A method for the production of sharp pn - by means of turns in half conductors - arrangements of semiconductor bodies by means of melting it together a p - conductive zone with an n - conductive zone in a erhitzungs - process

摘要

727,447. Semi-conductor devices. INTERNATIONAL BUSINESS MACHINES CORPORATION. April 16, 1953 [April 19, 1952], No. 10411/53. Class 37. [Also in Groups II and XXII] A P-N junction is produced by placing a P-type semi-conductor body in contact with an N-type body of the same basic material and applying heat in a neutral or reducing atmosphere so as to raise the temperature of one body to its melting-point at the junction. In Fig. 1, an N-type body 10 of germanium is placed in a graphite crucible 12 which is then filled with a powder 14 of P-type germanium. The whole is enclosed in a quartz envelope 18 which is evacuated, or contains a neutral or reducing atmosphere such as hydrogen or helium. The powder 14 is heated to about 946‹ C. from above by a radiant heater 16 of graphite so that only the powder and the upper surface of body 10 melt. The mass is then cooled at a controlled rate (e.g. 10‹ per minute down to a temperature of 550‹ C., at which it is maintained for 16 hours) so that the whole mass becomes a single crystal. The process may be repeated to form N-P-N or P-N-P junction blocks. In place of the powder 14, a solid body of P-type material may be used. The P and N portions may be interchanged, and silicon may be used in place of germanium. In an alternative method (Fig. 3) for use with materials such as germanium which expand on freezing, a wafer 10SP1/SP of N-type material is placed in contact with a wafer 141 of P-type material of smaller crosssectional area. Pressure is applied by means of a quartz rod 28 and graphite plates 22 and 24, whereby the melting-point of wafer 14SP1/SP is reduced so that it is slightly below that of wafer 10SP1/SP. The whole, in envelope 18, is then heated by means of coil 161 so that wafer 14, but not wafer 10, just melts, and as the contact area increases the materials freeze again due to the reduction in applied force per unit area. P-N furnace 32 and cover 34 are used to facilitate temperature control. The wafers 10SP1/SP and 14SP1/SP need not be of constant cross-sectional area. A plurality of wafers may be provided, or the operation may be repeated to provide N-P-N or P-N-P junction blocks. Reference is made to the production of P-N junctions by impurity diffusion, and also by withdrawing a seed crystal from a molten mass arranged to have a particular temperature gradient.