High voltage isolation structure based on silicon on insulator

Abstract

A high voltage isolation structure based on silicon on an insulator includes that a surface passivation layer is arranged on an N-type epitaxial layer in a silicon structure on the insulator, a high voltage circuit area, a multi-deep-groove isolation structure and a low voltage circuit area are arranged in the N-type epitaxial layer, the high voltage circuit area is enclosed by the multi-deep-groove isolation structure, and the multi-deep-groove isolation structure is composed of 2 to 20 deep groove isolation structures. The high voltage isolation structure is characterized in that a high-resistance polycrystalline silicon field plate is arranged on the surface passivation layer, the N-type epitaxial layer of the high voltage circuit area and the low voltage circuit area is electrically connected with electrode contact holes, and the N-type epitaxial layer between every adjacent deep groove isolation structures is electrically connected with middle electrode contact holes. Two ends of the high-resistance polycrystalline silicon field plate are respectively electrically connected with the electrode contact holes in the high voltage circuit area and the low voltage circuit area, and the high-resistance polycrystalline silicon field plate is sequentially electrically connected with each electrode contact hole from inside to outside.

Description

Technical field [0001] The invention relates to an isolation structure in a high-voltage integrated circuit, which is used to solve the problem of electrical isolation between high and low voltage areas. Background technique [0002] High-voltage power integrated circuits usually refer to circuits that integrate power devices, logic control circuits, and protection circuits on a single silicon chip. Insulator Gate Bipolar Transistor (IGBT) is widely used as a power transistor for power integrated circuits due to its advantages of high current capability and low conduction voltage drop. However, bulk silicon technology is not suitable for integrated IGBTs, because IGBTs have conductivity modulation effects, that is, a large number of minority carriers are injected into the drift region when they are turned on, which will inject carriers into the substrate, which will affect the normality of other circuits in the chip. jobs. The buried oxide layer in the Silicon On Insulator (SOI...

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Problems solved by technology

However, due to process limitations and heat dissipation considerations, the sidewall oxide layer cannot be made very thick

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