Chemical mechanical polishing solution

Abstract

This invention discloses a chemical mechanical polishing slurry for copper polishing, comprising: abrasive particles, a five-membered nitrogen-containing heterocyclic compound, a six-membered carbonyl-containing heterocyclic compound, amino acids, an oxidant, and water. The chemical mechanical polishing slurry of this invention maintains a high copper removal rate while exhibiting a high selectivity for tantalum / tantalum nitride / silicon dioxide, and can significantly improve the surface roughness of the polished copper while inhibiting corrosion of the copper surface by the polishing slurry.

Description

Technical Field

[0001] This invention relates to the field of chemical mechanical polishing, and more particularly to a chemical mechanical polishing solution for polishing copper. Background Technology

[0002] With the advancement of semiconductor integrated circuit technology and the miniaturization of electronic components, feature sizes have reached the nanometer level. An integrated circuit contains millions of transistors, and ensuring the rapid switching of such a vast number of transistors during operation is crucial. Traditionally used aluminum or aluminum alloy interconnects suffer from drawbacks such as low signal transmission speed and high energy consumption during current transmission, hindering the development of semiconductor integrated circuit technology. Therefore, integrated circuit wiring needs to shift from traditional aluminum interconnect processes to new materials with high-speed electrical signal transmission capabilities. Compared to aluminum, copper interconnects offer advantages such as low resistivity, high electromigration resistance, and short RC delay time. Consequently, copper interconnects possess excellent conductivity, accelerating signal transmission between transistors in integrated circuits. They also exhibit lower parasitic capacitance and reduced circuit sensitivity to electromigration. Therefore, copper interconnects can replace aluminum as the interconnect metal in semiconductor integrated circuits and have a promising future in the technological development of semiconductor integrated circuits.

[0003] However, in the manufacturing process of copper integrated circuits, it was found that effective plasma etching or wet etching of copper materials is not feasible. Therefore, the commonly used technical solution for copper interconnection is the dual damascene damascene process. This involves forming trenches in the first layer, filling the trenches with a copper barrier layer and copper, forming metallic conductors that cover the dielectric layer. Then, a chemical mechanical polishing (CMP) process removes the excess copper / copper barrier layer from the dielectric layer, leaving a single interconnect in the trench. The copper CMP process generally consists of three steps: the first step uses high pressure 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 uses a lower removal rate to remove the remaining metallic copper and stop at the barrier layer; the third step uses a barrier layer polishing slurry to remove the barrier layer, part of the dielectric layer, and metallic copper, achieving planarization.

[0004] As wafer sizes increase, the number of active devices grows, and feature sizes shrink, planarization needs to meet more stringent requirements. Copper polishing must remove excess copper from the barrier layer as quickly as possible, while also achieving the smoothest possible surface with minimal surface damage (i.e., sufficiently low surface roughness) and minimizing defects that may form on the copper surface during polishing, such as organic residues, particle adsorption, surface corrosion, and scratches. These defects can affect device reliability, electrical performance, and in severe cases, may even lead to device malfunction and reduced yield.

[0005] With the development of integrated circuits, on the one hand, in the traditional IC industry, in order to improve integration density, reduce energy consumption, and shorten latency, linewidths are becoming narrower, low-k materials with lower mechanical strength are used in dielectric layers, and the number of wiring layers is increasing. To ensure the performance and stability of integrated circuits, the requirements for copper chemical mechanical polishing are also becoming increasingly stringent. Typically, it is required to reduce polishing pressure while ensuring the copper removal rate, improve the planarization of the copper line surface, and control surface defects. On the other hand, due to physical limitations, linewidths cannot be infinitely reduced. The semiconductor industry no longer simply relies on integrating more devices on a single chip to improve performance, but is shifting towards multi-chip packaging. Through-Silicon Vias (TSV) technology, as a cutting-edge technology that creates vertical conductions between chips and wafers to achieve chip interconnection, has gained widespread industry recognition. TSV enables the highest density of chip stacking in three dimensions with the smallest form factor, greatly improving chip speed and low-power performance. Current TSV processes combine traditional IC processes to form copper vias through the silicon substrate; that is, copper is filled into the TSV openings to achieve conductivity. After filling, excess copper also needs to be removed using chemical mechanical polishing to achieve planarization. Unlike traditional IC manufacturing, through-silicon vias (TSVs) are very deep, and the excess copper on the surface after filling is typically several to tens of micrometers thick. To quickly remove this excess copper, a very high copper removal rate is usually required, while simultaneously achieving a smooth polished surface with few defects. This presents new challenges to the copper polishing process. Summary of the Invention

