CN112175756A

CN112175756A - Cleaning solution for removing surface residues after CMP of multi-layer copper interconnection barrier layer

Info

Publication number: CN112175756A
Application number: CN202011219974.0A
Authority: CN
Inventors: 王辰伟; 刘玉岭; 罗翀; 高宝红; 何彦刚; 张保国
Original assignee: Tianjin Jingling Microelectronic Material Co ltd; Hebei University of Technology
Current assignee: Tianjin Jingling Microelectronic Material Co ltd; Hebei University of Technology
Priority date: 2020-11-05
Filing date: 2020-11-05
Publication date: 2021-01-05

Abstract

The invention discloses a cleaning solution for removing surface residues of a multi-layer copper interconnection barrier layer after CMP, and aims to provide a cleaning solution which is simple in component and can effectively remove the surface residues of the multi-layer copper interconnection barrier layer after CMP. The composite material comprises the following components in percentage by mass: 0.1-5% of chelating agent, 0.1-15% of surfactant, 1% of defoaming agent, pH regulator and the balance of deionized water; the pH value of the cleaning solution is 7-7.5; the surfactant is prepared by compounding a cationic surfactant, a nonionic surfactant and an anionic surfactant. The cleaning solution disclosed by the invention is prepared by compounding a cationic surfactant, a nonionic surfactant and an anionic surfactant, and can effectively remove the large particle number and surface residues on the surface of a multi-layer copper interconnection barrier layer after CMP through steric hindrance, so that the performances of the device such as reliability, electric energy and the like are improved, and the yield of the device is favorably improved.

Description

Cleaning solution for removing surface residues after CMP of multi-layer copper interconnection barrier layer

Technical Field

The invention relates to the technical field of microelectronics, in particular to a cleaning solution for removing surface residues of a multi-layer copper interconnection barrier layer after CMP and a preparation method thereof.

Background

At present, the development trend of integrated circuit technology is as follows: the wafer size is increased, the number of active devices is increased, the feature size is reduced, the requirement on the surface cleanliness of the copper interconnection barrier layer is strict, and the importance of cleaning in the semiconductor industry is attracted to people. CMP is used as a main planarization technology, which achieves planarization of a material surface through chemical reaction and mechanical friction, is applied to very large scale integrated circuits, and has local and global planarization effects. However, various defects may be formed on the surface of the workpiece during the CMP process. Including residues (organic residues and copper residues), particle adsorption, corrosion, scratch and the like, which all affect the reliability, electrical performance and other properties of the device, and more seriously may cause the functional failure of the device.

Residues, the most common defects in CMP processes, are mainly the extremely complex, miniaturized structures at sub-14 nm technology nodes, and the chemical design of the CMP slurry. These polishing solutions typically contain a variety of chemical additives including complexing agents, corrosion inhibitors, strong oxidizing agents, and stabilizers that remain persistent on the surface being treated by chemical mechanical polishing. If post-cleaning is not effective in removing these residues, it can adversely affect device performance and can directly affect device yield, performance, and reliability. Therefore, it is necessary to invent a cleaning solution capable of effectively removing the surface contamination.

Disclosure of Invention

The invention aims to provide a cleaning solution which has simple components and can effectively remove surface residues of a multi-layer copper interconnection barrier layer after CMP (chemical mechanical polishing), aiming at the technical defects in the prior art.

The invention also aims to provide a preparation method of the cleaning solution which is suitable for large-scale production and can effectively remove the surface residues of the multi-layer copper interconnection barrier layer after CMP.

The technical scheme adopted for realizing the purpose of the invention is as follows:

a cleaning solution for removing surface residues after CMP of a multi-layer copper interconnection barrier layer comprises the following components in percentage by mass: 0.1-5% of chelating agent, 0.1-15% of surfactant, 1% of defoaming agent, pH regulator and the balance of deionized water; the pH value of the cleaning solution is 7-7.5; the surfactant is prepared by compounding a cationic surfactant, a nonionic surfactant and an anionic surfactant.

The chelating agent is at least one of FA/O chelating agent, tetrahydroxyethyl ethylenediamine, ethylenediamine and triethanolamine.

