Chemical mechanical polishing solution

Abstract

Provided in the present invention is a chemical mechanical polishing solution. The chemical mechanical polishing solution comprises abrasive particles, a five-membered nitrogen-containing heterocyclic compound, a six-membered nitrogen-containing heterocyclic compound, a polycyclic aromatic hydrocarbon compound, an organic acid and an oxidizing agent. The chemical mechanical polishing solution of the present invention has a relatively high copper removal rate, and can also significantly reduce disc-shaped depressions and dielectric layer erosion of a copper wire area on a patterned wafer after polishing and reduce the static corrosion rate of cobalt.

Description

A chemical mechanical polishing liquid Technical Field

[0001] The present invention relates to the field of chemical mechanical polishing, in particular to a chemical mechanical polishing liquid. Background Art

[0002] Copper has low resistance and good conductivity, which speeds up signal transmission between transistors in circuits. It also provides lower parasitic capacitance and reduces circuit sensitivity to electromigration. These electrical advantages make copper a promising material for the development of semiconductor technology.

[0003] However, during copper integrated circuit manufacturing, it has been discovered that copper can migrate or diffuse into the transistor region of the integrated circuit, adversely affecting the performance of the semiconductor transistor. Therefore, copper interconnects can only be manufactured using a damascene process. This involves forming trenches in the first layer, filling the trenches with a copper barrier layer and copper, and then forming metal conductors overlying the dielectric layer. Chemical mechanical polishing (CMP) then removes the excess copper / barrier layer on the dielectric layer, leaving a single interconnect in the trench. The CMP process for copper generally consists of three steps. The first step involves applying high downforce to remove a large amount of copper from the substrate surface at a fast and efficient removal rate, leaving a certain thickness of copper. The second step involves removing the remaining copper metal at a lower removal rate, stopping at the barrier layer. In the third step, a barrier polishing solution is used to remove the barrier layer, along with portions of the dielectric layer and copper metal, achieving planarization. Copper polishing aims to quickly remove excess copper on the barrier layer while minimizing dishing of the copper wire after polishing.

[0004] With the advancement of integrated circuits, line widths have become increasingly narrower to increase integration density, reduce energy consumption, and shorten delay times. Consequently, the resistance generated by barrier materials has become a growing percentage of the overall resistance of the conductor. Traditional barrier materials like tantalum and tantalum nitride, due to their high resistivity, are difficult to adapt to the demands of more advanced process technologies. Cobalt is considered by the industry to be a promising alternative material for copper interconnects. Compared to tantalum and tantalum nitride, cobalt exhibits lower resistivity and excellent adhesion to copper, enabling its use as an adhesion layer. Copper can be electroplated directly onto the cobalt surface, eliminating the need for a copper seed layer. The cobalt adhesion layer also offers excellent gap-filling capabilities. Precisely due to these advantages, Intel announced at the 2017 IEDM conference the first use of a cobalt adhesion layer in its 10nm technology for high-volume manufacturing.

[0005] However, the introduction of cobalt also presents significant challenges to the copper chemical mechanical polishing process. Cobalt has high chemical activity and a lower redox potential, so during the chemical mechanical polishing of multi-layer copper wiring with a cobalt adhesion layer, cobalt corrosion must be suppressed. Summary of the Invention

[0006] The invention provides a copper chemical mechanical polishing solution, which can significantly reduce dishing depressions and dielectric layer erosion in copper wire areas while ensuring a high copper removal rate, and reduces the static corrosion rate of cobalt.

[0007] Specifically, the present invention provides a chemical mechanical polishing liquid, which includes abrasive particles, a five-membered nitrogen-containing heterocyclic compound, a six-membered nitrogen-containing heterocyclic compound, a polycyclic aromatic hydrocarbon compound, an organic acid and an oxidant.

