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Micro Electronic and Mechanical Systems 2009 Part 7

Tham khảo tài liệu 'micro electronic and mechanical systems 2009 part 7', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | Numerical Simulation of Plasma-Chemical Processing Semiconductors 201 Fig. 7. The flow gas structure. Processing regime p 0.5 torr Q 800 cm3 min Tw2 300 K 30 fraction O2 in CF4 O2. Fig. 8. The temperature distribution. Processing regime p 0.5 torr Q 200 cm3 min Tw2 473 K 30 fraction O2 in CF4 O2. Fig. 9. The fluorine concentration distribution. Processing regime p 0.5 torr Q 200 cm3 min Tw2 300 K 40 fraction O2 in CF4 O2. Fig. 10. The distribution of full flow of fluorine. Processing regime p 0.5 torr Q 200 cm3 min Tw2 300 K 40 fraction O2 in CF4 O2. 202 Micro Electronic and Mechanical Systems Fig. 11. Average etching rate as a function of percentage fraction of O2 in CF4 O2 input mixture. Processing regime p 0.5 torr Q 200 cm3 min Tw2 300 K. Case of inflow direction. The sticking coefficients of oxygen and fluorine atoms on silicon are defined as in Kopalidis Jorine 1993 SF 0.7 SO 0.2 which correspond to as 0.3. In Schoenborn at al. 1989 the chemical model included the similar parameter which was varied in the range 1 - 600. In our opinion such a range is too large because it is clear the rise of as corresponds to increasing of ratio of sticking coefficients Eq. 36 . Thereat in calculations the following values were examined as 0.3 1 5 10 50 100. It was obtained that the average etching rate dependence on percentage fraction of O2 in parent gas mixture has the maximum value about 40 of O2. It takes place in the range of gas flow rate 100-400 cm3 min see Fig. 11 curve as 0.3 . In this case the maximum value of etching rate exceeds one s value in pure CF4 more than in three times. With increasing of the gas flow rate up to 800 cm3 min the maximum of etching rate moves to 30 of O2. The location of extremum is independent of the feed gas flow direction and the gas temperature. With increasing O2 percentage in gas mixture the fluorine concentration rises and has the maximum at 40 O2. The decrease of CF2 CF3 CF4 COF concentrations accompanies by the growth of fluorine .