| 摘要 |
<p>1,214,151. Semi-conductor devices. ASSOCIATED SEMICONDUCTOR MFGS. Ltd. 5 Feb., 1968 [7 Feb., 1967], No. 5717/67. Heading H1K. A semi-conductor device comprises a semiconductor wafer with at least first, second and third regions 31, 32, 33 of successively opposite conductivity type, the first region 31, which may be annular, underlying a depression 39 in one face of the wafer and the PN junction 36 between the second and third regions having a stepped formation under the first region with its periphery extending to a bevelled surface 45 of the body. The peripheral surface of the wafer is bevelled and the angle between this junction 36 and the surface is between 170 and 180 degrees. Electrodes are connected to the regions. In the embodiment shown in Fig. 3 where the device is a thyristor a further conductivity region 34 exists in the wafer opposite the depression 39, and a further bevel exists at the peripheral surface at an angle of between 15 and 60 degrees with the PN junction 37. The emitter electrode 51 may overlap the second zone 32 in selected areas to provide shorted emitter characteristics. In a further embodiment, Fig. 1, not shown, the depression (9) is annular with the first zone (1) surrounding the depression. In a thyristor of this type the control electrode (23) is connected in the centre of the annulus to the second region. In the manufacture of the silicon device the second region 32 is formed in a composite manner by firstly diffusing gallium to give a relatively deep P region, the depression 39 then being formed by etching or ultrasonic drilling, and secondly diffusing boron to form a narrow width portion of the region particularly under the depression. Electrodes are provided by electroless plating of nickel and gold, and the wafer is soldered, after plating, to a molybdenum disc 56 with an interposed gold-germanium preformed solder disc.</p> |
