Metal capacitor structure and preparation method thereof

Abstract

The invention provides a metal capacitor structure and a preparation method thereof. The structure is characterized by comprising a substrate, a capacitor structure, a plurality of openings, a recess, and a side wall; the capacitor structure comprises a bottom metal layer, an interlayer dielectric layer and a top metal layer which are sequentially stacked on the substrate; the plurality of openings penetrate through the top metal layer and extend downwards into the interlayer dielectric layer; the recess is positioned on the side wall of the opening and extends downwards into the interlayer dielectric layer from the bottom of the opening; and the side wall is located in the opening and extends downwards from the side wall of the top metal layer to fill the recess; The breakdown voltage of the metal capacitor structure is improved.

Description

technical field [0001] The invention relates to the technical field of semiconductors, in particular to a metal capacitor structure and a preparation method thereof. Background technique [0002] Metal-insulator-metal (MIM), due to its small parasitic resistance, is widely used in analog circuits and radio frequency circuits. Different application requirements have different requirements for the parasitic resistance of metal capacitors. If it is used in radio frequency circuits, due to the high frequency (GHz), its capacitive reactance is low, and the total impedance of the parasitic resistance in the entire metal capacitor is high, which needs to be reduced as much as possible. However, for low-frequency analog circuits, such as in the application of panel driver chips, metal capacitors are used as storage for charge pumps, which require a higher breakdown voltage, and the corresponding time-dependent dielectric breakdown of metal capacitors (Time Dependent Dielectric Brea...

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Problems solved by technology

Wherein the thickness and the width of the relative interlayer dielectric layer 22 between the bottom metal layer 21 and the top metal layer 23 determine the capacitance value of the metal capacitor structure, the thinner the thickness of the dielectric layer, the larger the capacitance value, but the impact of the metal capacitor structure The lower the breakdown voltage, the worse the reliability under the working voltage (characterized by time-dependent dielectric breakdown TDDB). TDDB is one of the reliability indicators for evaluating the quality of the dielectric layer. A constant voltage is applied to both ends of the metal capacitor structure. Make the metal capacitor structure in the accumulation state, after a period of time, the dielectric layer will break down, this period of time is the life of the metal capacitor structure under this condition, if the TDDB performance of the metal capacitor structure declines, then the metal capacitor structure is easy to break down chip failure

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