Micromachined Scanning Thermal Probe
Inventors: Yogesh Gianchandani, Mo-Huang Li, Julius Wu
The Wisconsin Alumni Research Foundation (WARF) is seeking commercial partners interested in developing a micromachined scanning thermal probe that provides 100 times the temperature-sensing resolution of current Wollaston wire probes.
Scanning thermal probes hold promise for many applications, including high-resolution temperature mapping (e.g., for ULSI circuit diagnostics), topographical mapping, photothermal absorption spectroscopy and subsurface imaging. Previous thermal probes have employed a variety of temperature-sensing techniques; for example, the commercially available Wollaston probe senses temperature by reading a resistance change in a bent wire. Due to the high themal conductivity of metals, however, wire-based probes may place a greater thermal load on samples than probes micromachined from other materials.
UW-Madison researchers have developed a micromachined scanning thermal probe with polyimide as its structural material and an embedded thin-film thermocouple as its temperature-sensing element. Probes are micromachined using a low-temperature, multimask process that can be easily integrated into a CMOS fabrication sequence, and contain a built-in scanning tip that is exposed by a unique flip-over assembly step at the end of processing.
- High-resolution temperature mapping
- Thermal properties mapping
- Photothermal absorption spectroscopy
- Biological diagnostics
- Provides 100 times the temperature-sensing resolution of current Wollaston wire probes
- Fabrication process allows batch-manufacture of probes at very low cost.
- Polyimide’s low thermal conductivity increases the probe’s temperature sensitivity, while greatly reducing the thermal load on samples.
- High spatial resolution and extremely low spring constant make the probe well suited for scanning soft materials.
- Polyimide’s mechanical flexibility allows flip-over assembly, eliminating the need to dissolve the substrate wafer under the probe.
- May be used to make thermal conductance measurements on a wide range of materials, including heat-insulating materials (e.g. photoresists) and soft materials (e.g., biological specimens)