Non-contact Temperature Measurement of Micro-heaters with Two-color Method Using a Single Photon Detector

We present a contactless measurement method to characterize the temperature of on-chip micro-heaters through thermal radiation detection. These micro-heaters have widths ranging from 1 to 5 mu m and lengths ranging from 10 to 15 mu m. The temperature is determined by the thermal radiation power ratio within two different wavelength bands, known as the two-color method. A single photon detector (SPD) is employed to enhance the capability of detecting sub-pW radiation signals. This method can accurately measure the temperature of tungsten heaters as low as 700 K. Initial attempts to use this method to measure realistically sized HAMR NFTs temperature have not yet been successful due the signal to background limitations. We present measurements on optically heated NFTs that quantify the required radiation collection efficiency and scattered pump light suppression at the detector that would be necessary to achieve a sufficient signal-to-noise ratio (SNR) to allow NFT temperature measurement using this method.