Tungsten separation

摘要

Methods of selectively etching tungsten from the surface of a patterned substrate are described. The etch electrically separates vertically arranged tungsten slabs from one another as needed, for example, in the manufacture of vertical flash memory devices. The tungsten etch may selectively remove tungsten relative to films such as silicon, polysilicon, silicon oxide, aluminum oxide, titanium nitride and silicon nitride. The methods include exposing electrically-shorted tungsten slabs to remotely-excited fluorine formed in a capacitively-excited chamber plasma region. The methods then include exposing the tungsten slabs to remotely-excited fluorine formed in an inductively-excited remote plasma system. A low electron temperature is maintained in the substrate processing region during each operation to achieve high etch selectivity.

主权项

1. A method of etching a patterned substrate, the method comprising:
placing the patterned substrate in a substrate processing region of a substrate processing chamber, wherein the patterned substrate comprises electrically-shorted tungsten slabs arranged in at least one of two adjacent vertical columns, wherein a trench is disposed between the two adjacent vertical columns; flowing a first fluorine-containing precursor into a chamber plasma region within the substrate processing chamber and exciting the first fluorine-containing precursor in a first remote plasma in the chamber plasma region to produce first plasma effluents, wherein the chamber plasma region is fluidly coupled with the substrate processing region through a showerhead and the first remote plasma is capacitively-coupled; flowing the first plasma effluents into the substrate processing region through the showerhead and isotropically etching the electrically-shorted tungsten slabs; flowing a second fluorine-containing precursor into a remote plasma system outside the substrate processing chamber and exciting the second fluorine-containing precursor in a second remote plasma with an external remote plasma power in the remote plasma system to produce second plasma effluents, wherein the second remote plasma is inductively-coupled with the external remote plasma power of between 2,000 watts and 10,000 watts; flowing the second plasma effluents into the substrate processing region; and anisotropically etching additional tungsten material.