The cationic surfactant is dodecyl dimethyl amine oxide, the nonionic surfactant is at least one of fatty alcohol-polyoxyethylene ether and FA/O surfactant, and the anionic surfactant is at least one of polyvinylpyrrolidone, fatty alcohol-polyoxyethylene ether ammonium sulfate, sodium dodecyl benzene sulfonate, ammonium dodecyl sulfate and dodecyl benzene sulfonic acid.

The pH regulator is nitric acid or potassium hydroxide.

The defoaming agent is an organic silicon defoaming agent.

A preparation method of a cleaning solution for removing surface residues after CMP of a multi-layer copper interconnection barrier layer comprises the following steps: sequentially adding the chelating agent, the active agent and the defoaming agent into a proper amount of deionized water according to the formula amount, uniformly stirring in a step-by-step mixing mode, finally supplementing the deionized water to 1000g, continuously stirring uniformly, adding the pH regulator, and regulating the pH value to 7-7.5.

Compared with the prior art, the invention has the beneficial effects that:

1. the cleaning solution disclosed by the invention is prepared by compounding a cationic surfactant, a nonionic surfactant and an anionic surfactant, and can effectively remove the large particle number and surface residues on the surface of a multi-layer copper interconnection barrier layer after CMP through steric hindrance, so that the performances of the device such as reliability, electric energy and the like are improved, and the yield of the device is favorably improved.

2. The pH value of the cleaning liquid is 7-7.5, the cleaning liquid is neutral, does not corrode equipment and does not pollute the environment.

3. The cleaning solution consists of a chelating agent, a surfactant, a pH regulator and deionized water, and has the advantages of simple components, good stability, low price and capability of adopting domestic raw materials.

4. The preparation method of the cleaning solution is simple, pollution-free and suitable for the requirement of large-scale industrial production.

Drawings

FIG. 1 is a map of the residual defect before cleaning of copper pattern C1;

FIG. 2 is a Scanning Electron Microscope (SEM) image of copper pattern piece C1 before cleaning;

FIG. 3 is a map showing the residual defects of the copper pattern sheet C1 after being cleaned with the cleaning solution S1;

FIG. 4 is a Scanning Electron Microscope (SEM) image of a copper pattern piece C1 after being washed with a washing liquid S1;

FIG. 5 is a map showing the residual defect map before cleaning of copper pattern piece C2;

FIG. 6 is a Scanning Electron Microscope (SEM) image of copper pattern piece C2 before cleaning;

FIG. 7 is a map showing the residual defects of the copper pattern sheet C2 after being cleaned with the cleaning solution S2;

FIG. 8 is a Scanning Electron Microscope (SEM) image of a copper pattern piece C2 after being washed with a washing liquid S2;

FIG. 9 is a map showing the residual defect map before cleaning of copper pattern piece C3;

FIG. 10 is a Scanning Electron Microscope (SEM) image of copper pattern piece C3 before cleaning;

FIG. 11 is a map showing the residual defects of the copper pattern sheet C3 after being cleaned with the cleaning solution S3;

FIG. 12 is a Scanning Electron Microscope (SEM) photograph of the copper pattern piece C3 after washing with the washing liquid S3.

FIG. 13 is a map showing the residual defect map before cleaning of copper pattern piece C4;

FIG. 14 is a Scanning Electron Microscope (SEM) image of copper pattern piece C4 before cleaning;

FIG. 15 is a map showing the residual defects of the copper pattern sheet C4 after being washed with the washing liquid S4;

FIG. 16 is a Scanning Electron Microscope (SEM) photograph of the copper pattern piece C4 after washing with the washing liquid S4.

Detailed Description

The invention is described in detail below with reference to the figures and specific examples.

