CN-122003142-A - Interconnection structure and preparation method thereof

CN122003142ACN 122003142 ACN122003142 ACN 122003142ACN-122003142-A

Abstract

The application discloses an interconnection structure and a preparation method thereof, wherein the interconnection structure comprises the steps of forming a first metal layer in a first dielectric layer on a substrate, forming a second dielectric layer of a low dielectric constant material on the first dielectric layer, forming a through hole connected with the first metal layer on the second dielectric layer, forming an organic hydrophobic layer of a monomolecular layer on the first metal layer at the bottom of the through hole by using a gas phase self-assembly process, performing first treatment on the side wall of the through hole to improve the adhesiveness and interface diffusion blocking capability of the surface of the low dielectric constant material, forming a tantalum layer on the side wall of the through hole, inhibiting the tantalum layer from being formed on the organic hydrophobic layer, removing the organic hydrophobic layer, and filling the through hole inside the tantalum layer with the second metal layer electrically connected with the first metal layer. The application can effectively reduce the specific gravity of the resistance of the diffusion barrier layer in the whole through hole, realize lower resistance and interconnection stability, and well meet the technical requirements of advanced nodes.

Inventors

WANG SHIJING
LI JIAN
LI KE
WU KUN
CHEN SHIMING
LU BIN

Assignees

上海邦芯半导体科技有限公司

Dates

Publication Date: 20260508
Application Date: 20260407

Claims (10)

1. A method of fabricating an interconnect structure, comprising: Providing a substrate; forming a first dielectric layer on the surface of the substrate, and forming a first metal layer located in the first dielectric layer on the surface of the first dielectric layer; Forming a second dielectric layer on the surface of the first dielectric layer, and covering the first metal layer, wherein the material of the second dielectric layer comprises a low dielectric constant material; forming a through hole with the bottom connected with the surface of the first metal layer on the surface of the second dielectric layer; Selectively forming an organic hydrophobic layer of a monolayer on the exposed surface of the first metal layer at the bottom of the via hole using a gas phase self-assembly process; Performing first treatment on the side wall of the through hole by using nitrogen free radicals excited by metastable particles so as to improve the adhesiveness and the interface diffusion blocking capability of the surface of the low dielectric constant material on the side wall; Selectively forming a tantalum layer on the sidewall after the first treatment while suppressing the tantalum layer from forming on the surface of the organic hydrophobic layer; And removing the organic hydrophobic layer, and filling a second metal layer electrically connected with the first metal layer in the through hole inside the tantalum layer.
2. The method of claim 1, wherein the first treatment is performed to react nitrogen radicals with bond bonds on the surface of the low-k material on the sidewall to form a nitrogen-rich surface layer to block interfacial diffusion and optimize surface energy and improve continuity and uniformity of the tantalum layer when formed directly on the sidewall, and/or wherein the low-k material comprises a silicon-based low-k material.
3. The method of claim 1, further comprising performing a second treatment on the surface of the tantalum layer to reduce the surface state density using hydrogen radicals excited by metastable particles after forming the tantalum layer.
4. The method of claim 1, further comprising performing at least one of a third treatment and a fourth treatment on the exposed surface of the first metal layer on the via bottom using hydrogen radicals excited by metastable particles to generate surface activity, wherein the third treatment is performed before forming the organic hydrophobic layer and the fourth treatment is performed after removing the organic hydrophobic layer.
5. The method for manufacturing the interconnection structure according to claim 1, wherein the nitrogen free radical is obtained by exciting nitrogen by using helium metastable particles and filtering out charged particles therein, the helium metastable particles are obtained by exciting helium and filtering out charged particles therein, and when the first treatment is performed, the flow of the helium is 1000 sccm-9000 sccm, the flow of the nitrogen is 1:1-10:1, the temperature is 50 ℃ to 200 ℃, the source power is 1W-100W, the pressure is 10 mTorr-1000 mTorr, the time is 5 s-300 s, ion filtering is turned on, and the bias power is turned off.
6. The method for manufacturing the interconnection structure according to claim 3, wherein the hydrogen radicals are obtained by exciting hydrogen gas by using helium metastable particles and filtering out charged particles therein, the helium metastable particles are obtained by exciting helium gas and filtering out charged particles therein, argon gas is further added into the hydrogen gas during the second treatment, the concentration of the hydrogen gas is adjusted, the flow rate of the helium gas is 1000 sccm-2000 sccm, the flow rate of a mixed gas of the hydrogen gas and the argon gas is helium gas=0.1:1-2:1, the flow rate of the hydrogen gas is argon gas=1:1-1:3, the temperature is 100 ℃ to 200 ℃, the source power is 100 w-500 w, the pressure is 10 mtorr-1000 mtorr, the time is 5 s-300 s, and the ion filtration is turned on to turn off the bias power.
7. The method for manufacturing the interconnection structure according to claim 4, wherein the hydrogen radicals are obtained by exciting hydrogen gas by using helium metastable particles and filtering out charged particles therein, the helium metastable particles are obtained by exciting helium gas and filtering out charged particles therein, and when the third treatment or the fourth treatment is performed, the flow rate of the helium gas is 1000 sccm-9000 sccm, the flow rate of the hydrogen gas is 1:1-10:1, the temperature is 50 ℃ to 200 ℃, the source power is 1W-100W, the pressure is 10 mTorr-1000 mTorr, the time is 5 s-300 s, and the ion filtering is turned on to close the bias power.
8. The method of manufacturing an interconnect structure according to claim 1, wherein the organic hydrophobic layer is formed using an organic molecule containing thiol or an organic molecule containing silicon as a precursor and adding a dilution gas.
9. The method according to claim 8, wherein the thiol-containing organic molecule comprises an alkyl thiol, the silicon-containing organic molecule comprises an organosilane, and/or the gas phase self-assembly process is performed at a temperature of 50 ℃ to 150 ℃ and a pressure of 100mtorr to 10000mtorr for 10s to 300s, and/or the diluent gas comprises at least one of nitrogen, hydrogen, and an inert gas, and/or the organic hydrophobic layer is removed by thermal decomposition at a temperature of 300 ℃ to 400 ℃.
10. An interconnect structure obtained using the method of manufacturing an interconnect structure according to any one of claims 1-9.

