Etienne Lemaire

Micromachined temperature calibration tool for contact Scanning Thermal Microscope probes

Local thermal probing has become a major tool for studying transport phenomena at micro and nanoscale levels, detecting hot spots and failures of microelectronic devices or measuring surface temperature distribution at these scales. If contact point measurement of a local tip is expected to provide the best spatial resolution, the fundamental aspect of the interaction between the probe tip and the sample remains the key point on which any quantitative measurement relies. We focus on the calibration procedure that will allow measuring the thermal response (error) of a contact probe used for temperature measurement on a surface. For this purpose, a micro-hotplate made of platinum heater suspended on thin silicon nitride (SiN) membrane represents an interesting tool. The objective is to develop heated reference samples with localized temperature sensors embedded on its surface to probe the temperature during the probe contact. We report on the thermal design of low-power calibration chip and the first results obtained when contacting wire based micro-thermocouple Scanning Thermal Microscope (SThM) probes.

Nanoscale thermal imaging of active devices by fluorescent SThM

We describe a scanning thermal microscope that uses a fluorescent nanocrystal as a temperature probe. The nanocrystal is made of an inorganic fluoride material doped with erbium ions. The temperature is determined by measuring the fluorescence intensity ratio between two adjacent fluorescence lines. We first visualized the heating of a Cr stripe, and observed two different heat transfer channels, by direct contact between the tip and the device and by conduction through the air gap. We then measured the temperature map of a Joule heated submicron wide Pt wire and observed that the temperature elevation is uniform all along the wire. The measured images are obtained with a submicron lateral resolution and demonstrate the good reliability of the technique for characterizing the thermal properties of nanoscale devices and structures.