In the cleaning solution, the surfactant is prepared by compounding a cationic surfactant, a nonionic surfactant and an anionic surfactant. Due to the surface effect of the nanomaterial, SiO₂The surface of the particles has a plurality of charges or functional groups and high surface energy, and the characteristics determine SiO₂The surface energy of the particles tends to be small, agglomeration occurs, and the particles are adsorbed on the surface of the wafer and are difficult to clean. After the composite active agent is added into the cleaning solution, because the nonionic is not easy to ionize in the aqueous solution, the stability is high, the complex is easy to prepare, and the anion permeability is good, the hydrophilic group is fully extended in the aqueous solution, and the lipophilic group is adsorbed on the surface of the particle to form a layer of film. When the particles are close to each other, the repulsion energy exists in the boundary area, so that the particles can keep enough safe distance to generate steric hindrance effect, further the molecular reaction activity is reduced, and the collision focus and gravity sedimentation of the particles are hindered. The active agent adsorbed on the surface of the particle repels the surrounding particles not only by its own charge but also by being sparseThe water radical and steric resistance effect prevent the particles moving in brownian to approach, thereby generating a composite stabilizing effect. The synergistic effect of multiple surfactants reduces the agglomeration capacity of particles, so that the abrasive particles keep a stable state with the lowest energy, and finally the stability of the whole system is achieved, so that the number of large particles on the surface of the copper pattern sheet is reduced, and the number of surface defects in the barrier layer CMP is reduced.

Comparative example 1

Taking 1% of FA/O chelating agent, 2% of dodecyl dimethyl amine Oxide (OA) and 1% of organosilicon antifoaming agent (AFE-1410). The preparation method comprises the following steps: sequentially adding the FA/O chelating agent, the OA and the defoaming agent into a proper amount of deionized water, uniformly stirring in a step-by-step mixing mode, finally filling the deionized water to 1000g, continuously stirring uniformly, adding a pH regulator (nitric acid or potassium hydroxide), and regulating the pH value to 7.5 to obtain the cleaning solution S1.

Residual defect testing experiment: the polished copper pattern piece was cleaned with a cleaning solution S1, and then surface residue was examined by Scanning Electron Microscopy (SEM). The number of residual defects is shown in Table 1, the map of residual defects is shown in FIG. 3, and the SEM image is shown in FIG. 4.

Comparative example 2

Taking 1% of FA/O chelating agent, 2% of dodecyl dimethyl amine Oxide (OA), 4% of FA/O surfactant and 1% of organosilicon antifoaming agent (AFE-1410). The preparation method comprises the following steps: sequentially adding the FA/O chelating agent, the OA, the FA/O surfactant and the defoaming agent into a proper amount of deionized water, uniformly stirring in a step-by-step mixing mode, finally supplementing the deionized water to 1000g, continuously stirring uniformly, adding a pH regulator (nitric acid or potassium hydroxide), and regulating the pH value to 7.5 to obtain the cleaning solution S2.

Residual defect testing experiment: the polished copper pattern piece was cleaned with a cleaning solution S2, and then surface residue was examined by Scanning Electron Microscopy (SEM). The number of residual defects is shown in Table 1, the map of residual defects is shown in FIG. 7, and the SEM image is shown in FIG. 8.

Example 1

Taking 1% of FA/O chelating agent, 2% of dodecyl dimethyl amine Oxide (OA), 4% of FA/O surfactant, 6% of dodecyl benzene sulfonic acid (LABSA) and 1% of organosilicon antifoaming agent (AFE-1410). The preparation method comprises the following steps: sequentially adding the FA/O chelating agent, the OA, the FA/O surfactant, the LABSA and the defoaming agent into a proper amount of deionized water, uniformly stirring in a step-by-step mixing mode, finally filling the deionized water to 1000g, continuously stirring uniformly, adding a pH regulator (nitric acid or potassium hydroxide), and regulating the pH value to 7.5 to obtain the cleaning solution S3.

Residual defect testing experiment: the polished copper pattern piece was cleaned with a cleaning solution S4, and then surface residue was examined by Scanning Electron Microscopy (SEM). The number of residual defects is shown in Table 1, the residual defect map is shown in FIG. 11, and the SEM image is shown in FIG. 12.

Example 2

Taking 1% of FA/O chelating agent, 2% of dodecyl dimethyl amine Oxide (OA), 4% of FA/O surfactant, 6% of dodecyl benzene sulfonic acid (LABSA), 3% of fatty alcohol polyoxyethylene ether (JFC) and 1% of organosilicon antifoaming agent (AFE-1410). The preparation method comprises the following steps: sequentially adding the FA/O chelating agent, the OA, the FA/O surfactant, the LABSA and the defoaming agent into a proper amount of deionized water, uniformly stirring in a step-by-step mixing mode, finally filling the deionized water to 1000g, continuously stirring uniformly, adding a pH regulator (nitric acid or potassium hydroxide), and regulating the pH value to 7.5 to obtain the cleaning solution S4.

