Method for etching an etch layer
A method of etching features in a stack comprising a dielectric material on a substrate is provided. In a step (a) an etch plasma is generated from an etch gas, exposing the stack to the etch plasma, and partially etching features in the stack. In a step (b) after step (a) an atomic layer deposition process is provided to deposit a protective film on sidewalls. The atomic layer deposition process comprises a plurality of cycles, wherein each cycle comprises exposing the stack to a first reactant gas comprising WF6, wherein the first reactant gas is adsorbed onto the stack and exposing the stack to a plasma formed from a second reactant gas, wherein the plasma formed from the second reactant gas reacts with the adsorbed first reactant gas to form the protective film over the stack. In a step (c) steps (a)-(b) are repeated at least one time.
1. A method of etching features in a dielectric layer comprising SiO 2 below a hardmask comprising one or more of amorphous carbon, boron doped carbon, boron doped silicon, metal doped carbon, or polysilicon in a stack on a substrate, the method comprising:
(a) generating an etch plasma from an etch gas, exposing the stack to the etch plasma, and partially etching features in the stack in a plasma processing chamber;
(b) after (a) providing an atomic layer deposition process performed in-situ in the plasma processing chamber to deposit a protective film on sidewalls of the features, the atomic layer deposition process comprising a plurality of cycles, wherein each cycle comprises:
(i) exposing the stack to a first reactant gas comprising WF 6 , wherein the first reactant gas is adsorbed onto the stack, wherein the exposing the stack to the first reactant gas exposes the stack to the first reactant gas when the first reactant gas is plasmaless; and
(ii) exposing the stack to a plasma formed from a second reactant gas, wherein the plasma formed from the second reactant gas reacts with adsorbed first reactant gas to form the protective film over the stack, wherein the second reactant gas comprises an oxygen containing component to provide oxidation, wherein the providing the atomic layer deposition process further comprises maintaining a stack temperature below 150° C.; and
(c) repeating (a)-(b) at least one time in-situ in the plasma processing chamber.
2. The method, as recited in claim 1 , wherein the second reactant gas comprises at least one of COS, CO 2 , CO, SO 2 , O 2 , or O 3 .
3. The method, as recited in claim 1 , wherein the providing the atomic layer deposition process is performed for 2 to 100 cycles.
4. The method, as recited in claim 1 , wherein each cycle further comprises:
purging the first reactant gas after exposing the stack to the first reactant gas and before exposing the stack to the plasma formed by the second reactant gas; and
purging the plasma formed from the second reactant gas, after exposing the stack to the plasma formed from the second reactant gas.
5. The method, as recited in claim 1 , wherein the providing the atomic layer deposition process further comprises maintaining a stack temperature below 80° C.