WO2018120811A1 - Chemical-mechanical polishing solution and application thereof - Google Patents

Abstract

A chemical-mechanical polishing solution, comprising abrasive particles, a corrosion inhibitor, a complexing agent, an oxidant, and at least one sulphonate anionic surfactant. The polishing solution can be used for polishing copper metal. The present invention improves the effect of the polishing solution on the polishing selection ratio of copper to a tantalum barrier layer and, when used for polishing wafers, can improve dielectric layer corrosion and dishing of polished copper wire, without defects such as copper residue and corrosion after polishing.

Description

[Name of invention established by ISA according to Rule 37.2] Chemical mechanical polishing liquid and its application Technical field

The invention relates to the field of chemical mechanical polishing, in particular to a chemical mechanical polishing liquid and its application in polishing metallic copper.

Background technique

With the development of semiconductor technology and the miniaturization of electronic components, an integrated circuit contains millions of transistors. In the process of operation, the integration of such a large number of transistors that can be quickly switched, the traditional aluminum or aluminum alloy interconnects, the signal transmission speed is reduced, and the current transfer process consumes a lot of energy, in a sense, It also hinders the development of semiconductor technology. In order to further develop, people began to look for the use of materials with higher electrical properties instead of aluminum. It is well known that copper has low electrical resistance and good electrical conductivity, which speeds up the transmission of signals between transistors in a circuit, and also provides a smaller parasitic capacitance capability and a smaller circuit sensitivity to electromigration. These electrical advantages make copper have a good development prospect in the development of semiconductor technology.

However, in the copper integrated circuit manufacturing process, it is found that copper migrates or diffuses into the transistor region of the integrated circuit, thereby adversely affecting the performance of the semiconductor transistor, and thus the copper interconnect can only be fabricated by a damascene process, namely: A trench is formed in the first layer, and a copper barrier layer and copper are filled in the trench to form a metal wiring and overlying the dielectric layer. The excess copper/copper barrier on the dielectric layer is then removed by chemical mechanical polishing leaving a single interconnect in the trench. The chemical mechanical polishing process of copper is generally divided into three steps. The first step is to remove a large amount of copper on the surface of the substrate and leave a certain thickness of copper with a high and low removal rate. Steps remove the remaining metallic copper with a lower removal rate and stop at the barrier layer. In step 3, the barrier layer and a portion of the dielectric layer and metallic copper are removed by a barrier polishing solution to achieve planarization.

On the one hand, copper polishing should remove excess copper on the barrier layer as soon as possible, and on the other hand, minimize the dishing of the polished copper wire. Prior to copper polishing, the metal layer is partially recessed above the copper wire. When polishing, The copper on the dielectric material is easily removed (higher) at the bulk pressure, while the copper at the depression is subjected to a lower polishing pressure than the bulk pressure, and the copper removal rate is small. As the polishing progresses, the height difference of the copper is gradually reduced to achieve flattening. However, during the polishing process, if the chemical action of the copper polishing solution is too strong and the static etching rate is too high, the passivation film of copper is easily removed even at a lower pressure (such as a copper line depression), resulting in planarization efficiency. Reduced, the disc shape after polishing increases.

With the development of integrated circuits, on the one hand, in the traditional IC industry, in order to improve integration, reduce energy consumption, shorten delay time, and narrower line width, the dielectric layer uses low dielectric (low dielectric) with low mechanical strength (low -k) Materials, wiring layers are also more and more, in order to ensure the performance and stability of integrated circuits, the requirements for copper chemical mechanical polishing are also higher and higher. It is required to reduce the polishing pressure while ensuring the removal rate of copper, improve the flattening of the surface of the copper wire, and control surface defects. On the other hand, due to physical limitations, the linewidth cannot be reduced indefinitely, and the semiconductor industry no longer relies on integrating more devices on a single chip to improve performance, but instead shifts to multi-chip packages. Through-silicon via (TSV) technology is widely recognized in the industry as the latest technology for interconnecting between chips and chips, and between wafers and wafers to achieve interconnection between chips. TSV enables the chip to be stacked in the three-dimensional direction with the highest density and smallest form factor, greatly improving chip speed and low power consumption.

