How would they actually manufacture this? Camera sensors are basically chips, so they are made out of silicon wafers, right?

If so, can curved wafers be made? Or start with a flat wafer and build up enough layers on top of it so that the surface is curved? Or make several tiny sensor pieces out of flat wafers, put them on a curved surface, and seamlessly connect them together? All of these ideas seem crazy, but they must have some way.