Micron Technology, Inc.
THREE-NODE ACCESS DEVICE FOR VERTICAL THREE DIMENSIONAL (3D) MEMORY

Abstract:

Systems, methods and apparatus are provided for a three-node access device in vertical three dimensional (3D) memory. An example method includes a method for forming arrays of vertically stacked memory cells, having horizontally oriented access devices and vertically oriented access lines. The three-node access devices include a first source/drain region (1) and a second source/drain region (2) separated by a channel and gates (3) opposing the channel, but do not have a direct, electrical body contact to a body region and/or channel of the access devices. The method includes depositing alternating layers of a dielectric material and a sacrificial semiconductor material in repeating iterations to form a vertical stack, a first region of the sacrificial semiconductor material in which to form a first and a second source/drain region separated laterally by a channel region. An etchant process is used to form a first vertical opening exposing vertical sidewalls in the vertical stack adjacent the first region. The first region is selectively etched to form a first horizontal opening removing the sacrificial semiconductor material a first horizontal distance back from the first vertical opening. A source/drain material, a channel material, and a first source/drain material are deposited in the first horizontal opening to form the three-node access device for a memory cell among the arrays of vertically stacked memory cells.