Programmable 3-dimensional memories based on current induced conductivity in hydrogenated amorphous silicon nitride

Changes of several orders of magnitude in the low field conductivity of hydrogenated amorphous silicon alloy metal-semiconductor-metal MSM devices can be obtained by current stressing. This feature is suitable for memory applications, since the device can be programmed from an unstressed state to a stressed state with a ratio greater than 104. The change in conductivity is attributed to the creation of a large concentration of silicon dangling bond states during current stressing which form a defect band with a low activation energy for current transport. In this paper, we consider the use of current induced conductivity in hydrogenated amorphous silicon nitride (a-SiNx:H) multi-layer structures and show that, in principle, highly complex three dimensional circuits could be made. In particular, the potential of this approach is illustrated by using a simple MSMSM device with two silicon rich silicon nitride layers. An array with 1×10 elements has been fabricated and programmed to store 28 bits of binary information with three outputs per input.