Contactless flash memory with buried diffusion bit/virtual ground lines

Abstract

A contactless Flash memory has memory cells between each pair of adjacent diffused lines and about half as many metal lines as diffused lines. Bank select cells at the top of a bank in the memory connect the metal lines to pairs of diffused lines that are offset relative to pairs of diffused lines connected to the metal lines via bank select cells at the bottom of the bank. Decoding circuits activate the bank select cells at one end of a bank to access memory cells in odd-numbered columns of the bank and activate the bank select cells at the other end to access memory cells in even-numbered columns of the bank. For the access, all metal lines to one side of a selected memory cell are grounded, while all metal lines on the other side are biased for reading or programming of the selected memory cell.