TW202132492A - Chemical mechanical polishing slurry - Google Patents

Abstract

The present invention provides a chemical mechanical polishing slurry, including abrasive particles, a catalyst, a stabilizer, a corrosion inhibitor containing adenine organic acid structure, an oxidant, water and a pH regulating agent. It can not only simultaneously polish metal tungsten and silicon oxide, and achieve a high polishing rate of tungsten metal and a middling polishing rate of silicon oxide, but also effectively inhibit static corrosion of tungsten metal, improve the surface condition of polished metal.

Description

Chemical mechanical polishing liquid

The invention relates to a chemical mechanical polishing liquid.

Modern semiconductor integrated circuits are a collection of millions of tiny components on a substrate. These components form an interconnection structure through multi-layer interconnects to perform corresponding functions. For example, a typical multilayer interconnection structure includes a first metal layer, a dielectric layer, and second or more metal layers. Each layer structure is prepared by techniques such as physical vapor deposition (PVD), chemical vapor deposition (CVD) and plasma enhanced chemical vapor deposition (PECVD), and then a new layer is formed on top of it. As multiple layers of material are deposited and removed, the uppermost surface of the wafer becomes uneven. These unevenness may lead to various defects of the product, so the planarization technology of the conductive layer and the insulating dielectric layer becomes very important. In the 1980s, the chemical mechanical polishing technology pioneered by IBM was considered to be the most effective method for global planarization.

In recent years, tungsten has been increasingly used in the manufacture of semiconductor circuits. Because tungsten has strong resistance to electron migration under high current density and can form a good ohmic contact with silicon, it is often used to prepare metal vias and contacts. At the same time, adhesive layers, such as TiN and Ti, are used to connect them. Connect with SiO _2. Chemical mechanical polishing can be used to polish tungsten to reduce the thickness of the tungsten layer and the corresponding bonding layer to obtain a flat surface that _{exposes the SiO 2 surface.} In this process, first an etchant capable of reacting with tungsten is converted into a soft oxide film, and then the oxide film is removed by mechanical grinding. The specific method is as follows: the wafer is fixed on the polishing head, and the front surface of the wafer is in contact with the polishing pad. The polishing head moves relative to the wafer on the polishing pad. At the same time, a polishing composition ("slurry") is injected between the wafer and the polishing pad, and the slurry is spread on the polishing pad due to centrifugal action for polishing. However, in practical applications, since the polishing slurry contains active oxidizers, corrosive compounds and other components, tungsten or its oxides can be converted into soluble salts, causing unexpected corrosion of tungsten, resulting in surface depression or erosion. For example, severe corrosion may form deep tungsten vias, causing uneven tungsten surfaces to further appear on the next layer of metal/non-metal components, causing the deposition of metal layers on subsequent layers of the device to become complicated, which in turn leads to poor electrical contact. problem. Corrosion can also lead to the appearance of "keyhole", which can also cause serious contact problems, resulting in a decrease in yield.

To solve this problem, it is necessary to add a corrosion inhibitor to the polishing composition. For example, US patent US 6136711 discloses a method of using amino acids as corrosion inhibitors for tungsten polishing, which can inhibit tungsten corrosion to a certain extent. US patent US6083419 discloses a polishing composition containing oxazolidine, sulfide, and nitrogen heterocyclic tungsten corrosion inhibitor, the best effect of which can reduce corrosion by about 97%, but no information such as polishing rate is given. US Patent No. 8858819 discloses a polishing combination using polyethyleneimine as a tungsten corrosion inhibitor, which can significantly reduce the static corrosion of tungsten at room temperature. However, at a temperature greater than 40 degrees, the effect is average, and even if only 3 ppm is added, the polishing rate of tungsten will be greatly reduced (decreased by about 30%). US Patent No. 8865013 discloses a tungsten polishing composition containing a double quaternary ammonium salt corrosion inhibitor. The composition can better inhibit the static corrosion of metal tungsten, but its oxidant is KIO3 instead of hydrogen peroxide, resulting in a very low tungsten polishing speed of the composition. US Patent US 9566686 discloses a tungsten polishing composition, which uses abrasive particles modified with a permanent positive charge (>15 mV) and a quaternary ammonium salt corrosion inhibitor with a long alkyl chain. Although this system can better inhibit tungsten corrosion, the preparation of abrasive particles is complicated, the cost is high, and the tungsten polishing rate is not high.

