New optomechanical technique for measuring layer thickness in MEMS processes

Dimensional metrology improvements are needed to achieve the fabrication of repeatable devices, This research presents a new optomechanical technique for measuring the thickness of a suspended material in two distinct microel ectromechanical system (MEMS) fabrication processes. This technique include s design of test structure, choice of measurement tools, method of measurem ent, and computation of thickness. Two tools, the stylus profilometer and o ptical interferometer, are used to take measurements, Non-contact measureme nts are possible on structures as narrow as 5 mum. Local thickness measurem ents are achievable with combined standard uncertainty values of less than 10 nm, Benefits of using the new technique include greater likelihood of fa bricating repeatable devices and more accurate measurements of material par ameters. The proposed technique is also applicable for measuring layers tha t are thinner and made of materials other than the conventional suspended m aterial used in this research.