| 摘要 |
PURPOSE:To enable the formation of an aluminum impurity addition region by ion implantation by covering the surface of a semiconductor substrate with an oxide film and a nitride film in sequence at a temperature of 500 deg.C or lower temperature before annealing after an aluminum ion is implanted. CONSTITUTION:The ion of an aluminum atom is implanted in a silicon substrate 1. In this case, the conditions of implanting the ion 2 are accelerating voltage 40-60keV, dosage 5X10<14>-1X10<15>atoms/cm<2> and an ion species <27>Al<+>. An oxide film 4 is formed on the substrate, e.g., using SiH4 and O2 by normal pressure CVD at a substrate temperature of 300-400 deg.C. The most appropriate thickness of the oxide film 4 is approx. 0.1mum since the time of coating the oxide film is short, the quantity of aluminum diffused out from the substrate 1 in the oxide film is made minimum and the oxide film is a buffer film of Si and Si3N4. Then, a mixed gas of SiH4 and NH3 is decomposed in a high frequency discharge on the oxide film 4 and a nitride film 5 is deposited on the substrate at 450 deg.C or a lower temperature. The nitride film 5 is required to be formed having a uniform thickness and being thin and 0.07-0.10mum is optimum. Then, annealing is carried out for 20-60hr at 1,200-1,250 deg.C in the atmosphere of nitrogen.
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