[0006] In order to overcome the above-mentioned technical challenges, the present invention aims to provide a chemical mechanical polishing slurry that can maintain a high copper removal rate while having a high selectivity for tantalum / tantalum nitride / silicon dioxide, and can significantly improve the roughness of the copper surface after polishing and inhibit the corrosion of the copper surface by the polishing slurry.

[0007] Specifically, this invention discloses a chemical mechanical polishing fluid, comprising: abrasive particles, amino acids, a five-membered nitrogen-containing heterocyclic compound, a six-membered carbonyl-containing heterocyclic compound, an oxidant, and water.

[0008] Furthermore, the structure of the six-membered carbonyl-containing heterocyclic compound is as follows:

[0009]

[0010] Among them, R1, R4 and R5 are C containing functional groups. 0～5 The carbon chain structure is H, and the functional group is selected from amino, methyl, aminomethyl, aminobutyl, hydroxy, or carboxyl; preferably, the carbon chain length is C. 0～3 Preferably, R1, R4 and R5 are hydrogen atoms, and the preferred functional groups are aminomethyl and methyl.

[0011] Among them, R2 and R3 are C containing functional groups. 0～5 The carbon chain structure is H, and the functional group is selected from amino, methyl, hydroxy, aminomethyl, amide, or carboxyl groups; preferably, the carbon chain length is C. 0～3 Preferably, R2 and R3 are hydrogen atoms, and the preferred functional groups are amino, methyl, and hydroxyl.

[0012] Wherein, X1 and X2 are carbon or nitrogen atoms, preferably carbon atoms or nitrogen atoms.

[0013] Furthermore, the mass percentage content of the six-membered carbonyl-containing heterocyclic compound is 0.003% to 0.01%.

[0014] Furthermore, the five-membered nitrogen-containing heterocyclic compound is selected from one or more of 1,2,4-triazole, 3-methyl-1,2,4-triazole, and benzotriazole.

[0015] Furthermore, the mass percentage content of the five-membered nitrogen-containing heterocyclic compound is 0.01%-0.2%.

[0016] Furthermore, the amino acid is selected from one or more of glycine, alanine, serine, arginine, histidine, and lysine; preferably, glycine, alanine, and serine are one or more of these.

[0017] Furthermore, the mass percentage content of the amino acid is 0.8% to 1.5%.

[0018] Furthermore, the mass percentage concentration of the grinding particles is 0.05% to 0.5%.

[0019] Furthermore, the average particle size of the grinding particles is 20–200 nm.

[0020] Furthermore, the oxidant is hydrogen peroxide.

[0021] Furthermore, the oxidant has a mass percentage content of 0.05%-3.0%.

[0022] Furthermore, the pH value of the chemical mechanical polishing solution is 5.0-8.0.

[0023] The structural formulas of some representative six-membered carbonyl-containing heterocyclic compounds are shown in Table 1. However, it should be noted that the six-membered carbonyl-containing heterocyclic compounds involved in this invention are not limited to the compounds shown.

[0024] Table 1 shows some representative structural formulas of six-membered carbonyl-containing heterocyclic compounds.

[0025] R1 R2 R3 R4 R5 X1 X2 Compound 1 hydrogen atom amino amino none hydrogen atom nitrogen atoms nitrogen atoms Compound 2 methyl aminomethyl hydrogen atom hydrogen atom hydrogen atom nitrogen atoms carbon atom Compound 3 hydrogen atom carboxyl methyl hydrogen atom hydrogen atom nitrogen atoms carbon atom Compound 4 hydrogen atom carboxyl hydrogen atom methyl methyl nitrogen atoms carbon atom Compound 5 hydrogen atom carboxyl hydrogen atom hydrogen atom hydrogen atom nitrogen atoms carbon atom Compound 6 aminobutyl hydrogen atom hydrogen atom hydrogen atom hydrogen atom nitrogen atoms carbon atom Compound 7 hydrogen atom aminomethyl hydrogen atom methyl hydrogen atom nitrogen atoms carbon atom Compound 8 hydrogen atom amide group hydrogen atom hydrogen atom hydroxyl nitrogen atoms carbon atom Compound 9 hydrogen atom amino hydrogen atom none hydrogen atom nitrogen atoms nitrogen atoms Compound 10 methyl hydrogen atom hydrogen atom hydrogen atom hydrogen atom nitrogen atoms carbon atom Compound 11 methyl hydrogen atom amino hydrogen atom hydrogen atom nitrogen atoms carbon atom Compound 12 hydrogen atom hydrogen atom hydrogen atom hydrogen atom hydrogen atom nitrogen atoms carbon atom