In order to solve the technical drawbacks of chemical mechanical polishing liquids in the prior art that cannot simultaneously maintain a high polishing rate for tungsten metal, maintain a moderate polishing rate for silicon oxide, and efficiently inhibit static corrosion of tungsten metal, the present invention provides a chemical mechanical polishing solution. The polishing liquid includes: abrasive particles, catalysts, stabilizers, corrosion inhibitors containing adenine organic acid structure, oxidants, water and pH adjusters.

其中，橋連基團R選自亞烷基（如(CH₂ )_n ， n = 1-6）、或者含雜原子（如O、N、S）的烷基橋 （如(CH₂ )_n O(CH₂ )_m ，n = 1-3，m = 1-3；和/或(CH₂ )_n NH(CH₂ )_m ，n=1-3，m=1-3；和/或(CH₂ )_n S(CH₂ )_m ，n=1-3，m=1-3），其中，所述雜原子不限於本申請中已經列舉的O、N、S，還可以為其他原子； X選自C、P、S， 當X = C時，n = 1，m= 1； 當X = P 時，n = 2，m= 1； 當X = S 時，n = 1，m= 2。In some embodiments, the corrosion inhibitor containing an adenine organic acid structure has an adenine, and at the same time has a bridging group (R) and an organic acid substituent on the adenine, the adenine-containing organic acid The structure of the acid structure corrosion inhibitor is as follows:

Wherein, the bridging group R is selected from alkylene groups (such as (CH ₂ ) _n , n = 1-6), or alkyl bridges containing heteroatoms (such as O, N, S) (such as (CH ₂ ) _n O(CH ₂ ) _m , n = 1-3, m = 1-3; and/or (CH ₂ ) _n NH(CH ₂ ) _m , n=1-3, m=1-3; and/or ( CH ₂ ) _n S(CH ₂ ) _m , n=1-3, m=1-3), wherein the heteroatom is not limited to the O, N, and S already listed in this application, and may also be other atoms; X is selected from C, P, S, when X = C, n = 1, m = 1; When X = P, n = 2, m = 1; When X = S, n = 1, m = 2 .

In some embodiments, the corrosion inhibitor containing an organic acid structure of adenine is Tenofovir ((R)-9-(2-phosphomethoxypropyl)-adenine, the chemical formula is C ₉ H ₁₄ N ₅ O ₄ P), or adefovir (9-(2-phosphinomethoxyethyl) adenine, chemical formula: C ₈ H ₁₂ N ₅ O ₄ P).

In some embodiments, the concentration of the corrosion inhibitor containing adenine organic acid structure ranges from 0.005% to 0.1%.

In some embodiments, the concentration of the corrosion inhibitor containing adenine organic acid structure ranges from 0.005% to 0.05%.

In some embodiments, the abrasive particles are SiO2.

In some embodiments, the concentration of the abrasive particles ranges from 0.5% to 3%.

In some embodiments, the concentration of the abrasive particles ranges from 1% to 3%.

In some embodiments, the catalyst is a metal cation catalyst.

In some embodiments, the metal cation catalyst is ferric nitrate nonahydrate.

In some embodiments, the concentration of the ferric nitrate nonahydrate ranges from 0.01% to 0.1%.

In some embodiments, the concentration of the ferric nitrate nonahydrate ranges from 0.01% to 0.07%.

In some embodiments, the stabilizer is an organic stabilizer.

In some embodiments, the organic stabilizer is a carboxylic acid that can be complexed with iron.

