| 摘要 |
945,097. Semi-conductor devices. MULLARD Ltd. Nov. 13, 1961 [Feb. 20, 1961], No. 6150/61. Heading H1K A current of inert gas containing a controlled amount of oxygen or water vapour is passed over a heated boron supply and the resulting boron-containing current passed over a heated semi-conductor body into which the boron diffuses. The boron source may be commercial boron nitride or a metal boride, preferably freed of oxygen by a preliminary heating in nitrogen, and the inert gas may be argon or nitrogen. Suitable sources of water through which the dry inert gas is passed are mixtures of water with glycerol or diethylene glycol, aqueous sulphuric acid, aqueous solutions of salts such as sodium or potassium hydroxide, and crystals containing water of hydration. The water content of the resulting gas may be adjusted by admixture with dry inert gas. Oxygen can be introduced into an inert gas stream via a small orifice. In a typical process (Fig. 1), nitrogen is passed through zinc oxidecopper oxide catalyst 1 heated to 170‹ C. to convert oxygen to water which is then absorbed in activated alumina 3, and thence through glass wool filter 4 and liquid air trap 5 to a vessel 6 containing a mixture of diethylene glycol and 1 % by volume of water. The resulting wet gas is passed over a source 14 of boron and wafers 12 of 1 ohm em. N-type silicon, both heated to 1200 ‹ C. for a period of 2 hours to form sub-surface PN junctions in the wafers. Even exposure of the entire surface of the wafers, which are alternatively of germanium, is ensured by use of slotted holder (Fig. 2, not shown). |
