CN-122028444-A - MIM capacitor and preparation method thereof

CN122028444ACN 122028444 ACN122028444 ACN 122028444ACN-122028444-A

Abstract

The embodiment of the application provides an MIM capacitor and a preparation method thereof, wherein in the preparation method, a manganese-copper alloy layer is used as a seed crystal layer of a lower polar plate of the capacitor, then a lower polar plate metal material layer is formed on the seed crystal layer, the seed crystal layer is used as a growth substrate of the lower polar plate metal material layer, the seed crystal layer can enhance the adhesive force between the lower polar plate metal material layer and the interlayer dielectric layer, and prevent the lower polar plate metal material layer from falling off in the subsequent process. In addition, the application directly forms the upper polar plate metal material layer on the middle insulating layer, and then obtains the final upper polar plate of the capacitor through photoetching, etching and other processes, and no additional alignment process is needed before the upper polar plate of the MIM capacitor is deposited, thereby simplifying the process steps and reducing the production cost.

Inventors

Zhang Haona
Cheng Jiugeng
CAO QIPENG
CHENG LIUSUO
ZHANG JILIANG

Assignees

华虹半导体(无锡)有限公司

Dates

Publication Date: 20260512
Application Date: 20260107

Claims (10)

1. A method of fabricating a MIM capacitor comprising: providing a semiconductor structure, wherein a metal interconnection layer is formed in the semiconductor structure, an interlayer dielectric layer is formed on the semiconductor structure, a through hole structure is formed in the interlayer dielectric layer, and a bottom wall of the through hole structure exposes part of the metal interconnection layer; Forming a seed crystal layer, wherein the seed crystal layer covers the side wall and the bottom wall of the through hole structure and covers the interlayer dielectric layer, and the seed crystal layer is a copper-manganese alloy layer; forming a lower plate metal material layer which covers the seed crystal layer and fills the through hole structure; Performing a thermal annealing process on the semiconductor structure after the lower plate metal material layer is formed; grinding and removing the lower polar plate metal material layer and the seed crystal layer which exceed the upper surface of the interlayer dielectric layer, so that the upper surface of the lower polar plate metal material layer in the through hole structure is flush with the upper surface of the interlayer dielectric layer on the side of the through hole structure; Forming an intermediate insulating layer, wherein the intermediate insulating layer covers the interlayer dielectric layer and the lower polar plate metal material layer in the through hole structure; forming an upper electrode plate metal material layer, wherein the upper electrode plate metal material layer covers the middle insulating layer; And etching part of the upper polar plate metal material layer and stopping on the surface of the middle insulating layer above the through hole structure, wherein the upper polar plate metal material layer, the middle insulating layer and the lower polar plate metal material layer in the through hole structure form an MIM capacitor.
2. The method of fabricating a MIM capacitor according to claim 1, wherein the seed layer is formed using a metal sputtering process.
3. The method of claim 1, wherein the seed layer has a thickness of 400 angstroms to 500 angstroms.
4. The method of claim 1, further comprising thinning the top plate metal material layer after forming the top plate metal material layer and before etching a portion of the top plate metal material layer and stopping on the surface of the intermediate insulating layer above the via structure.
5. The method of claim 1, wherein the thermal annealing process is a furnace tube annealing process during the thermal annealing process performed on the semiconductor structure after the bottom plate metal material layer is formed.
6. The method for manufacturing the MIM capacitor according to claim 5, wherein in the process of performing a furnace tube process on the semiconductor structure after the lower plate metal material layer is formed, the process temperature is 140-400 ℃, and the process duration is 10-120 min.
7. The method of fabricating a MIM capacitor according to claim 1, wherein the bottom plate metal material layer is formed by an electrochemical plating process.
8. The method of claim 1, wherein the bottom plate metal material layer is copper.
9. The method of fabricating the MIM capacitor according to claim 1, wherein after etching portions of the top plate metal material layer and stopping on the surface of the intermediate insulating layer above the via structure, the method of fabricating the MIM capacitor further comprises: and forming a cap layer, wherein the cap layer covers the upper polar plate metal material layer and the middle insulating layer.
10. A MIM capacitor, comprising: a semiconductor structure, wherein a metal interconnection layer is formed in the semiconductor structure, an interlayer dielectric layer is formed on the semiconductor structure, a through hole structure is formed in the interlayer dielectric layer, and a bottom wall of the through hole structure exposes part of the metal interconnection layer; the seed crystal layer covers the side wall and the bottom wall of the through hole structure, wherein the seed crystal layer is a copper-manganese alloy layer; a lower plate metal material layer covering the seed layer and filling the via structure; an intermediate insulating layer covering the interlayer dielectric layer and the lower plate metal material layer in the via structure; And the upper polar plate metal material layer covers part of the middle insulating layer above the through hole structure, wherein the upper polar plate metal material layer, the middle insulating layer and the lower polar plate metal material layer in the through hole structure form an MIM capacitor.

