Apparatus and method for forming aperture of vertical cavity surface emitting laser by selective oxidation

A method of forming an aperture of a vertical cavity surface emitting laser (VCSEL) by selective oxidation, comprising:

• providing a furnace having a stage, and a first window and a second window for transmitting light, and placing a wafer for the VCSEL with a pre-oxide layer where an aperture is to be formed, on the stage;
• emitting light onto a top of the wafer for the VCSEL seated on the stage through the first window;
• receiving light reflecting from the wafer for the VCSEL and passing through the second window;
• supplying at least one of oxygen and water vapor into the furnace to create an oxidation atmosphere;
• detecting a peak wavelength variation from light received through the second window, which varies according to a degree of oxidation of the pre-oxide layer;
• and
• adjusting at least one of power and oxidation atmosphere of the furnace based on the detected peak wavelength variation to cease an oxidation reaction, thereby adjusting a size of the aperture.