| 摘要 |
1,100,846. Semi-conductor devices. SIEMENS-SCHUCKERTWERKE A.G. 26 April, 1965 [25 April, 1964], No. 17573/65. Heading HlK. In a semi-conductor device having a plane junction meeting the surface at an angle other than 90 degrees, the surface adjacent to the junction contacts a substance which produces a surface charge such that when the junction is reverse biased the maximum field strength at the surface is reduced. A diode produced by diffusing aluminium and gallium into an N-type silicon wafer, ultrasonically machining to produce a bevelled edge, and alloying-in contacts, is placed in a container which may be filled with moist nitrogen, dry nitrogen or ozone to produce a strong positive, weak positive or strong negative surface charge respectively. If the more lightly doped region is N-type and its bevelled surface makes an obtuse angle with the junction, the surface charge should be strongly negative, Fig. 3 (not shown). If the surface of this region makes an acute angle with the junction and has an N-type surface region near the junction, then the maximum field strength occurs near the N-type region and the surface charge should therefore be weakly positive to reduce the field at this point, Fig. 5 (not shown). As shown, Fig. 8, an SCR is produced by diffusing both aluminium and gallium into an N-type silicon wafer 83 to produce relatively heavily doped P-type regions 84 and 85. Aluminium wafer 86, gold-boron wafer 87 and gold-antimony ring 89 are alloyed to the surfaces to form the collector, gate and emitter contacts respectively. The edge of the wafer is bevelled and a gold-antimony ring 90 is alloyed to region 83. The device is mounted on a metal carrier disc 92. A ring of lacquer 93 producing a strong negative surface charge is applied to region 83 at the emergence of junction 81 and a ring of lacquer 94 producing a weak positive surface charge is applied to region 83 adjacent to N-type region 91. The substance used to produce the surface charges may be a silicone lacquer or a resin. Certain commercial products are mentioned, alizarin being added to some to modify the charge produced. Reference has been directed by the Comptroller to Specification 968,106. |
