CMP polishing solution composition and application thereof in copper polishing

Abstract

The invention provides a CMP polishing solution composition and application thereof in copper polishing, the polishing solution composition comprises grinding particles, a complexing agent, a corrosion inhibitor, an anionic surfactant, a bactericide, a pH regulator and an oxidizing agent, and the polishing solution composition is prepared by combining a benzene ring-containing corrosion inhibitor and a benzene ring-free corrosion inhibitor according to a certain proportion. The polishing defects of copper can be greatly reduced, and organic residues are not formed to influence the smoothness of the copper surface; the anionic surfactant is added, so that the removal rate of copper is not influenced while the polishing defects of copper are greatly reduced; a purine compound is further added to serve as a third corrosion inhibitor, the number of scratches can be reduced on the basis that the polishing rate is not affected, and therefore the more excellent polishing effect is achieved.

Description

Technical Field

[0001] The present invention relates to a chemical mechanical polishing liquid composition, and particularly to a chemical mechanical polishing liquid composition for copper process. Background Art

[0002] In modern integrated circuit manufacturing, since the resistivity of copper is much lower than that of aluminum, under the same wiring length and cross-sectional area, the resistance of copper wires is smaller, which can transmit current more effectively, reduce signal transmission delay, and lower power consumption. This is of great significance for improving the operating speed and reducing energy consumption of integrated circuits, especially suitable for high-speed and high-frequency integrated circuits.

[0003] Due to the low resistivity of copper, when carrying the same current, its wiring cross-sectional area can be smaller than that of aluminum connections, thereby reducing the parasitic capacitance between adjacent connections and correspondingly reducing signal crosstalk. A smaller parasitic capacitance means less distortion of the signal during transmission, which can improve the signal integrity and reliability, and this is very crucial for integrated circuits processing high-speed signals.

[0004] The electromigration resistance of copper is much better than that of aluminum. Compared with traditional aluminum connections, the electromigration resistance of copper connections has increased by two orders of magnitude, and there are no connection voids caused by stress migration, greatly improving the stability and service life of integrated circuits.

[0005] Since copper cannot be etched like aluminum, the chemical mechanical polishing technology (CMP) of copper has been developed. Copper is placed in a polishing liquid composed of nanoscale abrasive particles, chemical oxidants, etc., and copper is removed under the dual action of chemistry and mechanics. During the copper CMP process, the performance of the polishing liquid directly affects the polishing effect, which not only determines the removal rate of copper, but also affects the surface quality and defect conditions after polishing. When the polishing liquid is not reasonably designed, defects that affect the product yield, such as dish-shaped defects and damage formed by edge over erosion (EOE), will occur.

[0006] In the prior art, although various copper polishing liquid formulations have been developed, there are still some problems that need to be solved urgently. CN106916536B reduces the EOE phenomenon by adjusting the selection ratio between various film materials of the barrier layer polishing liquid. However, when the EOE phenomenon caused by severe corrosion of copper occurs during the copper polishing process, it is difficult to correct this phenomenon during the barrier layer polishing. When some polishing liquids pursue a high removal rate, they may cause defects such as dish-shaped defects and edge over-corrosion on the surface after polishing, affecting the product yield; while when the polishing liquid solves the edge defect problem, it often has a negative impact on the polishing rate of copper, resulting in a decrease in polishing efficiency and being unable to meet the requirements of high-efficiency and high-quality polishing in integrated circuit manufacturing. Therefore, developing a copper polishing liquid composition that can effectively reduce edge defects and does not affect the polishing rate has become a technical problem that needs to be solved urgently. Summary of the Invention

[0007] To solve the problem of edge over-corrosion (EOE) caused by excessive corrosion of copper, the present invention provides a CMP polishing liquid for polishing copper, which comprises abrasive particles, complexing agents, corrosion inhibitors, anionic surfactants, fungicides, pH regulators, and oxidants;

[0008] Furthermore, the corrosion inhibitor includes a first corrosion inhibitor and a second corrosion inhibitor: the first corrosion inhibitor is a nitrogen-containing heterocyclic compound containing a benzene ring, and the second corrosion inhibitor is a nitrogen-containing heterocyclic compound without a benzene ring;

[0009] And / or, the corrosion inhibitor further includes a third corrosion inhibitor, and the third corrosion inhibitor is a purine compound.

[0010] Furthermore, the ratio of the first corrosion inhibitor to the second corrosion inhibitor is 1:10 - 1:100, preferably 1:20 - 1:50;

[0011] And / or, the content of the third corrosion inhibitor in the polishing liquid is 1 ppm - 200 ppm, preferably 1 ppm - 50 ppm.

[0012] Furthermore, the pH of the polishing liquid is 6 - 9, preferably pH = 6 - 8;

[0013] Furthermore, the mass fraction of the abrasive particles is 0.1% - 0.5%, more preferably 0.1% - 0.3%;

[0014] And / or, the mass fraction of the anionic surfactant is 0.001% - 1.0%, preferably 0.005% - 0.05%;

[0015] And / or, the mass fraction of the oxidant is 0.1% - 5.0%, preferably 0.5% - 2.0%;

[0016] And / or, the mass fraction of the complexing agent is 0.5%-8.0%, preferably 1%-5%;

[0017] And / or, the mass fraction of the first corrosion inhibitor is 0.001%-0.01%, and the mass fraction of the second corrosion inhibitor is 0.01%-0.5%.

[0018] And / or, the mass fraction of the bactericide is 0.001%-0.05%.

