Investigation of Thermal Coefficient for Polycrystalline Silicon Thermal Sensor Diode

Abstract

Thermal sensors utilizing p-n junction diodes built into the polycrystalline silicon layer are developed. The effective factors influencing the thermal coefficient of polycrystalline silicon thermal sensor diodes are clarified. It is found that diodes with a light boron dose have a larger thermal coefficient than those with a heavy boron dose. The plural p-n diodes connected with more cascade series number have a larger thermal coefficient than ones with less cascade series number. The periphery of the thermal sensor seems to have little effect on the thermal coefficient. In addition, the thermal coefficient will become higher as a larger forward current is selected. The thermal coefficient of the sensor with a boron dose of 1×1015 cm-2 will reach a saturation value of -2 mV/K when the forward current is above 2 µA.