Seminar "Indirect thermographic measurements of semiconductor temperatures".

Semiconductor diodes manufactured on a silicon carbonide (SiC) substrate, compared with diodes manufactured on a silicon (Si) substrate, are characterized by less heat generation in the package. For this reason, their operation is more stable, even at high currents and voltages. In addition, diodes manufactured on a SiC substrate can be subjected to higher electrical loads than similar diodes manufactured on a Si substrate. Diodes manufactured on SiC substrates are used in switch-mode power supplies, photovoltaic systems and in the automotive industry (electric cars). They are therefore among the devices on which safety and comfort depend.

As the current load on the semiconductor diode increases, the temperature inside the package rises. This dependence can also be observed in the case of diodes fabricated on a SiC substrate. As the temperature of the diode matrix increases, its parameters change. As a result, the flow of currents and the distribution of voltage drops in the device of which the diode is a part can change. This can lead to malfunction of the entire device. It should be added that a diode operating at a higher temperature is more prone to failure, and has a shorter life. That's why it's important to know the diode's matrix temperature.

It's difficult to obtain information on the matrix temperature of a semiconductor diode manufactured on a SiC substrate. Because of the high value of the current that can be conducted through the diode, using the contact temperature sensor can be dangerous. Another solution is to use thermography. This non-contact method is safe. Its use eliminates the risk of electric shock. An additional advantage of using thermography is the possibility of obtaining the temperature distribution over the diode surface.

Thermography, despite its significant advantages, also has its drawbacks.  To carry out such a thermographic temperature measurement, which is burdened with the lowest possible error, it is necessary to know the value of the emissivity factor ε. Another problem to be solved is the choice of observation site on the semiconductor diode package.  Depending on the choice of observation site, the values of the differences between die temperature and package temperature will be different. For this reason, research has been undertaken, the result of which is to indicate such a location on the housing of the semiconductor diode fabricated on the SiC substrate, so that the difference between die temperature and package temperature is as small as possible.