半導体用析出ケイ素棒製造の中間工業化試験

抄録

Deposited silicon rods of 600mm in length and 25mm in diameter were produced by the reaction of trichlorosilane with hydrogen on the thin rods maintained at the temperature of 1100-1150°C by direct passage of electric current. A water cooled reaction vessel of stainless steel containing two silicon rods was used. The silicon rods were preheated by radiation from a heater contained in the reaction vessel and successively heated up to the definited temperature by direct passage of electric current from the circuit having a saturable reactor. The ratio of hydrogen to trichlorosilane were 10-20 and the rate of feeding the trichlorosilane was 0.0378 mole /h·cm² (surface area of silicon rod). The yields of silicon from the trichlorosilane were 25-30%. The growing rates of the diameter of silicon rods were about 0.225mm/h. The electric power reqired for the deposition were 1.0-0.9kWh/g Si and the electric current for heating the silicon rods of 4mm×4mm were about 40A and 350-400A for 25mm in diameter. The trichlorosilane and silicon tetrachloride contained in the outlet gases were caught in a cold trap maintained at about -70°C and analyzed by fractional distilation. From these results, it was revealed that about 30% of the feeded trichlorosilane was converted to deposited silicon, 20% to silicon tetrachloride and 50% was retained as unchanged trichlorosilane. These silicon rods had n type resistvities higher than 150 ohm cm and life time of 200μsec after 2 zone passes of floating zone refining in argon.