| 摘要 |
1,031,446. Semi-conductor devices. SIEMENS & HALSKE A.G. Aug. 11, 1964 [Aug. 12, 1963], No. 32635/64. Heading H1K. Doping of selected areas of an oxide covered semi-conductor crystal is effected by depositing an additional material on the oxide which, at the diffusing temperature concerned, forms with the oxide a vitreous mesh permeable to the material to be diffused; the additional material may comprise the dopant or this may be applied separately. In one example, an N-type silicon wafer is covered with a 1Á layer of SiO 2 and a 0À25Á layer of Na 2 O is then deposited on selected areas of the oxide, the amount being chosen to be appropriate for the Na 2 O-SiO 2 system eutectic. Diffusion of the desired impurity is then effected through the permeable eutectic areas. In another example, B 2 O 3 is used as the additional material and in this case the boron itself acts as the dopant. Alternatively, FeO or MnO may be used to form the eutectic, the iron or manganese serving to form recombination centres in the silicon; other materials include PbO which may be used for the gettering of heavy metal ions from the silicon, and K 2 O or a salt such as Na 2 F 2 . It is also possible to utilize a three or multi-substance system to form the liquid phase for example by using an alkaline earth metal oxide and an alkali metal oxide, e.g. SiO 2 : CaO : Na 2 O. Other semi-conductor materials such as germanium and A 2 B 6 or A 3 B 5 compounds such as gallium arsenide may be used; in these eases foreign oxide layers such as SiO 2 are used. |
