Photothermal Measurement of Metal Film Thickness in Integrated Circuit Devices

Metal films have been used extensively in very-large-scale integration (VLSI) devices. They are used to build interconnects, field-effect transistor gates, diffusion barriers, and conduction pads for input or output leads. Metals such as aluminum, tungsten, titanium and platinum are deposited on an insulating layer [1,2]. The metal film thicknesses range from 100 A to 1 µm. Due to the ever-growing need for high speed, high density, and low power dissipation in integrated circuit (IC) technology, accurate control of the metallization process becomes essential to ensure the quality and yield of the final product. One of the important parameters in the metallization process control is the film thickness.