In some embodiments, the carboxylic acid that can be complexed with iron is one or more of phthalic acid, oxalic acid, malonic acid, succinic acid, adipic acid, citric acid, and maleic acid.

In some embodiments, the carboxylic acid that can be complexed with iron is malonic acid.

In some embodiments, the concentration of malonic acid ranges from 0.08% to 0.27%.

In some embodiments, the concentration of malonic acid ranges from 0.1% to 0.27%.

In some embodiments, the oxidant is H ₂ O ₂ .

In some embodiments, the concentration of the oxidant is 1 to 2%.

In some embodiments, the pH adjusting agent is HNO ₃ .

In some embodiments, the pH is 2~4. When the pH is less than 2, the chemical mechanical polishing liquid is a dangerous product, and when the pH is more than 4, it will cause the instability of the abrasive particles and the precipitation of Fe.

It should be understood that the% in the concentration in the present invention all refers to the percentage by mass.

All reagents of the present invention are commercially available.

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

The invention provides a chemical mechanical polishing liquid, which can polish metal tungsten and silicon oxide at the same time, so as to maintain a high polishing rate for tungsten metal, maintain a medium polishing rate for silicon oxide, and efficiently inhibit static corrosion of tungsten metal, and improve The condition of the metal surface after polishing.

The advantages of the present invention will be described in detail below in conjunction with specific embodiments.

Hereinafter, the chemical mechanical polishing composition for polishing tungsten of the present invention will be described in detail through specific examples, so as to better understand the present invention, but the following examples do not limit the scope of the present invention.

Example

The specific examples and comparative examples are according to the formula given in Table 1, all the components are dissolved and mixed uniformly, and the mass percentage is made up to 100% with water. Adjust the pH to the desired value with a pH adjuster.

