High aspect ratio plasma etch for 3D NAND semiconductor applications
Embodiments of the present disclosure provide methods for forming features in a film stack that may be utilized to form stair-like structures with accurate profiles control in manufacturing three dimensional (3D) stacking of semiconductor chips. In one example, a method of etching a material layer disposed on a substrate using synchronized RF pulses includes providing an etching gas mixture into a processing chamber having a film stack disposed on a substrate, synchronously pulsing a RF source power and a RF bias power into the etching gas mixture at a ratio of less than 0.5, and etching the film stack disposed on the substrate.
1. A method of etching a material layer disposed on a substrate using synchronized RF pulses comprising:
providing an etching gas mixture into a processing chamber having a film stack disposed on a substrate;
synchronously pulsing a RF source power and a RF bias power into the etching gas mixture, wherein an energy ratio of the RF source power to the RF bias power is about less than 0.5; and
etching the film stack disposed on the substrate.
2. The method of claim 1 , wherein the film stack includes a multi-material layer made from repeated pairs of layers.
3. The method of claim 2 , wherein each repeated pair includes first layer that is a dielectric layer and a second layer that is a dielectric layer or a conductive layer.
4. The method of claim 3 , wherein the first layer is a silicon oxide layer and the second layer is a silicon nitride layer.
5. The method of claim 1 , wherein the RF source power has a frequency greater than 2.5 MHz and the RF bias power has a frequency less than 2.5 MHz.
6. The method of claim 1 , wherein the RF source power has a frequency of about 13 MHz.
7. The method of claim 1 , wherein the RF bias power has a frequency of about 2 MHz.
8. The method of claim 1 , wherein the RF source power and the RF bias power are synchronously pulsed at a pulsing frequency between about 500 Hz and about 5 kHz.
9. The method of claim 1 , wherein the etching gas mixture comprises a fluorine-carbon containing gas.
10. The method of claim 9 , wherein a molecule of the fluorine-carbon containing gas has greater than 3 carbon atoms.
11. The method of claim 9 , wherein the etching gas mixture further comprises a halogen containing gas and a oxygen containing gas.
12. The method of claim 11 , wherein the halogen containing gas is NF 3 and the oxygen containing gas is O 2 .
13. The method of claim 9 , wherein the fluorine-carbon containing includes C 4 F 6 , C 4 F 8 and CF 4 .
14. The method of claim 1 , wherein synchronously pulsing the RF source power and the RF bias power further comprises:
synchronously pulsing the RF source power and the RF bias power while continuously applying the etching gas mixture into the processing chamber.
15. The method of claim 1 , wherein synchronously pulsing the RF source power and the RF bias power further comprises:
pulsing the RF source power and the RF bias power at a ratio between about 0.5:1 and about 0.01:1.
16. The method of claim 1 , wherein providing the etching gas mixture into the processing chamber further comprises:
maintaining a process pressure at between about 0.1 mTorr and about 50 mTorr.
17. A method of etching a film stack disposed on a substrate using synchronized RF pulses comprising:
providing an etching gas mixture into a processing chamber having a film stack disposed on a substrate, wherein the film stack includes repeated pairs of layers;
synchronously pulsing a RF source power at a frequency greater than 2.5 MHz and a RF bias power at a frequency less than 2.5 MHz into the etching gas mixture, wherein an energy ratio of the RF source power to the RF bias power is about less than 0.5; and
etching the film stack disposed on the substrate.
18. The method of claim 17 , wherein the etching gas mixture comprises CF 4 C 4 F 6 or C 4 F 8 .
19. The method of claim 18 , wherein the etching gas mixture further comprises NF 3 and O 2 .
20. A method of etching a film stack disposed on a substrate using synchronized RF pulses, the film stack utilized to form a stair-like structures on the substrate comprising:
providing an etching gas mixture including a fluorine-carbon containing and a halogen containing gas into a processing chamber having a film stack disposed on a substrate, wherein the film stack includes repeated pairs of layers;
synchronously pulsing a RF source power at a frequency greater than 2.5 MHz and a RF bias power at a frequency less than 2.5 MHz into the etching gas mixture, wherein an energy ratio of the RF source power to the RF bias power is about less than 0.5; and
etching the film stack disposed on the substrate to form features with aspect ratio greater than 20:1.