KR20130091333A - Chemical mechanical polishing slurry - Google Patents

Abstract

The present invention relates to a slurry for chemical mechanical polishing comprising abrasive particles, an oxidant, an amino acid, a quaternary ammonium base, and water, wherein the pH of the slurry for chemical mechanical polishing is alkaline. The slurry can promote the polishing rate of copper and silicon simultaneously under alkaline conditions.

Description

Chemical Mechanical Polishing Slurry {CHEMICAL MECHANICAL POLISHING SLURRY}

The present invention relates to abrasive materials, in particular to slurries for chemical mechanical polishing.

Through-Silicon-Via (TSV) technology is a new technology that enables chip interconnect by forming vertical access between chips and chips and wafers and wafers. Compared with conventional stacking technology using bump and IC bonding packaging, the advantage of TSV is that the chip density can be maximized in three-dimensional direction to improve the speed of the chip and lower the power consumption. Minimize the form and reduce the interconnection. In the case of polishing, the backside thinning technology of TSV technology requires a fairly high polishing rate of silicon and copper at the same time.

In order to achieve high polishing rates, silicon is generally polished under alkaline conditions. For example, US2002032987 discloses slurries comprising alcohol amines as additives to improve the removal rate of polysilicon, with the most preferred additive being 2-dimethylamino-2-methyl-1-propanol. US2002151252 provides a polishing composition comprising a plurality of carboxylic acids as chelating agent to improve the removal rate of polysilicon, wherein the chelating agent is preferably EDTA or DPTA. EP1072662 discloses a slurry having organic materials that share an unlocalized structure made by a non-covalent electron pair and a double bond so that the slurry can promote the removal rate of polysilicon, and the organic materials are preferably guanidine and salts thereof. US2006014390 discloses one type of polishing solution used to improve the removal rate of polysilicon, the solution comprising 4.25 to 18.5 weight percent abrasive, and 0.05 to 1.5 weight percent additive. And the additive is selected from the group consisting of quaternary ammonium, quaternary ammonium salts, ethanol amines and the like. In addition, the polishing solution further comprises a nonionic surfactant such as a homo or copolymer of ethylene glycol or propylene glycol. CN101497765A significantly improves the polishing rate of silicon by exploiting the synergistic effects of biguanides and azoles.

In order to achieve high polishing rates, copper is generally polished under acidic conditions using the high oxidation potential of the oxidizing agent (hydrogen peroxide), and the properties of copper tend to complex and dissolve under acidic conditions. For example, CN1705725 discloses a slurry for polishing a copper surface, which removes the copper surface using an oxidizing agent (such as hydrogen peroxide), a chelating agent and a passivation agent at a pH between 2.5 and 4. CN1787895A discloses a CMP composition comprising a rheology agent, an oxidizing agent, a chelating agent, a passivating agent, an abrasive and a solvent. Under acidic conditions, this kind of CMP composition advantageously improves material selectivity and can be used to polish semiconductor substrates having copper thereon without dishing into polished copper or other adverse planarization defects. CN01818940A discloses copper-polishing slurries that can significantly improve the removal rate of copper by further combining oxidants such as hydrogen peroxide and / or corrosion inhibitors such as benzotriazole. And while maintaining a high polishing rate while maintaining local pH stability, substantially reducing local and local corrosion.

Sometimes copper is polished under alkaline conditions. For example, CN1644640A discloses aqueous compositions useful for polishing copper under alkaline conditions. The composition comprises 0.001 to 6 weight percent inhibitor for nonferrous metals, 0.05 to 10 weight percent complexing agent for metals, 0.01 to 25 weight percent copper remover to promote removal of copper, 0.5 to 40 weight percent abrasive And the like, and promote the removal rate of copper by the interaction of imidazole to promote polishing of copper and BTA. CN1398938A discloses a wide area planarization CMP slurry for multilayer copper wire in large scale integrated circuits and is used to improve the removal rate of copper. The slurry contains the following components: 18 to 50 weight percent abrasive, 0.1 to 10 weight percent chelating agent, 0.005 to 25 weight percent complexing agent, 0.1 to 10 weight percent active agent, 1 to 20 weight percent oxidant And deionized water.

In the prior art, although the polishing rate of copper was high under acidic conditions, the polishing rate of silicon is generally slow. This is because the silicon surface oxidizes to form silicon dioxide because of the effect of the oxidizer under acidic conditions, and silicon dioxide is more difficult to remove than silicon. Although the polishing rate of silicon can be high under alkaline conditions without oxidizing agent, the polishing rate of copper is generally slow. This is because copper needs to be oxidized in order to be easily removed. However, if an oxidant such as hydrogen peroxide is added, the silicon surface will oxidize to form silicon dioxide due to the effect of the oxidant. In addition, oxidants such as hydrogen peroxide are unstable under alkaline conditions and decompose quickly.

