High-k dielectric stack in a MIM capacitor and method for its fabrication

Abstract

According to one exemplary embodiment, a high-k dielectric stack situated between upper and lower electrodes of a MIM capacitor comprises a first high-k dielectric layer, where the first high-k dielectric layer has a first dielectric constant. The high-k dielectric stack further comprises an intermediate dielectric layer situated on the first high-k dielectric layer, where the intermediate dielectric layer has a second dielectric constant. According to this exemplary embodiment, the high-k dielectric stack further comprises a second high-k dielectric layer situated on the intermediate dielectric layer, where the second high-k dielectric layer has a third dielectric constant. The second dielectric constant can be lower than the first dielectric constant and the third dielectric constant. The high-k dielectric stack further comprises first and second cladding layers, where the first cladding layer is situated underneath the first high-k dielectric layer and the second cladding layer is situated on the second high-k dielectric layer.

Description

BACKGROUND OF THE INVENTION [0001] 1. Field of the Invention [0002] The present invention is generally in the field of semiconductor fabrication. More specifically, the invention is in the field of fabrication of capacitors in semiconductor dies. [0003] 2. Related Art [0004] High performance mixed signal and RF circuits require high density integrated capacitors. Metal-insulator-metal (“MIM”) capacitors can be considered for use in the fabrication of integrated mixed signal and RF circuits on semiconductor dies. In an effort to increase the capacitance density of MIM capacitors, dielectrics having a high dielectric constant (“high-k”) have been utilized in MIM capacitors. However, high-k dielectrics, such as tantalum oxide (“Ta2O5”) or hafnium oxide (“HfO2”), also tend to exhibit very high leakage current and low breakdown voltage. [0005] In one approach to solving the problems of high leakage current and low breakdown voltage, a dielectric stack including a high-k dielectric layer ...

AI Technical Summary

Benefits of technology

The present invention is about a new way to make a high-k dielectric stack in a MIM capacitor that reduces leakage current and increases breakdown voltage. This is important because it addresses a problem in the art where the dielectric layer in a MIM capacitor had low breakdown voltage and high leakage current. The new method involves using an intermediate dielectric layer made of Al2O3 between two layers of high-k dielectric layers. This results in a higher breakdown voltage and reduced leakage current. The high-k dielectric layers can be made of different dielectric constants, and there can be additional cladding layers to further improve performance. Overall, this new method improves the reliability and performance of MIM capacitors.

Problems solved by technology

However, high-k dielectrics, such as tantalum oxide (“Ta2O5”) or hafnium oxide (“HfO2”), also tend to exhibit very high leakage current and low breakdown voltage.

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