| 摘要 |
809,643. Semi-conductor devices. WESTERN ELECTRIC CO. Inc. June 13, 1956 [June 20, 1955], No. 18258/56. Class 37. The invention relates to a semi-conductor body having two contiguous surface layers of opposite conductivity types produced by heating the body in the presence of a donor and an acceptor impurity, the relative concentrations of donors and acceptors being such that the impurity having the larger diffusivity has the lower surface concentration in the body. In one example (Fig. IE) a transistor is manufactured by heating an N-type silicon body in the presence of Sb 2 O 3 for 1“ hours at 1250‹ C. to form an N+ layer 11. AlSb, or InSb, or pure A1 or In is then diffused into the surface to convert an inner layer 12 to P-type, without destroying layer 11, since aluminium and indium have greater diffusivity and lower solubility in silicon than antimony. The connection 14 to the 'base zone 12 is of annular shape and is produced by evaporating a thin (1 mil.) film of aluminium on the surface and heating to 800‹ C. so that the converted P-region 14 reaches the interior 10A. An aluminium wire 15 is bonded to zone 14. The emitter zone consists of that part of layer 11 within the base electrode and connection thereto is provided by passing a current pulse through a gold antimony coated tungsten wire 16, thus avoiding penetration to layer 12. Connection to the collector zone 10A is made by heating a gold antimony film to 500‹ C. to form N zone 17. The end portions of the body are then etched away to form the finished transistor, as shown in Fig. 1F, which is encapsulated. The arrangement provides an impurity gradient in the base zone to produce an electric field. Arsenic and bismuth may be used in place of antimony, and if indium antimonide is used, for example the two layers 11 and 12 may be provided in one heating step. Fig. 2B shows a modification in which the base and emitter contacts are provided by aluminium tube 21 and wire 22. For high-frequency applications (Fig. 3C) the emitter contact may consist of an evaporated, alloyed line 32 of goldantimony and the base contact of an evaporated, alloyed line 31 of aluminium, if desired, on both sides of line 32. Alternatively aluminium, or aluminium coated tungsten wire could be used. Diffusion into the semi-conductor body may be effected by having impurities in gaseous state in the presence of an inert gas, or by evaporating as film, if necessary mixed with an inert material, and then heating. For making connection to the base zone, aluminium or indium could be diluted with tin, or thallium (low solubility) could be used. A PNP body could be made by using bismuth as the donor to form the intermediate base zone, and gold and antimony for the connection to this zone. The use of phosphorus as donor, and gallium or boron as acceptor is also referred to. The manufacture of PNIP and NPIN arrangements are also described. Specifications 700,231 and 809,642 are referred to. |
