Image of the Month

December 2012

UHV Scanning Thermal Microscopy for Nanometer Resolution Quantitative Thermometry


Figure 6. (a) Scanning electron microscope image of a 200 nm wide Pt line; (b) 3D topographic of a 2.5 μm x 2.5 μm region where the 200 nm wide Pt line lies on top of a 1 μm wide Pt line; (c) thermal image of the same region shown in panel b. The temperature rise of the 200 nm line is seen to be lower in the region where it intersects the 1 μm wide line because the 1 μm wide Pt line acts as a fin.

Microscope: RHK Technology, Customized UHV7500 STM/AFM

Control System: RHK Technology SPM1000

Credits – Kyeongtae Kim, Wonho Jeong, Woochul Lee, and Pramod Reddy – University of Michigan, Ann Arbor

Reference – ACS Nano, 2012, 6 (5), pp 4248–4257

Abstract – Understanding energy dissipation at the nanoscale requires the ability to probe temperature fields with nanometer resolution. Here, we describe an ultra-high vacuum (UHV)-based scanning thermal microscope (SThM) technique that is capable of quantitatively mapping temperature fields with ∼15 mK temperature resolution and ∼10 nm spatial resolution. In this technique, a custom fabricated atomic force microscope (AFM) cantilever, with a nanoscale AuCr thermocouple integrated into the tip of the probe, is used to measure temperature fields of surfaces. Operation in an UHV environment eliminates parasitic heat transport between the tip and the sample enabling quantitative measurement of temperature fields on metal and dielectric surfaces with nanoscale resolution. We demonstrate the capabilities of this technique by directly imaging thermal fields in the vicinity of a 200 nm wide, self-heated, Pt line. Our measurements are in excellent agreement with computational results; unambiguously demonstrating the quantitative capabilities of the technique. UHV-SThM techniques will play an important role in the study of energy dissipation in nanometer-sized electronic and photonic devices and the study of phonon and electron transport at the nanoscale.
Keywords: scanning thermal microscopy . ultrahigh vacuum . quantitative temperature profiling . nanoscale thermal contact . thermocouple probe