The Etching Characteristics of Polyimide Thin Films using CF4O2 Gas Plasma

CF4O2 gas 플라즈마를 이용한 폴리이미드 박막의 식각

  • 강필승 (중앙대학교 전자전기공학부) ;
  • 김창일 (중앙대학교 전자전기공학부) ;
  • 김상기 (ETRI 반도체 신기술 연구소)
  • Published : 2002.05.01


Polyimide (PI) films have been studied widely as the interlayer dielectric materials due to a low dielectric constant, low water absorption, high gap-fill and planarization capability. The polyimide film was etched using inductively coupled plasma system. The etcying characteristics such as etch rate and selectivity were evaluated at different $CF_4/(CF_4+O_2)$chemistry. The maximum etch rate was 8300 ${\AA}/min$ and the selectivity of polyimide to SiO$_2$was 5.9 at $CF_4/(CF_4+O_2)$ of 0.2. Etch profile of polyimide film with an aluminum pattern was measured by a scanning electron microscopy. The vertical profile was approximately $90^{\circ}$ at $CF_4/(CF_4+O_2)$ of 0.2. As 20% $CF_4$ were added into $O_2$ plasma from the results of the optical emission spectroscopy, the radical densities of fluorine and oxygen increased with increasing $CF_4$ concentration in $CF_4/O_2$ from 0 to 20%, resulting in the increased etch rate. The surface reaction of etched PI films was investigated using x-ray photoelectron spectroscopy.



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