Description

MIM capacitor and preparation method thereof Technical Field The application relates to the technical field of semiconductor manufacturing, in particular to an MIM capacitor and a preparation method thereof. Background In the traditional MIM capacitor process of the aluminum (Al) process, the upper and lower metal polar plates are aluminum layers, the metal polar plates can only be applied to small-current chips, the application is limited, in the MIM capacitor process of the copper (Cu) process, the compatibility of copper and an advanced semiconductor process (such as 7nm and below nodes) is better, the metal polar plates can be seamlessly integrated with a copper interconnection process, the process steps and the cost are reduced, meanwhile, the chemical stability of copper is better, the oxidation rate of the metal polar plates in a high-temperature and high-humidity environment is lower than that of aluminum, and the long-term use reliability of the capacitor is prolonged, so that in certain specific application scenes, the MIM capacitor of the copper (Cu) process has advantages over the MIM capacitor of the aluminum (Al) process. However, in the conventional MIM capacitor process of copper (Cu), there are problems such as bulging (Hillock) in the metal bottom plate, which results in that the MIM capacitor cannot achieve a high capacitance density of 1.5fF or higher, and also affects the reliability of the device, and in order to solve the problem that the metal top plate of the MIM capacitor has low transparency, which results in the failure of alignment by photolithography, a process of alignment (AMARK) needs to be added before the formation of the metal top plate (alignment marks are formed in the semiconductor structure film layer by photolithography, etching, etc.), which results in an increase in production cost. Disclosure of Invention The application provides an MIM capacitor and a preparation method thereof, which can solve at least one of the problems that the metal lower polar plate is easy to bulge in the MIM capacitor process in the traditional copper (Cu) process, thereby influencing the capacitor density and the capacitor reliability, and the metal upper polar plate of the MIM capacitor is increased in the alignment process due to low transparency, thereby increasing the production cost and the like. In one aspect, an embodiment of the present application provides a method for manufacturing a MIM capacitor, including: providing a semiconductor structure, wherein a metal interconnection layer is formed in the semiconductor structure, an interlayer dielectric layer is formed on the semiconductor structure, a through hole structure is formed in the interlayer dielectric layer, and a bottom wall of the through hole structure exposes part of the metal interconnection layer; Forming a seed crystal layer, wherein the seed crystal layer covers the side wall and the bottom wall of the through hole structure and covers the interlayer dielectric layer, and the seed crystal layer is a copper-manganese alloy layer; forming a lower plate metal material layer which covers the seed crystal layer and fills the through hole structure; Performing a thermal annealing process on the semiconductor structure after the lower plate metal material layer is formed; grinding and removing the lower polar plate metal material layer and the seed crystal layer which exceed the upper surface of the interlayer dielectric layer, so that the upper surface of the lower polar plate metal material layer in the through hole structure is flush with the upper surface of the interlayer dielectric layer on the side of the through hole structure; Forming an intermediate insulating layer, wherein the intermediate insulating layer covers the interlayer dielectric layer and the lower polar plate metal material layer in the through hole structure; forming an upper electrode plate metal material layer, wherein the upper electrode plate metal material layer covers the middle insulating layer; And etching part of the upper polar plate metal material layer and stopping on the surface of the middle insulating layer above the through hole structure, wherein the upper polar plate metal material layer, the middle insulating layer and the lower polar plate metal material layer in the through hole structure form an MIM capacitor. Optionally, in the method for manufacturing the MIM capacitor, the seed layer is formed by a metal sputtering process. Optionally, in the method for manufacturing the MIM capacitor, the seed layer has a thickness of 400 angstroms to 500 angstroms. Optionally, in the preparation method of the MIM capacitor, after forming the upper plate metal material layer and before etching part of the upper plate metal material layer and stopping on the surface of the intermediate insulating layer above the through hole structure, the preparation method of the MIM capacitor further comprises thinning the upper plate metal material la