Semiconductor memory device having unequal pitch vertical channel transistors employed as selection transistors and method for programming the same

Abstract

A semiconductor device comprises a set of selection transistors, such as in a three-dimensional memory structure or stack having resistance change memory cells arranged along vertical bit lines. Each selection transistor has a non-shared control gate and a shared control gate. The transistor bodies may have an unequal pitch and a common height. Some of the transistor bodies can be misaligned with the vertical bit lines to fit the transistors to the stack. A method for programming the three-dimensional memory structure includes forming one or two channels in a transistor body to provide a current to selected memory cells. Programming can initially use one channel and subsequently use two channels based on a programming progress. A method for fabricating a semiconductor device includes etching a gate conductor material so that shared and non-shared control gates have a common height.