Methods of forming transistor gates
View Patent ↗Some embodiments include methods of forming charge storage transistor gates and standard FET gates in which common processing is utilized for fabrication of at least some portions of the different types of gates. FET and charge storage transistor gate stacks may be formed. The gate stacks may each include a gate material, an insulative material, and a sacrificial material. The sacrificial material is removed from the FET and charge storage transistor gate stacks. The insulative material of the FET gate stacks is etched through. A conductive material is formed over the FET gate stacks and over the charge storage transistor gate stacks. The conductive material physically contacts the gate material of the FET gate stacks, and is separated from the gate material of the charge storage transistor gate stacks by the insulative material remaining in the charge storage transistor gate stacks. Some embodiments include gate structures.
1. A method of forming a plurality of charge storage transistor gates and field effect transistor (FET) gates, comprising:
forming a stack over a semiconductor substrate; the stack comprising a gate dielectric material, a gate material over the gate dielectric material, an electrically insulative material over the gate material, a sacrificial material over the electrically insulative material, and a protective material over the sacrificial material;
patterning the stack into a plurality of pillars; some of the pillars being at charge storage transistor gate locations, and some of the pillars being at FET gate locations;
forming electrically insulative spacers along sidewalls of the pillars;
after forming the electrically insulative spacers, removing the protective material from over the sacrificial material;
removing the sacrificial material from all of the pillars to form cavities at the tops of all of the pillars; individual cavities being bounded by the electrically insulative material along the bottom, and by the spacers along the sides;
after removing the sacrificial material, removing at least some of the electrically insulative material of the pillars at the FET locations to extend the cavities through the electrically insulative material and expose the gate material, while not etching through the electrically insulative material of the pillars at the charge storage transistor locations;
forming a first electrically conductive material conformally within all of the cavities to partially fill the cavities and thereby narrow the cavities, the first electrically conductive material physically contacting the gate material within the extended cavities of the pillars at the FET gate locations, and being separated from the gate material of the pillars at the charge storage transistor gate locations by the electrically insulative material; and
forming second electrically conductive material within the narrowed cavities to entirely fill the cavities.
2. The method of claim 1 wherein the pillars and the spacers along the pillar sidewalls together form a plurality of spaced apart gate constructions, and further comprising, prior to the removal of the protective material, forming an electrically insulative material within spaces between the spaced apart gate constructions.
3. The method of claim 2 wherein the removing the protective material comprises planarization across the electrically insulative material and pillars; and wherein the planarization removes upper regions of the spacers during the removal of the protective material.
4. The method of claim 1 wherein the first electrically conductive material comprises a metal-containing composition.
5. The method of claim 1 wherein the first electrically conductive material comprises a metal nitride.
6. The method of claim 1 wherein the first electrically conductive material comprises one or both of tungsten nitride and tantalum nitride.
7. The method of claim 6 wherein the second electrically conductive material consists of one or more metals.
8. The method of claim 6 wherein the second electrically conductive material consists of tungsten.