Patent ID: 8765493

Claim:
A method of characterizing the emission wavelength of a semiconductor light-emitting device structure of a product wafer having a substrate, comprising: establishing a relationship between a device-layer stress S(x,y) and the emission wavelength λ E (x,y) for the device structures formed on the product wafer by measuring the device-layer stress S(x,y) of a test product wafer, dicing the test product wafer to form dies, and measuring the emission wavelengths of the dies as a function of their device-layer stress and corresponding device structure locations (x,y); measuring a change in curvature ΔC(x,y) of the test product wafer based on curvature measurements of the substrate performed before and after substrate processing to form the device structures; calculating the device-layer stress S(x,y) in the test product wafer based on the measured changed in curvature ΔC; and associating the actual emission wavelength λ E with the device structures based on the relationship between the device-layer stress S(x,y) and the (x,y) positions on the test product wafer to establish a predicted emission wavelength for the device structures that corresponds to the emission wavelength λ E .