Semiconductor memory device and method of manufacturing semiconductor memory device

A semiconductor memory device comprising:

• a first stacked body in which first conductive layers and first insulating layers are alternately stacked one by one, the first conductive layers including a first staircase part in a staircase shape extending in a first direction intersecting with a stacking direction of the first conductive layers;
• a first interlayer insulating film covering the first staircase part;
• a second stacked body in which second conductive layers and second insulating layers are alternately stacked one by one, the second stacked body being provided above the first stacked body, the second conductive layers including a second staircase part in a staircase shape continuous to the first staircase part in the first direction;
• a second interlayer insulating film covering the second staircase part;
• a first platy member extending in the first direction and penetrating the first stacked body in the stacking direction, the first platy member including a first insulating material;
• a second platy member extending in the first direction and penetrating the second stacked body in the stacking direction, the second platy member being connected to an upper end of the first platy member, the second platy member including the first insulating material;
• and
• a bridging member provided on the upper end of the first platy member, the first bridging member connecting the first interlayer insulating films on both sides of the first platy member, the first bridging member including a material different from the first insulating material, wherein
• side surfaces in a second direction of the first and second platy members have a wave shape with periodicity in the first direction, the second direction being a direction intersecting with the first direction and the stacking direction, and
• a lower end of the bridging member is positioned above an uppermost first conductive layer in the first stacked body.

A method of manufacturing a semiconductor memory device, the method comprising:

• forming a first stacked body in which first insulating layers and second insulating layers are alternately stacked one by one, the second insulating layers including a first staircase part processed in a staircase shape extending in a first direction intersecting with a stacking direction of the second insulating layers;
• forming a first interlayer insulating film to cover the first staircase part;
• forming a first groove, the first groove penetrating the first stacked body in the stacking direction and extending in the first direction;
• forming a first bridging member in an upper end of the first groove, the first bridging member connecting the first interlayer insulating films on both sides of the first groove, the first bridging member including a lower end positioned above the second insulating layer;
• forming a second stacked body in which third insulating layers and fourth insulating layers are alternately stacked one by one in the stacking direction, the second stacked body being formed above the first stacked body, the fourth insulating layers including a second staircase part processed in a staircase shape continuous to the first staircase part in the first direction;
• forming a second interlayer insulating film to cover the second staircase part;
• forming a second groove, the second groove penetrating the second stacked body in the stacking direction and extending in the first direction;
• and
• forming a second bridging member in an upper end of the second groove, the second bridging member connecting the second interlayer insulating films on both sides of the second groove, the second bridging member including a lower end positioned above the fourth insulating layer.

A method of manufacturing a semiconductor memory device, the method comprising:

• forming a first stacked body in which first insulating layers and second insulating layers are alternately stacked one by one, the second insulating layers including a first staircase part processed in a staircase shape extending in a first direction intersecting with a stacking direction of the second insulating layers;
• forming a first interlayer insulating film to cover the first staircase part;
• forming first holes penetrating the first stacked body in the stacking direction, the first holes being arranged at a predetermined interval in the first direction;
• forming a first bridging member between the first holes, the first bridging member connecting the first interlayer insulating films on both sides, the first bridging member including a lower end positioned above the second insulating layer;
• forming a second stacked body in which third insulating layers and fourth insulating layers are alternately stacked one by one in the stacking direction, the second stacked body being formed above the first stacked body, the fourth insulating layers including a second staircase part processed in a staircase shape continuous to the first staircase part in the first direction;
• forming a second interlayer insulating film to cover the second staircase part;
• forming second holes penetrating the second stacked body in the stacking direction, the second holes being arranged at a predetermined interval in the first direction;
• forming a first groove and a second groove each extending in the first direction, the forming being performed by
• expanding diameters of the first and second holes in the first direction and a second direction intersecting with the first direction and the stacking direction, and
• coupling the first holes adjacent to each other and the second hole adjacent to each other in the first direction, respectively;
• and
• forming a second bridging member in an upper end of the second groove, the second bridging member connecting the second interlayer insulating films on both sides of the second groove, the second bridging member including a lower end positioned above the fourth insulating layer.