration of N-O complexes decreases, enhancing the inhibitory effect of primary defects.
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