Metal-insulator-metal capacitor structure and forming method thereof

Abstract

The invention provides a metal-insulator-metal capacitor structure. The metal-insulator-metal capacitor structure comprises a lower electrode, a dielectric layer, an interface layer and an upper electrode; the dielectric layer is formed on the lower electrode; the upper electrode is formed on the dielectric layer; the interface layer is formed between the dielectric layer and the upper electrode, and / or the interface layer is formed between the dielectric layer and the lower electrode; the lower electrode comprises an interconnection metal layer and a metal barrier layer, the metal barrier layer is located between the interconnection metal layer and the dielectric layer, the thickness of the metal barrier layer is larger than 400 angstroms, the roughness of the interface layer is smaller than that of the surface, facing the dielectric layer, of the metal barrier layer, and the dielectric constant of the interface layer is larger than that of the dielectric layer. According to the invention, the surface of the lower electrode is smoothed by increasing the thickness of the metal barrier layer in the lower electrode and additionally arranging the interface layer to cover the upper surface of the metal barrier layer and / or the dielectric layer, so that the breakdown voltage of the lower electrode is improved, and the capacitance value of the lower electrode is improved by utilizing that the second dielectric constant is greater than the first dielectric constant.

Description

technical field [0001] The invention relates to the technical field of semiconductors, in particular to a metal-insulator-metal capacitor structure and a forming method. Background technique [0002] Capacitors are used in semiconductor integrated circuits as charge storage, coupling, and filter devices. Among them, the metal-insulator-metal capacitor structure (metal-insulator-metal, MIM) has a small parasitic resistance and can be formed directly using the interconnection layer of the device. Therefore, the MIM capacitor structure is widely used in analog circuits and radio frequency circuits. Specifically, in different application scenarios, there are different requirements for the MIM. For example, in high-frequency radio frequency circuits, MIM is required to have a large capacitance to reduce capacitive reactance; in low-frequency analog circuits, MIM is used as a charge pump to store charges, and it needs to have a higher breakdown voltage, that is, for MIM The time...

AI Technical Summary

Problems solved by technology

The thinner the thickness of the dielectric layer, the greater the capacitance value of the corresponding MIM. On the other hand, when the dielectric layer is thinner at the same voltage, the roughness of the lower electrode surface has a greater impact on the upper electrode (MIM capacitor), and the more likely it is to occur The tip discharge breaks down the MIM capacitor, causing the breakdown voltage of the MIM to drop, that is, the existing MIM cannot better balance between a large capacitance value and a large breakdown voltage

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