Low voltage low capacitance flash memory array

Abstract

In a p-type flash memory array, separate programming and read bit lines are provided. The programming bit line is used only to program the floating gate transistors in the memory cells connected to that bit line. The read bit line is used only to read the state of a floating gate transistor in a selected memory cell connected to that bit line during the operation of the memory circuit. The resulting structure allows the use of low voltages during both programming and operation of the memory array. This makes possible the use of transistors in the memory array with feature sizes less than, for example, 0.18 microns. At the same time variable, unpredictable capacitances associated with each bit line in prior art p-type flash memory structures using comparable low programming voltages are eliminated when a particular memory cell attached to that bit line is being read out.