During the operation of memory cell arrays including nonvolatile memory cells such as twin flash memory cells, for instance, minority carriers arise within a semiconductor zone such as, for instance, a well zone of the memory cells. The lifetime of such minority carriers is, for example in known memory cell arrays composed or crystalline silicon, so long that they can diffuse to an extent of many micrometers before recombination with a majority carrier takes place. During this diffusion, the minority carriers can also reach interface states of a lower oxide layer of an ONO (Oxide-Nitride-Oxide) memory layer of adjacent memory cells, be trapped there or even be injected into the nitride layer given the presence of corresponding electric fields. In this case, the charge state changes within the ONO memory layer of the adjacent memory cells, which entails an undesirable loss of information.
A memory cell array of nonvolatile semiconductor memory cells in which the problem explained above in connection with the diffusion of minority carriers is alleviated or does not occur would be desirable.
USPTO Backgrounds
USPTO Backgrounds