WO2018120807A1

WO2018120807A1 - Chemical mechanical polishing liquid and applications thereof

Info

Publication number: WO2018120807A1
Application number: PCT/CN2017/094303
Authority: WO
Inventors: 张建; 荆建芬; 杨俊雅; 宋凯; 蔡鑫元; 姚颖; 潘依君; 杜玲曦; 王春梅; 王雨春
Original assignee: 安集微电子科技（上海）股份有限公司
Priority date: 2016-12-28
Filing date: 2017-07-25
Publication date: 2018-07-05
Also published as: TW201823395A; CN108251845A

Abstract

A chemical mechanical polishing liquid comprising abrasive particles, a corrosion inhibitor, a complexing agent, an oxidizing agent, and at least one polyacrylic anionic surfactant. Also disclosed are applications of the chemical mechanical polishing liquid in polishing copper metal.

Description

Chemical mechanical polishing liquid and application thereof

Technical field

The invention relates to the field of chemical mechanical polishing liquids, 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. During 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 the delay time, the line width is narrower and narrower, and the dielectric layer uses a low dielectric with low mechanical strength ( Low-k) materials, the number of layers of wiring is 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. . U.S. Patent No. 5,552,742 provides a metal chemical mechanical polishing slurry comprising a surfactant comprising aramid silicone, an alkane polysiloxane, a polyoxyalkylene ether and copolymers 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 CN103074632A provides a chemical mechanical polishing slurry containing an organic phosphonic acid, a polyacrylic acid and/or a salt thereof and/or a polyacrylic acid copolymer for use in copper polishing, and has a high polishing option for copper. Sex. However, the pH of the polishing solution is 2 to 5, and the removal rate of the silica dielectric layer is high under acidic conditions, and the erosion of the dielectric layer is difficult to control. 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.

In summary, the polishing liquid disclosed in the prior art has a corrosion phenomenon on the surface of the polishing substrate in an acidic environment, which is disadvantageous for the utilization of the substrate after polishing, and the polishing efficiency is low.

Summary of the invention

In order to solve the above problems, the present invention provides a chemical mechanical polishing liquid, which improves the polishing selection of the copper and tantalum barrier layer by the polishing liquid by adding a polyacrylic anionic surfactant. The ratio is improved to improve the dishing of the polished copper wire and the erosion of the dielectric layer (Erosion), and there is no defects such as copper residue and corrosion after polishing.

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 polyacrylic anionic surfactant.

Wherein, preferably, the polyacrylic anionic surfactant is a polyacrylic acid homopolymer and/or copolymer and a salt thereof; preferably, the polyacrylic acid homopolymer is polyacrylic acid and/or polymalan The polyacrylic acid copolymer is a polyacrylic acid-polyacrylate copolymer and/or a polyacrylic acid-polymaleic acid copolymer; the salt is a potassium salt and ammonium of a polyacrylic acid homopolymer and/or copolymer. Salt and / or sodium salt.

Preferably, the polyacrylic anionic surfactant has a molecular weight of 1,000 to 10,000; preferably, the polyacrylic anionic surfactant has a molecular weight of 2,000 to 5,000.

Preferably, the polyacrylic anionic surfactant has a concentration of 0.0005 to 0.5% by weight; preferably, the polyacrylic anionic surfactant has a concentration of 0.001 to 0.1% by weight.

Preferably, the abrasive particles comprise silica, alumina, doped aluminum or aluminum-coated silica, ceria, titania and/or polymeric abrasive particles; preferably, the abrasive particles are dioxide Silica sol.

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 from 0.1 to 3% by weight. 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; preferably, the benzene ring-free azole compound is 1,2,4-trinitrogen Oxazole, 3-amino-1,2,4-triazole, 4-amino-1,2,4-triazole, 3,5-diamino-1,2,4-triazole, 5-carboxyl -3-amino-1,2,4-triazole, 3-amino-5-mercapto-1,2,4-triazole, 5-acetic acid-1H-tetrazole, 5-methyltetrazolium And one or more of 5-amino-1H-tetrazole.

Preferably, the corrosion inhibitor concentration is 0.001 to 2 wt%; preferably, the rot The concentration of the etch inhibitor is 0.005 to 1% by weight.

Preferably, the oxidizing agent is hydrogen peroxide, urea peroxide, peroxyformic acid, peracetic acid, persulfate, percarbonate, periodic acid, perchloric acid, perboric acid, potassium permanganate and nitric acid. One or more of iron; 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 provides a chemical mechanical polishing liquid as described above in a metal

Application in the polishing of copper.

