Laser machined ultrathin microscale platinum thermometers on transparent oxide substrates

TL;DR

This paper presents the fabrication of ultrathin, laser-machined platinum microscale thermometers on transparent oxide substrates capable of high-temperature sensing up to 650°C, with demonstrated stability over multiple cycles.

Contribution

The study introduces a novel fabrication process for durable, high-temperature platinum thermometers on transparent substrates, including optimization of materials and processing conditions.

Findings

Sensors with 50 μm width and 50 nm thickness can withstand multiple heating cycles.

Amorphous Ge layers enable sensors to measure up to 650°C repeatedly.

10 μm sensors fail to survive multiple thermal cycles.

Abstract

Ultrathin microscale resistive thermometers are of key value to many applications. 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 ${^\circ}$ 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 TiO2 as adhesion layers, and lastly alumina and silicon oxide as capping layer. In-situ resistance monitoring helps to verify the multi-cycle stability of the sensor and guide the optimization. 10 ${\mu}$m sized sensors can be laser machined but will not survive multiple heating and cooling cycles. We demonstrate that the sensors with amorphous Ge thin layers can also repeatably measure temperatures up to 650 ${^\circ}$ C. It is anticipated that this sensor can be used for fast and high spatial resolution temperature probing for laser processing applications.