The current TSV process combines a conventional IC process to form copper vias through a silicon substrate, that is, copper is filled in the TSV opening to achieve conduction, and excess copper after filling needs to be removed by chemical mechanical polishing to achieve planarization. Unlike the traditional IC industry, the excess copper in the surface after filling is usually several to several tens of micrometers thick due to the deep through-silicon via. In order to quickly remove these extra copper. It is usually required to have a high copper removal rate while the surface roughness after polishing is good. In order to make copper better in semiconductor technology, people are constantly trying to improve the new polishing solution.

Chinese patent CN1256765C provides a polishing liquid containing a chelating organic acid buffer system composed of citric acid and potassium citrate. CN1195896C employs a polishing liquid containing an oxidizing agent, a carboxylate such as ammonium citrate, an abrasive slurry, an optional triazole or triazole derivative. CN1459480A provides a copper chemical mechanical polishing liquid comprising a film forming agent and a film forming aid: the film forming agent is composed of a buffer solution composed of a mixture of a strong base and acetic acid, and the film forming aid is potassium nitrate (sodium) salt. . US Patent No. 552,742 provides a metal chemical mechanical polishing slurry comprising an aramid silicone, an alkane polysiloxane, A surfactant of a polyoxyalkylene ether and a copolymer thereof. US Pat. No. 6,821,897 B2 provides a copper chemical mechanical polishing method using a polishing agent containing a polymer complexing agent, which employs a negatively charged polymer including sulfuric acid and its salts, sulfates, phosphoric acid, phosphates, phosphates, and the like. . The US5527423 metal chemical mechanical polishing slurry comprises a surfactant: aramid siloxane, polysiloxane, polyoxyalkylene ether and copolymers thereof. Chinese Patent CN1334961A provides a metal polishing liquid containing a metal oxide dissolving agent, a protective film forming agent and a dissolution aid of the protective film forming agent, wherein the dissolving aid of the protective agent forming agent is a polycarboxylate or ethylene. One or more of a surfactant such as a base polymer, a sulfonic acid, a sulfonate or an amide. The dissolution aid is used to improve the solubility properties of the protective film forming agent. Chinese Patent CN101418187A provides a polishing solution in which a cationic surfactant (polyethyleneimine), a quaternary ammonium surfactant (cetyltrimethylammonium chloride) and a nonionic surfactant are added. (Polyethylene glycol), the removal rate of the barrier Ta/TaN can be lowered.

However, the present invention is directed to a chemical mechanical polishing liquid which maintains high removal of copper by adding a combination of a benzene ring-free azole-based corrosion inhibitor and a sulfonate-based anionic surfactant to the polishing liquid. The rate reduces the removal rate of the barrier layer, thereby improving the polishing ratio of the polishing solution to the copper and tantalum barrier layer, and improving the dishing and dielectric corrosion of the polished copper wire. And after polishing, there are no defects such as copper residue and corrosion.

Summary of the invention

Specifically, an aspect of the present invention provides a chemical mechanical polishing polishing liquid comprising abrasive particles, a corrosion inhibitor, a complexing agent, an oxidizing agent, and at least one sulfonate anionic surfactant.

Wherein the sulfonate anionic surfactant is an alkyl sulfonate or an alkyl aryl sulfonate.

Preferably, the alkyl sulfonate is a C10-C18 alkyl sulfonate, and the alkyl aryl sulfonate is a C12-C18 alkylbenzene sulfonate having a degree of polymerization of 200 ～. 600 polystyrene sulfonate, 4-vinyl benzene sulfonate and methylene dinaphthalene sulfonate, the salts being potassium and sodium salts.

Preferably, the sulfonic acid anionic surfactant is contained in an amount of 0.001 to 0.5% by weight; preferably, the sulfonic acid anionic surfactant is contained in an amount of 0.005 to 0.1% by weight.

Preferably, the abrasive particles are silica sols.

Preferably, the abrasive particles have a particle diameter of 20 to 150 nm; preferably, the abrasive particles have a particle diameter of 50 to 120 nm.