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

1) The present invention adds a combination of a benzene ring-free azole-based corrosion inhibitor and a polyacrylic anionic surfactant to the polishing liquid, maintaining a high copper removal rate and reducing 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 is achieved;

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 display area in which a copper wire width of a copper pattern chip polished in Comparative Example 1 is 5 μm and a dielectric material line width is 1 μm;

2 is a topographical view of a dense line display region in which a copper wire width of 5 nm and a dielectric material line width of 1 μm in the copper pattern chip after polishing in Example 25.

detailed description

Table 1 shows Examples 1 to 24 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 Example 1-24

Table 2 shows Examples 25 to 35 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 . Add oxidizing agent before use and mix well.

Table 2 Comparative Examples 1-4 and Examples 25-35

Effect embodiment

The copper (Cu) and tantalum (Ta) were polished with the comparative polishing liquid and the polishing liquids 25 to 35 of the present invention under the following conditions. Specific polishing conditions: lower pressure 1.5 psi, 2.0 psi; polishing disc and polishing head speed 73/67 rpm, polishing pad IC1010, polishing liquid flow rate 350 ml/min, polishing machine table 12" Reflexion LK, polishing time 1 min.

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 Residual copper was about 3000 A, and then the residual copper was removed on a polishing disc 2 with a pressure of 1.5 psi. 5/1 micron on a patterned copper wafer was measured with an XE-300P atomic force microscope (copper line width/dielectric material) The dishing value (Dishing) and the dielectric layer erosion value (Erosion) at the dense line array of the line width are shown in Table 3.

Table 3 Comparison of Polishing Effect of Polishing Liquid and Polishing Liquid 25-35 of the Present Invention

1 and 2 are the surface shape of a dense line array region of 5/1 micron (copper line width/dielectric material line width) in a polished copper pattern chip using Comparative Example 1 and Inventive Example 25 as a polishing liquid, respectively. Look at the picture. As can be seen from the figure, using Comparative Example 1 as a polishing liquid, the polished copper wire has a dishing depression of 84.5 nm and a dielectric layer erosion of 51.9 nm; and using this Example 25 as a polishing liquid, the polished copper wire The dishing depression is reduced to 43 nm, and the dielectric layer erosion is reduced to 0.2 nm. The polishing liquid of the present invention has a remarkable effect on the surface morphology after polishing, in particular, the erosion of the dielectric layer.

Meanwhile, it can be seen from Table 3 that, in comparison with Comparative Example 1, the addition of a polyacrylic acid-containing surfactant to the polishing liquid of the present invention can reduce the removal rate of ruthenium while maintaining a high removal rate of copper. The rate ratio greatly increases the Cu/Ta removal rate selection ratio, thus effectively reducing the dishing and dielectric layer erosion values after polishing of the pattern chip, and Comparative Example 1 cannot be effective even if more corrosion inhibitors are added. The ground removal rate of the crucible is suppressed, resulting in high dishing and dielectric layer erosion values. By comparison with the comparative example 2, it can be found that the combination of the azole-based corrosion inhibitor benzotriazole and the polyacrylic surfactant with a benzene ring can reduce the removal rate of ruthenium, but greatly inhibits the copper. The removal rate does not effectively remove copper. In comparison with the examples of the present invention, Comparative Examples 3 and 4 also employed a group of an azole corrosion inhibitor without a benzene ring and a polyacrylic anionic surfactant. However, the pH of Comparative Example 3 was too low, and the removal rates of copper and bismuth were 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 uses a combination of an azole ring-free azole-based corrosion inhibitor and a polyacrylic anionic surfactant in the polishing liquid to maintain a high copper removal rate while reducing the ruthenium barrier removal. Rate, increasing the polishing selectivity of the polishing solution to the copper and tantalum barrier layer; the polishing of the wafer of the present invention can improve the dishing and dielectric corrosion of the polished copper wire, and has no copper residue after polishing. And 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. Any equivalent modifications and substitutions to 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