Table 1. The types of components and their corresponding concentrations in each embodiment and comparative example Example Abrasive particles Oxidant catalyst stabilizer Corrosion inhibitor pH regulator pH type concentration type concentration type concentration type concentration type concentration Example 1 SiO ₂ 3.0% Hydrogen peroxide 2.00% Ferric Nitrate Nonahydrate 0.03% Malonate 0.08% Adefovir 0.005% HNO ₃ 2 Example 2 SiO ₂ 3.0% Hydrogen peroxide 2.00% Ferric Nitrate Nonahydrate 0.03% Malonate 0.08% Adefovir 0.010% HNO ₃ 2 Example 3 SiO ₂ 3.0% Hydrogen peroxide 2.00% Ferric Nitrate Nonahydrate 0.03% Malonate 0.08% Adefovir 0.030% HNO ₃ 2 Example 4 SiO ₂ 3.0% Hydrogen peroxide 2.00% Ferric Nitrate Nonahydrate 0.07% Malonate 0.27% Adefovir 0.030% HNO ₃ 2 Example 5 SiO ₂ 3.0% Hydrogen peroxide 2.00% Ferric Nitrate Nonahydrate 0.03% Malonate 0.08% Tenofovir 0.030% HNO ₃ 2 Example 6 SiO ₂ 3.0% Hydrogen peroxide 2.00% Ferric Nitrate Nonahydrate 0.07% Malonate 0.27% Tenofovir 0.030% HNO ₃ 2 Example 7 SiO ₂ 3.0% Hydrogen peroxide 2.00% Ferric Nitrate Nonahydrate 0.10% Malonate 0.27% Tenofovir 0.030% HNO ₃ 2 Example 8 SiO ₂ 3.0% Hydrogen peroxide 2.00% Ferric Nitrate Nonahydrate 0.07% Malonate 0.10% Tenofovir 0.030% HNO ₃ 2 Example 9 SiO ₂ 3.0% Hydrogen peroxide 2.00% Ferric Nitrate Nonahydrate 0.07% Malonate 0.18% Tenofovir 0.030% HNO ₃ 2 Example 10 SiO ₂ 3.0% Hydrogen peroxide 2.00% Ferric Nitrate Nonahydrate 0.07% Malonate 0.27% Tenofovir 0.030% HNO ₃ 2 Example 11 SiO ₂ 3.0% Hydrogen peroxide 2.00% Ferric Nitrate Nonahydrate 0.07% Malonate 0.27% Tenofovir 0.005% HNO ₃ 2 Example 12 SiO ₂ 3.0% Hydrogen peroxide 2.00% Ferric Nitrate Nonahydrate 0.07% Malonate 0.27% Tenofovir 0.050% HNO ₃ 2 Example 13 SiO ₂ 3.0% Hydrogen peroxide 2.00% Ferric Nitrate Nonahydrate 0.07% Malonate 0.27% Tenofovir 0.070% HNO ₃ 2 Example 14 SiO ₂ 3.0% Hydrogen peroxide 2.00% Ferric Nitrate Nonahydrate 0.07% Malonate 0.27% Tenofovir 0.100% HNO ₃ 2 Example 15 SiO ₂ 0.5% Hydrogen peroxide 2.00% Ferric Nitrate Nonahydrate 0.07% Malonate 0.27% Tenofovir 0.030% HNO ₃ 2 Example 16 SiO ₂ 2.0% Hydrogen peroxide 2.00% Ferric Nitrate Nonahydrate 0.07% Malonate 0.27% Tenofovir 0.030% HNO ₃ 2 Example 17 SiO ₂ 3.0% Hydrogen peroxide 1.00% Ferric Nitrate Nonahydrate 0.07% Malonate 0.27% Tenofovir 0.030% HNO ₃ 2 Example 18 SiO ₂ 3.0% Hydrogen peroxide 2.00% Ferric Nitrate Nonahydrate 0.01% Malonate 0.27% Tenofovir 0.030% HNO ₃ 2 Example 19 SiO ₂ 3.0% Hydrogen peroxide 2.00% Ferric Nitrate Nonahydrate 0.07% Malonate 0.27% Tenofovir 0.030% HNO ₃ 3 Example 20 SiO ₂ 3.0% Hydrogen peroxide 2.00% Ferric Nitrate Nonahydrate 0.07% Malonate 0.27% Tenofovir 0.030% HNO ₃ 4 Comparative example 1 SiO ₂ 3.0% Hydrogen peroxide 2.00% Ferric Nitrate Nonahydrate 0.07% Malonate 0.27% —— —— HNO ₃ 2 Comparative example 2 SiO ₂ 3.0% Hydrogen peroxide 2.00% Ferric Nitrate Nonahydrate 0.07% Malonate 0.27% Adenine 0.030% HNO ₃ 2 Comparative example 3 SiO ₂ 3.0% Hydrogen peroxide 2.00% Ferric Nitrate Nonahydrate 0.07% Malonate 0.27% 6-carboxypurine 0.030% HNO ₃ 2

Effect example

Perform polishing and static corrosion tests on tungsten wafers and silicon oxide wafers according to the formula in Table 1 according to the following experimental conditions, and the results in Table 2 are obtained.

Specific polishing conditions: The polishing machine is a 12-inch machine Reflexion LK from Applied Materials, with a pressure of 3.0 psi, a polishing disc and head rotating speed of 93/87 rpm, a polishing pad IC1010, a polishing fluid flow rate of 150 ml/min, and a polishing time of 1 minute. .

Static corrosion test of tungsten: immerse a 5 cm×5 cm tungsten wafer in a polishing slurry at room temperature or a preheated 45°C, immerse it for 2 minutes, take it out and rinse. Before the wafer was put in and after it was taken out and cleaned, the thickness of the metal layer of the wafer was tested with a Napson four-point probe tester (model RT 70/RG 7B) to obtain the corrosion value.