Preferably, the abrasive particles have a concentration of 0.05 to 2% by weight. Preferably, the abrasive particles have a concentration of from 0.1 to 1% by weight.

Preferably, the complexing agent is an aminocarboxylate compound and a salt thereof. Preferably, the aminocarboxylate compound and its salt are glycine, alanine, valine, leucine, valine, phenylalanine, tyrosine, tryptophan, lysine, arginine , histidine, serine, aspartic acid, glutamic acid, asparagine, glutamine, ammonia triacetic acid, ethylenediaminetetraacetic acid, cyclohexanediaminetetraacetic acid, ethylenediamine disuccinic acid, diethylene One or more of triamine pentaacetic acid and triethylenetetramine hexaacetic acid.

Preferably, the concentration of the complexing agent is 0.1 to 5 wt%; preferably, the concentration of the complexing agent is 0.5 to 3 wt%.

Preferably, the corrosion inhibitor is one or more of a benzene ring-free azole compound. Specifically: 1,2,4-triazole, 3-amino-1,2,4-triazole, 4-amino-1,2,4-triazole, 3,5-diamino-1, 2,4-triazole, 5-carboxy-3-amino-1,2,4-triazole, 3-amino-5-mercapto-1,2,4-triazole, 5-acetic acid-1H- One or more of tetrazolium, 5-methyltetrazolium and 5-amino-1H-tetrazole.

Preferably, the corrosion inhibitor concentration is 0.001 to 2% by weight; preferably, the corrosion inhibitor concentration is 0.005 to 1% by weight.

Preferably, the oxidizing agent is hydrogen peroxide.

Preferably, the concentration of the oxidizing agent is 0.05 to 5 wt%; preferably, the concentration of the oxidizing agent is 0.1 to 3 wt%.

Preferably, the chemical mechanical polishing liquid has a pH of 5-8.

In addition, the polishing liquid further includes a pH adjuster, a viscosity modifier, and an antifoaming agent.

Further, the polishing liquid may be prepared by concentration, diluted with deionized water at the time of use, and added with an oxidizing agent to the concentration range of the present invention.

Another aspect of the present invention is to provide an application of the above chemical mechanical polishing liquid in the polishing of metallic copper.

Compared with the prior art, the advantages of the present invention are:

1) The invention adds a combination of a benzene ring-free azole-based corrosion inhibitor and a sulfonate-based anionic surfactant to the polishing liquid, maintains a high removal rate of copper, and reduces the removal rate of the ruthenium barrier layer. The effect of improving the polishing selection ratio of the polishing liquid to the barrier layer of copper and bismuth;

2) The polishing of the wafer of the present invention can improve the dishing and dielectric corrosion of the polished copper wire, and has no defects such as copper residue and corrosion after polishing.

DRAWINGS

1 is a topographical view of a dense line array region in which a copper wire width of a copper pattern chip polished in Comparative Example 1 is 5 μm and a dielectric material width is 1 μm;

2 is a topographical view of a dense line array region having a copper line width of 5 μm and a dielectric material width of 1 μm in the copper pattern chip polished in Example 28.

detailed description

Examples 1 to 27

Table 1 shows Examples 1 to 27 of the chemical mechanical polishing liquid of the present invention. According to the formulation given in the table, the components other than the oxidizing agent were uniformly mixed, and the mass percentage was made up to 100% with water. Adjust to the desired pH with KOH or HNO ₃ . Add oxidizing agent before use and mix well.

Table 1 Examples 1 to 27

Effect embodiment

Table 2 shows Examples 28 to 37 and Comparative Examples 1 to 4 of the chemical mechanical polishing liquid of the present invention, according to the formulation given in the table, the components other than the oxidizing agent were uniformly mixed, and the mass percentage was made up to 100 with water. %. Adjust to the desired pH with KOH or HNO ₃ . The oxidizing agent is added before use, and the mixture is uniformly mixed, and the specific embodiment is as follows.

Table 2 Comparative Examples 1 to 4 and Examples 28 to 37

The copper (Cu) and tantalum (Ta) were polished with the comparative polishing liquid and the polishing liquids 28 to 37 of the present invention under the following conditions. Specific polishing conditions: pressure 1.5 psi and / or 2.0 psi; polishing disc and polishing head speed 73 / 67 rpm, polishing pad IC1010, polishing fluid flow rate 350ml / min, polishing machine is 12" Reflexion LK, polishing time is 1min.

