Method of manufacturing mask read-only memory

The present invention discloses a method of manufacturing a mask read-only memory. After a grid and a side wall of the grid are finished, a layer of interlayer medium is deposited and flattened, so that a later made island type pattern stands on the grid more firmly. The photoetching process windows are increased, and a deposited medium layer adapts a part of or the whole contacting hole medium layer without needing additional growth or removing, thereby not increasing the manufacture cost additionally.