Patent ID: 7469164

Claim:
A method for instructing a process tool to make adjustments to a process comprising the steps of: emitting a first incident light beam at a first substrate; receiving a first reflected light beam from the first substrate; determining a first spectrum of the first reflected light beam; determining a first property of a first layer of the first substrate based at least in part on the first spectrum; determining a second property of a second layer of the first substrate based at least in part on the first spectrum; determining a virtual cross-section of the substrate based on the first property and the second property; comparing the first property to a first reference property; comparing the second property to a second reference property; wherein comparing the first property to the first reference property and comparing the second property to the second reference property comprises comparing the virtual cross-section of the substrate to a desired cross section; determining desired adjustments to the process to make the properties of the first and second layers more closely conform to the first and second reference properties, based at least in part on the first property comparison and the second property comparison; and providing instructions to the process tool to make the desired adjustments.