We developed a measurement technique that can quantitatively map out the dopant density profile of a silicon integrated-circuit device. This method obtains the quantitative doping density profile by simultaneously carrying out local heating, temperature sensing, and thermoelectric voltage measurement at the tip of a diamond thermocouple probe. This probe, which is the key component of the proposed scheme, is fabricated through a nano-fabrication technique that makes use of boron-doped diamond film that can resist stress up to 10 Gpa, which is necessary for stable electric contact with silicon samples. The tip and cantilever of the probe are made of B-doped diamond by means of the silicon lost-mold technique that guarantees a sharper tip apex than that of a diamond-coated probe. A gold-chromium thermocouple junction is integrated at the tip apex for simultaneous heating and sensing. The size of the thermocouple is about 500 nm and the radius of the tip apex is less than 50 nm. The measurement technique is demonstrated by measuring the thermopower distribution across a silicon p-n junction and the result is compared with the theoretical values.