NAND string containing self-aligned control gate sidewall cladding

摘要

A method of making a NAND string includes forming a tunnel dielectric over a semiconductor channel, forming a charge storage layer over the tunnel dielectric, forming a blocking dielectric over the charge storage layer, and forming a control gate layer over the blocking dielectric. The method also includes patterning the control gate layer to form a plurality of control gates separated by trenches, and reacting a first material with exposed sidewalls of the plurality of control gates to form self aligned metal-first material compound sidewall spacers on the exposed sidewalls of the plurality of control gates.

主权项

1. A NAND string, comprising:
a semiconductor channel; a tunnel dielectric located over a semiconductor channel; a plurality of floating gates separated by trenches located over the tunnel dielectric; a plurality of blocking dielectric regions separated by the trenches, each of the plurality of blocking dielectric regions is located over at least a respective one of the plurality of floating gates; a plurality of control gates separated by the trenches, each of the plurality of control gates is located over a respective one of the plurality of blocking dielectric regions; and a plurality of metal-first material compound sidewall spacers located on sidewalls of the plurality of control gates; wherein: the sidewall spacers protrude into the trenches beyond sidewalls of respective floating gates located under the control gates; each control gate comprises a first sidewall spacer on a first control gate sidewall and a second sidewall spacer on a second control gate sidewall; a width of each control gate comprises a distance from the first control gate sidewall to the second control gate sidewall; each floating gate comprises a first floating gate sidewall exposed in a first trench and a second floating gate sidewall exposed in a second trench; a width of each control gate comprises a distance from the first floating gate sidewall to the second floating gate sidewall; and the width of each floating gate is greater than the width of each respective control gate located above the respective floating gate.