Experiments & numerical analysis of charge accumulation and flat band voltage shifts in irradiated MIS capacitor

放射線이 照射된 MIS capacitor의 電荷 蓄積 및 flat band 전압 이동에 대한 實驗 및 數値的 硏究

  • 황금주 (청주대 대학원 전자공학과) ;
  • 김홍배 (청주대 이공대 반도체공학과) ;
  • 손상희 (청주대 이공대 반도체공학과)
  • Published : 1995.04.01

Abstract

To investigate the mechanism generated by irradiation in the insulator layer irradiated MIS (Metal - Insulator - Semiconductor) device, the various types of MIS capacitors depending on insulator thickness, insulator types and implanted impurities are fabricated on the P-type wafer. MIS capacitors exposed by 1Mrad Co$^{60}$ .gamma.-ray are measured for flat band voltage and charge density shifts pre- and post-irradiation. The measuring results of post-irradiation show the flat band voltage shifting toward negative direction and charge density increasing regardless of parameters. This results have a good agreement with calculated data by computer simulation. Si$_{3}$N$_{4}$ layers have a good radiation-hardness than SiO$_{2}$ layers compared to the results of post-irradiation. Also, radiation-induced negative trap is discovered in the implanted insulator layer. Using numerical analysis, four continuty equations (conduction-band electrons continuity equation, valence-band holes continuity equation, trapped electrons continuity equation, trapped holes continuity equation) are solved and charge distributions according to the distance and Si-Insulator interface states are investigated.

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