Search / Korean Journal of Chemical Engineering
HWAHAK KONGHAK,
Vol.39, No.1, 77-84, 2001
층간 절연막으로 응용하기 위한 저 유전체 불화탄소 플라즈마 고분자/SiO2 복합박막의 증착
Deposition of Low-Dielectric Fluorocarbon Plasma Polymer/SiO2 Composite Thin Film for Inter-layer Dielectric(ILD) Application
불화 탄소 박막 속에 소량의 SiO2를 첨가함으로써 저 유전상수를 유지하면서 열 안정성이 뛰어난 불화탄소 플라즈마 고분자/SiO2 복합 박막을 개발하였다. 이들 박막들은 평판형 안테나를 가진 유도 결합형 플라즈마 화학 증착 반응기를 이용하여 불화탄소 원료 원으로 perfluorobenzene(C6F6)단량체, SiO2 원료 원으로 hexa-methyldisiloxane(HMDSO) 단량체를 사용하고, 수소와 산소를 사용한 일정 유량의 동반가스 하에서 HMDSO/(C6F6+HMDSO)의 비를 변화시키면서 증착하였다. FTIR 분석 결과에 의하면 증착된 복합 박막들은 "비정질 PTEE"(740 cm-1 근방)와 "SiO2"(1,070 cm-1 근방)의 구조로 구성되어 있고, 유전 상수는 HMDSO/(C6F6+HMDSO)의 비의 변화에 따라 2.0에서 4.0 사이의 범위 내에서 변화하였다. 500℃ 온도까지 열처리하였을 때 박막의 두께 변화는 박막 속의 -OH 결합의 증발로 인해 -5% 범위 내에서 감소한 반면에 박막의 결합구조, 굴절률 계수, 그리고 유전 상수 등과 같은 박막의 특성은 거의 일정한 값을 유지하는 뛰어난 열 안정성을 보였다. 또한 박막의 두께에 대한 박막의 균질성을 보기 위해 거의 2㎛까지 약 2시간동안 증착하여 보았으나, 박막의 두께는 박막 증착 시간에 비례적으로 상승하였고 벗겨짐이 없이 안정하였으며 박막의 스트레스는 박막의 두께가 증가함에 따라 감소하였다.
The fluorocarbon plasma polymer/SiO2 composite films that exhibit excellent thermal stability(at least 450℃) and maintain low dielectric constant(between 2.0 to 4.0 depending on the ratio of source gases) were developed by incorporating a small amount of SiO2 into fluorocarbon thin films. The films were deposited by a planar-type inductively-coupled high density plasma chemical vapor deposition using perfluorobenzene(C6H6) as fluorocarbon source gas and hexamethyldisiloxane(HMDSO) as SiO2-film generating source gas. The infrared spectra of these composite films typically exhibited two distinctive absorption bands - one corresponding to SiO2(at around wavenumber 1,070 cm(-1)) and the other corresponding to amorphous PTFE(around wavenumber 740 cm(-1)). The dielectric constant was varied in the range of 2.0 to 4.0 with the ratio of the source gases. Also, these films exhibited good thermal stability - the variation of thickness is less than 5%, furthermore, the film maintained the dielectric constant and refractive index within 5% of its initial value when the film is subjected to temperature as high as 500℃. In order to investigate the change of film uniformity as film thickness is thicker, the films deposited up to 2 ㎛ for two hours were stable without peel-off and film stress was rather decreased with increasing film thickness.
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