The present disclosure relates to a flash memory device, and associated methods. In some embodiments, the flash memory device has a gate stack with a control gate separated from a floating gate by a control gate dielectric. An erase gate disposed on a first side of the gate stack. A word line is disposed on a second side of the gate stack that is opposite the first side. The word line has a height that monotonically increases from an outer side opposite to the gate stack to an inner side closer to the gate stack. The shape of the word line optimizes the contact resistance of the word line and allows for an overlying cap spacer formed on the word line to be well defined, which can provide more reliable read/write operations and/or better performance.