[0026] Compared with existing technologies, the above technical solution has the following advantages:

[0027] The chemical mechanical polishing slurry of the present invention has a high copper removal rate and a copper-to-tantalum / tantalum nitride / silicon dioxide removal rate selectivity, which can effectively reduce copper dish-shaped depressions after polishing, suppress the static corrosion rate of copper, and improve the surface roughness of copper wafers after polishing. Detailed Implementation

[0028] The advantages of the present invention will be further illustrated below with reference to specific embodiments.

[0029] It should be understood that all contents mentioned in this invention refer to mass percentages.

[0030] Table 2 shows Examples 1-12 and Comparative Examples 1-3 of the chemical mechanical polishing slurry of the present invention. According to the formulations given in the table, all components except the oxidant are mixed thoroughly in sequence. The pH value is adjusted to the required value using a pH adjuster (such as KOH or HNO3). The oxidant is added and mixed thoroughly before use. The polishing slurry of the present invention can also be pre-prepared as a concentrated sample, diluted with deionized water at a certain ratio, and then the oxidant is added before use.

[0031] The reagents and raw materials used in this invention are all commercially available.

[0032] Table 2. Components and contents of embodiments and comparative examples of the present invention.

[0033]

[0034]

[0035] The blank electroplated copper wafers were polished using the polishing slurry of the embodiments and the comparative polishing slurry of the present invention under the following conditions: the polishing machine was a 12” Reflexion LK, the polishing pad was an IC1000 (Dupont), the polishing pressure was 1.0 psi and 2.0 psi, the polishing disc and polishing head rotation speed was 93 / 87 rpm, the polishing slurry flow rate was 300 mL / min, and the polishing time was 1 minute.

[0036] The polishing slurry of the embodiments and the comparative polishing slurry of the present invention were used to polish blank tantalum, tantalum nitride and silicon dioxide wafers under the following conditions: the polishing machine was a 12” Reflexion LK, the polishing pad was an IC1000 (Dupont), the polishing pressure was 1.0 psi, the rotation speed of the polishing disk and polishing head was 93 / 87 rpm, the polishing slurry flow rate was 300 mL / min, and the polishing time was 1 minute.

[0037] The polishing slurry used in the embodiments and the comparative polishing slurry of the present invention were used to polish patterned wafers under the following conditions: a 12” Reflexion LK polishing machine, an IC1000 (Dupont) polishing pad, polishing pressures of 1.0 psi and 2.0 psi, respectively; polishing disc and polishing head rotation speeds of 93 / 87 rpm, and polishing slurry flow rate of 300 mL / min. The patterned copper wafer was polished on polishing disc 1 with a downward pressure of 2.0 psi until approximately [amount missing] copper residue remained. Then, the remaining copper was removed on polishing pad 2 with a downward pressure of 1.0 psi. Polishing was stopped after the endpoint was reached using an endpoint detector. The dishing value and surface roughness of the copper line array area with a 100 μm pad (copper line width) on the patterned copper wafer were measured using an XE-300P atomic force microscope.

[0038] The static etching rate (SER) of blank electroplated copper wafers was measured and evaluated using the polishing solutions of the embodiments and comparative examples of the present invention under the following conditions: the copper wafers were immersed in the polishing solution at 50°C for 5 minutes, and the thickness change of the copper wafers before and after immersion was measured using a four-point probe metal thin film measuring instrument, and the static etching rate of the polishing solution was calculated.

