Patent Number: 7,826,248

Title: Write verify method for resistive random access memory

Abstract: Write verify methods for resistance random access memory (RRAM) are provided. The methods include applying a reset operation voltage pulse across a RRAM cell to change a resistance of the RRAM cell from a low resistance state to a high resistance state and setting a counter to zero. Then the method includes applying a forward resetting voltage pulse across the RRAM cell if the RRAM cell has a high resistance state resistance value less than a selected lower resistance limit value and adding one to the counter. This step is repeated until either the counter reaches a predetermined number or until the high resistance state resistance value is greater than the lower resistance limit value. The method also includes applying a reverse resetting voltage pulse across the RRAM cell if the RRAM cell has a high resistance state resistance values is greater than a selected upper resistance limit value and adding one to the counter. The reverse resetting voltage pulse has a second polarity being opposite the first polarity. This step is repeated until either the counter reaches a predetermined number or until all the high resistance state resistance value is less than the upper resistance limit value.

Inventors: Xi; Haiwen (Prior Lake, MN), Xue; Song S. (Edina, MN)

Assignee: Seagate Technology LLC

International Classification: G11C 11/00 (20060101)

Expiration Date: 2019-11-02 0:00:00