CN111378366B

CN111378366B - Chemical mechanical polishing solution and application thereof

Info

Publication number: CN111378366B
Application number: CN201811613972.2A
Authority: CN
Inventors: 姚颖; 周文婷; 荆建芬; 杨俊雅; 李恒; 卞鹏程; 黄悦锐
Original assignee: Anji Microelectronics Shanghai Co Ltd
Current assignee: Anji Microelectronics Shanghai Co Ltd
Priority date: 2018-12-27
Filing date: 2018-12-27
Publication date: 2022-11-18
Anticipated expiration: 2038-12-27
Also published as: CN111378366A; TW202024292A; TWI826624B

Abstract

The invention provides a chemical mechanical polishing solution comprising abrasive particles and an ethoxylated butoxylated alkyl alcohol. The chemical mechanical polishing solution of the invention, by adding the nonionic surfactant with a specific molecular structure, greatly improves the surface roughness of the silicon dioxide (TEOS) after polishing while obtaining high silicon dioxide (TEOS) removal rate, effectively reduces the residue of surface pollutants, ensures that better wafer surface smoothness and flatness are obtained after polishing, and can meet the requirements on the surface of a dielectric material under various process conditions.

Description

Chemical mechanical polishing solution and application thereof

Technical Field

The invention relates to the technical field of polishing solution, in particular to chemical mechanical polishing solution for flattening a silicon dioxide substrate in the field of integrated circuit manufacturing and application thereof.

Background

In the fabrication of integrated circuits, thousands of structural units are often built on a silicon wafer substrate, and these structural units are interconnected by multiple layers of metal to further form functional circuits and devices. In the multilevel metal interconnection structure, silicon dioxide or silicon dioxide doped with other elements is filled between metal wires to be used as an interlayer Dielectric (ILD). With the development of integrated circuit metal interconnection technology and the increase of the number of wiring layers, chemical Mechanical Polishing (CMP) has been widely used for surface planarization in the chip manufacturing process. These planarized chip surfaces facilitate the production of multi-layer integrated circuits and prevent distortions caused by the application of dielectric layers on uneven surfaces.

The CMP process is the polishing of the surface of the integrated circuit using an abrasive-containing mixture and a polishing pad. In a typical chemical mechanical polishing process, a substrate is brought into direct contact with a rotating polishing pad, and a carrier is used to apply pressure to the backside of the substrate. During polishing, the pad and platen are rotated while maintaining a downward force on the back surface of the substrate, and an abrasive and chemically reactive solution (commonly referred to as a slurry or slurry) are applied to the pad, which reacts chemically with the film being polished to begin the polishing process.

Silicon dioxide, a commonly used dielectric material in integrated circuits, involves the removal of the silicon dioxide dielectric layer in many polishing processes. For example, in the polishing process of the oxide interlayer dielectric, the polishing slurry is mainly used for removing the oxide dielectric layer and flattening; when the shallow trench isolation layer is polished, the polishing solution is mainly used for removing and flattening the oxide dielectric layer and stopping on the silicon nitride; in barrier layer polishing, the polishing solution needs to remove silicon dioxide, copper and a copper barrier layer; in a Through Silicon Via (TSV) process, the formation of the Via also requires the removal of excess Silicon dioxide with a polishing solution. In these polishing processes, a higher removal rate of the oxide dielectric layer is required to ensure the productivity.

Oxide dielectric materials include thin film thermal oxide silicon dioxide (thin thermal oxide), high density plasma oxide (high density plasma oxide), borophosphosilicate glass (borophosphosilicate glass), tetraethoxy silicon dioxide (PETEOS), and carbon doped silicon dioxide (carbon doped oxide). Polishing abrasives used in the silica dielectric material polishing slurry are mainly ceria and silica, but the ceria abrasive easily scratches the surface during polishing. Silica generates less surface defects during polishing, so silica is used in a large amount as abrasive grains. However, to achieve higher oxide material removal rates, it is common to increase the amount of abrasive particles used, which increases the surface roughness of the wafer.

