Method of etching a thin film using pressure modulation
A method for transferring a feature pattern to a thin film on a substrate is described. The method comprises disposing a substrate comprising one or more mask layers overlying a thin film in a plasma processing system, and forming a feature pattern in the one or more mask layers. The method further comprises transferring the feature pattern in the one or more mask layers to the thin film by: performing a first plasma etching process at a first pressure less than about 80 mtorr, and performing a second plasma etching process at a second pressure greater than about 80 mtorr.
1. A method of transferring a pattern to a substrate in a single-wafer plasma processing system, comprising:
disposing a substrate comprising one or more mask layers overlying a thin film in said single-wafer plasma processing system;
forming a feature pattern in said one or more mask layers;
selecting a first process recipe including a first pressure of about 50 mTorr or less, a first etching chemistry comprising a first fluorocarbon-containing gas and a first oxygen-containing gas, a first fluorocarbon-containing gas flow rate of about 1-1000 sccm, a first oxygen-containing gas flow rate of about 1-1000 sccm, a first upper electrode RF bias of about 0-2000 W, a first upper electrode DC voltage of about 0 to about −2500 V, a first lower electrode RF bias of about 10-1000 W, and a first duration of time, and selecting a second process recipe including a second pressure of about 150 mTorr or greater, a second etching chemistry comprising a second fluorocarbon-containing gas and a second oxygen-containing gas, a second fluorocarbon-containing gas flow rate of about 1-1000 sccm, a second oxygen-containing gas flow rate of about 1-1000 sccm, a second upper electrode RF bias of about 0-2000 W, a second upper electrode DC voltage of about 0 to about −2500 V, a second lower electrode RF bias of about 10-1000 W, and a second duration of time, wherein said first process recipe is configured to reduce micro-loading in said feature pattern during a plasma etch transfer to said thin film and said second process recipe is configured to reduce feature roughness in said feature pattern during a plasma etch transfer to said thin film; and
transferring said feature pattern in said one or more mask layers to said thin film by:
performing a first plasma etching process using said first process recipe, and
performing a second plasma etching process using said second process recipe,
wherein said performing said first plasma etching process and said performing said second plasma etching process are alternatingly repeated two or more cycles until said pattern is transferred to said thin film.
2. The method of claim 1 , wherein said performing said first plasma etching process precedes said performing said second plasma etching process.
3. The method of claim 2 , wherein said first duration of time exceeds said second duration of time.
4. The method of claim 1 , wherein said performing said first plasma etching process comprises:
introducing said first etching chemistry to said plasma processing system according to said first fluorocarbon-containing gas flow rate and said first oxygen-containing gas flow rate;
setting said selected first pressure, first upper electrode RF bias, first upper electrode DC voltage, and first lower electrode RF bias in said plasma processing system; and
forming plasma from said first etching chemistry.
5. The method of claim 4 , wherein said first fluorocarbon-containing gas is selected from the group consisting of CF 4 , C 3 F 6 , C 4 F 6 , C 4 F 8 , C 5 F 8 , CHF 3 , and CH 2 F 2 , and wherein said first oxygen-containing gas is selected from the group consisting of O 2 , CO, CO 2 , NO, NO 2 , and N 2 O.
6. The method of claim 5 , wherein said first fluorocarbon-containing gas consists of CF 4 and said first oxygen-containing gas consists of CO.
7. The method of claim 4 , further comprising:
introducing an inert gas to said plasma processing system with said first etching chemistry.
8. The method of claim 4 , wherein said performing said second plasma etching process comprises:
introducing said second etching chemistry to said plasma processing system according to said second fluorocarbon-containing gas flow rate and said second oxygen-containing gas flow rate;
setting said selected second pressure, second upper electrode RF bias, second upper electrode DC voltage, and second lower electrode RF bias in said plasma processing system; and
forming plasma from said second etching chemistry.
9. The method of claim 8 , wherein said second fluorocarbon-containing gas is selected from the group consisting of CF 4 , C 3 F 6 , C 4 F 6 , C 4 F 8 , C 5 F 8 , CHF 3 , and CH 2 F 2 , and wherein said second oxygen-containing gas is selected from the group consisting of O 2 , CO, CO 2 , NO, NO 2 , and N 2 O.
10. The method of claim 9 , wherein said second fluorocarbon-containing gas consists of CF 4 and said second oxygen-containing gas consists of O 2 .
11. The method of claim 8 , further comprising:
introducing an inert gas to said plasma processing system with said second etching chemistry.
12. The method of claim 1 , wherein said thin film comprises a porous dielectric film or a non-porous dielectric film.
13. The method of claim 1 , wherein said thin film comprises an inorganic material, or an inorganic-organic hybrid material.
14. The method of claim 1 , wherein said thin film comprises a collective film including silicon, carbon, oxygen, and optionally hydrogen.
15. The method of claim 8 , wherein said first and second fluorocarbon-containing gases consist of CF 4 , said first oxygen-containing gas consists of CO and said second oxygen-containing gas consists of O 2 .