METHOD FOR MANUFACTURING GATE OF NAND FLASH

The present application discloses a method for manufacturing a NAND flash, comprising: step 1, sequentially form a floating gate dielectric layer and a first polysilicon layer; step 2, sequentially forming an inter-gate dielectric layer and a second polysilicon layer, wherein a first doping concentration of the second polysilicon layer is less than a target doping concentration; step 3, forming a pattern transfer mask layer; step 4, patterning the pattern transfer mask layer; step 5, performing gate etching, wherein the first and second polysilicon layers subjected to the gate etching respectively form a polysilicon floating gate and the polysilicon control gate; step 6, forming a first spacer, wherein the first spacer in a storage area fully fills a first interval area; and step 7, performing self-aligned ion implantation to increase a doping concentration of the polysilicon control gate to the target doping concentration.