Polishing solution for planarization of high-K dielectric metal gate ruthenium gate of chip as well as preparation method and application of polishing solution

Abstract

The invention relates to the technical field of chemical mechanical polishing, and discloses a polishing solution for planarization of a high-K dielectric metal gate ruthenium gate of a chip and a preparation method and application of the polishing solution. 0.05 to 0.2 wt% of an oxidizing agent; 20 to 80 mmol / L of a complexing agent; deionized water; the complexing agent is a DTPA (NH4) 5 composite complexing agent; the prepared polishing solution can effectively improve the removal rate in the chemical mechanical polishing process of the ruthenium gate, meanwhile, it is ensured that the surface of the polished ruthenium gate has the nanoscale surface roughness and the defect-free characteristic, the problem that the polishing rate is low due to high hardness and high chemical inertness of ruthenium is solved, and high-quality surface machining of the ruthenium gate is achieved.

Description

Technical Field

[0001] The present invention relates to the technical field of chemical mechanical polishing, and in particular to a polishing liquid for planarizing ruthenium gates of high-k dielectric metal gates of chips, a preparation method thereof, and an application thereof. Background Art

[0002] Chemical mechanical polishing (CMP) technology, as one of the key technologies in the semiconductor processing process, is applied throughout all links of wafer manufacturing and is almost used for every key layer in wafer manufacturing. The basic principle of CMP is that the material on the wafer surface reacts with the chemical substances in the polishing liquid to form a softened layer, and the softened layer is removed under the action of the contact pressure between the wafer and the polishing pad; during this process, the chemical reaction and the mechanical wear of the abrasive grains occur instantaneously and alternately, and the removal of the surface material of the wafer and the surface quality after sub-nanometer polishing are achieved under the synergistic effect of the two.

[0003] High-k dielectric metal gate (HKMG) is the mainstream advanced structure applied to three-dimensional field-effect transistors in the sub-10nm technology node. In the HKMG process, a high-dielectric constant medium is used to improve the gate leakage problem, and at the same time, a new metal gate is adopted to solve the Fermi level pinning and polysilicon gate depletion problems. One of the important technical requirements is to achieve precise control of the gate height, and generally, the non-uniformity of the gate height within the wafer and between wafers is required to be less than The chemical mechanical polishing of the metal gate, as the last step in HKMG manufacturing, can achieve global and local planarization of the wafer surface, determine the final height of the gate level, and is a key manufacturing process in the HKMG manufacturing process.

[0004] Ruthenium has the advantages of low resistivity (7.1 μΩ·cm), high chemical reaction inertness, and good thermal stability, and is currently used as a new barrier layer material for sub-10nm nodes. In the HKMG structure, using metal Ru instead of traditional Al or W as the gate material can significantly reduce the chip power consumption and improve the response speed. Currently, the research on the chemical mechanical polishing of Ru mainly focuses on the Cu / Ru interconnect structure when Ru is used as the barrier layer. If Ru is used as the filling metal layer material of HKMG, its polishing process is more complex, and the requirements for controlling surface / interface defects are more stringent.

[0005] Currently, the research on the chemical mechanical polishing process of Ru as the filling metal layer of HKMG at home and abroad is almost zero. Therefore, it is urgent to develop an effective polishing liquid applicable to ruthenium gates of high-k dielectric metal gates (HKMG) of semiconductor chips to fill this gap. Summary of the Invention

[0006] The object of the present invention is to provide a polishing liquid for the planarization of ruthenium gates in high-K dielectric metal gates of chips, a preparation method thereof, and an application thereof. The polishing liquid for the planarization of ruthenium gates in high-K dielectric metal gates of chips can achieve high-speed removal of ruthenium during the chemical mechanical polishing process of ruthenium gates, and at the same time ensure that the surface of the polished ruthenium gates has a nanoscale surface roughness and defect-free characteristics, realizing high-quality surface processing of ruthenium gates.

