Plasma etching with metal sputtering

1 . A method of etching a substrate, the method comprising:

loading the substrate into a plasma etch chamber, the substrate comprising a patterned hard mask layer and an underlying layer, the plasma etch chamber comprising

a chamber part having a surface comprising a refractory metal, and

a first electrode;

flowing a process gas comprising fluorine and carbon into the plasma etch chamber;

while flowing the process gas, applying a source power to the first electrode of the plasma etch chamber to generate a plasma in the plasma etch chamber; and

etching the underlying layer, the etching comprising

exposing the surface of the chamber part to the plasma to sputter the refractory metal from the surface of the chamber part, and

forming a recess in the underlying layer and a conductive polymer layer comprising the refractory metal over sidewalls of the patterned hard mask layer and the underlying layer, the forming comprising exposing the substrate to the plasma.

2 . The method of claim 1 , wherein the refractory metal is tungsten, molybdenum, niobium, tantalum, or ruthenium.

3 . The method of claim 1 , wherein the conductive polymer layer comprises metal carbide.

4 . The method of claim 1 , wherein the conductive polymer layer provides sidewall passivation during the etching.

5 . The method of claim 1 , further comprising discharging charges carried by ions from the sidewalls through the conductive polymer layer.

6 . The method of claim 1 , wherein the chamber part is a focus ring surrounding the substrate.

7 . The method of claim 1 , wherein the plasma is an inductively coupled plasma (ICP), and wherein the chamber part is a top plate disposed at an upper wall of the plasma etch chamber.

8 . The method of claim 1 , wherein the plasma is a capacitively coupled plasma (CCP), and wherein the chamber part is a second electrode disposed in an upper portion of the plasma etch chamber.

9 . A method of etching a substrate, the method comprising:

loading the substrate into a plasma etch chamber, the substrate comprising a patterned hard mask layer and an underlying layer, the plasma etch chamber comprising:

a focus ring having a surface comprising a refractory metal; and

a first electrode;

flowing a process gas comprising fluorine and carbon into the plasma etch chamber;

while flowing the process gas, applying a source power to the first electrode of the plasma etch chamber to generate a plasma in the plasma etch chamber; and

etching the underlying layer, the etching comprising

exposing the surface of the focus ring to the plasma to sputter the refractory metal from the surface of a chamber part of the plasma etch chamber, and

exposing the substrate to the plasma to form a recess in the underlying layer, wherein a conductive polymer layer comprising the refractory metal is deposited over the substrate with a radial gradient such that a concentration of the refractory metal in the conductive polymer layer near an edge portion of the substrate is higher than a central portion of the substrate.

10 . The method of claim 9 , wherein the refractory metal is tungsten, molybdenum, niobium, tantalum, or ruthenium.

11 . The method of claim 9 , wherein the conductive polymer layer comprises metal carbide.

12 . The method of claim 9 , further comprising tuning the radial gradient, the tuning comprising changing the source power.

13 . The method of claim 9 , further comprising tuning the radial gradient, the tuning comprising tuning a temperature of the substrate.

14 . The method of claim 13 , wherein tuning the temperature of the substrate further comprising creating a radial temperature gradient across the substrate.

15 . A method of etching a substrate, the method comprising:

loading the substrate into a plasma etch chamber, the substrate comprising a patterned hard mask layer and an underlying layer, the plasma etch chamber comprising

a top electrode having a surface comprising a first refractory metal,

a bottom electrode,

a first radio frequency (RF) power source connected to the bottom electrode,

a second radio frequency (RF) power source connected to the bottom electrode,

a direct current (DC) voltage source connected to the top electrode, and

a focus ring having a surface comprising a second refractory metal;

flowing a process gas comprising fluorine and carbon into the plasma etch chamber;

while flowing the process gas, applying a source power to the bottom electrode using the first RF power source to generate a plasma in the plasma etch chamber;

applying a bias power to the bottom electrode using the second RF power source;

applying a DC voltage to the top electrode using the DC voltage source; and

etching the underlying layer, the etching comprising

sputtering the first and second refractory metals from the top electrode, and

exposing the substrate to the plasma to form a recess in the underlying layer, wherein a conductive polymer layer comprising the first and second refractory metals is deposited on sidewalls of the patterned hard mask layer and the underlying layer.

16 . The method of claim 15 , wherein the first refractory metal is tungsten, molybdenum, niobium, tantalum, or ruthenium, and wherein the second refractory metal is tungsten, molybdenum, niobium, tantalum, or ruthenium.

17 . The method of claim 15 , wherein the first and second refractory metals are a same metal.

18 . The method of claim 15 , further comprising tuning the plasma such that the conductive polymer layer near an edge portion of the substrate is thicker than a central portion of the substrate.

19 . The method of claim 18 , wherein tuning the plasma comprises adjusting the source power, the bias power, or the DC voltage.

20 . The method of claim 18 , wherein tuning the plasma comprising creating a radial temperature gradient across the substrate.