The chemical mechanical polishing solution disclosed in chinese patent CN104449396A adopts sulfonic acid compounds to improve the surface defect degree of polished silica, and comprises water, colloidal silica abrasive, sulfonic acid additives, a clathrate, and an oxidizing agent, and the pH value is greater than or equal to 10. The chemical mechanical polishing solution has a silicon oxide removal rate of not less than 1000

Per minute, and promotes post-polishing dimensions>The SP1 defect count of 0.16 micron is less than or equal to 70, and the SP1 scratch number is less than or equal to 25. A number of patents also disclose the use of nonionic surfactants in polishing solutions. Chinese patent CN1688665A discloses the use of an amphiphilic nonionic surfactant in the chemical mechanical polishing process of copper, which reduces dishing and dielectric erosion by adding the surfactant, but does not address the effect of the surfactant on the silica surface. Chinese patent CN101280158A discloses a chemical mechanical polishing solution for polysilicon, which uses a polyol-type nonionic surfactant to inhibit the removal rate of polysilicon, so as to obtain the polysilicon/silicon dioxide removal rate selectivity ratio required by the process. But the effect of the nonionic surfactant on the silica surface is not mentioned.

In order to overcome the problems of large surface roughness and more residual pollutants of silicon dioxide (TEOS) in the polishing process of the conventional chemical polishing solution, a new chemical mechanical polishing solution is urgently needed.

Disclosure of Invention

In order to solve the problems, the invention provides a chemical mechanical polishing solution, which improves the problems of surface flatness and much pollutant residue of a polished wafer through a nonionic surfactant with a specific molecular structure.

In order to achieve the above purpose, the invention is realized by the following technical scheme: a chemical mechanical polishing slurry is provided comprising abrasive particles and an ethoxylated butoxylated alkyl alcohol.

Preferably, the ethoxy butoxylated alkyl alcohol has 5 to 20 ethoxy groups x, 5 to 20 butoxy groups y, and an alkyl group of 11 to 15 carbon atoms which is straight or branched.

Preferably, the concentration of the ethoxylated butoxylated alkyl alcohol is 0.0005 to 1% by mass

Preferably, the concentration of the ethoxylated butoxylated alkyl alcohol is 0.001% -0.5% by mass.

Preferably, the abrasive particles are selected from one or more of silicon dioxide, aluminum oxide, cerium oxide, aluminum-doped silicon dioxide, and polymer particles.

Preferably, the content of the abrasive particles is 5-30% by mass. .

Preferably, the content of the grinding particles is 10-25% by mass.

Preferably, the abrasive particles have a particle size of 30 to 200nm.

Preferably, the abrasive particles have a particle size of 50 to 180nm.

Preferably, the pH value of the chemical mechanical polishing solution is 8-12.

Preferably, the pH value of the chemical mechanical polishing solution is 9-12.

The chemical mechanical polishing solution can also comprise a metal corrosion inhibitor, a complexing agent, an oxidizing agent and the like which are used for polishing silicon dioxide and metal at the same time.

The chemical mechanical polishing solution of the present invention may further comprise other additives commonly used in the art, such as pH regulator, bactericide, etc

In another aspect, the present invention provides a use of the chemical mechanical polishing liquid described above in polishing silicon dioxide.

The chemical mechanical polishing solution can be prepared by the following method: mixing the above components at a certain proportion, and adjusting to desired pH value with pH regulator (such as KOH or HNO 3).

Compared with the prior art, the chemical mechanical polishing solution has the following beneficial effects: the chemical mechanical polishing solution greatly improves the surface roughness of silicon dioxide (TEOS) after polishing by the nonionic surfactant with a specific molecular structure, effectively reduces the residue of surface pollutants, obtains high silicon dioxide (TEOS) removal rate, ensures better wafer surface smoothness and flatness after polishing, and can meet the requirements on the surface of a dielectric material under various process conditions.

