Pulsed ultra-high aspect ratio dielectric etch
A method for selectively etching an ultra high aspect ratio feature dielectric layer through a carbon based mask in an etch chamber is provided. A flow of an etch gas is provided, comprising a fluorocarbon containing molecule and an oxygen containing molecule to the etch chamber. A pulsed bias RF signal is provided. An energizing RF signal is provided to transform the etch gas to a plasma.
1. A method for etching an ultra high aspect ratio feature dielectric layer through a carbon based mask in an etch chamber, comprising:
a selective etching the dielectric layer with respect to the carbon based mask, wherein the selective etching provides a net deposition of a fluorocarbon based polymer on the carbon based mask;
stopping the selective etch; and
a subsequent selective etching the dielectric layer with respect to the carbon based mask, comprising:
providing a flow of an etch gas, comprising a fluorocarbon containing molecule and an oxygen containing molecule to the etch chamber;
providing a pulsed bias RF signal; and
providing an energizing RF signal.
2. The method, as recited in claim 1 , wherein the selective etching the dielectric layer with respect to the carbon based mask, comprises:
providing a flow of an etch gas and a fluorocarbon polymer gas to the etch chamber;
providing a continuous wave bias RF signal; and
providing an energizing RF signal.
3. The method, as recited in claim 2 , wherein the carbon based mask is one of a photoresist and amorphous carbon.
4. The method, as recited in claim 2 , wherein the carbon based mask is amorphous carbon.
5. The method, as recited in claim 4 , wherein the ultra high aspect ratio feature has an aspect ratio of at least 30:1.
6. The method, as recited in claim 4 , wherein the selective etching has a selectivity greater than 3 to 1.
7. The method, as recited in claim 6 , wherein the subsequent selective etching has a selectivity greater than 3 to 1.
8. The method, as recited in claim 4 , wherein the selective etching has a selectivity greater than 5 to 1.
9. The method, as recited in claim 8 , wherein the subsequent selective etching has a selectivity greater than 5 to 1.
10. The method, as recited in claim 4 , wherein the selective etching has an infinite selectivity.
11. The method, as recited in claim 10 , wherein the subsequent selective etching has an infinite selectivity.
12. The method, as recited in claim 1 , wherein the dielectric layer is a silicon oxide or silicon nitride based layer.
13. The method, as recited in claim 12 , wherein the dielectric layer is a single uniform layer.
14. A method for selectively etching an ultra high aspect ratio feature dielectric layer through a carbon based mask in an etch chamber, comprising:
providing a flow of an etch gas, comprising a fluorocarbon containing molecule and an oxygen containing molecule to the etch chamber;
providing a pulsed bias RF signal;
providing an energizing RF signal to transform the etch gas to a plasma; and etching the carbon based mask until a feature has a high aspect ratio greater than 25.
15. The method, as recited in claim 14 , wherein the carbon based mask is amorphous carbon.
16. The method, as recited in claim 15 , wherein the ultra high aspect ratio feature has an aspect ratio of at least 30:1.
17. The method, as recited in claim 16 , wherein the selective etching has an infinite selectivity.
18. The method, as recited in claim 17 , wherein the dielectric layer is a single uniform silicon oxide or silicon nitride based layer.