[0007] The solution of the present invention is as follows:

[0008] A polishing liquid for the planarization of ruthenium gates in high-K dielectric metal gates (HKMG) of chips, comprising the following concentration components:

[0009] Aluminum oxide abrasive grains: 0.05 - 0.2 wt%;

[0010] Oxidant: 0.05 - 0.2 wt%;

[0011] Complexing agent: 20 - 80 mmol / L;

[0012] Deionized water;

[0013] The complexing agent is DTPA(NH 4 ) 5 a composite complexing agent, and the structural formula of the DTPA(NH 4 ) 5 composite complexing agent is shown as formula I below

[0014]

[0015] As a preferred technical solution, it further includes a pH regulator, and the pH regulator is selected from one or more of nitric acid and potassium hydroxide.

[0016] As a preferred technical solution, the oxidant is hydrogen peroxide.

[0017] As a preferred technical solution, the concentration of the aluminum oxide abrasive grains is one of 0.05 wt%, 0.1 wt%, 0.15 wt% and 0.2 wt%.

[0018] As a preferred technical solution, the oxidant concentration is one of 0.05%, 0.1%, 0.15% and 0.2%.

[0019] As a preferred technical solution, the concentration of the DTPA(NH 4 ) 5 composite complexing agent is one of 20 mmol / L, 40 mmol / L, 60 mmol / L and 80 mmol / L.

[0020] The present invention also discloses a method for preparing a polishing liquid for planarization of a ruthenium gate of a high-K dielectric metal gate for a chip, comprising the following steps:

[0021] 1) Diethylenetriaminepentaacetic acid (DTPA) and ammonia water are successively added to deionized water and mixed. While stirring, a saturated pH regulator is added to the solution until the diethylenetriaminepentaacetic acid (DTPA) is completely dissolved and the pH value of the solution is alkaline, obtaining a complexing agent;

[0022] 2) An oxidizing agent of 0.05-0.2 wt% is added to deionized water, and 20-80 mmol / L of the complexing agent prepared in step 1) is added, and the pH is adjusted to obtain a polishing liquid;

[0023] 3) When polishing, 0.05-0.2 wt% of alumina abrasive grains are added to the polishing liquid to obtain a polishing liquid for planarization of a ruthenium gate of a high-K dielectric metal gate for a chip.

[0024] As a preferred technical solution, the pH value of the polishing liquid in 2) is 8-11.

[0025] The present invention also discloses an application of a polishing liquid for planarization of a ruthenium gate of a high-K dielectric metal gate for a chip in chemical mechanical polishing.

[0026] As a preferred technical solution, when the polishing liquid for planarization of a ruthenium gate of a high-K dielectric metal gate for a chip is used for polishing, its physical parameters are: pressure: 2 psi; polishing head rotation speed: 101 rpm; polishing platen rotation speed: 99 rpm; polishing liquid flow rate: 100 mL / min; polishing time: 5 min.

[0027] Compared with the prior art, the beneficial effects of the present invention are:

[0028] (1) High-efficiency ruthenium removal performance: The polishing liquid provided by the present invention can achieve high-speed removal of ruthenium in the process of chemical mechanical polishing (CMP), significantly improving the process efficiency.

[0029] (2) Surface quality optimization: The surface of the ruthenium gate polished with the polishing liquid provided by the present invention has a nanoscale surface roughness and can ensure no defects, significantly improving the surface quality of the metal gate and meeting the high-standard process requirements of semiconductor chips.

[0030] (3) Precise process control: The present invention can achieve precise control of the gate height by optimizing the polishing liquid components and process parameters (such as pH, pressure, rotation speed, etc.), meeting the requirement that the height non-uniformity within and between wafers of the sub-10 nm technology node is less than . Description of the Drawings

[0031] Figure 1XPS 3d spectra of ruthenium surface after immersion in the polishing fluids of Example 1, Comparative Example 1, Comparative Example 2, Comparative Example 3 and Comparative Example 4 of the present invention; wherein, a is Comparative Example 1; b is Comparative Example 2; c is Comparative Example 3; d is Comparative Example 4; e is Example 1;

