Methods of making semiconductor devices

摘要

972,512. Semi-conductor devices. WESTERN ELECTRIC CO. Inc. Nov. 15, 1962, No. 43192/62. Heading H1K. A wafer of monocrystalline semi-conductor material is provided with a silicon dioxide coating on one major face, leaving a small area uncoated, and semi-conductor material of different conductivity type is deposited on the masking coating and on to the exposed area of the wafer. In one embodiment (Fig. 3) a silicone dioxide coating 12 is formed on one surface of an N-type silicon wafer 11 and P- type silicon is then vapour deposited on the mask and exposed area of the wafer, the device merely requiring electrodes to form a diode. A further oxide mask 16 is then provided followed by vapour diffusion of an N-type impurity to form a transistor element. The transistor device provided with ring and point electrodes may then be encapsulated in a sealed envelope (Fig. 4, not shown). The substrate used may initially contain a P-N junction in which case only a single masking step is employed. Many transistors may be manufactured on a common base crystal by this method and subsequently separated out. In a further arrangement (Fig. 7) an oxide layer 72 is formed on a low resistivity (N +) silicon substrate 71 and a layer of high melting point refractory metal, e.g. tantalum or molybdenum is then sputtered on top of the oxide layer. A chemical etch through a photo-resist mask removed a portion of the metal layer and underlying oxide layer, exposing the substrate on which a layer of P- type silicon is vapour deposited, followed by subsequent diffusion of N-type phosphorus providing an emitter zone. A four-layer device employing two intermediate layers of refractory metal (Fig. 8, not shown) is described in which peripheral portions of the wafer structure are removed by etching or ultrasonic cutting for the provision of electrode contact areas. Specification 972,511 is referred to.