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원거리 플라즈마에 의한 Photo-Resist 세정과 In-situ 표면 분석

In-situ Surface Analysis and Photo-Resist Cleaning by Remote Plasma

소현 전형탁¹ 김영채^†

Hyun Soh Hyeongtag Jeon¹ Young Chai Kim^†

한양대학교 화학공학과, 서울 133-791 ¹한양대학교 금속공학부, 서울 133-791

Department of Chemical Engineering, Hanyang University, Seoul 133-791, Korea ¹Divisions of Material Science & Engineering, Hanyang University, Seoul 133-791, Korea

HWAHAK KONGHAK, June 2002, 40(3), 382-387(6), NONE

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Abstract

원거리 산소, 수소 플라즈마를 이용하여 실리콘 웨이퍼 표면에 7,000 Å 두께의 감광제(Photo-Resist: PR)를 제거하는 건식세정을 수행하였다. 실시간 질량분석과 in-situ XPS 분석으로 분해되는 유기화합물의 기상 및 표면 변화특성을 관찰하였으며, 표면온도, 유량, 플라즈마 출력과 노출시간의 공정변수 영향을 조사하였다. 최소공정 조건(130 ℃, 10 sccm, 100 W와 180초)에서 PR 분해속도가 4,500 Å/min을 나타내었다. 산소 플라즈마는 유기화합물인 PR을 산화시켜 휘발성 물질로 전환시키는데 효과적이었으나 산소 라디칼이 실리콘 표면과 반응하여 산화막을 성장시키는 문제를 초래하였다. 따라서, 산소 플라즈마의 에싱(ashing)과정을 질량분석기로 모니터링하여 감광제를 제거한 후 수소 플라즈마를 적용하는 2단계 세정공정으로 실리콘 표면 위에 존재하는 유기화합물을 XPS 검출한계 이하로 제거하였다. 건식세정 후 평균 표면조도(RMS)가 2.93 Å의 평탄한 표면을 확인하였고, 물리, 화학적 변화가 없는 세정이 가능하였다.

Removal of photo-resist(PR) with the thickness of about 7,000 Å on Si wafer was carried out by dry cleaning with using remote oxygen and hydrogen plasmas. During the removal process, the changes of surface and gas composition were monitored by real-time mass spectroscopy and in-situ XPS. Effect of process parameters such as surface temperature, flow rate, plasma power and exposure time has been investigated. The results showed that decomposition rate of PR was accelerated upto 4,500 Å/min by the minimum process condition(130 ℃, 10 sccm, 100 W and 180 sec). Oxygen plasma effectively oxidized the PR into gaseous volatile compounds. However, oxygen radicals caused the growth of oxide layer. Therefore, two step process is proposed. Oxygen plasma ashing upto thin PR layer remained is followed by a subsequent cleaning with hydrogen plasma. The two step process removed carbon contaminants below the XPS detection limit, and substantially flat surface with mean surface roughness of 2.93 Å.

Keywords

Plasma Photo-Resist Cleaning Mass Spectroscopy and XPS

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