| 摘要 |
1,254,811. Semi-conductor devices. HUGHES AIRCRAFT CO. 28 Jan., 1970 [17 Feb., 1969], No. 4130/70. Heading H1K. A solid-state storage device is based upon an IGFET structure, with source and drain regions 102, 104, a first gate electrode 110 on a first insulating layer 108 and overlying a first part 105a of the channel 105, and a second gate electrode 116 on a second insulating layer 114 which covers the first gate electrode 110, the second gate electrode 116 overlying a second part 105b, 105c of the channel 105. For a Si substrate 100 the first insulating layer 108 may be of SiO 2 and the second insulating layer 114 may be of Si 3 N 4 . The channel 105 is induced by a potential applied to the first gate 110, but a depletion region is formed in part 105b of the channel by a suitable bias between the second gate 116 and the drain 104. This permits high energy carriers to surmount the potential barrier between the semi-conductor 100 and the first insulating layer 108 in the storage mode of the device, and to become trapped at dislocations, vacancies &c., in the second insulating layer 114 and adjacent the interface between the two insulating layers. This accumulation of stored charges modifies the conductance of the device to permit read-out of the stored information. If it is desired to use the device in an erase mode the first insulating layer 108 must be thin enough to permit tunneling of the trapped carriers therethrough back into the substrate 100. In a modification the first and second insulating layers both underlie the first gate 110, in which case a third insulating layer is required over the first gate 110 and beneath the second gate 116. The gates 110, 116 may both be metal layers, or non-metallic transducers such as piezo-electric crystals may be employed. In one form the second gate 116 is a sound transducer, and an array of storage devices may be used to store voice patterns. |