[0019] Furthermore, the first corrosion inhibitor is selected from at least one of 5-phenyl-1H-tetrazole, benzotriazole, 1,2,3-benzotriazole, 5-methylbenzotriazole, 5,6-dimethyl-1,2,3-benzotriazole, 1-[N,N-bis(hydroxyethyl)aminomethyl]benzotriazole, 1-(hydroxymethyl)benzotriazole, 1-(1,2-dicarboxyethyl)benzotriazole, benzimidazole, quinoline, quinoline-2-carboxylic acid, indazole, indazole-3-carboxylic acid;

[0020] Preferably, the first corrosion inhibitor is selected from at least one of 5-phenyl-1H-tetrazole, benzotriazole, 1,2,3-benzotriazole, 5-methylbenzotriazole, 5,6-dimethyl-1,2,3-benzotriazole, 1-[N,N-bis(hydroxyethyl)aminomethyl]benzotriazole, 1-(hydroxymethyl)benzotriazole, 1-(1,2-dicarboxyethyl)benzotriazole;

[0021] More preferably, the first corrosion inhibitor is selected from at least one of benzotriazole and 5-phenyl-1H-tetrazole;

[0022] And / or, the second corrosion inhibitor is selected from at least one of 5-amino-1H-tetrazole, 5-methyl-1H-tetrazole, 5-ethyl-1-methyltetrazole, 1H-tetrazole, 1-acetic acid-tetrazole, 1-methyltetrazole, 1-(β-aminoethyl)-tetrazole, 5-amino-1-H tetrazole, 1,2,3-triazole, 1,2,3-triazole-4-carboxylic acid, 5-methyl-1,2,3-triazole-4-carboxylic acid, 1,2,3,4-tetrazole, 5-methyl-1,2,3,4-tetrazole, 5-amino-1,2,3,4-tetrazole, 1,2,3,4-tetrazole-5-acetic acid, imidazole, imidazole-4-carboxylic acid;

[0023] Preferably, the second corrosion inhibitor is selected from at least one of 5-amino-1H-tetrazole, 5-methyl-1H-tetrazole, 5-ethyl-1-methyltetrazole, 1H-tetrazole, 1-acetic acid-tetrazole, 1-methyltetrazole, 1-(β-aminoethyl)-tetrazole, 5-amino-1-H tetrazole, 1,2,3-triazole, 1,2,3-triazole-4-carboxylic acid, 5-methyl-1,2,3-triazole-4-carboxylic acid, 1,2,3,4-tetrazole, 5-methyl-1,2,3,4-tetrazole, 5-amino-1,2,3,4-tetrazole, 1,2,3,4-tetrazole-5-acetic acid;

[0024] More preferably, the second corrosion inhibitor is selected from at least one of 1,2,4-triazole, 1,2,3,4-tetrazole, 5-aminotetrazole;

[0025] And / or, the third corrosion inhibitor is selected from at least one of adenosine, adenine, guanine, uric acid, caffeine, theophylline;

[0026] Preferably, the third corrosion inhibitor is selected from at least one of adenine, guanine, uric acid, more preferably guanine or uric acid;

[0027] And / or, the anionic surfactant is selected from at least one of sodium dodecyl sulfate, potassium dodecyl sulfate, ammonium dodecyl sulfate, dodecylbenzenesulfonic acid, dodecyl diphenyl ether monosulfonic acid, dodecyl diphenyl ether disulfonic acid, a mixture of dodecyl diphenyl ether monosulfonic acid and dodecyl diphenyl ether disulfonic acid, polyacrylic acid;

[0028] Preferably, the anionic surfactant is selected from one or several combinations of sodium dodecyl sulfate, potassium dodecyl sulfate, ammonium dodecyl sulfate, dodecylbenzenesulfonic acid, dodecyl diphenyl ether monosulfonic acid, dodecyl diphenyl ether disulfonic acid, a mixture of dodecyl diphenyl ether monosulfonic acid and dodecyl diphenyl ether disulfonic acid, more preferably sodium dodecylbenzenesulfonate;

[0029] And / or, the abrasive particles are selected from one or more of colloidal silica, fumed silica, alumina, preferably colloidal silica;

[0030] And / or, the complexing agent is selected from at least one of compounds with both amino and carboxyl groups and their salts, preferably one or more of glycine, arginine, alanine, valine, glutamic acid, cysteine, histidine, serine, ethylenediaminetetraacetic acid, diethylenetriaminepentaacetic acid, and triethylenetetraminehexaacetic acid, preferably glycine or ethylenediaminetetraacetic acid, more preferably glycine.

[0031] And / or, the pH regulator includes at least one of potassium hydroxide, ammonia water, tetraethylammonium hydroxide, nitric acid, and sulfuric acid; and / or, the oxidant is selected from at least one of hydrogen peroxide, iron nitrate, and ammonium persulfate, preferably hydrogen peroxide;

[0032] And / or, the bactericide includes at least one of isothiazolinone, 5-chloroisothiazolinone, and benzisothiazolinone, preferably isothiazolinone.

[0033] Furthermore, the abrasive particles are preferably colloidal silica abrasive particles, and the particle size distribution range is 30-90 nm, more preferably 45-80 nm.

[0034] More preferably, the polishing liquid includes colloidal silica abrasive particles with a mass fraction of 0.15 wt%, an average particle size of 60 nm, 1 wt% glycine complexing agent, 0.001 wt% of the first corrosion inhibitor benzotriazole, 0.05 wt% of the second corrosion inhibitor 1,2,4-triazole, 0.005 wt% of the anionic surfactant sodium dodecylbenzenesulfonate, 0.001 wt% of the bactericide isothiazolinone, 0.8 wt% of the oxidant hydrogen peroxide, and the pH of the polishing liquid is 7;

[0035] Or, the polishing liquid includes colloidal silica abrasive particles with a mass fraction of 0.15 wt%, an average particle size of 60 nm, 1 wt% glycine complexing agent, 0.001 wt% of the first corrosion inhibitor benzotriazole, 0.05 wt% of the second corrosion inhibitor 1,2,4-triazole, 0.005 wt% of the anionic surfactant sodium dodecylbenzenesulfonate, 0.005 wt% of the third corrosion inhibitor uric acid, 0.001 wt% of the bactericide isothiazolinone, 0.8 wt% of the oxidant hydrogen peroxide, and the pH of the polishing liquid is 7.

[0036] The present invention also provides the application of the above polishing liquid in CMP polishing of copper processes.