The patterned copper wafer was polished using the comparative polishing liquid and the polishing liquid of the present invention under the following conditions. Polishing conditions: polishing disc and polishing head rotation speed 73/67 rpm, polishing pad IC1010, polishing liquid flow rate 350 ml/min, polishing machine table 12" Reflexion LK. Polished patterned copper wafer was polished on the polishing disc 1 with a pressure of 2 psi to The residual copper was about 3000 A, and then the residual copper was removed on the polishing disk 2 with a downward pressure of 1.5 psi. 5 um/1 um (copper wire/dielectric material line width) on the patterned copper wafer was measured with an XE-300P atomic force microscope. The dishing of the copper wire array area (Dishing) and dielectric layer erosion (Erosion), the results are shown in Table 3:

Table 3 compares the polishing effects of the polishing liquids 1 to 4 and the polishing liquids 28 to 37 of the present invention.

It can be seen from Table 3 that the addition of a sulfonate-containing anionic surfactant to the polishing liquid of the present invention can reduce the enthalpy while maintaining a high copper removal rate as compared with Comparative Example 1. The removal rate ratio greatly improves the Cu/Ta removal selectivity ratio, thus effectively reducing the dishing value and the dielectric layer erosion value after polishing the pattern chip, while the comparative example 1 cannot be added even if more corrosion inhibitors are added. Effectively suppressing the removal rate of the crucible, resulting in higher dishing and dielectric layer erosion values.

Referring to FIG. 1 and FIG. 2, respectively, the surface topography of the dense line array region in which the copper wire width of the copper pattern chip polished in Comparative Example 1 and Example 28 is 5 micrometers and the dielectric material width is 1 micrometer is used. As can be seen from the figure, using Comparative Example 1 as a polishing liquid, the polished copper wire has 89.2 nm nano dish dishing and 57.5 nm dielectric layer etching; and using this Example 28 as a polishing liquid, polished copper The wire dish type depression is reduced to 25 nm, and the dielectric layer erosion is reduced to 4.2 nm. The polishing liquid of the present invention has a remarkable effect on the surface morphology of the polished surface, particularly the erosion of the dielectric layer. Meanwhile, in combination with the components of Example 28 and Comparative Example 2, it was found that the combination of the azole ring corrosion inhibitor benzotriazole and the sulfonate anionic surfactant having a benzene ring was selected, although the ruthenium was lowered. The removal rate, but greatly reduced the copper removal rate, could not effectively remove copper. Compared with Example 28 of the present invention, Comparative Examples 3 and 4 were added using a combination of an azole corrosion inhibitor without a benzene ring and a sulfonate anionic surfactant, but the pH of Comparative Example 3 was too low, copper. The removal rate of yttrium and yttrium is also high, resulting in large dishing and dielectric layer erosion. The pH of Comparative Example 4 was too high, resulting in a greatly reduced copper removal rate and inability to effectively remove copper.

In summary, the present invention adds a combination of a benzene ring-free azole-based corrosion inhibitor and a sulfonate-based anionic surfactant to the polishing liquid, maintaining a high removal rate of copper and reducing the removal of the ruthenium barrier layer. Rate, the effect of improving the polishing selection ratio of the polishing liquid to the copper and tantalum barrier layer; the polishing of the wafer for the present invention can improve the dishing and dielectric corrosion of the polished copper wire, and polishing There are no copper residues and no defects such as corrosion.

The specific embodiments of the present invention have been described in detail above, but are merely exemplary, and the invention is not limited to the specific embodiments described above. For those skilled in the art, any pair of this Equivalent modifications and substitutions made by the invention are also within the scope of the invention. Accordingly, equivalents and modifications may be made without departing from the spirit and scope of the invention.