[0032] Figure 2 Open circuit potential and electrochemical impedance diagrams of ruthenium of the present invention in different types of complexing agents; wherein, a is the open circuit potential; b is the Nyquist diagram and equivalent circuit diagram of the electrochemical impedance spectrum (EIS); c is the Bode modulus diagram; d is the Bode phase angle diagram;

[0033] Figure 3 Open circuit potential and electrochemical impedance spectrum diagrams of Ru of the present invention in different concentrations of DTPA(NH 4 ) 5 solution; wherein, a is the open circuit potential; b is the Nyquist diagram; c is the Bode modulus diagram; d is the Bode phase angle diagram;

[0034] Figure 4 Two-dimensional and three-dimensional morphology diagrams of Ru before and after polishing of the present invention: The left side is the two-dimensional morphology diagram, and the right side is the three-dimensional morphology diagram. a and b are before polishing; c and d are after polishing. Detailed implementation manners

[0035] The present invention will be described in detail below with reference to the accompanying drawings and specific embodiments. This embodiment is implemented on the premise of the technical solution of the present invention, and detailed implementation manners and specific operation processes are given, but the protection scope of the present invention is not limited to the following embodiments.

[0036] In the following examples and comparative examples, the test method for the polishing removal rate of Ru: The polishing experiment was carried out on a self-developed ultra-low down-pressure polishing machine. After polishing, deionized water was used to rinse to remove most of the colloidal alumina particles and other impurity particles adsorbed on the ruthenium surface due to electronegativity, and it was dried with nitrogen. The Ru-MRR was calculated by the weight difference of the samples weighed before and after the polishing experiment. The calculation formula is as follows:

[0037]

[0038] In the formula: MRR is the polishing rate; Δm is the mass difference before and after polishing; ρ is the density of ruthenium; r is the radius of the polished metal disc; t is the polishing time.

[0039] In the following examples and comparative examples, the electrochemical test of ruthenium was performed using a Princeton VersaSTAT 3 electrochemical workstation and a standard three-electrode electrolytic cell to compare their galvanic corrosion tendencies. During the test, a Pt electrode was used as the counter electrode, a saturated calomel electrode (SCE) was used as the reference electrode, and ruthenium (purity 99.99%) was used as the working electrode.

[0040] In the following examples and comparative examples, after static corrosion, X-ray photoelectron spectroscopy (XPS) tests were performed on the ruthenium surface using a PHI Quantera Ⅱ X-ray photoelectron spectrometer to determine the production products after ruthenium was immersed in different complexing agent solutions. Before the test, the ruthenium sample was immersed in 50 mM citric acid for 5 min to remove the natural oxide on the surface, then immersed in the complexing agent solution for 10 min, dried with nitrogen, and stored in vacuum.

[0041] In order to make the technical means, creative features, achieved purposes, and effects of the present invention easy to understand, the present invention will be further described below in conjunction with specific embodiments.

[0042] Take 3.15 g of diethylenetriaminepentaacetic acid (DTPA), 2.74 g of 25% ammonia water, add them to 44.11 g of deionized water and mix. Stir and slowly add saturated KOH to the solution at the same time until diethylenetriaminepentaacetic acid (DTPA) is completely dissolved and the pH value of the titrated solution is between 8.5 and 9.5, then the DTPA(NH 4 ) 5 complexing agent is obtained.

[0043] Example 1

[0044] Take 0.5 g of 30 wt% H 2 O 2 add it to 87 g of deionized water, then add 12.5 g of DTPA(NH 4 ) 5 complexing agent, add saturated KOH or saturated HNO 3 while stirring, and adjust the pH of the solution to 10. Then a polishing solution with a H 2 O 2 concentration of 0.15 wt% and a DTPA(NH 4 ) 5 complexing agent concentration of 20 mmol / L is obtained.

[0045] When the polishing solution prepared in this example is used for polishing, the addition amount of alumina abrasive is 0.2 wt% of the total mass of the polishing solution. The physical parameters during polishing are as follows: pressure: 2 psi; polishing head rotation speed: 101 rpm; polishing disc rotation speed: 99 rpm; polishing solution flow rate: 100 mL / min; polishing time: 5 min. The polishing rate of ruthenium under these conditions is 41.08 nm / min. Three-dimensional white light testing was performed on the polished ruthenium surface to measure the surface roughness of ruthenium before and after polishing.

