Korean Journal of Materials Research (한국재료학회지)

Materials Research Society of Korea (한국재료학회)
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Cleaning Effects by NH4OH Solution on Surface of Cu Film for Semiconductor Devices

NH4OH용액이 반도체 소자용 구리 박막 표면에 미치는 영향

  • Lee, Youn-Seoung (Department of Information & Communication Engineering, Hanbat National University) ;
  • Noh, Sang-Soo (Department of Information & Communication Engineering, Hanbat National University) ;
  • Rha, Sa-Kyun (Department of Materials Engineering, Hanbat National University)
  • 이연승 (한밭대학교 정보통신공학과) ;
  • 노상수 (한밭대학교 정보통신공학과) ;
  • 나사균 (한밭대학교 재료공학과)
  • Received : 2012.07.02
  • Accepted : 2012.08.13
  • Published : 2012.09.27
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Abstract

We investigated cleaning effects using $NH_4OH$ solution on the surface of Cu film. A 20 nm Cu film was deposited on Ti / p-Si (100) by sputter deposition and was exposed to air for growth of the native Cu oxide. In order to remove the Cu native oxide, an $NH_4OH$ cleaning process with and without TS-40A pre-treatment was carried out. After the $NH_4OH$ cleaning without TS-40A pretreatment, the sheet resistance Rs of the Cu film and the surface morphology changed slightly(${\Delta}Rs:{\sim}10m{\Omega}/sq.$). On the other hand, after $NH_4OH$ cleaning with TS-40A pretreatment, the Rs of the Cu film changed abruptly (${\Delta}Rs:till{\sim}700m{\Omega}/sq.$); in addition, cracks showed on the surface of the Cu film. According to XPS results, Si ingredient was detected on the surface of all Cu films pretreated with TS-40A. This Si ingredient(a kind of silicate) may result from the TS-40A solution, because sodium metasilicate is included in TS-40A as an alkaline degreasing agent. Finally, we found that the $NH_4OH$ cleaning process without pretreatment using an alkaline cleanser containing a silicate ingredient is more useful at removing Cu oxides on Cu film. In addition, we found that in the $NH_4OH$ cleaning process, an alkaline cleanser like Metex TS-40A, containing sodium metasilicate, can cause cracks on the surface of Cu film.

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References

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