Systems for etching a substrate using a hybrid wet atomic layer etching process
The present disclosure provides a system for etching an exposed material on a substrate disposed within a process chamber using a hybrid atomic layer etching (ALE) process that combines a gas-phase surface modification step with a liquid-phase dissolution step within the same process chamber. In the hybrid ALE process disclosed herein, a gas-phase reactant is used to modify an exposed surface of the material to create a modified surface layer, and one or more liquid-phase reactants are used to selectively dissolve the modified surface layer without dissolving the material underlying the modified surface layer. Once the modified surface layer is selectively dissolved, the substrate may be dried and the gas-phase surface modification and liquid-phase dissolution steps may be repeated for one or more ALE cycles until a desired amount of the material is etched.
1. A system configured to etch a substrate using a hybrid atomic layer etching (ALE) process, the system comprising:
a process chamber configured to receive the substrate;
a gas supply system comprising at least one reservoir containing a gas-phase reactant, wherein the gas supply system is coupled to supply the gas-phase reactant to the process chamber via a gas supply line coupled between the gas supply system and the process chamber;
a chemical supply system comprising one or more reservoirs containing one or more liquid-phase reactants, wherein the chemical supply system is coupled to supply the one or more liquid-phase reactants to the process chamber via a liquid supply line coupled between the chemical supply system and the process chamber; and
a controller comprising one or more non-transitory computer-readable mediums that store programming instructions and one or more programmable integrated circuits that execute the programming instructions to control process conditions within the process chamber while multiple cycles of the hybrid ALE process are performed to etch a material exposed on the substrate, wherein each cycle includes a gas-phase surface modification step and a liquid-phase dissolution step, and wherein the controller is configured to supply:
a first set of control signals to the gas supply system during the gas-phase surface modification step, wherein the first set of control signals cause the gas supply system to introduce the gas-phase reactant into the process chamber to expose the substrate to the gas-phase reactant, chemically modify an exposed surface of the material and provide a modified surface layer of the material; and
a second set of control signals to the chemical supply system during the liquid-phase dissolution step, wherein the second set of control signals cause the chemical supply system to dispense the one or more liquid-phase reactants onto a surface of the substrate to selectively dissolve the modified surface layer without dissolving the material underlying the modified surface layer.
2. The system of claim 1 , wherein the material includes a transition metal.
3. The system of claim 2 , wherein the material comprises molybdenum (Mo), tungsten (W), vanadium (V), niobium (Nb), tantalum (Ta), or chromium (Cr).
4. The system of claim 2 , wherein the gas-phase reactant is a gas-phase oxidizing agent, which oxidizes the exposed surface of the material to form a self-limiting oxide layer.
5. The system of claim 4 , wherein the process chamber further comprises a gas inlet, which is coupled to receive the gas-phase oxidizing agent from the gas supply system, and wherein the gas inlet is configured to introduce the gas-phase oxidizing agent into the process chamber to create an oxygen-containing gaseous environment within the process chamber.
6. The system of claim 4 , wherein the process chamber further comprises a gas nozzle, which is coupled to receive the gas-phase oxidizing agent from the gas supply system, and wherein the gas nozzle is configured to translate over the surface of the substrate to dispense the gas-phase oxidizing agent onto the surface of the substrate.
7. The system of claim 4 , wherein the one or more liquid-phase reactants comprise an aqueous solution, which selectively dissolves and removes the self-limiting oxide layer without dissolving the material underlying the self-limiting oxide layer.
8. The system of claim 4 , wherein the one or more liquid-phase reactants comprise a complexing agent dissolved in a first liquid solvent, and wherein the complexing agent binds to the self-limiting oxide layer to form a ligand-metal complex.
9. The system of claim 8 , wherein the ligand-metal complex is soluble in the first liquid solvent, and wherein the first liquid solvent dissolves the ligand-metal complex and removes the self-limiting oxide layer.
10. The system of claim 8 , wherein the one or more liquid-phase reactants further comprise a second liquid solvent, which is different from the first liquid solvent, wherein the ligand-metal complex is insoluble in the first liquid solvent and soluble in the second liquid solvent, and wherein the second liquid solvent dissolves the ligand-metal complex and removes the self-limiting oxide layer.
11. The system of claim 1 , wherein the process chamber further comprises a gas inlet or a gas nozzle, which is configured to supply a gas stream of air or nitrogen to the substrate to dry the surface of the substrate.
12. The system of claim 1 , wherein the process chamber further comprises a spinner configured to rotate at a rotational speed, wherein the substrate is held on the spinner, and wherein the controller is configured to control the rotational speed of the spinner to dry the surface of the substrate.
