Semiconductor device, method of manufacturing semiconductor device, and semiconductor memory device

A semiconductor device, comprising:

• a semiconductor substrate having a first region and a second region, each region containing a first-type impurity;
• a first insulating layer provided on a region between the first region and the second region in the semiconductor substrate;
• a first gate electrode having
• a first semiconductor layer provided on the first insulating layer and containing an impurity,
• a first conductive layer provided on the first semiconductor layer and containing titanium,
• a second conductive layer provided on the first conductive layer and containing nitrogen and either titanium or tungsten, and
• a third conductive layer provided on the second conductive layer and containing tungsten;
• a second insulating layer provided on the third conductive layer and containing oxygen and silicon;
• a third insulating layer provided on the second insulating layer and containing nitrogen and silicon;
• a seventh insulating layer provided on a side surface of the first gate electrode and containing oxygen and silicon;
• an eighth insulating layer provided on the seventh insulating layer to define a side wall together with the seventh insulating layer and containing nitrogen and silicon;
• a first contact provided on the first region;
• a second contact provided on the second region;
• and
• a third contact provided on the third conductive layer of the first gate electrode, the third contact penetrating through the second insulating layer and the third insulating layer, wherein
• a lower end of the third contact is closer to the semiconductor substrate than is an upper end of the side wall, and
• the lower end of the third contact is closer to the semiconductor substrate than are lower ends of both the second insulating layer and the third insulating layer.