| 摘要 |
PURPOSE:To obtain a semiconductor device which can operate at a high speed by implanting the second conductive type impurity ions to the first conductive type semiconductor base layer, etching the surface to partly remove the impurity, and heat treating it. CONSTITUTION:An n<+> type buried layer 2 is formed on a p type silicon substrate 1, an n type expitaxially grown layer 3 is formed to selectively implant boron B ions. The surface of the layer 3 is etched to remove the surface layer in which the implanted B and the damage due to the implantation exist in large qantity. A polycrystalline silicon film 11 is coated and annealed. The B distributed in the vicinity of the surface of the layer 3 is diffused in the film 11, the surface density of the layer 3 reduces, and a P type base region 6 having extremely small junction depth is formed. As ions are selectively implanted to the film 11, and heat treated to form an n<+> type emitter region 9. The base width can be extremely reduced to obtain a n-p-n type bipolar transistor which can operate at a high speed. |