A chemical mechanical polishing polishing fluid comprising abrasive particles, a corrosion inhibitor, a complexing agent, an oxidizing agent, and at least one polyacrylic anionic surfactant.
The chemical mechanical polishing liquid according to claim 1, wherein the polyacrylic anionic surfactant is a polyacrylic acid homopolymer and/or copolymer and a salt thereof.
The chemical mechanical polishing liquid according to claim 2, wherein the polyacrylic acid homopolymer is polyacrylic acid and/or polymaleic acid; and the polyacrylic acid copolymer is polyacrylic acid-polyacrylate copolymer. And/or a polyacrylic acid-polymaleic acid copolymer; the salt being a potassium, ammonium and/or sodium salt of a polyacrylic acid homopolymer and/or copolymer.
The chemical mechanical polishing liquid according to claim 1, wherein the polyacrylic anionic surfactant has a molecular weight of 1,000 to 10,000.
The chemical mechanical polishing liquid according to claim 4, wherein the polyacrylic anionic surfactant has a molecular weight of 2,000 to 5,000.
The chemical mechanical polishing liquid according to claim 1, wherein the polyacrylic anionic surfactant has a concentration of 0.0005 to 0.5% by weight.
The chemical mechanical polishing liquid according to claim 6, wherein the polyacrylic anionic surfactant has a concentration of from 0.001 to 0.1% by weight.
The chemical mechanical polishing liquid according to claim 1, wherein the abrasive particles are silica sol.
The chemical mechanical polishing liquid according to claim 1, wherein the abrasive particles have a particle diameter of 20 to 150 nm.
The chemical mechanical polishing liquid according to claim 10, wherein the abrasive particles have a particle diameter of 50 to 120 nm.
The chemical mechanical polishing liquid according to claim 1, wherein the abrasive particles have a concentration of 0.05 to 2% by weight.
The chemical mechanical polishing liquid according to claim 12, wherein said abrasive particles have a concentration of from 0.1 to 1% by weight.
The chemical mechanical polishing liquid according to claim 1, wherein the complexing agent is an aminocarboxylic acid compound and a salt thereof.
The chemical mechanical polishing liquid according to claim 14, wherein the aminocarboxylate compound and a salt thereof are glycine, alanine, valine, leucine, valine, phenylalanine, and tyramine. Acid, tryptophan, lysine, arginine, histidine, serine, aspartic acid, glutamic acid, asparagine, glutamine, ammonia triacetic acid, ethylenediaminetetraacetic acid, cyclohexane One or more of amine tetraacetic acid, ethylenediamine disuccinic acid, diethylenetriaminepentaacetic acid, and triethylenetetramine hexaacetic acid.
The chemical mechanical polishing liquid according to claim 1, wherein the concentration of the complexing agent is from 0.1 to 5% by weight.
The chemical mechanical polishing liquid according to claim 15, wherein the concentration of the complexing agent is from 0.5 to 3% by weight.
The chemical mechanical polishing liquid according to claim 1, wherein the corrosion inhibitor is one or more of a benzene ring-free azole compound.
The chemical mechanical polishing liquid according to claim 17, wherein said benzene ring-free azole compound is 1,2,4-triazole or 3-amino-1,2,4-triazo. Azole, 4-amino-1,2,4-triazole, 3,5-diamino-1,2,4-triazole, 5-carboxy-3-amino-1,2,4-triazole , one of 3-amino-5-mercapto-1,2,4-triazole, 5-acetic acid-1H-tetrazole, 5-methyltetrazole and 5-amino-1H-tetrazole Or a variety.
The chemical mechanical polishing liquid according to claim 1, wherein the corrosion inhibitor concentration is 0.001 to 2% by weight.
The chemical mechanical polishing liquid according to claim 19, wherein the corrosion inhibitor concentration is 0.005 to 1% by weight.
The chemical mechanical polishing liquid according to claim 1, wherein said oxidizing agent is hydrogen peroxide, urea peroxide, peroxycarboxylic acid, peracetic acid, persulfate, percarbonate, periodic acid, and high. One or more of chloric acid, perboric acid, potassium permanganate, and ferric nitrate.
The chemical mechanical polishing liquid according to claim 21, wherein said oxidizing agent is hydrogen peroxide.
The chemical mechanical polishing liquid according to claim 1, wherein the concentration of the oxidizing agent is 0.05 to 5% by weight.
The chemical mechanical polishing liquid according to claim 23, wherein the concentration of the oxidizing agent is from 0.1 to 3% by weight.
The chemical mechanical polishing liquid according to any one of claims 1 to 24, wherein the chemical mechanical polishing liquid has a pH of from 5 to 8.
Use of the chemical mechanical polishing liquid according to any one of claims 1 to 25 for polishing of metallic copper.