Laser machined ultrathin microscale platinum thermometers on transparent oxide substrates

Abstract

Ultrathin microscale platinum resistive thermometers are of key value to transient temperature measurements. Neither transparent oxide substrates nor femtosecond laser patterning have been investigated for the fabrication of Pt thin film thermometers. Here, we have fabricated a laser machined, 50 mu m wide and 50 nm thick, serpentine, Pt thin film sensor capable of sensing temperatures up to 650 degrees C over multiple heating and cooling cycles. Various materials and associated processing conditions were studied, including both sapphire and silica as transparent substrates, alumina and titanium dioxide as adhesion layers, and lastly alumina and silicon dioxide as capping layer. In situ resistance monitoring helps verify the multi-cycle stability of the sensor and guide the optimization. 10 mu m sized sensors could be laser-machined, but did not survive multiple heating and cooling cycles. We demonstrate that sensors with amorphous Ge thin layers can also repeatably measure temperatures up to 650 degrees C. It is anticipated that this sensor can be used for fast, high spatial resolution temperature probing for laser processing of thin films. (C) 2019 Elsevier B.V. All rights reserved.