Integrated temperature sensor with diamond Schottky diodes using a thermosensitive parameter
Résumé
Diamond Schottky diodes have been realized worldwide showing high figures of merit [1], [2]. The self-heating phenomenon on the Schottky barrier diodes has been highly investigated during the characterization process [3]. The Boron doped CVD has been widely used for these Schottky diodes, offering the best performances in specific ON resistance (Ron) vs Breakdown Voltage figure of merit. Due to the incomplete ionization of Boron dopants at room temperature, the self-heating effect can be used to decrease the diamond semiconductor forward losses. Moreover, a particular attention needs to be done on the parallelization of diamond Schottky diodes due to a negative temperature coefficient (from 0K to 400-600K) and a positive one (above 400-600K depending on the doping level), an accurate temperature management system is then required.
We propose here a monolithic integration of a small area Schottky barrier diode used as a wide range temperature sensor. The diode voltage drop is used as a thermosensitive parameter at a constant forward bias current. The linear variation of this voltage drop on a temperature range, from room temperature to 440K, at a constant bias current density of 2.5A/cm² allows a sensor sensitivity of 1.5mV/K. It is also demonstrated that this integrated temperature sensor is affected by the biasing conditions of the main Schottky diode, which is monolithically integrated as it is shown on Figure 2. The temperature measurement has to be done with the main diode in OFF state to have an accurate temperature information. A modified integrated structure is introduced in this work to prevent this limitation. This integrated temperature measurement allows an accurate junction temperature monitoring, offering reliable device paralleling opportunities and accurate self-heating monitoring.