A method of making an array of bi-directional non-volatile memory cells in a substrate of a substantially single crystalline semiconductive material, where the material has a first conductivity type with the substrate having a substantially planar surface, comprises forming a plurality of spaced apart substantially parallel trenches in a first direction in the planar surface. Each of the trenches has a sidewall and a bottom. A region of a second conductivity type is formed in the bottom of each trench. A floating gate is formed in each trench insulated and spaced apart from the sidewall of the trench. The floating gate has a first end near the bottom and a second end furthest away from the bottom. A layer of tunneling oxide is formed about the second end of each floating gate. A layer of word region is formed on the layer of tunneling oxide. The layer of word region extends in a second direction substantially perpendicular to the first direction. The layer of word region is cut into a plurality of strips in the second direction to form a plurality of spaced apart word lines. Each strip is spaced apart from one another and substantially parallel to one another, and cuts through the floating gate in each of the trenches. Electrical connections are made to each of the region of second conductivity type and each of the plurality of spaced apart word lines.