[0037] Beneficial effects:

[0038] 1. Simultaneously using a certain proportion of the first corrosion inhibitor containing a benzene ring and the second corrosion inhibitor without a benzene ring can not only effectively inhibit the edge over-corrosion (EOE) caused by too fast copper corrosion rate, but also will not form organic residues on the surface of copper to affect the surface finish;

[0039] 2. The addition of the anionic surfactant can further reduce the number of defects in copper polishing without affecting the copper removal rate, further optimizing the polishing effect and improving the stability and reliability of the polishing liquid.

[0040] 3. The polishing liquid composition of the present invention comprises abrasive particles, complexing agents, corrosion inhibitors, anionic surfactants, fungicides, pH regulators and oxidants. The pH of the polishing liquid is controlled between 6 and 8, which is suitable for chemical mechanical polishing of copper, can effectively reduce edge defects and improve polishing quality. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] Figure 1 : SEM images of the copper edge before (a) and after 30 seconds of polishing (b) in Example 1 of the present invention

[0042] Figure 2 : SEM images of the copper corner before (a) and after 30 seconds of polishing (b) in Example 1 of the present invention

[0043] Figure 3 : SEM images of the copper edge before (a) and after 30 seconds of polishing (b) in Comparative Example 1 of the present invention

[0044] Figure 4 : SEM images of the copper corner before (a) and after 30 seconds of polishing (b) in Comparative Example 1 of the present invention

[0045] Figure 5 : SEM image of the copper surface in Example 1 of the present invention

[0046] Figure 6 : SEM image of the copper surface in Comparative Example 2 of the present invention DETAILED DESCRIPTION OF THE INVENTION

[0047] Hereinafter, the present invention will be described in detail. However, the present invention is not limited to the embodiments including the following examples and can be variously modified within the scope that can achieve the object of the invention and does not exceed the gist of the invention.

[0048] The object of the present invention is to provide a CMP polishing liquid for polishing copper to solve the EOE phenomenon occurring in the copper CMP polishing process in the prior art without affecting the copper removal rate. The polishing liquid composition comprises the following components:

[0049] In the embodiments of the present invention, the polishing liquid for polishing copper mainly comprises abrasive particles, complexing agents, corrosion inhibitors, anionic surfactants, fungicides, pH regulators and oxidants, and the balance is water.

[0050] Since the polishing liquid of the present invention is used for polishing copper substrates, in order to avoid excessive removal of silicon dioxide, tantalum, and tantalum nitride, in the embodiments of the present invention, the abrasive particles can be selected from colloidal silica, fumed silica, alumina, etc. Colloidal silica abrasive particles are preferably selected, with a particle size distribution of 30 - 90 nm, specifically, for example, 30 nm, 35 nm, 40 nm, 45 nm, 50 nm, 55 nm, 60 nm, 65 nm, 70 nm, 75 nm, 80 nm, 85 nm, 90 nm, or any particle size within the above range. More preferably, the particle size distribution of the silica abrasive particles used in the embodiments of the present invention is more preferably in the range of 45 - 80 nm, and the preferred particle sizes can be one of 45 nm, 60 nm, and 80 nm.

[0051] Meanwhile, the mass fraction of the abrasive particles in the polishing liquid is 0.1% - 0.5%, specifically, it can be 0.1%, 0.15%, 0.2%, 0.25%, 0.3%, 0.5%, 0.4%, 0.45%, 0.5%, or any value within the above range. In the present invention, the mass fraction of the abrasive particles in the polishing liquid is preferably 0.1% - 0.3%, and particularly preferably, abrasive particles with a mass fraction of 0.1%, 0.15%, 0.2%, and 0.3% can avoid excessive removal of silicon dioxide, tantalum, and tantalum nitride.

[0052] In the embodiments of the present invention, a complexing agent is required to stabilize copper ions and form a water-soluble complex with copper ions. Selecting a suitable complexing agent can not only improve the polishing rate of copper, but also reduce surface defects to a certain extent, improve the flatness and smoothness of the copper surface, and achieve a better polishing effect. In the embodiments of the present invention, the complexing agent used is a compound and its salt containing both amino and carboxyl groups, including but not limited to one or more of glycine, arginine, alanine, valine, glutamic acid, cysteine, histidine, serine, ethylenediaminetetraacetic acid, diethylenetriaminepentaacetic acid, and triethylenetetraminehexaacetic acid, with glycine being preferred. In the present invention, the mass fraction of the complexing agent in the polishing liquid is 0.5% - 8.0%, specifically, it can be 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, or any value within the above range. In the embodiments of the present invention, the content of the complexing agent is preferably 1.0% - 5%, and more specifically, it is 1% glycine, 3% glycine, and 5% glycine.

[0053] In the present invention, the corrosion inhibitor can help control the removal rate of copper, while preventing the surface of copper from being over-corroded, reducing surface defects and achieving a planarization effect. Through research, it is found in the present invention that the corrosion inhibitor containing a benzene ring can provide strong adsorption ability, with high corrosion inhibition effect and stability. However, the benzene ring may have environmental or toxicity problems. Through experimental research, it is found in the present invention that although the corrosion inhibitor containing a benzene ring has a good inhibition effect on the over-corrosion of copper, it is likely to remain on the surface, affecting the polishing effect of copper. The corrosion inhibitor without a benzene ring will not form organic residues on the surface of copper, but its corrosion inhibition effect is poor. Therefore, two corrosion inhibitors are used simultaneously in the present invention: the first corrosion inhibitor is a nitrogen-containing heterocyclic compound containing a benzene ring, specifically, it can be 5-phenyl-1H-tetrazole, benzotriazole, 1,2,3-benzotriazole, 5-methylbenzotriazole, 5,6-dimethyl-1,2,3-benzotriazole, 1-[N,N-bis(hydroxyethyl)aminomethyl]benzotriazole, 1-(hydroxymethyl)benzotriazole, 1-(1,2-dicarboxyethyl)benzotriazole, benzimidazole, quinoline, quinoline-2-carboxylic acid, indazole, indazole-3-carboxylic acid, etc.; the second corrosion inhibitor is a nitrogen-containing heterocyclic compound without a benzene ring, specifically, such as 5-amino-1H-tetrazole, 5-methyl-1H-tetrazole, 5-ethyl-1-methyltetrazole, 1H-tetrazole, 1-acetic acid-tetrazole, 1-methyl-tetrazole, 1-(β-aminoethyl)-tetrazole, 5-amino-1-H tetrazole, 1,2,3-triazole, 1,2,3-triazole-4-carboxylic acid, 5-methyl-1,2,3-triazole-4-carboxylic acid, 1,2,3,4-tetrazole, 5-methyl-1,2,3,4-tetrazole, 5-amino-1,2,3,4-tetrazole, 1,2,3,4-tetrazole-5-acetic acid, imidazole, imidazole-4-carboxylic acid, pyrazole, pyridine, pyridine-3,4-dicarboxylic acid, etc.