Claims (23)

1. A chemical mechanical polishing polishing liquid comprising abrasive particles, a corrosion inhibitor, a complexing agent, an oxidizing agent, and at least one sulfonate anionic surfactant.
2. The chemical mechanical polishing liquid according to claim 1, wherein the sulfonate anionic surfactant is an alkyl sulfonate and/or an alkyl aryl sulfonate.
3. The chemical mechanical polishing liquid according to claim 2, wherein said alkyl sulfonate is a C10-C18 alkyl sulfonate, and said alkyl aryl sulfonate is a C12-C18 alkyl group. a benzenesulfonate having a degree of polymerization of from 200 to 600, a polystyrene sulfonate, a 4-vinylbenzenesulfonate and a methylene naphthalenesulfonate, wherein the salt is a potassium salt and/or a sodium salt. .
4. The chemical mechanical polishing liquid according to claim 1, wherein the sulfonic acid anionic surfactant is contained in an amount of from 0.001 to 0.5% by weight.
5. The chemical mechanical polishing liquid according to claim 4, wherein the sulfonic acid anionic surfactant is contained in an amount of from 0.005 to 0.1% by weight.
6. The chemical mechanical polishing liquid according to claim 1, wherein the abrasive particles are silica sol.
7. The chemical mechanical polishing liquid according to claim 1, wherein the abrasive particles have a particle diameter of 20 to 150 nm.
8. The chemical mechanical polishing liquid according to claim 7, wherein the abrasive particles have a particle diameter of 50 to 120 nm.
9. The chemical mechanical polishing liquid according to claim 1, wherein the abrasive particles are contained in an amount of 0.05 to 2% by weight;
10. The chemical mechanical polishing liquid according to claim 9, wherein the abrasive particles have a concentration of 0.1 to 1% by weight.
11. The chemical mechanical polishing liquid according to claim 1, wherein the complexing agent is an aminocarboxylic acid compound and a salt thereof.
12. The chemical mechanical polishing liquid according to claim 11, wherein said complexing agent is selected from the group consisting of Glycine, alanine, valine, leucine, valine, phenylalanine, tyrosine, tryptophan, lysine, arginine, histidine, serine, aspartic acid, Glutamate, asparagine, glutamine, ammonia triacetic acid, ethylenediaminetetraacetic acid, cyclohexanediaminetetraacetic acid, ethylenediamine disuccinic acid, diethylenetriaminepentaacetic acid and triethylenetetramine hexaacetic acid One or more.
13. The chemical mechanical polishing liquid according to claim 1, wherein the complexing agent is contained in an amount of from 0.1 to 5% by weight.
14. The chemical mechanical polishing liquid according to claim 13, wherein the complexing agent is contained in an amount of from 0.5 to 3% by weight.
15. The chemical mechanical polishing liquid according to claim 1, wherein the corrosion inhibitor is one or more of a benzene ring-free azole compound.
16. The chemical mechanical polishing liquid according to claim 15, wherein said corrosion inhibitor is selected from the group consisting of 1,2,4-triazole, 3-amino-1,2,4-triazole, and 4-amino group. -1,2,4-triazole, 3,5-diamino-1,2,4-triazole, 5-carboxy-3-amino-1,2,4-triazole, 3-amino- One or more of 5-mercapto-1,2,4-triazole, 5-acetic acid-1H-tetrazole, 5-methyltetrazolium, and 5-amino-1H-tetrazole.
17. The chemical mechanical polishing liquid according to claim 1, wherein the corrosion inhibitor is contained in an amount of from 0.001 to 2% by weight.
18. The chemical mechanical polishing liquid according to claim 17, wherein the corrosion inhibitor is contained in an amount of from 0.005 to 1% by weight.
19. The chemical mechanical polishing liquid according to claim 1, wherein the oxidizing agent is hydrogen peroxide.
20. The chemical mechanical polishing liquid according to claim 1, wherein said oxidizing agent has a concentration of 0.05 to 5% by weight.
21. The chemical mechanical polishing liquid according to claim 20, wherein said oxidizing agent has a concentration of 0.1 to 3% by weight.
22. The chemical mechanical polishing liquid according to any one of claims 1 to 21, wherein the chemical mechanical polishing liquid has a pH of 5 to 8.
23. Use of the chemical mechanical polishing liquid according to any one of claims 1 to 22 in the polishing of metallic copper.

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