[0046] Using ruthenium as the research electrode, open circuit potential (OCP) and electrochemical impedance spectroscopy (EIS) tests were carried out. The specific test results are shown inFigure 3 , Table 3.

[0047] Example 2

[0048] Take 0.5 g of H with a concentration of 30 wt% 2 O 2 and add it to 74.5 g of deionized water, then add 25 g of DTPA(NH 4 ) 5 complexing agent, and add saturated KOH or saturated HNO 3 while stirring, and adjust the pH of the solution to 10. Then obtain H 2 O 2 with a concentration of 0.15 wt%, and the concentration of DTPA(NH 4 ) 5 complexing agent is 40 mmol / L polishing solution.

[0049] When the polishing solution prepared in this example is used for polishing, the addition amount of alumina abrasive is 0.2 wt% of the total mass of the polishing solution. The physical parameters during polishing are: pressure: 2 psi; polishing head rotation speed: 101 rpm; polishing disc rotation speed: 99 rpm; polishing solution flow rate: 100 mL / min; polishing time: 5 min. The polishing rate of ruthenium under these conditions is 47.97 nm / min.

[0050] Using ruthenium as the research electrode, open circuit potential (OCP) and electrochemical impedance spectroscopy (EIS) tests are carried out. The specific test results are shown in Figure 3 , Table 3.

[0051] Example 3

[0052] Take 0.5 g of H with a concentration of 30 wt% 2 O 2 and add it to 62 g of deionized water, then add 37.5 g of DTPA(NH 4 ) 5 complexing agent, and add saturated KOH or saturated HNO 3 while stirring, and adjust the pH of the solution to 10. Then obtain H 2 O 2 with a concentration of 0.15 wt%, and the concentration of DTPA(NH 4 ) 5 complexing agent is 60 mmol / L polishing solution.

[0053] When the polishing liquid prepared in this example is used for polishing, the addition amount of alumina abrasive is 0.2 wt% of the total mass of the polishing liquid. The physical parameters during polishing are as follows: pressure: 2 psi; polishing head rotation speed: 101 rpm; polishing plate rotation speed: 99 rpm; polishing liquid flow rate: 100 mL / min; polishing time: 5 min. The polishing rate of ruthenium under these conditions is 57.53 nm / min.

[0054] Using ruthenium as the research electrode, open circuit potential (OCP) and electrochemical impedance spectroscopy (EIS) tests were carried out. The specific test results are shown in Figure 3 Table 3.

[0055] Example 4

[0056] Take 0.5 g of H with a concentration of 30 wt% 2 O 2 Add it to 49.5 g of deionized water, then add 50 g of DTPA(NH 4 ) 5 complexing agent, and add saturated KOH or saturated HNO 3 while stirring, and adjust the pH of the solution to 10. That is, a polishing liquid with a concentration of H 2 O 2 of 0.15 wt% and a DTPA(NH 4 ) 5 complexing agent concentration of 80 mmol / L is obtained.

[0057] When the polishing liquid prepared in this example is used for polishing, the addition amount of alumina abrasive is 0.2 wt% of the total mass of the polishing liquid. The physical parameters during polishing are as follows: pressure: 2 psi; polishing head rotation speed: 101 rpm; polishing plate rotation speed: 99 rpm; polishing liquid flow rate: 100 mL / min; polishing time: 5 min. The polishing rate of ruthenium under these conditions is 57.50 nm / min.

[0058] Using ruthenium as the research electrode, open circuit potential (OCP) and electrochemical impedance spectroscopy (EIS) tests were carried out. The specific test results are shown in Figure 3 Table 3.

