Fabrication method for a three-dimensional memory array of thin-film ferroelectric transistors formed with an oxide semiconductor channel

Abstract

A fabrication process for a memory structure including three-dimensional arrays of thin-film ferroelectric storage transistors is disclosed. In some embodiments, the ferroelectric storage transistors are organized in three-dimensional arrays of horizontal NOR memory strings. In some embodiments, the fabrication process uses a liner underlayer in the deposition process of the channel layer where the liner underlayer provides a uniform surface for the deposition of the channel layer and also serves as an etch stop layer in the subsequent metal replacement process. In another embodiment, the fabrication process applies a liner layer in vertical shafts during the local word line process to reduce or eliminate irregular features in the local word line structures, thereby enhancing the electrical characteristics and reliability of the memory arrays thus formed.