[0054] Furthermore, through research, it is found in the present invention that the corrosion inhibitor can also include purine compounds as the third corrosion inhibitor. Since in the chemical mechanical polishing process of copper, copper is first oxidized by an oxidant, and then an oxide film is formed on the surface of copper. The formation of this oxide film is beneficial to both the improvement of the removal rate of copper and the protection of the copper surface, avoiding the direct scratching of the copper surface by abrasives, and thus reducing the generation of scratches. The addition of purine compounds can inhibit the dissolution rate of CuO, resulting in a significant reduction in the number of scratches on the surface of the copper wafer after chemical mechanical polishing. Specifically, the third corrosion inhibitor can be selected from at least one of adenosine, adenine, guanine, uric acid, caffeine, theophylline, etc., preferably uric acid or guanine. The content of the third corrosion inhibitor in the polishing liquid is 1 ppm - 200 ppm, preferably 1 ppm - 50 ppm.

[0055] In the embodiments of the present invention, it is found through research that the addition ratio of two corrosion inhibitors needs to be controlled. Specifically, the ratio of the first corrosion inhibitor to the second corrosion inhibitor is 1:10 - 1:100, preferably between 1:20 - 1:50, which can avoid the formation of organic residues on the surface, and at the same time can obtain excellent corrosion inhibition effect, reduce edge over-corrosion and dish-shaped defects. The mass fraction of the first corrosion inhibitor is 0.001% - 0.01%, and the mass fraction of the second corrosion inhibitor is 0.01% - 0.5%.

[0056] In the present invention, preferably, the first corrosion inhibitor is benzotriazole, the second corrosion inhibitor is 1,2,4-triazole, the third corrosion inhibitor is guanine or uric acid, the ratio of the first corrosion inhibitor to the second corrosion inhibitor is 1:50, and the addition amount of the third corrosion inhibitor is 1 ppm.

[0057] Meanwhile, in the present invention, an anionic surfactant needs to be used in combination with the corrosion inhibitor to achieve a better polishing effect, reduce defects, and at the same time have no obvious impact on the copper removal rate. The anionic surfactants that can be used in the embodiments of the present invention include sodium dodecyl sulfate, potassium dodecyl sulfate, ammonium dodecyl sulfate, dodecylbenzenesulfonic acid, dodecyl diphenyl ether monosulfonic acid, dodecyl diphenyl ether disulfonic acid, a mixture of dodecyl diphenyl ether monosulfonic acid and dodecyl diphenyl ether disulfonic acid, polyacrylic acid, poloxamer 188, lauryldimethylamine oxide, polypropylene glycol, polyoxyethylene lauryl ether, polyvinylpyrrolidone, etc. To obtain a better polishing effect and fewer defects, anionic surfactants are preferably selected, such as anionic surfactants like sodium dodecyl sulfate, potassium dodecyl sulfate, ammonium dodecyl sulfate, dodecylbenzenesulfonic acid, dodecyl diphenyl ether monosulfonic acid, dodecyl diphenyl ether disulfonic acid, a mixture of dodecyl diphenyl ether monosulfonic acid and dodecyl diphenyl ether disulfonic acid, polyacrylic acid, etc. The mass fraction of the surfactant in the polishing solution in the embodiments of the present invention is 0.001% - 1.0%, preferably 0.001% - 0.05%. Considering the control of product stability, small-molecule anionic surfactants are preferably used.

[0058] In the present invention, the pH value of the polishing liquid is controlled between 6 and 9 by a pH regulator. Specifically, it can be 6, 7, 8, 9 or the range between any two of the above pH values; more preferably, the pH can be controlled between 6 and 8. Through research, it is found in the present invention that too low pH will increase the corrosion effect on copper, causing some defects on the copper surface, and at the same time, it will also affect the synergistic effect of the anionic surfactant in the polishing liquid. While in a too alkaline pH, the removal rate of the copper body will be affected. When the pH is between 6 and 9, especially between 6 and 8, it can weaken corrosion, reduce defects without affecting the copper removal rate. The pH regulators that can be selected in the embodiments of the present invention include at least one of potassium hydroxide, ammonia water, tetraethylammonium hydroxide, nitric acid, and sulfuric acid.

[0059] In the present invention, the oxidants used include, but are not limited to, hydrogen peroxide, iron nitrate, ammonium persulfate. In the embodiments of the present invention, hydrogen peroxide is preferably used; in the present invention, the mass fraction of the oxidant in the polishing liquid is 0.1%-5.0%, more preferably 0.5%-2.0%. Specifically, it can be 0.1%, 0.2%, 0.3%, 0.4%, 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, 1%, 2%, 3%, 4%, 5% or any range combination thereof. In the embodiments of the present invention, the oxidant used is hydrogen peroxide, and the mass fraction is 0.8%.

[0060] In the present invention, the bactericides used include at least one of isothiazolinone, 5-chloroisothiazolinone, and benzisothiazolinone. The mass fraction of the bactericide in the polishing liquid is 0.001%-0.05%. In the embodiments of the present invention, the bactericide is isothiazolinone, and the mass fraction in the polishing liquid is 0.001%.