[0039] Table 3 Polishing effects of embodiments and comparative examples of the present invention

[0040]

[0041] As shown in Table 3, compared with Examples 1-12 and Comparative Examples 1-3, the addition of the six-membered carbonyl heterocyclic compound improved the dish-shaped depressions and surface roughness of the copper wire region on the patterned wafer to varying degrees, and the polishing slurry also suppressed the static corrosion rate of the copper wafer. The polishing slurry prepared according to the formula has a high selectivity ratio for tantalum / tantalum nitride / silicon dioxide.

[0042] It should be noted that the embodiments of the present invention have better implementability and are not intended to limit the present invention in any way. Any person skilled in the art may use the above-disclosed technical content to change or modify it into equivalent effective embodiments. However, any modifications or equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solution of the present invention shall still fall within the scope of the technical solution of the present invention.

Claims

1. A chemical mechanical polishing slurry, characterized in that, include: The ingredients include abrasive particles, amino acids, five-membered nitrogen-containing heterocyclic compounds, six-membered carbonyl-containing heterocyclic compounds, oxidants, and water.

2. The chemical mechanical polishing slurry as described in claim 1, characterized in that, The six-membered carbonyl-containing heterocyclic compound has the general formula (I) and its specific structure is as follows: Among them, R1, R4 and R5 are C containing functional groups. 0～5 The carbon chain structure or H, and the functional group is selected from amino, methyl, aminomethyl, aminobutyl, hydroxy or carboxyl; Among them, R2 and R3 are C containing functional groups. 0～5 The carbon chain structure or H, and the functional group is selected from amino, methyl, hydroxy, aminomethyl, amide or carboxyl groups; X1 and X2 are carbon or nitrogen atoms.

3. The chemical mechanical polishing slurry as described in claim 1, characterized in that, The six-membered carbonyl-containing heterocyclic compound is selected from one or more of the following: 2-hydroxynicotinic acid, 2-aminonicotinic acid, 2-hydroxy-6-methylnicotinic acid, 2-hydroxy-4-methylnicotinic acid, 6-dimethyl-3-carboxy-2-pyridine copper, 2,6-dihydroxynicotinic acid, 3-(aminomethyl)-1-methyl-1,2-dihydropyridin-2-one, 3-(aminomethyl)-5-methylpyridin-2-ol, 2,6-dihydroxynicotinamide, 1-methyl-2-pyridinone, 4-amino-1-methylpyridin-ethyl ketone, 1-propylpyridin-2(1H)-one, hydroxypyridinone, 5-amino-4-pyrimidinone, 4,5-diamino-6-hydroxypyrimidin, 1-(4-aminobutyl)-1,2-dihydropyridin-2-one, glutarimide, 2-azahexanecycloone, cyanuric acid, isocyanuric acid, and N,N-dimethylpropenylurea.

4. The chemical mechanical polishing slurry as described in claim 1, characterized in that, The mass percentage content of the six-membered carbonyl-containing heterocyclic compound is 0.003% to 0.01%.

5. The chemical mechanical polishing slurry as described in claim 1, characterized in that, The five-membered nitrogen-containing heterocyclic compound is selected from one or more of 1,2,4-triazole, 3-methyl-1,2,4-triazole, and benzotriazole.

6. The chemical mechanical polishing slurry as described in claim 1, characterized in that, The mass percentage content of the five-membered nitrogen-containing heterocyclic compound is 0.01%-0.2%.

7. The chemical mechanical polishing slurry as described in claim 1, characterized in that, The amino acid is selected from one or more of glycine, alanine, serine, arginine, histidine, and lysine.

8. The chemical mechanical polishing slurry as described in claim 1, characterized in that, The amino acid content is 0.8% to 1.5% by mass.

9. The chemical mechanical polishing slurry as described in claim 1, characterized in that, The abrasive particles are silicon dioxide.

10. The chemical mechanical polishing slurry as described in claim 1, characterized in that, The mass percentage concentration of the grinding particles is 0.05%-0.5%.

11. The chemical mechanical polishing slurry as described in claim 1, characterized in that, The average particle size of the grinding particles is 20-200 nm.

12. The chemical mechanical polishing slurry as described in claim 1, characterized in that, The oxidant is hydrogen peroxide.

13. The chemical mechanical polishing slurry as described in claim 1, characterized in that, The oxidant has a mass percentage content of 0.05%-3.0%.

14. The chemical mechanical polishing slurry according to any one of claims 1-13, characterized in that, The pH value of the chemical mechanical polishing fluid is 5.0-8.0.

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