We have successfully developed an innovative barrier metal (BM)-less metal gate scheme with high cell reliability for the 8th generation 3D NAND flash memory. This scheme allows the memory cells to significantly lower the wordline resistance by 30%, enabling a dramatic scale-down in the lateral dimension of a multi-pillar block architecture in 3D NAND. In addition, both cell interference and vertical charge loss can be enhanced by increasing fluorine (F) passivation at the trap sites in the blocking oxide (BOX). Ingenious technologies are developed to suppress degradations originating from the work function change and increased F concentration in tungsten (W) gates. Finally, enhanced cell reliabilities, inclusive of high cycle endurance and long term retention, can be acquired for the 8th generation 512Gb 3D NAND product. Our BM-less metal gate structure provides a novel approach to designing highly competitive future-generation 3D NAND flash memory.