Therma‐Probe tool has long been established to monitor the implant dose. In this work, we demonstrate that the unmodified tool is also capable of meeting the stringent demands of junction depth monitoring for the current and future technology nodes. The ultra‐shallow junction (USJ) application development was carried out on the Therma‐Probe tool using the wafers provided by the International SEMATECH. The measured Therma‐Wave signal varies as a sinusoidal function of the SIMS‐based junction depth (at 1E18 ions/cm3) for wafers with various dose and energy conditions annealed around 1000°C. A theoretical model has been proposed to explain the source of the experimental signal response to the junction depth. A correlation table may be set up using the junction depth values provided by a reference method such as SIMS (Secondary Ion Mass Spectrometry) or SRP (Spreading Resistance Profiling); or the sheet resistance obtained using a 4‐point probe system. The existing user interface software has been modified to allow reporting the results directly terms of the correlated junction depth. For production‐worthy throughput conditions, the short‐term precision is found to be <0.5Å, while the long‐term stability is shown to be <2 Å for a variety of wafers tested. The USJ application package for the Therma‐Probe tool offers a method to monitor wafers using an in‐line, fast, and non‐destructive metrology in production. © 2003 American Institute of Physics