Techniques for reducing read disturb in partially written blocks of non-volatile memory

US9978456B2 · kind B2 · utility

Assignee

• Sandisk Technologies, Inc. · US

Inventors

• Anubhav Khandelwal · San Jose, US
• Dana Lee · Saratoga, US
• Abhijeet Manohar · Bengaluru, IN
• Henry Chin · Fremont, US
• Gautam Dusija · San Jose, US
• Daniel Tuers · Kapaa, US
• Chris Avila · Sunnyvale, US
• Cynthia Hsu · Fremont, US

Key dates

• Filing date: Nov 17, 2014
• Grant date: May 22, 2018
• Expiry date: Nov 17, 2034

Classification

• Technology area (CPC G): Physics
• CPC primary: G11C16/3418
• WIPO field: Computer technology
• WIPO sector: Electrical engineering

Abstract

Techniques are presented to reduce the amount of read disturb on partially written blocks of NAND type non-volatile memory, both for when determining the last written word line in a block and also for data read. In both cases, non-selected word lines that are unwritten or, in the case of finding the last written word line, may be unwritten are biased with a lower read-pass voltage then is typically used. The result of such reads can also be applied to an algorithm for finding the last written word by skipping a varying number of word lines. Performance in a last written page determination can also be improved by use of shorter bit line settling times than for a standard read.