CN106158578B

CN106158578B - Metal-insulator-metal capacitor structure and manufacturing method thereof

Info

Publication number: CN106158578B
Application number: CN201510128285.1A
Authority: CN
Inventors: 高永亮; 陈辉
Original assignee: CSMC Technologies Fab2 Co Ltd
Current assignee: CSMC Technologies Corp
Priority date: 2015-03-23
Filing date: 2015-03-23
Publication date: 2020-06-12
Anticipated expiration: 2035-03-23
Also published as: CN106158578A

Abstract

The invention relates to a manufacturing method of a metal-insulator-metal capacitor structure, which comprises the following steps: sequentially manufacturing a bottom metal layer, a dielectric layer and a top metal layer; performing anti-reflection treatment on the top metal layer to form an anti-reflection layer; and coating photoresist on the anti-reflection layer, and performing a pattern process. The invention also relates to a metal-insulator-metal capacitor structure used for the manufacturing method. According to the method and the structure, because the top metal layer is subjected to anti-reflection treatment, the standing wave effect during exposure can be effectively prevented when a pattern process is carried out, and the side wall of the photoresist is neat in appearance.

Description

Metal-insulator-metal capacitor structure and manufacturing method thereof

Technical Field

The invention relates to the technical field of integrated circuits, in particular to a metal-insulator-metal capacitor structure and a manufacturing method thereof.

Background

As circuit manufacturing technology develops and the degree of integration of circuits increases, some passive devices, such as capacitors, are gradually incorporated into the integrated circuits. Capacitors are present in integrated circuits as Metal-insulator-Metal (MIM) capacitor structures. The MIM capacitor structure typically includes a stacked bottom electrode, dielectric material, and top electrode.

For the MIM capacitor structure, when the reflectivity of the top electrode is high, when the top metal layer is patterned by using the photoresist, the standing wave effect is easily generated by exposing the photoresist, and the uneven appearance is formed on the side wall of the photoresist. As shown in fig. 1a, a bottom metal layer 1, a dielectric layer 2, and a top metal layer 3 are sequentially stacked. When the MIM capacitor structure is required to be patterned, a photoresist (photoresist) 4 is applied to the top metal layer 3, and is etched after exposure. When the reflectivity of the top metal layer 3 is high, light is reflected and then superposed with incident light to generate a standing wave effect, and the side wall of the photoresist 4 can form an uneven shape. As shown in fig. 1b, the lithographic sidewalls observed under the microscope were rugged after exposure due to standing wave effects.

Typically, MIM capacitor structures are larger than tens of microns in size and larger than hundreds of square microns in area. However, in order to improve the characteristics of the capacitor structure in practical product application, a MIM ring with a size larger than 1 μm is designed around the capacitor structure. In the above application, the requirement on the shape of the photoresist is not very high due to the large size of the MIM capacitor structure.

In some cases, the MIM ring is designed to be smaller, for example 0.4 μm, which requires a high profile after photoresist exposure.

Disclosure of Invention

In view of the foregoing, there is a need for a method for fabricating a metal-insulator-metal capacitor structure with improved photoresist profile.

In addition, a metal-insulator-metal capacitor with improved photoresist profile is provided.

A method for manufacturing a metal-insulator-metal capacitor structure comprises the following steps:

sequentially manufacturing a bottom metal layer, a dielectric layer and a top metal layer;

performing anti-reflection treatment on the top metal layer to form an anti-reflection layer;

and coating photoresist on the anti-reflection layer, and performing a pattern process.

In one embodiment, the thickness of the bottom metal layer is 3000-5000 angstroms, the thickness of the dielectric layer is 300-400 angstroms, the thickness of the top metal layer is 800-1200 angstroms, and the thickness of the anti-reflection layer is 8-12 angstroms.

In one embodiment, the bottom metal layer is made of copper-aluminum alloy, the copper-aluminum alloy contains 0.5% by mass of copper, the dielectric layer is made of silicon nitride material, and the top metal layer is made of titanium nitride material.

In one embodiment, in the step of performing the anti-reflection treatment on the top metal layer to form the anti-reflection layer, an oxide layer of titanium is generated as the anti-reflection layer.

In one embodiment, the surface of the top metal layer is oxidized using nitrous oxide to produce an oxide layer of titanium.

A metal-insulator-metal capacitor structure comprises a bottom electrode, a dielectric layer and a top electrode which are sequentially stacked, and is characterized in that an anti-reflection layer is formed on the surface of the top electrode.

In one embodiment, the thickness of the bottom electrode is 3000-5000 angstroms, the thickness of the dielectric layer is 300-400 angstroms, the thickness of the top electrode is 800-1200 angstroms, and the thickness of the anti-reflection layer is 8-12 angstroms.

In one embodiment, the bottom electrode is made of copper-aluminum alloy, the copper-aluminum alloy contains 0.5% by mass of copper, the dielectric layer is made of silicon nitride material, and the top electrode is made of titanium nitride material.

In one embodiment, the anti-reflective layer is an oxide layer of titanium.

According to the method and the structure, because the top metal layer is subjected to anti-reflection treatment, the standing wave effect during exposure can be effectively prevented when the pattern process is carried out, so that the side wall of the photoresist is neat in appearance.

Drawings

FIG. 1a is a schematic diagram of a photoresist sidewall having an uneven profile when patterned according to a conventional method;

FIG. 1b is a photomicrograph of the photoresist topography under a microscope after patterning by conventional methods;

FIG. 2 is a flow chart of a method for fabricating a MIM capacitor structure according to an embodiment;

FIG. 3a is a schematic diagram of a capacitor structure formed by the method of FIG. 2;

FIG. 3b is a photograph of the topography of the photoresist under a microscope after the method of FIG. 2 has been applied.

