Patent ID: 8716138

Claim:
A method for forming a conducting floating gate nonvolatile memory (NVM) device, the method comprising: implanting an impurity of a conductivity type opposite to that of a substrate into the substrate to form a plurality of implanted strips running in a first direction; sequentially depositing a first dielectric layer and a first poly-silicon film over a substrate surface; depositing and patterning a hard mask on the first poly-silicon film; etching through the first poly-silicon film and the first dielectric layer into the substrate to a depth to form a plurality of trenches on the substrate surface so that each implanted strip is divided into a plurality of pairs of spaced-apart sub-bitlines and selectively remains unetched in a plurality of contact landing regions on the substrate surface; depositing a second dielectric layer over the substrate surface; depositing and patterning a second ploy-silicon film on the second dielectric layer to form a plurality of control gates of a memory array of NVM cells; and forming a plurality of electrical contacts in the contact landing regions and depositing a conductive material in regions of column lines running in the first direction; wherein the trenches are arranged in a pattern that shifts a fraction of one column pitch in a second direction along the memory array of the NVM cells; wherein each sub-bitline is made up of a upper segment and a lower segment running along one side of one trench; wherein the upper segment connects first source/drain electrodes of a first number of consecutive cells in one column and the lower segment connects second source/drain electrodes of a second number of consecutive cells in the adjacent column; wherein the upper segment and the lower segment at a first layer are connected to a common column line at a second layer via one of the electrical contacts; and wherein the first number and the second number of the consecutive cells comprise no electrical contact being connected to the column lines.