Thermally guided chemical etching of a substrate and real-time monitoring thereof
A method of controlling a substrate etching process includes disposing a bottom surface or a top surface of a substrate adjacent to volume of etching fluid to produce an etchant-substrate interface and heating the etchant-substrate interface via spatially controlled electromagnetic radiation. The method also includes transmitting a monitoring beam through the substrate, the substrate and volume of etching fluid being at least partially transparent at the wavelength range of the monitoring beam and measuring a property of the substrate surface during the substrate etching process via the monitoring beam to produce a real-time measured property for the substrate. A corresponding etching system and computer-program product is also disclosed herein.
1. A method for controlling a substrate etching process, the method comprising:
disposing a bottom surface or a top surface of a substrate adjacent to a volume of etching fluid to produce an etchant-substrate interface;
heating the etchant-substrate interface via spatially controlled electromagnetic radiation;
transmitting a monitoring beam through the substrate, the substrate and volume of etching fluid being at least partially transparent at the wavelength range of the monitoring beam;
measuring a property of the substrate during the substrate etching process via the monitoring beam to produce a measured property for the substrate; and
adjusting the spatially controlled electromagnetic radiation during the substrate etching process responsive to the measured property for the substrate to provide electromagnetic radiation that is greater in some areas of the etchant-substrate interface than other areas of the etchant-substrate interface.
2. The method of claim 1 , wherein the volume of etching fluid comprises one or more of a liquid, a gas and a plasma.
3. The method of claim 1 , wherein adjusting the spatially controlled electromagnetic radiation changes the temperature of a selected portion of the substrate relative to other portions of the substrate and thereby changes an etching rate for the selected portion of the substrate relative to the other portions of the substrate.
4. The method of claim 1 , wherein adjusting the spatially controlled electromagnetic radiation changes the etching rate for a selected portion of the substrate relative to other portions of the substrate.
5. The method of claim 1 , further comprising placing the substrate below a vessel wall to form an etching vessel.
6. The method of claim 1 , further comprising placing an energy source for the spatially controllable electromagnetic radiation proximate to the substrate.
7. The method of claim 6 , wherein the energy source comprises one or more of a laser, a maser, an LED, a radio element, a gyrotron, a backward wave oscillator, and a thermal radiation emitter such as a filament, a thin film micro heater and a micro hotplate.
8. The method of claim 6 , wherein the energy source comprises an array of etch-assist emitters.
9. The method of claim 6 , wherein adjusting the spatially controlled electromagnetic radiation during the substrate etching process comprises adjusting one or more etch-assist emitters of an array of etch-assist emitters.
10. The method of claim 9 , wherein the array of etch-assist emitters is selected from the group consisting of a VCSEL array, a resistive heater array, a scanning mirror array and an LED array.
11. The method of claim 1 , further comprising placing a monitoring beam detector proximate to the substrate and measuring the measured property of the substrate via the monitoring beam detector.
12. The method of claim 11 , wherein the monitoring beam detector comprises one or more of a charge coupled device, a CMOS image sensor, a wavefront sensor, a scanning confocal microscopy device, an antenna array and an interferometry device.
13. The method of claim 12 , wherein the monitoring beam detector comprises an array of sensors.
14. The method of claim 1 , further comprising flushing the etchant from a retaining vessel previous to measuring the property of the substrate surface.
15. The method of claim 1 , further comprising using spatial light modulation to produce the spatially controlled electromagnetic radiation incident on the etchant-substrate interface.
16. The method of claim 1 , further comprising using a wavefront sensor to measure the property of the substrate surface during the substrate etching process.
17. The method of claim 1 , wherein the spatially controlled electromagnetic radiation is adjusted during the substrate etching process to achieve a desired surface profile for the substrate.
18. The method of claim 1 , wherein a wavelength range of the spatially controlled radiation overlaps with an absorption peak of the etching fluid.
19. The method of claim 1 , wherein adjusting the spatially controlled electromagnetic radiation during the substrate etching process comprises modulating the electromagnetic radiation with one or more electronically-controllable modulating elements.
20. The method of claim 19 , wherein the one or more electronically-controllable modulating elements comprise a liquid crystal device or a scanning mirror device.
21. The method of claim 1 , wherein heating the etchant-substrate interface via spatially controlled electromagnetic radiation comprises projecting an image onto the etchant-substrate interface.
22. The method of claim 21 , wherein adjusting the spatially controlled electromagnetic radiation during the substrate etching process comprises changing the image projected onto the etchant-substrate interface.