SRAM static noise margin (SNM) hold and read

[jackbian]

Hi all, i'm doing the simulation and measurement on the SRAM SNM (hold) and SNM (read)

All the papers and textbooks say SNM (hold) are supposed to be much larger than SNM (read), but my simulation result shows they're quite close, e.g. 226mV and 223mV. anything wrong? or is it possible they can be that close?

65nm cell size 120/160/240, one more thing is that is 220mV a too small SNM for that cell?

thanks in advance!