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0.35μm-비아(via) 식각공정을 개선하기 위하여 C2F6 가스의 식각특성을 분석하였다. 실험한 재료는 TEOS/SOG/TEOS 막을 올린 8인치 웨이퍼이며, 실험의 기법은 직교행열(Orthogonal array matrix) 실험 방식을 활용하였다. 산화막 식각에 이용된 장비는 transformer coupled plasma(TCP) source 방식이며 고밀도 플라즈마(HDP)장비이다. 실험의 결과는, 실험변수의 범위 내에서 C2F6는 0.8μm/min-1.1μm/min 범위의 식각속도를 보이며 균일도(Uniformity)는 ±6.9%미만으로 측정되었다. CD 변화(skew)는 식각 전과 후를 비교하여 10% 미만이었고 그 결과 비등방성(anisotropic) 식각의 특성이 우수하였다. C2F6를 20sccm 공급할 때 문제점이 발견되지 않았지만 14sccm을 공급하면 SOG 막의 내벽이 침식당하는 문제점이 있었다. 결과적으로 C2F6는 HDP TCP에서 빠른 식각비와 넓은 공정창(process window)을 가진 식각특성을 나타내었다.


In order to improve the 0.35μm-via hole etching process the etching characteristic of the gas C2F6 has been analyzed. The samples were triple-layer films(TEOS/SOG/TEOS) on 8-inch wafers and the orthogonal array matrix technique was used for the process. The equipment for etching was the transformer coupled plasma (TCP) source which is a type of high density plasma(HDP). This experiment showed the etching rate for C2F6 was 0.8μm/min-1.1μm/min and the measured uniformity was under ±6.9% in the matrix window. The CD skew comparison between pre and post-etching was under 10% which is an outstanding results in the window of profile in anisotropic etching. There was no problem in C2F6 with the flow rate of 20sccm, but when 14sccm of C2F6 was supplied there was a recess problem on the inner wall of SOG film. Consequently the etching characteristic of C2F6 shows a fast etching rate and a very wide process window in HDP TCP