Detailed Description

The following further description is made in conjunction with the accompanying drawings and examples.

The method of the following example can be used to fabricate MIM capacitor rings with ring sizes less than 1 micron. The MIM capacitor ring is a ring-shaped MIM capacitor structure.

Fig. 2 is a flowchart illustrating a method for fabricating a mim capacitor structure according to an embodiment. The method comprises the following steps.

Step S101: a bottom metal layer 100, a dielectric layer 200, and a top metal layer 300 are sequentially formed. The bottom metal layer 100, the dielectric layer 200 and the top metal layer 300 may be formed by a deposition process. Referring to FIG. 3, the thickness of the bottom metal layer 100 is 3000-5000 angstroms, preferably 4000 angstroms; the thickness of the dielectric layer 200 is 300-400 angstroms, preferably 350 angstroms; the thickness of the top metal layer 300 is 800-1200 angstroms, preferably 1000 angstroms.

In this embodiment, the bottom metal layer 100 is made of copper-aluminum alloy, and the copper-aluminum alloy contains 0.5% by mass of copper. The dielectric layer 200 is made of a silicon nitride (SiN) material, and the top metal layer 300 is made of a titanium nitride (TiN) material.

It is understood that other suitable metals, alloys, or dielectric materials may be used for bottom metal layer 100, dielectric layer 200, and top metal layer 300.

Step S102: the top metal layer 300 is subjected to an anti-reflection process to form an anti-reflection layer 400. The anti-reflective layer 400 can effectively reduce the reflection of light and reduce or even eliminate the standing wave effect. The thickness of the anti-reflection layer 400 is 8 to 12 angstroms, preferably 10 angstroms.

When the top metal layer 300 is made of titanium nitride (TiN), nitrous oxide (N) is used in this step₂O) the surface of the top metal layer 300 is oxidized to generate an oxide layer of titanium as the anti-reflection layer 400. The titanium oxide layer has a much lower reflectivity than titanium nitride.

It is understood that in other embodiments, the anti-reflection process may be performed in other manners, such as performing an epitaxial process or a deposition process on the top metal layer 300 to form an anti-reflection layer. But using nitrous oxide (N) as opposed to an epitaxial or deposition process₂O) oxidizing titanium nitride (TiN) with the reaction gas only containing nitrous oxide (N)₂The O) argon (Ar) process is simpler and the cost is lower. While the deposition process requires a greater variety of source gases.

It is understood that in other embodiments, titanium nitride (TiN) may be oxidized in other ways.

Step S103: and coating photoresist on the anti-reflection layer, and performing a patterning process. The patterning process includes exposure, development, and etching. Through this step, a desired MIM capacitor shape, such as a MIM capacitor ring, can be formed.

In the above processing, since the top metal layer 300 is subjected to the anti-reflection treatment, the standing wave effect during exposure can be effectively prevented during the patterning process, so that the sidewall morphology of the photoresist is regular, as shown in fig. 3b, after the processing by the above method, the sidewall morphology of the photoresist is more regular than that of the photoresist processed by the conventional method.

The above method can fabricate a metal-insulator-metal capacitor of an embodiment. The metal-insulator-metal capacitor comprises a bottom electrode, a dielectric layer and a top electrode which are sequentially stacked, wherein an anti-reflection layer is formed on the surface of the top electrode. The thickness of the bottom electrode is 3000-5000 angstroms, and is preferably 4000 angstroms. The thickness of the dielectric layer is 300-400 angstroms, preferably 350 angstroms. The thickness of the top electrode is 800-1200 angstroms, and preferably 1000 angstroms. The thickness of the anti-reflection layer is 8-12 angstroms, and preferably 10 angstroms. The bottom electrode is made of copper-aluminum alloy, the copper-aluminum alloy contains 0.5% of copper by mass, the dielectric layer is made of silicon nitride materials, and the top electrode is made of titanium nitride materials. The antireflection layer is an oxide layer of titanium.

The technical features of the embodiments described above may be arbitrarily combined, and for the sake of brevity, all possible combinations of the technical features in the embodiments described above are not described, but should be considered as being within the scope of the present specification as long as there is no contradiction between the combinations of the technical features.

The above-mentioned embodiments only express several embodiments of the present invention, and the description thereof is more specific and detailed, but not construed as limiting the scope of the invention. It should be noted that, for a person skilled in the art, several variations and modifications can be made without departing from the inventive concept, which falls within the scope of the present invention. Therefore, the protection scope of the present patent shall be subject to the appended claims.

Claims

1. A method for manufacturing a metal-insulator-metal capacitor structure, wherein the metal-insulator-metal capacitor structure is an MIM capacitor ring, and the ring size is less than 1 micron, the method comprises the following steps:

sequentially manufacturing a bottom metal layer, a dielectric layer and a top metal layer; the top metal layer is made of a titanium nitride material;

performing anti-reflection treatment on the top metal layer to form an anti-reflection layer; oxidizing the surface of the top metal layer by using nitrous oxide to generate a titanium oxide layer;

2. The method as claimed in claim 1, wherein the bottom metal layer has a thickness of 3000-5000 angstroms, the dielectric layer has a thickness of 300-400 angstroms, the top metal layer has a thickness of 800-1200 angstroms, and the anti-reflection layer has a thickness of 8-12 angstroms.

3. The method as claimed in claim 1, wherein the bottom metal layer is made of copper-aluminum alloy, the copper-aluminum alloy contains 0.5% by mass of copper, and the dielectric layer is made of silicon nitride.