[0059] Comparative Example 1

[0060] Take 0.5 g of H with a concentration of 30 wt% 2 O 2 Add it to 99.5 g of deionized water, without adding an additional complexing agent, and add saturated KOH or saturated HNO 3 while stirring, and adjust the pH of the solution to 10. Prepare H 2 O 2The polishing liquid with a content of 0.15 wt%. The ruthenium-coated wafer was immersed in the prepared polishing liquid for 10 min, and then X-ray photoelectron spectroscopy was performed. The specific test results are shown in Figure 1 and Table 1.

[0061] When the polishing liquid prepared in this comparative example was used for polishing, the addition amount of the abrasive was 0.2 wt% of the total mass of the polishing liquid. The physical parameters during polishing were: pressure: 2 psi; polishing head rotation speed: 101 rpm; polishing disc rotation speed: 99 rpm; polishing liquid flow rate: 100 mL / min; polishing time: 5 min. The polishing rate of ruthenium under these conditions was 15.26 nm / min.

[0062] Using ruthenium as the research electrode, open circuit potential (OCP) and electrochemical impedance spectroscopy (EIS) tests were performed. The specific test results are shown in Figure 2 and Table 2.

[0063] Comparative Example 2

[0064] Take 0.5 g of H with a concentration of 30 wt% 2 O 2 and add it to 99.15 g of deionized water. Add 0.35 g of K 2 SO 4 , and while stirring, add saturated KOH or saturated HNO 3 to adjust the pH of the solution to 10. A polishing liquid with an H 2 O 2 content of 0.15 wt% and a K 2 SO 4 content of 20 mmol / L was prepared. The ruthenium-coated wafer was immersed in the prepared polishing liquid for 10 min, and then X-ray photoelectron spectroscopy was performed. The specific test results are shown in Figure 1 and Table 1.

[0065] When the polishing liquid prepared in this comparative example was used for polishing, the addition amount of the abrasive was 0.2 wt% of the total mass of the polishing liquid. The physical parameters during polishing were: pressure: 2 psi; polishing head rotation speed: 101 rpm; polishing disc rotation speed: 99 rpm; polishing liquid flow rate: 100 mL / min; polishing time: 5 min. The polishing rate of ruthenium under these conditions was 23.18 nm / min.

[0066] Using ruthenium as the research electrode, open circuit potential (OCP) and electrochemical impedance spectroscopy (EIS) tests were performed. The specific test results are shown in Figure 2 and Table 2.

[0067] Comparative Example 3

[0068] Take 0.5 g of H with a concentration of 30 wt% 2 O2 Add 0.79 g of DTPA to 98.71 g of deionized water, and while stirring, add saturated KOH or saturated HNO 3 , and adjust the pH of the solution to 10. Prepare a polishing solution with an H 2 O 2 content of 0.15 wt% and a DTPA content of 20 mmol / L. Immerse the ruthenium-coated wafer in the prepared polishing solution for 10 min, and then perform X-ray photoelectron spectroscopy testing. The specific test results are shown in Figure 1 , Table 1.

[0069] When the polishing solution prepared in this comparative example is used for polishing, the addition amount of the abrasive is 0.2 wt% of the total mass of the polishing solution. The physical parameters during polishing are as follows: pressure: 2 psi; polishing head rotation speed: 101 rpm; polishing disc rotation speed: 99 rpm; polishing solution flow rate: 100 mL / min; polishing time: 5 min. The polishing rate of ruthenium under these conditions is 33.36 nm / min.

[0070] Using ruthenium as the research electrode, open circuit potential (OCP) and electrochemical impedance spectroscopy (EIS) tests are carried out. The specific test results are shown in Figure 2 , Table 2.

[0071] Comparative Example 4

[0072] Take 0.5 g of H with a concentration of 30 wt% 2 O 2 and add it to 98.84 g of deionized water. Add 0.66 g of (NH 4 ) 2 SO 4 , and while stirring, add saturated KOH or saturated HNO 3 , and adjust the pH of the solution to 10. Prepare a polishing solution with an H 2 O 2 content of 0.15 wt% and an (NH 4 ) 2 SO 4 content of 20 mmol / L. Immerse the ruthenium-coated wafer in the prepared polishing solution for 10 min, and then perform X-ray photoelectron spectroscopy testing. The specific test results are shown in Figure 1 , Table 1.

