CF₄/O₂ 반응가스계를 사용하여 저압화학증착된 텅스텐 박막의 플라즈마 식각 및 반응성 이온 식각을 수항하고 산소분율, 압력 및 RF 출력에 따른 텅스텐의 식각속도와 SiO₂에 대한 식각선택성을 조사하였다. 플라즈마 식각 및 반응성 이온 식각 모드에서 텅스텐의 식각속도는 반응가스중의 산소분율이 각각 40%와 50%일 때 최대속도를 나타내었다. SiO₂에 대한 텅스텐의 식각선택성은 플라즈마 모드에서 약 16이었으며 반응성 이온 식각에서는 2.3의 낮은 값을 나타내었다. 산소분율에 따른 텅스텐의 식각속도 측정과 질량분석기 및 분광분석기에 의한 플라즈마상의 식각성분을 분석한 결과, WF₆ 뿐만 아니라 WOF₄의 생성에 의한 텅스텐식각이 중요한 반응경로로 판단된다. 압력이 증가함에 따라 플라즈마 mode에서는 0.6torr에서 RIE mode에서는 200mtorr에서 텅스텐의 최대식각속도를 보였다. RF출력의 증가에 따라 식각속도는 크게 증가하지만 W/SiO₂의 식각선택성은 감소하였다.

Dry etching of LPCVD tungsten film was performed using CF₄/O₂ plasma in both reactive ion etching(RIE) and plasma etching(PE) modes. The etch rate of tungsten and the selectivity of tungsten to SiO₂ were examined as a function of oxygen content in feed gas, pressure and RF power. The maximum etch rate in PE and RIE modes were observed at 40 and 50% O₂ in feed gas, respectively. The maximum selectivities of tungsten to SiO₂ in both modes were about 16 and 2.3, respectively. Mass spectroscopy(MS) and optical emission spectroscopy (OES) were used to identify the reactive species in CF₄/O₂ plasma. The results of MS and OES analyses in measuring the etch rate as a function of O₂ percent suggest that WOF₄ and WF₆ are main etch products for tungsten etching. The maximum etch rate was obtained at 0.6 torr for PE mode and 200 mtorr for RIE mode. With the increase of RF power, the etch rates of both tungsten and SiO₂ increased, but the selectivity of tungsten to SiO₂ decreased.

Wells VA, "Tungsten and Other Refractory Metals for VLSI Applications III," Mater. Res. Soc., Pittsburgh, PA (1988)
Blewer RS, McConioca CM, "Tungsten and other Refractory Metals for VLSI Applications IV," Mater. Res. Soc. Pittsburgh, PA (1989)
Kim YT, Min SK, Hong JS, Kim CK, Appl. Phys. Lett., 58, 837 (1991) 
Chow TP, Steckl AJ, J. Electrochem. Soc., 131(10), 2325 (1984) 
Daubenspeck TH, Sukanek PC, J. Electrochem. Soc., 136, 3779 (1989) 
Kang S, Chow R, Wilson RH, Gorowitz B, Wiliams AG, J. Electron. Mater., 17, 213 (1988)
Chiou BS, Lo HS, Chang PH, J. Electron. Mater., 17, 397 (1988)
Tang CC, Hess DW, J. Electrochem. Soc., 131(1), 115 (1984) 
Pan WS, Steckl AJ, J. Vac. Sci. Technol. B, 6(4), 1073 (1988) 
Bestwick TD, Oehrlein GS, J. Appl. Phys., 66, 5037 (1989)
Oehrlein GS, Lindstom JL, J. Vac. Sci. Technol. A, 7, 1035 (1989) 
Fracassi F, Coburn JW, J. Appl. Phys., 63, 1758 (1988) 
Picard A, Turban G, Plasma Chem. Plasma Process., 5, 333 (1985) 
Balooch M, Fischl DS, Olander DR, Siekhaus WJ, J. Electrochem. Soc., 135, 2090 (1988) 
Fischl DS, Rodrigues GW, Hess DW, J. Electrochem. Soc., 135, 2016 (1988) 
Fischl DS, Hess DW, J. Electrochem. Soc., 134, 2265 (1987) 
Greene WM, Hess DW, Oldham WG, J. Electrochem. Soc., 134, 2265 (1987) 
Daubenspeck TH, White EJ, J. Vac. Sci. Technol. B, 7, 167 (1989) 
Karulkar C, Wirzbicki MA, J. Vac. Sci. Technol. B, 6, 1595 (1988) 
Mogab CJ, Adams AC, Flamm DL, J. Appl. Phys., 49, 3796 (1978) 
Lowenstein LM, J. Vac. Sci. Technol. A, 6, 1984 (1988) 
Flamm DL, Mogab CJ, Sklaver ER, J. Appl. Phys., 50, 6211 (1979) 
Dalvie M, Jensen KF, J. Electrochem. Soc., 137, 1062 (1990) 
HWAHAK KONGHAK, 29, 336 (1991)
Marcoux PJ, Foo PD, Solid State Technol., 115 (1981)
Nam CW, Woo SI, Kim YT, Min SK, Thin Solid Films, 209, 215 (1992) 
Coburn JW, WInters HF, Chuang TJ, J. Appl. Phys., 48, 3532 (1977) 
Coburn JW, Kay E, IBM J. Res. Dev., 23, 33 (1979)
Coburn JW, Winters HF, J. Vac. Sci. Technol., 16(2), 391 (1979) 
d'Agostino R, Cramarossa F, Benedicits SD, Ferraro G, J. Appl. Phys., 52, 1259 (1981) 
Coburn JW, Chen M, J. Appl. Phys., 51, 3134 (1980)