[0008] Preferably, the six-membered nitrogen-containing heterocyclic compound includes a compound as shown in formula (I),

[0009] The polycyclic aromatic hydrocarbon compounds include compounds as described in formula (II),

[0010] Preferably, the R1 group in formula (I) is selected from one of hydrogen atom, chlorine atom, methyl, amino, hydroxyl, carboxyl, sulfonic acid group, ethylamino, and ethylthio group; the R2 group in formula (I) is selected from one of hydrogen atom, chlorine atom, methyl, amino, hydroxyl, carboxyl, sulfonic acid group, ethylamino, and ethylthio group; the R3 group in formula (I) is selected from one of hydrogen atom, chlorine atom, methyl, amino, hydroxyl, carboxyl, sulfonic acid group, ethylamino, and ethylthio group.

[0011] Preferably, the mass percentage concentration of the six-membered nitrogen-containing heterocyclic compound is 0.001% to 0.2%.

[0012] Among them, some representative compound structures are shown in Table 1. However, it should be pointed out that the six-membered nitrogen-containing heterocyclic compounds involved in the present invention are not limited to the compound structures shown.

[0013] Table 1 Structural formulas of some representative six-membered nitrogen-containing heterocyclic compounds

[0014] Preferably, R4, R5, R6, R7, R8, R9, R10, R11, R12 and R13 in formula (II) are selected from hydrogen atom, amino group, hydroxyl group, hydroxyethyl group, carboxyl group, carboxyethyl group, sulfonic acid group, nitro group, sulfate group, phosphoric acid group, mercapto group, aminoacetic acid group and dodecyl group.

[0015] Among them, some representative compound structures are shown in Table 2. However, it should be pointed out that the polycyclic aromatic hydrocarbon compounds involved in the present invention are not limited to the compound structures shown.

[0016] Table 2 Structural formulas of some representative polycyclic aromatic hydrocarbons

[0017] Preferably, the mass percentage concentration of the polycyclic aromatic hydrocarbon compound is 0.0001% to 0.05%.

[0018] Preferably, the five-membered nitrogen-containing heterocyclic compound is one or more selected from imidazole, methylimidazole, mercaptoimidazole, imidazolidinyl urea, 1,2,4-triazole, 3-methyl-1,2,4-triazole, 3-amino-1,2,4-triazole, 4-amino-1,2,4-triazole, 3-mercapto-1,2,4-triazole, 3-carboxyl-1,2,4-triazole, 3-phenyl-1,2,4-triazole, tetrazole, 5-methyl-1H-tetrazole, 5-amino-1H-tetrazole, 5-mercapto-1H-tetrazole, 5-carboxyl-1H-tetrazole, and 5-phenyl-1H-tetrazole. The five-membered nitrogen-containing heterocyclic compound is one or more selected from imidazolidinyl urea, 1,2,4-triazole, tetrazole, 5-methyl-1H-tetrazole, 5-amino-1H-tetrazole, and 5-phenyl-1H-tetrazole.

[0019] Preferably, the mass percentage concentration of the five-membered nitrogen-containing heterocyclic compound is 0.001% to 0.3%.

[0020] Preferably, the abrasive particles are silicon dioxide abrasive particles, and the mass percentage concentration of the abrasive particles is 0.05%-0.5%.

[0021] Preferably, the average particle size of the abrasive particles is 20-80 nm.

[0022] Preferably, the organic acid is one or more selected from glycine, alanine, serine, arginine, histidine, and lysine.

[0023] Preferably, the mass percentage concentration of the organic acid is 0.5% to 3.0%.

[0024] Preferably, the oxidant is hydrogen peroxide with a mass percent concentration of 0.5%-2.0%.

[0025] Preferably, the pH value of the chemical mechanical polishing solution is 5.0-8.0.

[0026] Compared with the prior art, the chemical mechanical polishing solution of the present invention has a higher copper removal rate, and can significantly reduce the dishing of the copper line area and the erosion of the dielectric layer on the polished pattern wafer, and reduce the static corrosion rate of cobalt. DETAILED DESCRIPTION

[0027] The advantages of the present invention are further described below with reference to specific embodiments.

[0028] It should be understood that the contents described in the present invention refer to the percentage by mass.

[0029] Exemplary embodiments will be described in detail herein, with examples illustrated in the accompanying drawings. In the following description, when referring to the drawings, identical numerals in different figures represent identical or similar elements, unless otherwise indicated. The embodiments described in the following exemplary embodiments are not intended to represent all possible embodiments consistent with the present disclosure. Rather, they are merely examples of apparatus and methods consistent with certain aspects of the present disclosure, as detailed in the appended claims.