Description

Interconnection structure and preparation method thereof Technical Field The application relates to the technical field of semiconductor processing, in particular to an interconnection structure and a preparation method thereof. Background Currently, for logic back-end-of-line processes, a diffusion barrier layer in a copper (Cu) metal via typically employs a bilayer structure of tantalum nitride (TaN) and tantalum (Ta). The TaN is used for adhesion with a dielectric layer (advanced node is a low dielectric constant (LK) material and an ultra low dielectric constant (ULK) material), and the Ta is used for reducing the resistance and adhesion with Cu deposited in a through hole later, so that the diffusion barrier capability and the resistance reduction function can be achieved. However, as the line width is continuously reduced, requirements for high diffusion barrier capability, good interfacial affinity, low resistance, and high reliability are increasingly high. As the diameter size of the through hole is continuously reduced, the thickness of the whole film layer of the diffusion barrier layer adopting the combination of TaN and Ta is required to be thinner and thinner (the thickness of the diffusion barrier layer is larger and larger in proportion to the diameter of the whole Cu metal through hole, and becomes a main reason that the contact resistance and the RC delay are difficult to reduce), so that the interface affinity of the diffusion barrier layer becomes worse and worse, film pits and peeling defects tend to occur, low yield is caused, the thickness of the whole film layer of the diffusion barrier layer adopting the combination of TaN and Ta is difficult to continuously thin, the RC delay is serious, and the contact resistance of the rear section is difficult to reduce. Therefore, there is a need to develop a process that significantly ameliorates the above-mentioned problems. Disclosure of Invention The present application aims to overcome the above problems of the prior art and provide an interconnection structure and a method for manufacturing the same. In order to achieve the above purpose, the technical scheme of the application is as follows: according to a first aspect of the present application, an embodiment of the present application provides a method for manufacturing an interconnection structure, including: Providing a substrate; forming a first dielectric layer on the surface of the substrate, and forming a first metal layer located in the first dielectric layer on the surface of the first dielectric layer; Forming a second dielectric layer on the surface of the first dielectric layer, and covering the first metal layer, wherein the material of the second dielectric layer comprises a low dielectric constant material; forming a through hole with the bottom connected with the surface of the first metal layer on the surface of the second dielectric layer; Selectively forming an organic hydrophobic layer of a monolayer on the exposed surface of the first metal layer at the bottom of the via hole using a gas phase self-assembly process; Performing first treatment on the side wall of the through hole by using nitrogen free radicals excited by metastable particles so as to improve the adhesiveness and the interface diffusion blocking capability of the surface of the low dielectric constant material on the side wall; Selectively forming a tantalum layer on the sidewall after the first treatment while suppressing the tantalum layer from forming on the surface of the organic hydrophobic layer; And removing the organic hydrophobic layer, and filling a second metal layer electrically connected with the first metal layer in the through hole inside the tantalum layer. In some embodiments, by performing the first treatment, nitrogen radicals react with bond bonds on the surface of the low dielectric constant material on the sidewall to form a nitrogen-rich surface layer to block interfacial diffusion and optimize surface energy, improving the continuity and uniformity of the tantalum layer when formed directly on the sidewall. In some embodiments, the low dielectric constant material comprises a silicon-based low dielectric constant material. In some embodiments, after forming the tantalum layer, a second treatment is performed on the surface of the tantalum layer to reduce the surface state density using hydrogen radicals excited by metastable particles. In some embodiments, the method further comprises performing at least one of a third treatment and a fourth treatment on the exposed surface of the first metal layer on the bottom of the through hole using hydrogen radicals excited by metastable particles to generate surface activity, wherein the third treatment is performed before forming the organic hydrophobic layer, and the fourth treatment is performed after removing the organic hydrophobic layer. In some embodiments, the nitrogen free radical is obtained by exciting nitrogen by using heliu