Table 2. Polishing rate of polished tungsten wafers and corrosion rates of tungsten metal at different temperatures for each embodiment and comparative example Tungsten polishing speed (A/min) Silicon oxide polishing speed (A/min) Corrosion 25℃ (A/min) Corrosion 40℃ (A/min) Example 1 3088 542 16 35 Example 2 3050 546 10 27 Example 3 3004 561 5 twenty one Example 4 3428 627 15 34 Example 5 3098 580 3 18 Example 10 3472 622 11 29 Example 11 3549 613 18 33 Example 12 3374 627 2 16 Example 13 3325 624 1 5 Example 14 3267 618 0 0 Comparative example 1 3517 623 37 122 Comparative example 2 3508 611 31 108 Comparative example 3 3471 609 twenty four 73

Examples 1-5 and 10-14 show that the chemical mechanical polishing solution of the present invention can perform high-speed polishing of tungsten, and can effectively inhibit the static corrosion of tungsten (corrosion rate <35 A/min), the corrosion inhibition effect of the chemical mechanical polishing liquid of the present invention at room temperature is more obvious than the corrosion inhibition effect at other temperatures. From Examples 1-3 and 10-14, it can be seen that for the preferred corrosion inhibitor Tenofovir and Adefovir, it can be found that as the amount of corrosion inhibitor increases, the corrosion inhibition effect is correspondingly better. Among them, Dangtai The concentration of Novovir reaches 0.1%, which can even completely inhibit the static corrosion of tungsten (corrosion rate is 0). Specifically, as the concentration of the corrosion inhibitor containing adenine organic acid structure increased from 0.005% in Example 11 to 0.03% in Example 10, to 0.05% in Example 12, to 0.07 in Example 13 %, to 0.1% of Example 14. At 25°C, the corresponding tungsten corrosion rates are 18, 11, 2, 1, 0; at 40°C, the corresponding tungsten corrosion rates are 33, 29, 16, and 16 respectively. 5, 0. In addition, it can be seen from Examples 10-14 that the chemical mechanical polishing liquid containing Tenofovir has an insignificant effect on the polishing speed of tungsten, and at the same time has no effect on the polishing speed of silicon oxide.

From Example 3 and Example 5, it can be seen that the tungsten polishing rate, the silicon oxide polishing rate, and the effect of inhibiting static corrosion of tungsten are similar in the chemical mechanical polishing liquid containing Tenofovir and the chemical mechanical polishing liquid containing adefovir. .

Through the comparison of Comparative Example 1 and Examples 4 and 10, it is found that on the basis of the same abrasive particles, catalyst, stabilizer, oxidant and pH, the chemical mechanical polishing liquid without the corrosion inhibitor containing the adenine organic acid structure has no inhibition The technical effect of tungsten static corrosion, there is obvious tungsten corrosion.

Through the comparison of Comparative Example 2 and Example 10, it is found that the chemical mechanical polishing liquid containing adenine itself cannot inhibit the static corrosion of tungsten, while the chemical mechanical polishing liquid containing tenofovir has the technical effect of inhibiting the static corrosion of tungsten metal.

By comparing Comparative Example 3 with Examples 4 and 10, it is found that although the chemical mechanical polishing liquid containing 6-carboxyadenine can also inhibit the corrosion of tungsten to a certain extent, its effect is not as good as Tenofovir and Adefovir.

In summary, the chemical mechanical polishing liquid of the present application overcomes the technical defects that the prior art cannot simultaneously maintain a high polishing rate for tungsten metal, maintain a moderate polishing rate for silicon oxide, and efficiently inhibit static corrosion of tungsten metal. The chemical mechanical polishing liquid provided by the present invention can polish metal tungsten and silicon oxide at the same time, so as to maintain a high polishing rate for tungsten metal, maintain a medium polishing rate for silicon oxide, and efficiently inhibit static corrosion of tungsten metal, and improve polishing After the metal surface condition.

The specific embodiments of the present invention are described in detail above, but they are only examples, and the present invention is not limited to the specific embodiments described above. For those skilled in the art, any equivalent modifications and substitutions made to the present invention are also within the scope of the present invention. Therefore, all equivalent changes and modifications made without departing from the spirit and scope of the present invention should all fall within the scope of the present invention.