13. A system configured to etch a substrate using a hybrid atomic layer etching (ALE) process, the system comprising:
a process chamber configured to receive the substrate;
a gas supply system comprising at least one reservoir containing a gas-phase reactant, wherein the gas supply system is coupled to supply the gas-phase reactant to the process chamber via a gas supply line coupled between the gas supply system and the process chamber;
a chemical supply system comprising one or more reservoirs containing one or more liquid-phase reactants, wherein the chemical supply system is coupled to supply the one or more liquid-phase reactants to the process chamber via a liquid supply line coupled between the chemical supply system and the process chamber; and
a controller comprising one or more non-transitory computer-readable mediums that store programming instructions and one or more programmable integrated circuits that execute the programming instructions to control process conditions within the process chamber while multiple cycles of the hybrid ALE process are performed to etch a material exposed on the substrate, wherein each cycle includes a gas-phase surface modification step and a liquid-phase dissolution step, and wherein the controller is configured to supply:
a first set of control signals to the gas supply system during the gas-phase surface modification step, wherein the first set of control signals cause the gas supply system to introduce the gas-phase reactant into the process chamber to expose the substrate to the gas-phase reactant, chemically modify an exposed surface of the material and provide a modified surface layer of the material;
a second set of control signals to the chemical supply system during the liquid-phase dissolution step, wherein the second set of control signals cause the chemical supply system to dispense the one or more liquid-phase reactants onto a surface of the substrate to selectively dissolve the modified surface layer without dissolving the material underlying the modified surface layer;
wherein the controller is programmed to control timing of the gas-phase surface modification step and the liquid-phase dissolution step performed during each cycle of the hybrid ALE process, so that the one or more liquid-phase reactants are dispensed onto the surface of the substrate while the substrate is exposed to the gas-phase reactant; and
wherein the one or more liquid-phase reactants dispensed during the liquid-phase dissolution step segregate the gas-phase surface modification step from the liquid-phase dissolution step by displacing the gas-phase reactant from the surface of the substrate.
14. The system of claim 13 , wherein the process chamber further comprises a spinner configured to rotate at a rotational speed, wherein the substrate is held on the spinner, and wherein the controller controls the rotational speed of the spinner during the liquid-phase dissolution step, so that the one or more liquid-phase reactants are dispensed onto the surface of the substrate in the presence of the gas-phase reactant while the spinner is rotating at a first rotational speed.
15. The system of claim 14 , wherein rotation of the spinner at the first rotational speed causes the one or more liquid-phase reactants to propagate outward along the surface of the substrate to dissolve the modified surface layer and prevent the gas-phase reactant from reaching the surface of the substrate and re-oxidizing underlying portions of the substrate.
16. The system of claim 15 , wherein after the liquid-phase dissolution step is performed to selectively dissolve the modified surface layer, the controller controls the rotational speed of the spinner during a spin drying step to flush the one or more liquid-phase reactants from the surface of the substrate and re-expose the exposed surface of the material to the gas-phase reactant in a subsequent gas-phase surface modification step.
17. The system of claim 16 , wherein the controller controls the rotational speed of the spinner during the spin drying step, so that the spinner rotates at a second rotational speed, which is greater than the first rotational speed.
18. A system configured to etch a substrate using a hybrid atomic layer etching (ALE) process, the system comprising:
a process chamber configured to receive the substrate;
a gas supply system comprising at least one reservoir containing a gas-phase reactant, wherein the gas supply system is coupled to supply the gas-phase reactant to the process chamber via a gas supply line coupled between the gas supply system and the process chamber;
a chemical supply system comprising one or more reservoirs containing one or more liquid-phase reactants, wherein the chemical supply system is coupled to supply the one or more liquid-phase reactants to the process chamber via a liquid supply line coupled between the chemical supply system and the process chamber; and
a controller comprising one or more non-transitory computer-readable mediums that store programming instructions and one or more programmable integrated circuits that execute the programming instructions to control process conditions within the process chamber while multiple cycles of the hybrid ALE process are performed to etch a material exposed on the substrate, wherein each cycle includes a gas-phase surface modification step and a liquid-phase dissolution step, and wherein the controller is configured to supply:
a first set of control signals to the gas supply system during the gas-phase surface modification step, wherein the first set of control signals cause the gas supply system to introduce the gas-phase reactant into the process chamber to expose the substrate to the gas-phase reactant, chemically modify an exposed surface of the material and provide a modified surface layer of the material; and
a second set of control signals to the chemical supply system during the liquid-phase dissolution step, wherein the second set of control signals cause the chemical supply system to dispense the one or more liquid-phase reactants onto a surface of the substrate to selectively dissolve the modified surface layer without dissolving the material underlying the modified surface layer; and
wherein the controller is programmed to control a temperature and a pressure within the process chamber, so that the gas-phase surface modification step and the liquid-phase dissolution step are performed at roughly the same temperature and the same pressure.
19. The system of claim 18 , wherein the controller is programmed to control the temperature and the pressure within the process chamber, so that the gas-phase surface modification step and the liquid-phase dissolution step are both performed at or near atmospheric pressure and room temperature.
20. The system of claim 18 , wherein the controller is programmed to control the temperature and/or the pressure within the process chamber, so that the temperature and/or the pressure changes no more than 20% between the gas-phase surface modification step and the liquid-phase dissolution step.