[0061] In the present invention, preferably, the polishing liquid includes silica abrasive particles with a mass fraction of 0.15 wt% and an average particle size of 60 nm, 1 wt% glycine complexing agent, 0.001 wt% of the first corrosion inhibitor benzotriazole, 0.05 wt% of the second corrosion inhibitor 1,2,4-triazole, 0.005 wt% of the anionic surfactant sodium dodecylbenzenesulfonate, 0.001 wt% of the bactericide isothiazolinone, 0.8 wt% of the oxidant hydrogen peroxide, and the pH of the polishing liquid = 7;

[0062] Alternatively, more preferably, the polishing liquid comprises silica abrasive particles with a mass fraction of 0.15 wt% and an average particle size of 60 nm, 1 wt% glycine complexing agent, 0.001 wt% benzotriazole as the first corrosion inhibitor, 0.05 wt% 1,2,4-triazole as the second corrosion inhibitor, 0.005 wt% sodium dodecylbenzenesulfonate as the anionic surfactant, 0.005 wt% uric acid as the third corrosion inhibitor, 0.001 wt% isothiazolinone as the bactericide, and 0.8 wt% hydrogen peroxide as the oxidizing agent, and the pH of the polishing liquid is 7.

[0063] Example

[0064] In the following examples, unless otherwise specified, the raw material reagents or processing techniques used are common commercially available raw materials or conventional processing techniques in the art.

[0065] In the polishing liquids of the embodiments of the present invention, commercially available gel silica abrasive particles are used as the abrasive particles, and hydrogen peroxide is used as the oxidizing agent, and the mass fraction of hydrogen peroxide is 0.8%. In each example, pH is adjusted using pH regulators nitric acid and / or potassium hydroxide as follows:

[0066] Example 1

[0067] Polishing liquid is prepared by using silica abrasive particles with a mass fraction of 0.15 wt% and an average particle size of 60 nm, 1 wt% glycine complexing agent, 0.001 wt% benzotriazole as the first corrosion inhibitor, 0.05 wt% 1,2,4-triazole as the second corrosion inhibitor, 0.005 wt% sodium dodecylbenzenesulfonate as the anionic surfactant, 0.001 wt% isothiazolinone as the bactericide, and 0.8 wt% hydrogen peroxide as the oxidizing agent, adding deionized water and adjusting the pH to around 7 using a pH regulator.

[0068] For the preparation methods of the polishing liquids of Example 2 - 12 and Comparative Examples 1 - 9, refer to Example 1. The contents, selected types of each component in the formula, and the pH control of the slurry composition are as listed in Table 1, so as to prepare different polishes.

[0069] Table 1 Composition of the polishing liquids of Example 1 - 12 and Comparative Examples 1 - 9

[0070]

[0071]

[0072] Example 2

[0073] Using silica abrasive particles with a mass fraction of 0.3 wt% and an average particle size of 80 nm, 5 wt% glycine complexing agent, 0.001 wt% of the first corrosion inhibitor benzotriazole, 0.05 wt% of the second corrosion inhibitor 1,2,4-triazole, 0.007 wt% of the anionic surfactant polyacrylic acid (Mw = 5000), 0.001 wt% of the bactericide isothiazolinone, and 0.8 wt% of the oxidant hydrogen peroxide, deionized water is added and the pH is adjusted to around pH = 6 with a pH regulator to prepare the polishing liquid.

[0074] Example 3

[0075] Using silica abrasive particles with a mass fraction of 0.2 wt% and an average particle size of 45 nm, 0.5 wt% glycine complexing agent, 0.001 wt% of the first corrosion inhibitor benzotriazole, 0.09 wt% of the second corrosion inhibitor 1,2,4-triazole, 0.001 wt% of the anionic surfactant potassium dodecyl sulfate, 0.001 wt% of the bactericide isothiazolinone, and 0.8 wt% of the oxidant hydrogen peroxide, deionized water is added and the pH is adjusted to around pH = 8 with a pH regulator to prepare the polishing liquid.

[0076] Example 4

[0077] Using silica abrasive particles with a mass fraction of 0.15 wt% and an average particle size of 60 nm, 8 wt% glycine complexing agent, 0.001 wt% of the first corrosion inhibitor benzotriazole, 0.1 wt% of the second corrosion inhibitor 1,2,4-triazole, 1 wt% of the anionic surfactant sodium dodecylbenzenesulfonate, 0.001 wt% of the bactericide isothiazolinone, and 0.8 wt% of the oxidant hydrogen peroxide, deionized water is added and the pH is adjusted to around pH = 7 with a pH regulator to prepare the polishing liquid.

[0078] Example 5

[0079] Using silica abrasive particles with a mass fraction of 0.5 wt% and an average particle size of 30 nm, 6 wt% glycine complexing agent, 0.002 wt% of the first corrosion inhibitor benzotriazole, 0.15 wt% of the second corrosion inhibitor 1,2,4-triazole, 0.08 wt% of the anionic surfactant ammonium dodecyl sulfate, 0.05 wt% of the bactericide isothiazolinone, and 0.8 wt% of the oxidant hydrogen peroxide, deionized water is added and the pH is adjusted to around pH = 7 with a pH regulator to prepare the polishing liquid.

[0080] Example 6

[0081] Prepare a polishing solution by using silica abrasive particles with a mass fraction of 0.15 wt% and an average particle size of 60 nm, 1 wt% of glycine complexing agent, 0.01 wt% of the first corrosion inhibitor benzotriazole, 0.3 wt% of the second corrosion inhibitor 1,2,3,4-tetrazole, 0.1 wt% of the anionic surfactant sodium dodecylbenzenesulfonate, 0.001 wt% of the fungicide isothiazolinone, 0.8 wt% of the oxidant hydrogen peroxide, adding deionized water and adjusting the pH to around 7 with a pH regulator.

