Analytical Sciences

Determination of Metallic Impuritiesin a Silicon Wafer by Local Etching and Electrothermal Atomic AbsorptionSpectrometry

Hye-Young CHUNG,* Sang-Hak LEE,** Young-Hun KIM,* Ki-Sang LEE,* andDae-Hong KIM*

*R & D Center, LG Siltron Inc., 283Imsoo-dong, Gumi, 730-350, Korea
**Department of Chemistry, KyungpookNational University, 1370 Sankyuk-dong, Puk-gu, Daegu 702-701,Korea

An etching technique for the determinationof the metallic impurities distribution in silicon wafers has beendeveloped. An area of 10 mmφ and 10 µm depth was etched by 100µL of an etching solution with a HF and HNO₃ mixture. Theacid matrix was evaporated on the wafer surface by IR lamp illumination andvacuum exhaust. Metallic impurities remaining on the wafer surface wereredissolved into the collection solution, which was measured byelectrothermal atomic absorption spectrometry (ET-AAS). The recoveryinvested by local etching/ET-AAS was within 95 - 112% for Fe, Cu and Ni.The detection limit (3σ) for Fe, Cu and Ni in silicon was 1 x10¹³ atoms/cm³. To confirm the applicability, localetching was applied to evaluate the effects of metallic impurities in agettering study and the electronic properties of semiconductor devices. Itwas found that local etching is a useful sample preparation technique forthe analysis of metallic impurities in a specific area on a siliconwafer.

J-STAGE: View this article in J-STAGE