A study on copper thin film growth by chemical vapor deposition onto silicon substrates

실리콘 기판 위에 화학적 방법으로 증착된 구리 박막의 특성 연구

  • Published : 1996.08.01

Abstract

This study is to investigate a chemical vapor deposition technique of copper film which is expected to be more useful as metallizations of microcircuit fabrication. An experimental equipment was designed and set-up for this study, and a Cu-precursor used that is a metal-organic compound, named (hfac)Cu(I)VTMS ; (hevaflouoroacetylacetonate trimethyvinylsilane copper). Base pressure of the experimental system is in $10^{-6}$ Torr, and the chamber pressure and the substrate temperature can be controlled in the system. Before the deposition of copper thin film, tungsten or titanium nitride film was deposited onto the silicon wafer. Helium has been used as carrier gas to control the deposition rate. As a result, deposition rate was measured as $1,800\;{\AA}/min$ at $220^{\circ}C$ which is higher than the results of previous studies, and the average surface roughness was measured as about $200\;{\AA}$. A deposition selectivity was observed between W or TiN and $SiO_{2}$ substrates below $250^{\circ}C$, and optimum results are observed at $180^{\circ}C$ of substrate temperature and 0.8 Torr of chamber pressure.

본 연구는 초고집적회로의 금속 배선으로써 보다 유용할 것으로 기대되는 구리박막의 화학적인 증착기술에 관한 것으로 precursor 물질로는 (hfac)Cu(I)VTMS ; (hevaflouoroacetylacetonate trimethyvinylsilane copper)로 명명된 금속 유기 물질을 사용하였다. 실험시스템의 초기 압력은 $10^{-6}$ Torr를 유지하고, 시스템의 챔버압력과 기판온도가 조정 가능하도록 설계, 제작되었다. 공정 조건에 따른 구리 박막 결정의 성장속도, Grain size, 전기적 성질을 측정하였다. 구리 박막을 증착하기 전에 W(tungsten) 또는 TiN(titanium nitride)이 증착되어 있는 실리콘 웨이퍼를 사용하였다. 본 연구에서는 $250^{\circ}C$이하의 상대적으로 낮은 실리콘 웨이퍼 온도에서의 실험이 가능하였으며 헬륨을 carrier gas로 사용하였는데 연구 결과 구리 박막 증착율이 $220^{\circ}C$에서 최대 $1,800\;{\AA}/분$으로 증가한 반면 표면 거칠기는 $200\;{\AA}$를 갖는 다결정 구리 박막을 관찰하게 되었다. 기판 온도가 $250^{\circ}C$이하일 때의 W(또는 TiN)과 $SiO_{2}$ 기판사이에서 구리 증착 선택성이 관찰되었으며, 최적의 기판 증착 온도는 약 $180^{\circ}C$와 반응용기 압력 0.8 Torr로 나타났다.

Keywords

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