[0073] When the polishing solution prepared in this comparative example is used for polishing, the addition amount of the abrasive is 0.2 wt% of the total mass of the polishing solution. The physical parameters during polishing are as follows: pressure: 2 psi; polishing head rotation speed: 101 rpm; polishing disc rotation speed: 99 rpm; polishing solution flow rate: 100 mL / min; polishing time: 5 min. The polishing rate of ruthenium under these conditions is 39.60 nm / min.

[0074] Using ruthenium as the research electrode, open circuit potential (OCP) and electrochemical impedance spectroscopy (EIS) tests were carried out. The specific test results are shown in Figure 2 Table 1 and Table 2.

[0075] Comparative Example 5

[0076] Take 0.5 g of H with a concentration of 30 wt% 2 O 2 and add it to 96.61 g of deionized water. Then add 0.79 g of DTPA and 0.66 g of (NH 4 ) 2 SO 4 . While stirring, add saturated KOH or saturated HNO 3 to adjust the pH of the solution to 10. A polishing solution with a H 2 O 2 content of 0.15 wt%, and both DTPA and (NH 4 ) 2 SO 4 content of 20 mmol / L was prepared. Immerse the ruthenium-coated wafer in the prepared polishing solution for 10 min, and then perform X-ray photoelectron spectroscopy test. The specific test results are shown in Figure 1 Table 1.

[0077] When the polishing solution prepared in this comparative example was used for polishing, the addition amount of the abrasive was 0.2 wt% of the total mass of the polishing solution. The physical parameters during polishing were: pressure: 2 psi; polishing head rotation speed: 101 rpm; polishing disc rotation speed: 99 rpm; polishing solution flow rate: 100 mL / min; polishing time: 5 min. The polishing rate of ruthenium under these conditions was 41.08 nm / min.

[0078] Using ruthenium as the research electrode, open circuit potential (OCP) and electrochemical impedance spectroscopy (EIS) tests were carried out. The specific test results are shown in Figure 2 Table 1 and Table 2.

[0079] Table 1 Proportion of Ru surface components after immersion in different solutions

[0080]

[0081] Table 2 Fitting results of electrochemical impedance spectroscopy of Ru in different types of complexing agents Complexing agent type Solution resistance (Ω·cm 2 ) Admittance constant (10 -6 F·cm -2 ) Polarization resistance (Ω·cm 2 ) Fitting degree (10 -3 )

[0082]

[0083] Table 3 Fitting Results of Electrochemical Impedance Spectroscopy of Ru in Solutions with Different Concentrations of DTPA(NH 4 ) 5 in Solutions

[0084]

[0085] As can be seen from Table 1 and Figure 1 analysis, after adding different types of complexing agents, the content of metallic Ru on the surface of Ru increases, the content of RuO 2 decreases, and the content of RuO 3 increases, indicating that the complexing agent can react with the oxides on the surface of ruthenium, and the dense RuO 2 passivation layer on the surface is damaged, thereby increasing the removal rate of ruthenium during the polishing process. Compared with the comparative example, the complexing agent DTPA(NH 4 ) 5 added in Example 1 has the best complexing effect.

[0086] As can be seen from Table 2 and Figure 2 analysis, with the successive introduction of K + , DTPA x- , NH 4 + , DTPA(NH 4 ) 5 , the open circuit potential of Ru decreases successively, and the polarization resistance decreases successively, indicating that the complexing effect of the above ions on Ru increases successively. When an equal amount of DTPAK 5 and (NH 4 ) 2 SO 4 are simultaneously added to the solution, the changes in electrochemical parameters are similar to those when DTPA(NH 4 ) 5 is added alone, indicating that the complexing ability of the complexing agent DTPA(NH 4 ) 5 comes from the complexing effect of DTPA 4 ) 5 ionized from DTPA(NH x- ) 4 on Ru and its oxides and the ammoniation and complexing effects of NH 5 ionized from DTPA(NH 4 + )

[0087] As can be seen from Table 3 and Figure 3 analysis, with the complexing agent DTPA(NH 4 ) 5With the increase in concentration, the open-circuit potential of Ru decreases. The polarization resistance on the surface of Ru gradually decreases, and the polishing rate gradually increases. It shows that DTPA(NH 4 ) 5 can reduce the compactness of the oxide film on the surface of Ru and exhibits a strong complexing effect during the Ru CMP process.

