| abstract |
A semiconductor memory device, such as a NAND flash memory device, capable of eliminating a factor that impedes fast charge transfer of a metal wiring, preventing damage to the surface of the metal wiring, and realizing a high-speed operation of the semiconductor memory device. A manufacturing method is provided. A method of manufacturing a semiconductor memory device includes contact plugs 40, 42, 43, and a first interlayer insulating film 39 and a second interlayer insulating film 41 surrounding the contact plugs 40, 42, 43 on a substrate 30. A step of forming, a step of forming a metal wiring structure M overlying the contact plugs 40, 42, 43, including a diffusion prevention film 46 made of a patterned Ti / TiN film and a metal wiring 47 made of a tungsten film, and a metal wiring Using a cleaning chemical obtained by mixing H 2 SO 4, H 2 O 2, deionized water and HF in order to oxidize the surface of 47 and form a protective film 49 on the surface of the metal wiring 47. [Selection] Figure 3B |