It is an object of the present invention to provide a slurry for chemical mechanical polishing which can simultaneously promote the polishing rate of copper and silicon under alkaline conditions.

The chemical mechanical polishing slurry of the present application includes abrasive particles, oxidizing agent, amino acid, quaternary ammonium base and water, and the pH of the chemical mechanical polishing slurry is alkaline.

In the present invention, the abrasive particles are SiO ₂ , Al ₂ O ₃ , ZrO ₂ , CeO ₂ , SiC, Fe ₂ O ₃ , TiO ₂ And / or Si ₃ N ₄ . And the concentration of abrasive particles may range from 1-30% (weight percent).

In the present invention, the oxidant may be at least one selected from the group consisting of bromate, chlorate, iodide, periodic acid and / or periodic acid. The bromate may be potassium bromide, the chlorate may be potassium chlorate, the iodide may be potassium iodide, and the periodate may be ammonium iodide. And the concentration of the oxidant may range from 0.5-4% (weight percent).

In the present invention, the amino acid may be selected from glycine and / or L-glutamic acid. And the concentration of the amino acid may range from 1-8% (weight percent).

In the present invention, the quaternary ammonium base may be tetramethylammonium hydroxide (TMAH). And the concentration of the quaternary ammonium may range from 5-12% (weight percent).

In the present invention, the pH of the chemical mechanical polishing slurry may be in the range of 8.00 to 13.00.

A beneficial effect according to the invention is that the polishing slurry according to the invention can significantly promote the polishing rate of Cu and silicon under alkaline conditions.

The following examples illustrate the invention in detail but of course should not be construed in a way that limits the scope of the invention. And in the following examples,% means weight percent.

Table 1 provides a composition uniformly mixed with deionized water to prepare a slurry for chemical mechanical polishing according to each of Examples 1-23 and Comparative Examples 1-4. And pH was adjusted to the desired value using a pH adjuster (50% KOH).

Examples 1-23 and Comparative Examples 1-4 of the chemical mechanical polishing slurry of the present invention Abrasive particle Oxidant Polyhydroxy
compound Quaternary ammonium base PH Kinds density Kinds density Kinds density Kinds density Comparative Example 1 SiO ₂ One% TMAH 0.10% 10.5 Comparative Example 2 SiO ₂ 2% TMAH 0.10% 10.5 Comparative Example 3 SiO ₂ 5% TMAH 0.10% 10.5 Comparative Example 4 SiO ₂ 15% TMAH 0.10% 10.5 Example 1 SiO ₂ One% Potassium bromate 0.50% Glycine 2% TMAH 8.00% 11.46 Example 2 SiO ₂ One% Potassium bromate One% Glycine 2% TMAH 8.00% 11.51 Example 3 SiO ₂ 2% Potassium bromate 2% Glycine 2% TMAH 8.00% 10.603 Example 4 SiO ₂ 2% Potassium bromate 2% Glycine 4% TMAH 10.00% 10.8 Example 5 SiO ₂ 2% Potassium bromate 4% Glycine 4% TMAH 10.00% 11.4 Example 6 SiO ₂ 2% Potassium iodide 2% Glycine 4% TMAH 10.00% 10.894 Example 7 SiO ₂ 2% Periodic acid One% Glycine 4% TMAH 10.00% 10.8 Example 8 SiO ₂ 2% Periodic acid 2% Glycine 4% TMAH 10.00% 10.592 Example 9 SiO ₂ 2% Periodic acid One% L-glutamic acid 4% TMAH 10.00% 10.8 Example 10 SiO ₂ 2% Periodic acid One% L-glutamic acid 2% TMAH 8.00% 10.8 Example 11 SiO ₂ 5% Periodic acid One% Glycine 2% TMAH 8.00% 10.593 Example 12 SiO ₂ 15% Periodic acid One% Glycine One% TMAH 6.00% 10.373 Example 13 SiO ₂ 15% Potassium chlorate One% Glycine One% TMAH 6.00% 10.5 Example 14 SiO ₂ 30% Periodic acid One% Glycine 8% TMAH 12.00% 11.35 Example 15 Fe ₂ O ₃ 5% Potassium bromate 3% Glycine 2% TMAH 8.00% 10 Example 16 TiO ₂ 5% Periodic acid 3% Glycine One% TMAH 5.00% 11.13 Example 17 SiO ₂ 15% Potassium bromate 3% Glycine 4% TMAH 10.00% 10.63 Example 18 Al ₂ O ₃ 15% Potassium iodide 3% Glycine 8% TMAH 12.00% 13 Example 19 Si ₃ N ₄ 15% Potassium bromate One% L-glutamic acid 6% TMAH 11.00% 10.44 Example 20 SiC 15% Ammonium Periodic Acid 0.50% L-glutamic acid 6% TMAH 11.00% 12 Example 21 SiO ₂ 25% Potassium bromate 3% Glycine 2% TMAH 8.00% 8 Example 22 CeO ₂ 25% Ammonium Periodic Acid 0.50% Glycine 2% TMAH 8.00% 10.54 Example 23 ZrO ₂ 30% Potassium bromate 4% L-glutamic acid One% TMAH 5.00% 10.2