[0082] Example 7

[0083] Prepare a polishing solution by using silica abrasive particles with a mass fraction of 0.15 wt% and an average particle size of 60 nm, 1 wt% of ethylenediaminetetraacetic acid complexing agent, 0.001 wt% of the first corrosion inhibitor benzotriazole, 0.02 wt% of the second corrosion inhibitor 1,2,4-triazole, 0.05 wt% of the anionic surfactant sodium dodecylbenzenesulfonate, 0.001 wt% of the fungicide isothiazolinone, 0.8 wt% of the oxidant hydrogen peroxide, adding deionized water and adjusting the pH to around 8 with a pH regulator.

[0084] Example 8

[0085] Prepare a polishing solution by using silica abrasive particles with a mass fraction of 0.1 wt% and an average particle size of 90 nm, 3 wt% of glycine complexing agent, 0.009 wt% of the first corrosion inhibitor 5-phenyl-1H-tetrazole, 0.45 wt% of the second corrosion inhibitor 5-amino-1H-tetrazole, 0.01 wt% of the anionic surfactant sodium dodecylbenzenesulfonate, 0.001 wt% of the fungicide isothiazolinone, 0.8 wt% of the oxidant hydrogen peroxide, adding deionized water and adjusting the pH to around 7 with a pH regulator.

[0086] Example 9

[0087] Prepare a polishing solution by using silica abrasive particles with a mass fraction of 0.15 wt% and an average particle size of 60 nm, 1 wt% of glycine complexing agent, 0.01 wt% of the first corrosion inhibitor benzotriazole, 0.15 wt% of the second corrosion inhibitor 1,2,4-triazole, 0.001 wt% of the anionic surfactant sodium dodecylbenzenesulfonate, 0.001 wt% of the fungicide isothiazolinone, 0.8 wt% of the oxidant hydrogen peroxide, adding deionized water and adjusting the pH to around 9 with a pH regulator.

[0088] Example 10

[0089] Using silica abrasive particles with a mass fraction of 0.15 wt% and an average particle size of 60 nm, 1 wt% glycine complexing agent, 0.001 wt% of the first corrosion inhibitor benzotriazole, 0.05 wt% of the second corrosion inhibitor 1,2,4-triazole, 0.005 wt% of the anionic surfactant sodium dodecylbenzenesulfonate, 0.0001 wt% of the third corrosion inhibitor guanine, 0.001 wt% of the bactericide isothiazolinone, 0.8 wt% of the oxidant hydrogen peroxide, adding deionized water and adjusting to pH = 7 nearby with a pH regulator to prepare a polishing solution.

[0090] Example 11

[0091] Using silica abrasive particles with a mass fraction of 0.15 wt% and an average particle size of 60 nm, 1 wt% glycine complexing agent, 0.001 wt% of the first corrosion inhibitor benzotriazole, 0.05 wt% of the second corrosion inhibitor 1,2,4-triazole, 0.005 wt% of the anionic surfactant sodium dodecylbenzenesulfonate, 0.0001 wt% of the third corrosion inhibitor uric acid, 0.001 wt% of the bactericide isothiazolinone, 0.8 wt% of the oxidant hydrogen peroxide, adding deionized water and adjusting to pH = 7 nearby with a pH regulator to prepare a polishing solution.

[0092] Example 12

[0093] Using silica abrasive particles with a mass fraction of 0.15 wt% and an average particle size of 60 nm, 1 wt% glycine complexing agent, 0.001 wt% of the first corrosion inhibitor benzotriazole, 0.05 wt% of the second corrosion inhibitor 1,2,4-triazole, 0.005 wt% of the anionic surfactant sodium dodecylbenzenesulfonate, 0.005 wt% of the third corrosion inhibitor uric acid, 0.001 wt% of the bactericide isothiazolinone, 0.8 wt% of the oxidant hydrogen peroxide, adding deionized water and adjusting to pH = 7 nearby with a pH regulator to prepare a polishing solution.

[0094] Comparative Example 1

[0095] Using silica abrasive particles with a mass fraction of 0.15 wt% and an average particle size of 60 nm, 1 wt% glycine complexing agent, 0.001 wt% of the first corrosion inhibitor benzotriazole, 0.05 wt% of the second corrosion inhibitor 1,2,4-triazole, 0.005 wt% of the bactericide isothiazolinone, 0.8 wt% of the oxidant hydrogen peroxide, adding deionized water and adjusting to pH = 7 nearby with a pH regulator to prepare a polishing solution.

[0096] Comparative Example 2

[0097] A polishing liquid is prepared by using silica grinding particles with a mass fraction of 0.15 wt%, an average particle size of 60 nm, 1 wt% of glycine complexing agent, 0.051 wt% of the first corrosion inhibitor benzotriazole, 0.005 wt% of anionic surfactant sodium dodecylbenzenesulfonate, 0.001 wt% of biocide isothiazolinone, 0.8 wt% of oxidant hydrogen peroxide, adding deionized water and adjusting the pH to around pH = 7 with a pH regulator.

[0098] Comparative Example 3

[0099] A polishing liquid is prepared by using silica grinding particles with a mass fraction of 0.15 wt%, an average particle size of 60 nm, 1 wt% of glycine complexing agent, 0.051 wt% of the second corrosion inhibitor 1,2,4-triazole, 0.005 wt% of anionic surfactant sodium dodecylbenzenesulfonate, 0.001 wt% of biocide isothiazolinone, 0.8 wt% of oxidant hydrogen peroxide, adding deionized water and adjusting the pH to around pH = 7 with a pH regulator.

[0100] Comparative Example 4

[0101] A polishing liquid is prepared by using silica grinding particles with a mass fraction of 0.15 wt%, an average particle size of 60 nm, 1 wt% of glycine complexing agent, 0.01 wt% of the first corrosion inhibitor benzotriazole, 0.041 wt% of the second corrosion inhibitor 1,2,4-triazole, 0.005 wt% of anionic surfactant sodium dodecylbenzenesulfonate, 0.001 wt% of biocide isothiazolinone, 0.8 wt% of oxidant hydrogen peroxide, adding deionized water and adjusting the pH to around pH = 7 with a pH regulator.

