Patent ID: 8289776
Filing Date: 2012-10-16
Classification: G11C

Abstract:
1. A method for operating memory cells, comprising: applying a read voltage to a word line of a selected cell while applying a pass voltage to word lines of unselected cells, the memory cells programmable to a number of positive program states and a number of negative program states, wherein a lowermost threshold voltage (Vt) corresponding to the number of negative program states is −2V to −4V and an uppermost Vt corresponding to the number of positive program states is 2V to 4V; applying a boost voltage to a source line coupled to the selected cell, wherein the boost voltage is 1V to 2V, and wherein the read voltage is 0V to a sum of the uppermost Vt corresponding to the number of positive program states and the boost voltage; applying a voltage greater than the boost voltage to a bit line of the selected cell; applying a ground potential to a well region associated with the selected cell; and sensing a current variation of the bit line in response to the selected cell changing from a non-conducting state to a conducting state.