[0030] Table 3 shows Examples 1-15 and Comparative Examples 1-5 of the chemical mechanical polishing solution of the present invention. According to the formula given in the table, the other components except the oxidant are mixed in sequence and uniformly. A pH adjuster (such as KOH or HNO3) is used to adjust the pH to the desired value. The oxidant is added and mixed uniformly before use. The polishing solution of the present invention can also be pre-constituted as a concentrated sample. When used, it is diluted with deionized water in a certain proportion to a concentration within the range of the present invention, and the oxidant is added before use.

[0031] The reagents and raw materials used in the present invention are commercially available.

[0032] Table 3 Chemical Mechanical Polishing Liquid Examples 1-15 and Comparative Examples 1-5

[0033] The blank electroplated copper wafer was polished using the polishing liquid of the embodiment of the present invention and the comparative polishing liquid under the following conditions. The specific polishing conditions are: the polishing machine is 12" Reflection LK, the polishing pad is IC1000, the polishing pressure is 1.0 psi and 2.0 psi, the polishing disk and polishing head speed are 93 / 87 rpm, the polishing slurry flow rate is 300 mL / min, and the polishing time is 1 minute.

[0034] The polishing liquid of the embodiment of the present invention and the comparative polishing liquid were used to polish the wafer containing the pattern under the following conditions. The specific polishing conditions were: the polishing machine was 12" Reflection LK, the polishing pad was IC1000, the polishing pressure was 1.0 psi and 2.0 psi; the polishing disc and polishing head speed was 93 / 87 rpm, and the polishing slurry flow rate was 300 mL / min. The patterned copper wafer was polished on the polishing disc 1 with a down pressure of 2.0 psi until the residual copper was about The remaining copper was then removed using a downforce of 1.0 psi on polishing pad 2. Atomic force microscopy was used to measure dishing in a 100 μm copper pad area and dielectric erosion in a 0.18 / 0.18 μm (copper line width / dielectric line width) copper line array area on the patterned copper wafer.

[0035] The static etch rate (SER) of the polishing solution of the embodiment of the present invention and the comparative polishing solution was measured and evaluated under the following conditions: the cobalt wafer was immersed in the polishing solution at 30°C for 5 minutes, and the thickness change of the cobalt wafer before and after immersion was measured using a four-point probe metal film measuring instrument to calculate the static etch rate of the polishing solution.

[0036] Table 4 shows the implementation effects of Examples 1-9 and Comparative Examples 1-5.

[0037] Table 4 Chemical Mechanical Polishing Solution Examples 1-9 and Comparative Examples 1-5 Implementation Effects

[0038] Table 5 shows the implementation effects of Examples 1-9 and Comparative Examples 3 and 5.

[0039] Table 5 Cobalt static corrosion rate of chemical mechanical polishing liquid examples 1-9 and comparative examples 3 and 5

[0040] It can be seen from the polishing effects and cobalt static corrosion rates of the comparative examples and embodiments in Tables 4 and 5 that, since the suitable six-membered nitrogen-containing heterocyclic compounds, five-membered nitrogen-containing heterocyclic compounds, polycyclic aromatic hydrocarbon compounds and abrasive particles disclosed in the present invention were not selected in Comparative Examples 1-5, the dishing value and dielectric layer erosion value of the copper wire array area after polishing were high, and the static corrosion rate of cobalt was high, which could not meet the application requirements of the copper polishing solution.

[0041] Compared to Comparative Examples 1-5, the polishing solution in Example 1-15 utilizes abrasive particles with a particle size of 20-80 nm, controls the pH to 5.0-8.0, and incorporates a six-membered nitrogen-containing heterocyclic compound, a five-membered nitrogen-containing heterocyclic compound, and a polycyclic aromatic hydrocarbon compound. The polishing solution in Example 1-9 exhibits a high copper removal rate, significantly reduces dishing in the copper line area and dielectric layer erosion on polished patterned wafers, and reduces the static corrosion rate of cobalt.

