1064 nm Wavelength p-i-n Photodiode with Low Influence of Periphery on Dark Currents

In the process of carrying out various studies, the problem of an uncontrolled increase in the dark current level of guard-ring photodiodes is observed, being manifested both at a temperature T = 293 K and (largely) when testing devices at elevated temperature (T = 358 K). As it is known, microelectronics technology always uses surface protection (passivation) of semiconductor devices and integrated circuits. In this case, the best solution is a thermally grown SiO2 layer. However, even a surface protected by a dielectric layer does not always remain stable. The article presents the results of the development of a p-i-n photodiode based on high-resistivity p-type silicon of increased responsivity and reduced dark current level of the guard ring at a wavelength of 1064 nm. In the proposed design of the photodiode, the thickness of the peripheral oxide of the crystal is decreased to reduce the influence of the dislocation component of the current and charge states on the inverse characteristics. After phosphorus diffusion (driving-in), phosphorosilicate glass was removed, and additional photolithography was performed, during which the entire layer of peripheral oxide was etched. In the second stage of phosphorus diffusion (distillation), the antireflection oxide 190-220 nm thick was grown in photosensitive areas and at the periphery of the crystal. The photosensitive areas, the guard ring, and the peripheral part of the crystal were separated by an oxide 650-700 nm thick grown in the first thermal operation. The production of photodiodes was performed using the same operating conditions as in commercial production, and their parameters were compared with devices manufactured in a standard design. The analysis showed that the photodiodes of the proposed design are characterized by lower and more stable dark currents than commercial devices not only at room temperature, but also at a temperature of 358 K.