Application of Infrared Spectroscopy in the Determination of Oxygen and Carbon Content in Silicon
Tianjin Port East Technology Co., Ltd. Applied Analysis Department
Abstract: Monocrystalline silicon is used in the manufacture of solar cells, semiconductor devices, and other products. Due to the specific requirements of these applications, its purity must reach 99.9999% or higher. During the production process, impurities such as carbon and oxygen are inevitably introduced due to factors including raw materials and manufacturing methods, which directly affect the performance of the monocrystalline silicon. Therefore, it is necessary to control the oxygen and carbon content in monocrystalline silicon.
In accordance with GB/T 1558-2009 and GB/T 1557-2006, infrared spectroscopy can be used to simultaneously perform qualitative and quantitative analyses of substitutional carbon and interstitial oxygen in monocrystalline silicon, offering the advantages of speed, convenience, and accuracy.
Keywords:Infrared Spectroscopy Monocrystalline Silicon Carbon and Oxygen Content Quantitative Analysis
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· Principle
By utilizing the characteristic absorption peaks of substituent carbon atoms and interstitial oxygen atoms in silicon at wavenumbers of 607.2 cm⁻¹ and 1107 cm⁻¹, respectively, the concentrations of substituent carbon atoms and interstitial oxygen atoms can be determined based on the absorption coefficients of these peaks.
· Experimental Conditions
Instruments and Accessories:
FTIR-650 Fourier Transform Infrared Spectrometer;
Oxygen-carbon testing accessories; Oxygen-carbon testing holder for silicon;
Test conditions:
Resolution: 2 cm⁻¹
Number of scans: 64
Detector: DTGS
Other:
Micrometer: Accurate to 0.01 mm
Hydrofluoric acid (HF): Analytical grade (A.R.)
· Sample Preparation
Select appropriate reference wafers and test wafers in accordance with the requirements of GB/T 1558-2009 and GB/T 1557-2006. Remove surface oxides from both using hydrofluoric acid (HF), measure their thicknesses, and then prepare them for testing.
· Sample Testing
1. Using the FTIR-650 silicon oxygen and carbon content testing software, perform the following steps in order: background scan → enter reference thickness → scan reference sample → enter sample thickness → scan sample → record data;
2. Scan the sample twice and record the data; the results are shown in the figure below.
3、Test data
· Conclusion
Therefore, the FTIR-650 oxygen and carbon content analysis software enables convenient and rapid quantitative determination of substituent carbon atoms and interstitial oxygen atoms in monocrystalline silicon materials.