Thyristor-based memory cells, devices and systems including the same and methods for forming the same
View Patent ↗Semiconductor devices including a plurality of thyristor-based memory cells, each having a cell size of 4F 2 , and methods for forming the same are provided. The thyristor-based memory cells each include a thyristor having vertically superposed regions of alternating dopant types, and a control gate. The control gate may be electrically coupled with one or more of the thyristors and may be operably coupled to a voltage source. The thyristor-based memory cells may be formed in an array on a conductive strap, which may function as a cathode or a data line. A system may be formed by integrating the semiconductor devices with one or more memory access devices or conventional logic devices, such as a complementary metal-oxide-semiconductor (CMOS) device.
1. A method of forming a conductive line laterally adjacent at least one sidewall of vertically oriented semiconductor structure, comprising:
forming conductive material laterally adjacent a vertically oriented semiconductor structure;
forming liner material over and laterally adjacent the conductive material;
anisotropically etching the liner material to expose the conductive gate material and leave the liner material laterally adjacent the conductive material; and
using the anisotropically etched liner material as a mask while wet undercut etching the conductive material to form a conductive line laterally adjacent the vertically oriented semiconductor structure.
2. The method of claim 1 comprising removing all of the liner material after forming the conductive line.
3. The method of claim 1 wherein the liner material has a lateral thickness of from about 50 Angstroms to about 100 Angstroms.
4. The method of claim 1 wherein the liner material comprises polysilicon.
5. The method of claim 1 wherein the conductive material comprises at least one of titanium nitride, thallium nitride tungsten, and aluminum.
6. The method of claim 1 wherein the liner material comprises polysilicon; the conductive material comprises at least one of titanium nitride, thallium nitride tungsten, and aluminum; and etching chemistry during the wet undercut etching comprises ammonium hydroxide, hydrogen peroxide, and deionized water.
7. The method of claim 1 comprising forming the conductive line to comprise a transistor gate line, and providing a gate dielectric between the conductive material and the vertically oriented semiconductor structure.
8. A method of forming a control gate line laterally adjacent only a single side of a vertically oriented thyristor material pillar having laterally opposing sidewalls, comprising:
forming a gate dielectric and a conductive control gate line laterally adjacent each of opposing sidewalls of a vertically oriented thyristor material pillar; and
removing only one of the conductive control gate lines from being laterally adjacent one of the opposing sidewalls.
9. The method of claims 8 wherein the removing comprises:
depositing masking material;
forming an aperture through the masking material that exposes the one conductive control gate line; and
etching the one control gate line through the aperture.
10. A method of forming a semiconductor device, comprising:
forming a semiconductor structure comprising amorphous silicon over an electrically insulative material, a conductive material over the amorphous silicon, and semiconductor material over the conductive material;
removing portions of the semiconductor material, the conductive material, and the amorphous silicon to form a plurality of channels exposing the electrically insulative material;
after forming the channels, removing portions of the semiconductor material to form a plurality of pillars; individual of the pillars being provided to include a first doped region and a second doped region over and oppositely doped with respect to the first doped region;
forming at least one control gate laterally adjacent at least one sidewall surface of each pillar of the plurality of pillars; and
providing a third doped region over and oppositely doped with respect to the second doped region, and a fourth doped region over the third doped region.