Rapid and precise temperature control for thermal etching

A method comprising:

• supporting a substrate in a processing chamber having chamber walls using only a pedestal having a plurality of substrate supports that each contact an edge region of the substrate;
• heating, while the substrate is supported by only the plurality of substrate supports, the substrate to a first temperature by emitting visible light from a plurality of light emitting diodes (LEDs) under the substrate, wherein the visible light has wavelengths between 400 nanometers (nm) and 800 nm;
• etching, while the substrate is supported by only the plurality of substrate supports and while the substrate is at the first temperature, a surface of the substrate;
• measuring, using one or more temperature sensors, a temperature of the substrate, wherein the one or more temperature sensors include a pyrometer having a detector and an emitter, wherein a top of the processing chamber includes a port that includes a sensor window, wherein the detector is outside the processing chamber and connected to the port and sensor window, and wherein the emitter is positioned in the pedestal and below the window;
• and
• adjusting, based on the measuring, a power of at least a first set of the plurality of LEDs during the heating, maintaining, and/or etching.

A method comprising:

• emitting visible light from a plurality of light emitting diodes (LEDs) in a pedestal of a processing chamber, wherein the visible light has wavelengths between 400 nanometers (nm) and 800 nm, and wherein a window is above the LEDs in the pedestal;
• measuring, using one or more sensors configured to detect the visible light emitted from the plurality of LEDs, one or more metrics of the visible light emitted by the LEDs, wherein the one or more sensors include a pyrometer having a detector and an emitter, wherein a top of a processing chamber includes a port that includes a sensor window, wherein the detector is outside the processing chamber and connected to the port and sensor window, and wherein the emitter is positioned in the pedestal and below the window;
• and
• adjusting, based at least in part on the measuring, a power of a first set of the plurality of LEDs, wherein the first set includes less LEDs than the plurality of LEDs.