Method of doping a polycrystalline transistor channel for vertical nand device

摘要

It discloses a method of doping the polycrystalline channel in vertical FLASH device. The method uses a plurality of high-energy ion implantation to dope the channel at different depths of the channels. In some embodiments, as implanted ions passing through at least a portion of the periphery of the ONO stack, these ion implantation at an angle deviating from the normal direction is performed. By passing through the ONO stack, the distribution of distance each ion reaches may differ and distribution in the case of a vertical injection.