Patent ID: 8969153
Filing Date: 2015-03-03
Classification: H01L

Abstract:
1. A method of making a NAND string, comprising: 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; forming a control gate layer over the blocking dielectric; patterning the control gate layer to form a plurality of control gates separated by trenches, wherein the step of patterning the control gate layer comprises a first etching step of etching the control gate layer and stopping the first etching step prior to reaching the semiconductor channel; 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; and a second etching step of etching the charge storage layer after the step of forming the metal silicide sidewall spacers to extend the trenches to at least one of the tunnel dielectric and the semiconductor channel, wherein: the step of reacting the first material comprises depositing a first material layer into the trenches such that the first material layer contacts exposed metal or metal nitride sidewalls of the plurality of control gates, followed by annealing the first material layer to react the first material layer with the exposed metal or metal nitride sidewalls of the plurality of control gates; the first material layer comprises a silicon layer and the metal-first material compound sidewall spacers comprise metal silicide sidewall spacers; and the step of patterning the control gate layer comprises a first etching step of etching the control gate layer and stopping the first etching step prior to reaching the semiconductor channel.