Semiconductor storage device and method of manufacturing semiconductor storage device

A semiconductor storage device comprising:

• a substrate;
• an electric charge holder includes a first part and a second part in a cross section along a surface of the substrate, the second part having a larger curvature than the first part;
• and
• a channel layer includes, in the cross section, a first part and a second part, the first part of the channel layer being alongside the first part of the electric charge holder, the second part of the channel layer being alongside the second part of the electric charge holder,
• wherein the second part of the channel layer has a larger film thickness than the first part of the channel layer.

A method of manufacturing a semiconductor storage device comprising:

• forming a channel layer intermediate body and an oxide film inside the channel layer intermediate body by supplying a semiconductor material to an inside of a memory hole provided in a laminate and performing heat treatment;
• removing the oxide film using a first solution while a portion of the oxide film is left behind;
• and
• forming a channel layer by slimming the channel layer intermediate body using a second solution different from the first solution in a state in which a portion of the oxide film is left behind.