Patent ID: 7187589
Filing Date: 2007-03-06
Classification: G11C

Abstract:
1. A method for writing data into a non-volatile semiconductor memory that includes a first bit and a second bit that are erased simultaneously, wherein initial states stored in the first bit and in the second bit are changed to final states by executing one step in a group of steps a), b), c) and d), wherein the method comprises: a) if the final states of both the first bit and the second bit coincide with their respective initial states, maintaining the initial states of the first bit and the second bit; b) if both the first bit and the second bit have erased final states and the initial states of either the first bit or the second bit is not erased, erasing both the first bit and the second bit; c) if neither the first bit nor the second bit is to be changed from a programmed initial state to an erased final state, programming the first bit if the first bit is to be changed from an erased initial state to a programmed final state and/or programming the second bit if the second bit is to be changed from an erased initial state to a programmed final state; and d) if only one of the first bit and the second bit is to be changed from a programmed initial state to an erased final state, first erasing both the first bit and the second bit and then programming the first bit if the first bit is programmed in the final state or programming the second bit if the second bit is programmed in the final state.