 This is the root cause of flash wear-out (see Flash memory#Memory wear), which is specified as the chip's “endurance.” In order to reduce the occurrence of such short circuits, floating gate flash is manufactured using a thick tunnel oxide (~100Å), but this slows erase when Fowler-Nordheim tunneling is used and forces the design to use a higher tunneling voltage, which puts new burdens on other parts of the chip.A charge trapping cell is relatively immune to such difficulties, since the charge trapping layer is an insulator.A short circuit created by an oxide defect between the charge trapping layer and the channel will drain off only the electrons in immediate contact with the short, leaving the other electrons in place to continue to control the threshold voltage of the transistor.