Radical-activated etching of metal oxides
The present disclosure describes methods and systems for radical-activated etching of a metal oxide. The system includes a chamber, a wafer holder configured to hold a wafer with a metal oxide disposed thereon, a first gas line fluidly connected to the chamber and configured to deliver a gas to the chamber, a plasma generator configured to generate a plasma from the gas, a grid system between the plasma generator and the wafer holder and configured to increase a kinetic energy of ions from the plasma, a neutralizer between the grid system and the wafer holder and configured to generate electrons and neutralize the ions to generate radicals, and a second gas line fluidly connected to the chamber and configured to deliver a precursor across the wafer. The radicals facilitate etching of the metal oxide by the precursor.
1. A method, comprising:
treating a surface of a metal oxide on a wafer with a first plasma;
generating a second plasma from a gas;
generating, with a grid system and a neutralizer, radicals from the second plasma, wherein the grid system comprises a screen grid, an accelerator grid, and a decelerator grid;
vaporizing a precursor with a vaporizer;
delivering the vaporized precursor to a wafer having a metal oxide disposed thereon; and
activating a ligand exchange reaction on the treated surface of the metal oxide with the radicals and the vaporized precursor.
2. The method of claim 1 , wherein the generating the radicals from the second plasma comprises:
separating ions from the second plasma with the screen grid;
accelerating the ions from the second plasma with the accelerator grid;
generating electrons with the neutralizer; and
neutralizing the ions with the electrons to form the radicals.
3. The method of claim 1 , wherein the activating the ligand exchange reaction comprises:
distributing the vaporized precursor across the surface of the metal oxide;
increasing a kinetic energy of the precursor with the radicals; and
etching the surface of the metal oxide with the precursor via the ligand exchange reaction.
4. The method of claim 1 , further comprising distributing the second plasma above the grid system with a gas distribution plate.
5. The method of claim 1 , further comprising blocking, with the decelerator grid, electrons generated by the neutralizer.
6. The method of claim 1 , further comprising heating the metal oxide with a heating system.
7. The method of claim 1 , further comprising cleaning the surface of the metal oxide with a third plasma.
8. A method, comprising:
delivering a first gas with a first gas line to a chamber, wherein the chamber comprises a wafer holder configured to hold a wafer with a metal oxide disposed thereon;
distributing the first gas uniformly above the wafer;
generating a plasma from the first gas with a plasma generator;
generating, with a grid system and a neutralizer, radicals from the plasma, wherein the grid system is configured to increase a kinetic energy of ions in the plasma;
delivering a second gas with a second gas line to the wafer, wherein the second gas line is adjacent to the wafer; and
activating a ligand exchange reaction on a surface of the metal oxide with the radicals and the second gas.
9. The method of claim 8 , wherein the generating the radicals from the plasma comprises:
separating ions from the plasma with a screen grid in the grid system;
accelerating, with an accelerator grid in the grid system, the ions from the plasma;
generating electrons with the neutralizer; and
neutralizing the ions with the electrons to form the radicals.
10. The method of claim 8 , wherein the activating the ligand exchange reaction comprises:
distributing the second gas across the wafer;
increasing a kinetic energy of the second gas with the radicals; and
etching the surface of the metal oxide with the second gas via the ligand exchange reaction.
11. The method of claim 8 , wherein distributing the first gas uniformly above the wafer comprises distributing the first gas above the grid system with a gas distribution plate.
12. The method of claim 8 , further comprising blocking, with a decelerator grid in the grid system, electrons generated by the neutralizer.
13. The method of claim 8 , further comprising heating the wafer with a heating system in the wafer holder.
14. The method of claim 8 , further comprising cleaning the surface of the metal oxide with a plasma of a third gas.
15. A method, comprising:
delivering a first gas with a first gas line to a chamber, wherein the chamber comprises a wafer holder configured to hold a wafer with a metal oxide disposed thereon;
generating a first plasma from the first gas with a plasma generator;
treating the metal oxide with the first plasma;
delivering a second gas with the first gas line to the chamber;
generating a second plasma from the second gas with the plasma generator;
increasing a kinetic energy of ions in the second plasma with a grid system;
neutralizing the ions into radicals with a neutralizer;
delivering a third gas to the wafer with a second gas line; and
activating a ligand exchange reaction on a surface of the treated metal oxide with the radicals and the third gas.
16. The method of claim 15 , wherein the increasing the kinetic energy of the ions comprises:
separating the ions from the second plasma with a screen grid in the grid system; and
accelerating, with an accelerator grid in the grid system, the ions from the plasma.
17. The method of claim 15 , wherein the activating the ligand exchange reaction comprises:
increasing a kinetic energy of the third gas with the radicals; and
etching the surface of the metal oxide with the third gas via the ligand exchange reaction.
18. The method of claim 15 , wherein the neutralizing the ions into the radicals comprises:
generating electrons with the neutralizer; and
neutralizing the ions with the electrons to form the radicals.
19. The method of claim 15 , further comprising distributing the first and second gases above the grid system with a gas distribution plate.
20. The method of claim 15 , further comprising blocking, with a decelerator grid in the grid system, electrons generated by the neutralizer.