[0102] Comparative Example 5

[0103] A polishing liquid is prepared by using silica grinding particles with a mass fraction of 0.15 wt%, an average particle size of 60 nm, 1 wt% of glycine complexing agent, 0.0003 wt% of the first corrosion inhibitor benzotriazole, 0.0507 wt% of the second corrosion inhibitor 1,2,4-triazole, 0.005 wt% of anionic surfactant sodium dodecylbenzenesulfonate, 0.001 wt% of biocide isothiazolinone, 0.8 wt% of oxidant hydrogen peroxide, adding deionized water and adjusting the pH to around pH = 7 with a pH regulator.

[0104] Comparative Example 6

[0105] A polishing liquid is prepared by using silica grinding particles with a mass fraction of 0.15 wt%, an average particle size of 60 nm, 1 wt% of glycine complexing agent, 0.001 wt% of the first corrosion inhibitor benzotriazole, 0.05 wt% of the second corrosion inhibitor 1,2,4-triazole, 0.005 wt% of the anionic surfactant sodium dodecylbenzenesulfonate, 0.001 wt% of the bactericide isothiazolinone, 0.8 wt% of the oxidant hydrogen peroxide, adding deionized water and adjusting the pH to around 3 with a pH regulator.

[0106] Comparative Example 7

[0107] A polishing liquid is prepared by using silica grinding particles with a mass fraction of 0.15 wt%, an average particle size of 60 nm, 1 wt% of glycine complexing agent, 0.001 wt% of the first corrosion inhibitor benzotriazole, 0.05 wt% of the second corrosion inhibitor 1,2,4-triazole, 0.005 wt% of the surfactant poloxamer 188, 0.001 wt% of the bactericide isothiazolinone, 0.8 wt% of the oxidant hydrogen peroxide, adding deionized water and adjusting the pH to around 7 with a pH regulator.

[0108] Comparative Example 8

[0109] A polishing liquid is prepared by using silica grinding particles with a mass fraction of 0.15 wt%, an average particle size of 60 nm, 1 wt% of glycine complexing agent, 0.001 wt% of the first corrosion inhibitor benzotriazole, 0.05 wt% of the second corrosion inhibitor 1,2,4-triazole, 0.005 wt% of the surfactant polyethylene glycol (Mw = 400), 0.001 wt% of the bactericide isothiazolinone, 0.8 wt% of the oxidant hydrogen peroxide, adding deionized water and adjusting the pH to around 7 with a pH regulator.

[0110] Comparative Example 9

[0111] A polishing liquid is prepared by using silica grinding particles with a mass fraction of 1 wt%, an average particle size of 60 nm, 1 wt% of glycine complexing agent, 0.001 wt% of the first corrosion inhibitor benzotriazole, 0.05 wt% of the second corrosion inhibitor 1,2,4-triazole, 0.005 wt% of the anionic surfactant sodium dodecylbenzenesulfonate, 0.001 wt% of the bactericide isothiazolinone, 0.8 wt% of the oxidant hydrogen peroxide, adding deionized water and adjusting the pH to around 7 with a pH regulator.

[0112] Test polishing conditions: Cu blanks and Cu 754 wafers were polished using an LK (CMP tool), a DH3000W polishing pad (purchased from DINGLONG Co., Ltd.) under a pressure of 1.8 psi, a polishing platen / polishing head rotation speed of 93 / 87 rpm, and a polishing fluid flow rate of 300 ml / min. The evaluation results are shown in Table 2.

[0113] <Cu Removal Rate Measurement>

[0114] The NAPSON RG3000 was used to measure the thickness difference before and after one minute of polishing time to obtain the removal rate.

[0115] <OX Removal Rate>

[0116] The ellipsometer ME-mapping-L was used to measure the thickness difference before and after one minute of polishing time to obtain the removal rate.

[0117] <Ta Removal Rate>

[0118] The analytical balance weighing method was used for measurement. Weighing was performed before and after one minute of polishing time, and then the removal rate was calculated.

[0119] <Corrosion Current Icorr (μA)>

[0120] Tested by a Princeton electrochemical workstation.

[0121] <Number of Damages, Scratches and Organic Residue>

[0122] Observed by scanning electron microscope.

[0123] <Test on Corrosion Rate of Copper Oxide>

[0124] In this example, the test method for the corrosion rate of copper oxide is as follows: 10 g of the polishing fluid described in the example was added to a centrifuge tube, and then the centrifuge tube was placed in a water bath at 25 °C for heat preservation for 15 min. Then, 0.05 g of copper oxide powder was weighed and added to the centrifuge tube, and then it was kept warm for 100 min. Subsequently, the centrifuge tube was placed in a centrifuge and centrifuged at 10000 rpm for 40 min. Then, the supernatant was taken and the content of Cu2+ in the supernatant was measured using ICP-OES.

[0125] Table 2: Polishing Effect Test Data of Examples 1-12 and Comparative Examples 1-9

[0126]

[0127]

[0128] It can be found through Example 1 and Comparative Examples 1-3 that when there is only a corrosion inhibitor containing a benzene ring in the polishing liquid, although the corrosion current of copper can be reduced, organic residues are likely to form on the surface of copper; while if only compounds without a benzene ring are used as the corrosion inhibitor, although no organic residues will appear, the effect of inhibiting the corrosion of copper is not good, and there will still be a relatively large number of defects, affecting the polishing effect; and when the polishing liquid only contains a corrosion inhibitor and no surfactant, there are still a certain number of defects. Therefore, it is necessary to have both corrosion inhibitors and surfactants at the same time to reduce the number of defects to 0. And through Examples 1-8 and Comparative Examples 4-5, it can be seen that the two inhibitors need to be controlled within a certain proportion range to play a better synergistic effect and achieve the effect of zero defects.

