Technology and design in electronic equipment, 2023, no. 1-2, pp. 43-49.
DOI: 10.15222/TKEA2023.1-2.43
UDC 621.382
Improvement of inverse characteristics of silicon varicap by using low-temperature gettering
(in Ukrainian)
Litvinenko V. N.1, Shutov S.V.2

Ukraine, 1Kherson State Agrarian and Economic University; 2Kyiv, V. E. Lashkaryov Institute of Semiconductor Physics NAS of Ukraine.

Varicaps are widely used in radio electronics as a variable capacitance, the value of which is controlled by voltage. However, it should be noted that the cost of varicaps remains relatively high due to a low yield of suitable devices. This is caused by high levels of reverse currents and low breakdown voltages of varicaps, which is determined by the significant dependence of the reverse characteristics of varicaps on the density of structural defects and heavy metal impurities in their active regions.
This study aimed to discover the causes and mechanisms of degradation of the reverse characteristics of varicaps with an ohmic contact based on nickel during annealing of a nickel film during the formation of an ohmic contact. Another goal was to determine the possibility of using gettering operations to prevent degradation of the reverse characteristics of varicaps and increase the yield of suitable devices.
The conducted experimental studies have shown that the reason for the degradation of the reverse characteristics of varicaps during the formation of a nickel-based ohmic contact is that, during the annealing of the nickel film, the excess nickel atoms not involved in the formation of NiSi silicide penetrate into the region of the space charge of the p-n junction.
The authors consider in detail the proposed technology for manufacturing nickel-based varicap structures with an ohmic contact using gettering of excess nickel atoms by carrying out additional low-temperature annealing of varicap structures using a ready-made "intrinsic geter" the Si-NiSi interface.
It is shown that the developed technology for fabricating varicap structures using gettering makes it possible to clean the active regions of varicaps from nickel atoms, which ensures a significant decrease in the level of varicap reverse currents and an increase in the yield of suitable devices.

Keywords: nickel atoms, ohmic contact, gettering, varicap, structural defects, reverse current.

Received 25.12 2022
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