[0088] As Figure 4 can be seen, after polishing with the polishing liquid prepared in Example 1, the surface roughness Sa of Ru decreases from 5.00 nm to 1.24 nm. The surface quality after polishing has been significantly improved, which can meet the processing requirements of ruthenium (Ru) gates for high-k metal gates (HKMG).

[0089] The above shows and describes the basic principles, main features and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited by the above embodiments. The above embodiments and the descriptions in the specification only illustrate the principles of the present invention. Without departing from the spirit and scope of the present invention, the present invention will have various changes and improvements, and these changes and improvements all fall within the scope of the present invention claimed. The scope of the present invention claimed is defined by the appended claims and their equivalents.

Claims

1. A polishing liquid for planarizing high-K dielectric metal gate ruthenium gate of a chip, characterized in that: Contains the following concentration components: Alumina abrasive 0.05-0.2wt%; Oxidant 0.05-0.2wt%; Complexing agent 20~80mmol / L; Deionized water; The complexing agent is a DTPA (NH4) 5 composite complexing agent, and the structural formula of the DTPA (NH4) 5 composite complexing agent is as follows:

2. The polishing liquid for planarizing a high-K dielectric metal gate and a ruthenium gate of a chip according to claim 1, characterized in that: The invention also comprises a pH regulator, wherein the pH regulator is selected from one or more of nitric acid and potassium hydroxide.

3. The polishing liquid for planarizing a high-K dielectric metal gate and a ruthenium gate of a chip according to claim 1, characterized in that: The oxidant is hydrogen peroxide.

4. The polishing liquid for planarizing a high-K dielectric metal gate and a ruthenium gate of a chip according to claim 1, characterized in that: The concentration of the aluminum oxide abrasive grains is one of 0.05wt%, 0.1wt%, 0.15wt% and 0.2wt%.

5. The polishing liquid for planarizing a high-K dielectric metal gate and a ruthenium gate of a chip according to claim 1, characterized in that: The concentration of the oxidant is one of 0.05%, 0.1%, 0.15% and 0.2%.

6. The polishing liquid for planarizing a high-K dielectric metal gate or ruthenium gate of a chip according to claim 1, characterized in that: The concentration of the DTPA(NH4)5 composite complexing agent is one of 20mmol / L, 40mmol / L, 60mmol / L and 80mmol / L.

7. A method for preparing a polishing liquid for planarizing a high-K dielectric metal gate or ruthenium gate of a chip as claimed in any one of claims 1 to 6, characterized in that: The following steps are involved: 1) adding diethylenetriaminepentaacetic acid and ammonia water to deionized water in sequence, mixing, stirring and adding a saturated pH regulator to the solution until the diethylenetriaminepentaacetic acid is completely dissolved and the pH value of the solution is alkaline, thereby obtaining a complexing agent; 2) adding 0.05-0.2 wt% of an oxidant to deionized water, and then adding 20-80 mmol / L of the complexing agent prepared in step 1), adjusting the pH, and obtaining a polishing solution; 3) When polishing, 0.05-0.2 wt % of aluminum oxide abrasive particles are added to the polishing liquid to obtain a polishing liquid for planarizing a high-K dielectric metal gate and a ruthenium gate of a chip.

8. The method of preparing a polishing liquid for planarizing a high-K dielectric metal gate and a ruthenium gate of a chip according to claim 7, characterized in that: The pH value of the polishing liquid in 2) is 8-11.

9. Use of the polishing liquid for planarizing a high-K dielectric metal gate or ruthenium gate of a chip as claimed in any one of claims 1 to 6 in chemical mechanical polishing.

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