Trench Schottky diode and manufacturing method thereof

Abstract

The invention provides a trench Schottky diode and a manufacturing method thereof. The manufacturing method comprises the following steps: oxidizing a silicon epitaxial layer, coating photoresist on the oxide layer, photoetching according to a design layout, removing the oxide layer in an etching region, and etching a silicon substrate by adopting a C4F8 and SF6 alternate etching mode to obtain a silicon trench; removing the residual photoresist and the oxide layer, oxidizing the silicon groove and the silicon substrate, growing a thick gate oxide layer, annealing the upper end of the gate oxide layer, and forming a silicon oxynitride layer on a part of the thickness of the gate oxide layer; according to the manufacturing method, polycrystalline silicon is deposited in a groove, then photoetching and etching are carried out, field oxide layers are deposited on the surface of the polycrystalline silicon after photoetching and the surface of a silicon oxynitride layer, and finally subsequent processing is carried out on the field oxide layers by adopting a manufacturing process of the groove Schottky diode, so that the field oxide layer with relatively thin thickness can be formed. And the over-corrosion problem of the gate oxide layer on the side wall of the groove caused by high corrosion rate of the field oxide layer is also reduced.

Description

technical field [0001] The invention belongs to the technical field of manufacturing Schottky diodes, in particular to a trench Schottky diode and a manufacturing method thereof. Background technique [0002] Schottky diodes have been widely used in power rectification devices due to their low forward conduction voltage and fast reverse recovery time, but the traditional planar silicon Schottky diodes have large reverse leakage and are not suitable for high-voltage devices. The parasitic resistance is high, so the advantage of the low forward voltage of the planar Schottky diode is not obvious. Due to the effect of electric field coupling, the trench Schottky diode transfers the maximum electric field intensity from the Schottky surface to the silicon body, which reduces the leakage current. Under the premise of maintaining the same breakdown voltage, a relatively high doping concentration can be used. The epitaxial layer, so as to achieve a lower forward conduction voltage...

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Problems solved by technology

[0003] In the manufacturing process of the trench Schottky diode, when forming the Schottky contact, it is necessary to accurately control the over-etching amount of the field oxide layer. When the traditional process is used for processing, the field oxide layer is thick and the corrosion rate is fast. Only by over-etching the field oxide layer can the field oxide layer be corroded completely; at the same time, when the field oxide layer is corroded cleanly, the gate oxide layer on the side wall of the trench needs to be preserved, and the gate oxide layer on the side wall of the trench must not be corroded when the field oxide layer is over-etched. Corrosion is clean, so it is more difficult to process

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