[0129] In Comparative Examples 7-8, non-anionic surfactants were used, and the effect was worse than that of the anionic surfactants in the examples; in Comparative Example 9 with excessive abrasive particles, the removal rates of OX, Ta, etc. were too fast, and it was impossible to better control the polishing defects; at the same time, the pH range also needed to be controlled. In Comparative Example 6 with too low pH, the corrosion rate of copper would be accelerated during the polishing process of the copper body, and at the same time, it might damage the synergistic effect of the surfactant and the corrosion inhibitor to a certain extent, resulting in a large number of defects and unable to achieve a satisfactory polishing effect. Therefore, the pH needs to be controlled near neutral.

[0130] Therefore, by simultaneously using two nitrogen-containing corrosion inhibitors and an anionic surfactant in the present invention, not only can damage be completely eliminated, but also there is no obvious influence on the removal rate of copper, and the EOE phenomenon caused by copper corrosion can be effectively inhibited.

[0131] In addition, the present invention adds purine compounds and their derivatives as the third corrosion inhibitor to the polishing liquid, and the number of scratches on the surface of the copper wafer after chemical mechanical polishing is significantly reduced. During the chemical mechanical polishing process of copper, copper is first oxidized by an oxidant, and then an oxide film is formed on the surface of copper. The formation of this oxide film is beneficial to the improvement of the removal rate of copper and can also protect the surface of copper to avoid direct scratching of the copper surface by the abrasive, thereby reducing the generation of scratches. In Examples 10-12, different types and contents of purine compounds and their derivatives were added, and the scratches on the copper surface were significantly reduced. And only by adding as low as 1 ppm of purine compounds can the scratches on the copper surface be significantly reduced.

Claims

1. A CMP polishing liquid for polishing copper, characterized in that, It includes abrasive particles, complexing agent, first corrosion inhibitor, second corrosion inhibitor, anionic surfactant, bactericide, pH regulator and oxidant, and the pH of the polishing liquid is 6 - 9; The first corrosion inhibitor is a nitrogen-containing heterocyclic compound containing a benzene ring, and the second corrosion inhibitor is a nitrogen-containing heterocyclic compound without a benzene ring; the ratio of the first corrosion inhibitor to the second corrosion inhibitor is 1:10 - 1:

100.

2. The polishing liquid according to claim 1, wherein The mass fraction of the first corrosion inhibitor is 0.001% - 0.01%, and the mass fraction of the second corrosion inhibitor is 0.01% - 0.5%.

3. The polishing liquid according to any one of claims 1-2, characterized in that, The polishing liquid further includes a third corrosion inhibitor, and the third corrosion inhibitor is a purine compound.

4. The polishing liquid according to claim 3, wherein The mass fraction of the third corrosion inhibitor is 1 ppm - 200 ppm, preferably 1 ppm - 50 ppm.

5. The polishing liquid according to any one of claims 1-4, characterized in that, The mass fraction of the abrasive particles is 0.1% - 0.5%; the mass fraction of the anionic surfactant is 0.001% - 1%, the mass fraction of the oxidant is 0.1% - 5.0%, the mass fraction of the complexing agent is 0.5% - 8%, and the mass fraction of the bactericide is 0.001% - 0.05%.

6. The polishing liquid according to claim 5, wherein, In the polishing liquid, the mass fraction of the anionic surfactant is 0.005% - 0.05%, the mass fraction of the oxidant is 0.5% - 2.0%, and the mass fraction of the complexing agent is 1% - 5%.

7. The polishing liquid according to any one of claims 1 - 6, characterized in that The first corrosion inhibitor is selected from at least one of 5 - phenyl - 1H - tetrazole, 1,2,3 - benzotriazole, 5 - methylbenzotriazole, 5,6 - dimethyl - 1,2,3 - benzotriazole, 1 - [N,N - bis(hydroxyethyl)aminomethyl]benzotriazole, 1 - (hydroxymethyl)benzotriazole, 1 - (1,2 - dicarboxyethyl)benzotriazole, benzimidazole; The second corrosion inhibitor is selected from at least one of 5 - amino - 1H - tetrazole, 5 - methyl - 1H - tetrazole, 5 - ethyl - 1 - methyltetrazole, 1H - tetrazole, 1 - acetic acid - tetrazole, 1 - methyl - tetrazole, 1 - (β - aminoethyl) - tetrazole, 5 - amino - 1 - H tetrazole, 1,2,3 - triazole, 1,2,3 - triazole - 4 - carboxylic acid, 5 - methyl - 1,2,3 - triazole - 4 - carboxylic acid, 1,2,3,4 - tetrazole, 5 - methyl - 1,2,3,4 - tetrazole, 5 - amino - 1,2,3,4 - tetrazole, 1,2,3,4 - tetrazole - 5 - acetic acid, imidazole, imidazole - 4 - carboxylic acid; The third corrosion inhibitor is selected from at least one of adenosine, adenine, guanine, uric acid, caffeine, theophylline.

8. The polishing liquid according to any one of claims 1 to 7, characterized in that, The anionic surfactant is selected from at least one of sodium dodecyl sulfate, potassium dodecyl sulfate, ammonium dodecyl sulfate, dodecylbenzenesulfonic acid, dodecyl diphenyl ether monosulfonic acid, dodecyl diphenyl ether disulfonic acid, a mixture of dodecyl diphenyl ether monosulfonic acid and dodecyl diphenyl ether disulfonic acid, and polyacrylic acid; and / or, the complexing agent is selected from at least one of glycine, arginine, alanine, valine, glutamic acid, cysteine, histidine, serine, ethylenediaminetetraacetic acid, diethylenetriaminepentaacetic acid, and triethylenetetraminehexaacetic acid; and / or, the pH regulator includes at least one of potassium hydroxide, ammonia water, tetraethylammonium hydroxide, nitric acid, and sulfuric acid; and / or, the oxidizing agent is selected from at least one of hydrogen peroxide, iron nitrate, and ammonium persulfate; and / or, the bactericide includes at least one of isothiazolinone, 5-chloroisothiazolinone, and benzisothiazolinone.

9. The polishing liquid according to any one of claims 1-8, characterized in that, The grinding particles are selected from one or more of colloidal silica, fumed silica, and alumina.

10. Application of the polishing liquid according to any one of claims 1-9 in CMP polishing of copper processes.

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