Claims (23)

A chemical mechanical polishing liquid includes abrasive particles, a catalyst, a stabilizer, a corrosion inhibitor containing an organic acid structure of adenine, an oxidizer, water and a pH regulator. The chemical mechanical polishing liquid according to claim 1, wherein the corrosion inhibitor containing an organic acid structure of adenine has an adenine, and at the same time has a bridging group (R) and an organic acid substitution on the adenine The structure of the corrosion inhibitor containing adenine organic acid structure is as follows:

Wherein, the bridging group R is selected from an alkylene group or a heteroatom-containing alkyl bridge, X is selected from one or more of C, P, and S, when X = C, n = 1, m = 1; When X = P, n = 2, m = 1; When X = S, n = 1, m = 2. The chemical mechanical polishing liquid according to claim 2, wherein the corrosion inhibitor containing an organic acid structure of adenine is tenofovir or adefovir. The chemical mechanical polishing liquid according to claim 3, wherein the concentration of the corrosion inhibitor containing the adenine organic acid structure ranges from 0.005% to 0.1%. The chemical mechanical polishing liquid according to claim 4, wherein the concentration of the corrosion inhibitor containing the organic acid structure of adenine ranges from 0.005% to 0.05%. The chemical mechanical polishing liquid according to claim 1, wherein the abrasive particles are SiO2. The chemical mechanical polishing liquid according to claim 6, wherein the concentration of the abrasive particles ranges from 0.5% to 3%. The chemical mechanical polishing liquid according to claim 7, wherein the concentration of the abrasive particles ranges from 1% to 3%. The chemical mechanical polishing liquid according to claim 1, wherein the catalyst is a metal cation catalyst. The chemical mechanical polishing liquid according to claim 9, wherein the metal cation catalyst is ferric nitrate nonahydrate. The chemical mechanical polishing liquid according to claim 10, wherein the concentration of the ferric nitrate nonahydrate ranges from 0.01% to 0.1%. The chemical mechanical polishing liquid according to claim 11, wherein the concentration of the ferric nitrate nonahydrate ranges from 0.01% to 0.07%. The chemical mechanical polishing liquid according to claim 1, wherein the stabilizer is an organic stabilizer. The chemical mechanical polishing liquid according to claim 13, wherein the organic stabilizer is a carboxylic acid that can be complexed with iron. The chemical mechanical polishing liquid according to claim 14, wherein the carboxylic acid that can be complexed with iron is phthalic acid, oxalic acid, malonic acid, succinic acid, adipic acid, citric acid, maleic acid One or more of. The chemical mechanical polishing liquid according to claim 15, wherein the carboxylic acid that can be complexed with iron is malonic acid. The chemical mechanical polishing liquid according to claim 16, wherein the concentration of the malonic acid ranges from 0.08% to 0.27%. The chemical mechanical polishing liquid according to claim 17, wherein the concentration of the malonic acid ranges from 0.1% to 0.27%. The chemical mechanical polishing liquid according to claim 1, wherein the oxidizing agent is H ₂ O ₂ . The chemical mechanical polishing liquid according to claim 1, wherein the concentration of the oxidizing agent is 1 to 2%. The chemical mechanical polishing liquid according to claim 1, wherein the pH adjusting agent is HNO ₃ . The chemical mechanical polishing liquid according to claim 1, wherein the pH of the chemical mechanical polishing liquid is 2~4. The chemical mechanical polishing liquid according to claim 2, wherein the alkylene group is (CH ₂ ) _n , n=1-6; the heteroatom-containing alkyl bridge is (CH ₂ ) _n O(CH ₂ ) _m , n=1-3, m=1-3; and/or (CH ₂ ) _n NH(CH ₂ ) _m n=1-3, m=1-3; and/or (CH ₂ ) _n S(CH ₂ ) _m , n = 1-3, m = 1-3.