Post-manufacturing analysis of a semiconductor device is enhanced via a method that uses a light emitting diode (LED) formed in a semiconductor die. According to an example embodiment of the present invention, a LED is formed within a semiconductor die having a circuit side opposite a back side. The LED is activated and generates radiation. Substrate is removed from the device, and the amount of radiation that passes through the substrate is detected. The amount of radiation that passes through the die is a function of the absorption characteristics of the die and the substrate thickness. By detecting the radiation and using the absorption characteristics of the die, the amount of substrate remaining in the back side of the die is determined and the substrate removal process is controlled therefrom.