[0042] While the specific embodiments of the present invention have been described in detail above, these are merely exemplary and the present invention is not limited thereto. For those skilled in the art, any equivalent modifications and substitutions to the present invention are also within the scope of the present invention. Therefore, any equivalent changes and modifications made without departing from the spirit and scope of the present invention are intended to be encompassed within the scope of the present invention.

Claims

1. A chemical mechanical polishing liquid, characterized in that, including abrasive particles, a five-membered nitrogen-containing heterocyclic compound, a six-membered nitrogen-containing heterocyclic compound, a polycyclic aromatic hydrocarbon compound, an organic acid, and an oxidizing agent. The six-membered nitrogen-containing heterocyclic compound has the structure of formula (I). The polycyclic aromatic hydrocarbon compound has the structure of formula (II).

2. The chemical mechanical polishing liquid according to claim 1, wherein In formula (I), the R1 group is selected from one of a hydrogen atom, a chlorine atom, a methyl group, an amino group, a hydroxyl group, a carboxyl group, a sulfonic acid group, an ethylamino group, and an ethylthio group; in formula (I), the R2 group is selected from one of a hydrogen atom, a chlorine atom, a methyl group, an amino group, a hydroxyl group, a carboxyl group, a sulfonic acid group, an ethylamino group, and an ethylthio group; in formula (I), the R3 group is selected from one of a hydrogen atom, a chlorine atom, a methyl group, an amino group, a hydroxyl group, a carboxyl group, a sulfonic acid group, an ethylamino group, and an ethylthio group.

3. The chemical mechanical polishing liquid according to claim 1, wherein the mass percentage concentration of the six-membered nitrogen-containing heterocyclic compound is 0.001% to 0.2%.

4. The chemical mechanical polishing liquid according to claim 1, wherein in formula (II), R4, R5, R6, R7, R8, R9, R10, R11, R12, and R13 are selected from a hydrogen atom, an amino group, a hydroxyl group, a hydroxyethyl group, a carboxyl group, a carboxyethyl group, a sulfonic acid group, a nitro group, a sulfate group, a phosphate group, a dodecyl group, and a hexadecyl group.

5. The chemical mechanical polishing liquid according to claim 1, wherein the mass percentage concentration of the polycyclic aromatic hydrocarbon compound is 0.0001% to 0.05%.

6. The chemical mechanical polishing liquid according to claim 1, wherein the five-membered nitrogen-containing heterocyclic compound is selected from one or more of imidazole, methylimidazole, mercaptoimidazole, imidazolidinyl urea, 1,2,4-triazole, 3-methyl-1,2,4-triazole, 3-amino-1,2,4-triazole, 4-amino-1,2,4-triazole, 3-mercapto-1,2,4-triazole, 3-carboxy-1,2,4-triazole, 3-phenyl-1,2,4-triazole, tetrazole, 5-methyl-1H-tetrazole, 5-amino-1H-tetrazole, 5-mercapto-1H-tetrazole, 5-carboxy-1H-tetrazole, and 5-phenyl-1H-tetrazole. Among them, the five-membered nitrogen-containing heterocyclic compound is selected from one or more of imidazolidinyl urea, 1,2,4-triazole, tetrazole, 5-methyl-1H-tetrazole, 5-amino-1H-tetrazole, and 5-phenyl-1H-tetrazole. the mass percentage concentration of the five-membered nitrogen-containing heterocyclic compound is 0.001% to 0.3%.

7. The chemical mechanical polishing liquid according to claim 1, wherein the abrasive particles are silica abrasive particles, and the mass percentage concentration of the abrasive particles is 0.05% - 0.5%. The average particle size of the abrasive particles is 20 - 80 nm.

8. The chemical mechanical polishing liquid according to claim 1, wherein the organic acid is selected from one or more of glycine, alanine, serine, arginine, histidine, and lysine. the mass percentage concentration of the organic acid is 0.5% to 3.0%.

9. The chemical mechanical polishing liquid according to claim 1, wherein the oxidizing agent is hydrogen peroxide, and the mass percentage concentration is 0.5% - 2.0%.

10. The chemical mechanical polishing liquid according to claim 1, wherein the pH value of the chemical mechanical polishing liquid is 5.0 - 8.0.

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