Strain Engineering to Improve Data Retention Time in Nonvolatile Memory

Experimental data show that tensile stress improves and compressive stress degrades retention time for nonvolatile memory (NVM) devices. External mechanical tensile stress and compressive stress are introduced into the NVM floating-gate and nitride trap based memories via four-point wafer bending. The enhanced retention time under tensile stress results from stress-altered changes in the $\hbox{SiO}_{2}/\hbox{Si}$ barrier height and out-of-plane conductivity mass for floating-gate memories and from changes in the trap activation energy in nitride based memories.