Sunrise Memory Corporation

Vinod Purayath

Eli Harari

Wu-Yi Henry Chien

Jie Zhou

Shohei Kamisaka

Christopher John Petti

George Samachisa

Yosuke Nosho

Michiru Nakane

A process for manufacturing a 3-D NOR memory array provides thin-film storage transistors of each NOR memory string in either shafts or portions of a trench between adjacent shafts.

Methods for fabricating a 3-dimensional memory structure of nor memory strings

A method for forming a three-dimensional memory structure above a semiconductor substrate includes forming two or more active stack sections, each formed on top of each other and separated by a dielectric buffer layer, where each active stack section includes multilayers separated by isolation dielectric layers and trenches with shafts filled with a sacrificial material. After the multiple active stack sections are formed, the method removes the sacrificial material in the shafts and removes portions of the dielectric buffer layer between shafts of adjacent active stack sections. The method fills the openings with a gate dielectric layer and a gate conductor. In some embodiments, the gate dielectric layer is discontinuous in the shaft over the depth of the multiple active stack sections.

Three-dimensional memory structure fabricated using repeated active stack sections

A process for fabricating a three-dimensional NOR memory string of storage transistors implements a channel-last fabrication process with channel replacement using silicon germanium (SiGe). In particular, the process uses silicon germanium as a sacrificial layer, to be replaced with the channel material after the charge-storage layer of the storage transistors is formed. In this manner, the channel region is prevented from experiencing excessive high-temperature processing steps, such as during the annealing of the charge-storage layer.

Three-dimensional memory structure fabrication using channel replacement

Thin-film Ferroelectric field-effect transistor (FeFET) may be organized as 3-dimensional NOR memory string arrays. Each 3-dimensional NOR memory string array includes a row of active stack each including a predetermined number of active strips each provided one on top of another and each being spaced apart from another by an isolation layer. Each active strip may include a shared source layer and a shared drain layer shared by the FeFETs provided along the active strip. Data storage in the active strip is provided by ferroelectric elements that can individually electrically set into one of two polarization states. FeFETs on separate active strips may be configured for read, programming or erase operations in parallel.

Three-dimensional memory string array of thin-film ferroelectric transistors

In the highly efficient fabrication processes for HNOR arrays provided herein, the channel regions of the storage transistors in the HNOR arrays are protected by a protective layer after deposition until the subsequent deposition of a charge-trapping material before forming local word lines. Both the silicon for the channel regions and the protective material may be deposited in amorphous form and are subsequently crystallized in an anneal step. The protective material may be silicon boron, silicon carbon or silicon germanium. The protective material induces greater grain boundaries in the crystallized silicon in the channel regions, thereby providing greater charge carrier mobility, greater conductivity and greater current densities.

Process for a 3-dimensional array of horizontal nor-type memory strings

A process includes (a) providing a semiconductor substrate having a planar surface; (b) forming a plurality of thin-film layers above the planar surface of the semiconductor substrate, one on top of another, including among the thin-film layers first and second isolation layers, wherein a significantly greater concentration of a first dopant specie is provided in the first isolation layer than in the second isolation layer; (c) etching along a direction substantially orthogonal to the planar surface through the thin-films to create a trench having sidewalls that expose the thin-film layers; (d) depositing conformally a semiconductor material on the sidewalls of the trench; (e) annealing the first isolation layer at a predetermined temperature and a predetermined duration such that the first isolation layer act as a source of the first dopant specie which dopes a portion of the semiconductor material adjacent the first isolation layer; and (f) selectively etching the semiconductor material to remove the doped portion of the semiconductor material without removing the remainder of the semiconductor material.

Process for preparing a channel region of a thin-film transistor in a 3-dimensional thin-film transistor array

3-dimensional memory string array of thin-film ferroelectric transistors

A process for building a 3-Dimensional NOR memory array avoids the challenge of etching a conductor material that is aimed at providing local word lines at a fine pitch. The process defines the local word lines between isolation shafts that may be carried out at a lower aspect ratio than would be required for etching the conductor material.

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Sedona, AZ, United States of America

Vinod Purayath