Effect Example

In order to further observe the polishing effect of the present invention, polishing was carried out according to the following conditions: Logitech (UK) 1PM 52 polishing machine, Polytex polishing pad, 4cm * 4cm square wafer, downward pressure = 3 psi; Rotational speed of the polishing plate = 70rpm, rotational speed of the polishing head = 150rpm; Flow rate of abrasive slurry = 100 mL / min. The results are shown in Table 2.

Polishing Effect and Comparative Example 1-4 of Example 1-23 of Chemical Mechanical Polishing Slurry of the Present Invention RR of Cu RR in POLY A / min A / min Comparative Example 1 130 1455 Comparative Example 2 224 1581.6 Comparative Example 3 376 1704 Comparative Example 4 392 1904.4 Example 1 1715 3610 Example 2 1908 3795.6 Example 3 4049 4227.2 Example 4 4604 4754.8 Example 5 6010 4850 Example 6 1520 3453.6 Example 7 4520 4933.2 Example 8 6044 4511 Example 9 3284 3421 Example 10 1550 3204 Example 11 4719 5216 Example 12 4135 3365.5 Example 13 1245 2591 Example 14 4601 5010

From the results of Comparative Examples 1-4, it can be seen that the slurry rate of silicon and copper is very slow under alkaline conditions when the slurry contains only abrasive particles.

When comparing Example 1-2 with Comparative Example 1, it was found that under the same concentration of abrasive particles, the slurry rates of silicon and copper increased significantly when the alkaline slurry included certain oxidants, amino acids and quaternary ammonium bases of the present application. Able to know.

Comparing Examples 3-10 to Comparative Example 2, it was found that under the same concentration of abrasive particles, the slurry rates of silicon and copper increased significantly when the alkaline slurry contained certain oxidants, amino acids and quaternary ammonium bases of the present application. Able to know.

Comparing Example 11 with Comparative Example 3, it can be seen that under the same concentration of abrasive particles, the slurry rates of silicon and copper increase significantly when the alkaline slurry comprises certain oxidants, amino acids and quaternary ammonium bases of the present application. have.

Comparing Examples 12-13 with Comparative Example 4, it was found that under the same concentration of abrasive particles, the slurry rates of silicon and copper increased significantly when the alkaline slurry contained certain oxidants, amino acids and quaternary ammonium bases of the present application. Able to know.

When comparing Example 1 to Example 2, Example 4 to Example 5, and Example 7 to Example 8, under the same concentration of amino acids, the slurry rate of copper was increased by changing the concentration of the oxidant of the alkaline slurry. It can be seen that with the increase of the concentration, the increase significantly, and at the same time, the slurry rate of silicon is not suppressed.

When Example 3 is compared with Comparative Example 4 and Example 10, it can be seen that the slurry rates of copper and silicon increase significantly with increasing concentrations of amino acids.

When Example 7 is compared with Comparative Example 11, it can be seen that the slurry rates of copper and silicon increase significantly with increasing concentration of abrasive particles.

Claims (11)

A slurry for chemical mechanical polishing, comprising abrasive particles, oxidizing agents, amino acids, quaternary ammonium bases, and water, wherein the pH is alkaline. The method of claim 1,
The abrasive particles are SiO ₂ , Al ₂ O ₃ , ZrO ₂ , CeO ₂ , SiC, Fe ₂ O ₃ , TiO ₂ And / or at least one slurry selected from the group consisting of Si ₃ N ₄ . The method of claim 1,
Wherein the weight concentration of the abrasive particles is in the range of 1-30%. The method of claim 1,
Wherein the oxidant is at least one selected from the group consisting of bromate, chlorate, iodide, periodic acid and / or periodic acid salt. The method of claim 4, wherein
Wherein said bromate is potassium bromate, said chlorate is potassium chlorate, said iodide is potassium iodide, and said periodate is ammonium periodate. The method of claim 1,
Wherein the weight concentration of the oxidant is in the range of 0.5-4%. The method of claim 1,
Wherein said amino acid is selected from glycine and / or L-glutamic acid. The method of claim 1,
Slurry for chemical mechanical polishing wherein the weight concentration of the amino acid is in the range of 1-8%. The method of claim 1,
Wherein said quaternary ammonium base is tetramethylammonium hydroxide. The method of claim 1,
Wherein the weight concentration of the quaternary ammonium base is in the range of 5-12%. The method of claim 1,
PH of the chemical mechanical polishing slurry is 8.00-13.00 chemical mechanical polishing slurry.