Residual defect testing experiment: the polished copper pattern piece was cleaned with a cleaning solution S4, and then surface residue was examined by Scanning Electron Microscopy (SEM). The number of residual defects is shown in table 1, the residual defect map is shown in fig. 15, and the SEM image is shown in fig. 16.

Comparison of surface Defect number before and after cleaning after CMP for one Barrier layer

Before cleaning	Cleaning liquid	After cleaning, cleaning
			2611	S1	946
2658	S2	812
			2885	S3	312
2809	S4	30

As can be seen from the residual defect data in table one and the residual defect map and SEM images of the comparative example and the examples, the cleaning solution containing only the cationic surfactant and the surfactant in which the cationic surfactant and the nonionic surfactant are compounded can reduce the surface staining, but the number of residual defects is still large. The cleaning solution of the invention adopts the surfactant compounded by the cationic surfactant, the nonionic surfactant and the anionic surfactant, so that the surface contamination can be greatly reduced.

The surfactant in the cleaning solution is prepared by compounding a cationic surfactant, a nonionic surfactant and an anionic surfactant. The positively charged end of the cationic surfactant is combined with surface contamination, so that the cationic surfactant is easy to clean, and the surface contamination is reduced. The cationic surfactant and the nonionic surfactant are compounded, so that the surface tension is increased, the surface is more hydrophilic, the anionic surfactant has a strong osmosis effect, the surface contamination can be greatly reduced by compounding the three surfactants, the large particle number on the surface of the copper pattern sheet is obviously reduced, and the cleaning effect is good.

The foregoing is only a preferred embodiment of the present invention, and it should be noted that, for those skilled in the art, various modifications and decorations can be made without departing from the principle of the present invention, and these modifications and decorations should also be regarded as the protection scope of the present invention.

Claims

1. The cleaning solution for removing the surface residues of the multi-layer copper interconnection barrier layer after CMP is characterized by comprising the following components in percentage by mass: 0.1-5% of chelating agent, 0.1-15% of surfactant, 1% of defoaming agent, pH regulator and the balance of deionized water; the pH value of the cleaning solution is 7-7.5; the surfactant is prepared by compounding a cationic surfactant, a nonionic surfactant and an anionic surfactant.

2. The cleaning solution for removing the post-CMP surface residue of the multi-layer copper interconnect barrier layer according to claim 1, wherein the chelating agent is at least one of an FA/O chelating agent, tetrahydroxyethyl ethylenediamine, ethylenediamine and triethanolamine.

3. The cleaning solution for removing the post-CMP surface residue of the multilayer copper interconnection barrier layer according to claim 1, wherein the cationic surfactant is dodecyl dimethyl amine oxide, the nonionic surfactant is at least one of fatty alcohol-polyoxyethylene ether and FA/O surfactant, and the anionic surfactant is at least one of polyvinylpyrrolidone, ammonium fatty alcohol-polyoxyethylene ether sulfate, sodium dodecyl benzene sulfonate, ammonium dodecyl sulfate and dodecyl benzene sulfonic acid.

4. The cleaning solution for removing the post-CMP surface residue of the multi-layer copper interconnect barrier layer according to claim 1, wherein the pH regulator is nitric acid or potassium hydroxide.

5. The cleaning solution for removing the post-CMP surface residue of the multilayer copper interconnect barrier layer according to claim 1, wherein the defoaming agent is a silicone defoaming agent.

6. The preparation method of the cleaning solution for removing the post-CMP surface residue of the multi-layer copper interconnect barrier layer according to claim 1, comprising the following steps: sequentially adding the chelating agent, the active agent and the defoaming agent into a proper amount of deionized water according to the formula amount, uniformly stirring in a step-by-step mixing mode, finally supplementing the deionized water to 1000g, continuously stirring uniformly, adding the pH regulator, and regulating the pH value to 7-7.5.