Abnormal V<inf>TH</inf>/V<inf>FB</inf> shift caused by as-grown mobile charges in Al<inf>2</inf>O<inf>3</inf> and its impacts on Flash memory cell operations

Abstract

High-k stacks will be used in Flash memory cells for technology beyond sub-30 nm generations. Abnormal window shift during memory operations has been observed and was attributed to trapping/detrapping of electrons or dielectric relaxation in the high-k layer. In this work, the cause of abnormal V TH /V FB shift at low operating electric fields is investigated. For the first time, extensive experimental evidences show that this shift is caused by as-grown mobile charges in Al 2 O 3 layers. Its impacts on program/erase windows and read/pass disturbance in Flash memory cells are evaluated.