Detailed Description

The present invention will be further described with reference to the following specific examples. It should be understood that the following examples are illustrative only and are not intended to limit the scope of the present invention.

The reagents and starting materials used in the present invention are commercially available.

The wt% of the invention refers to mass percentage.

Preparation examples:

table 1 shows the components and contents of the polishing solutions of examples 1 to 11 of the present invention and comparative examples 1 to 3. And preparing polishing solutions of examples and comparative examples according to the table, uniformly mixing the components, supplementing the mass percent to 100% with water, and adjusting the pH to a corresponding value by using a pH regulator to obtain the polishing solutions of the examples and the comparative examples.

TABLE 1 polishing slurry compositions of inventive examples 1-11 and comparative examples 1-3

Effect embodiment:

silica (TEOS) was polished using comparative polishing solutions 1 to 3 and polishing solutions of examples 1 to 11 under the following polishing conditions: the polishing machine is a 12-Reflexion LK machine, the polishing pad is IC1010pad, the downward pressure is 4.0psi, the rotating speed is that the polishing disk/polishing head =93/87rpm, the flow rate of the polishing solution is 300ml/min, and the polishing time is 1min. The results of the removal rate, the surface roughness of the polished silicon dioxide wafer measured by atomic force microscope AFM, and the number of contaminant particles on the surface of the polished silicon dioxide wafer measured by defect scanner SP2 are shown in table 2.

TABLE 2 removal Rate, surface roughness, surface contaminant particle count for TEOS for comparative polishing solutions 1-3 and polishing solutions of examples 1-11

The results are shown in table 2: the addition of the ethoxy butoxyl alkyl alcohol greatly improves the surface roughness of TEOS after polishing and effectively reduces the residue of surface pollutants, so that the polishing solution of the invention can obtain high silicon dioxide removal rate, simultaneously ensure better wafer surface smoothness and flatness after polishing, and can meet the requirements on the surface of a dielectric material under various process conditions.

It should be noted that the embodiments of the present invention have been described in a preferred embodiment and not limited to the embodiments, and those skilled in the art may modify and modify the above-disclosed embodiments to equivalent embodiments without departing from the scope of the present invention.

Claims

1. A chemical mechanical polishing solution comprising abrasive particles and an ethoxylated butoxylated alkyl alcohol;

in the ethoxylated butoxylated alkyl alcohol, the number x of ethoxylation groups is 5-20, the number y of butoxylation groups is 5-20, and alkyl is a straight chain or branched chain with 11-15 carbon atoms;

the mass percentage concentration of the ethoxylated butoxylated alkyl alcohol is 0.0005 to 1 percent;

the pH value of the chemical mechanical polishing solution is 8-12.

2. The chemical mechanical polishing solution of claim 1, wherein the ethoxylated butoxylated alkyl alcohol is present in a concentration of 0.001% to 0.5% by weight.

3. The chemical mechanical polishing solution of claim 1 wherein the abrasive particles are selected from one or more of silicon dioxide, aluminum oxide, cerium oxide, aluminum-doped silicon dioxide, and polymer particles.

4. The chemical mechanical polishing solution of claim 1, wherein the abrasive particles are present in an amount of 5 to 30% by mass.

5. The chemical mechanical polishing solution of claim 4, wherein the content of the abrasive particles is 10-25% by mass.

6. The chemical mechanical polishing solution of claim 1, wherein the abrasive particles have a particle size of 30 to 200nm.

7. The chemical mechanical polishing solution of claim 6, wherein the abrasive particles have a particle size of 50 to 180nm.

8. The chemical mechanical polishing solution according to claim 1, wherein the pH of the chemical mechanical polishing solution is 9 to 12.

9. Use of a chemical mechanical polishing liquid according to any one of claims 1 to 8 for polishing silica.