TW201311874A - Chemical mechanical polishing liquid - Google Patents

Abstract

This invention relates to a chemical mechanical polishing liquid, comprising grinding particles, an oxidant, amino acids, a quaternary ammonium base and the water, wherein the pH value of the chemical mechanical polishing liquid belongs to alkaline, such that the polishing liquid can achieve a very high polishing speed to both the silicon and the copper in an alkaline polishing environment.

Description

Chemical mechanical polishing fluid

The present invention relates to an abrasive material, and more particularly to a chemical mechanical polishing fluid.

TSV technology (Through-Silicon-Via) is the latest technology to achieve interconnection between wafers by making vertical conduction between wafer and wafer, between wafer and wafer. Unlike previous IC package bonding and bump overlay technology, TSV has the advantage of maximizing the density of stacked wafers in three dimensions, minimizing the size, and shortening interconnects to improve wafer speed and low power consumption. performance. In the TSV technology, backside thinning requires a very high polishing speed for both tantalum and copper materials during polishing.

Polishing of the crucible is usually carried out under alkaline conditions to obtain a higher polishing speed. For example, US2002032987 discloses a polishing solution using an alcoholamine as an additive to increase the removal rate of polysilicon, wherein the additive is preferably 2-(dimethylamino)-2-methyl-1-propanol. . US 2002151252 discloses a polishing fluid comprising a complexing agent having a plurality of carboxylic acid structures for increasing the rate of polysilicon removal, wherein the preferred complexing agents are EDTA (ethylenediaminetetraacetic acid) and DTPA (diethyltriaminepentaacetic acid). . EP1072662 discloses a polishing liquid containing a lone pair of electrons and a double bond to produce a delocalized organic substance to increase the removal rate of polysilicon. Preferably, the compound is a compound of a terpenoid and a salt thereof. US2006014390 discloses a polishing slurry for increasing the removal rate of polycrystalline germanium comprising from 4.25 to 18.5% by weight of an abrasive and from 0.05 to 1.5% by weight of an additive. The additive is mainly selected from organic bases such as quaternary ammonium salts, quaternary ammonium bases and ethanolamines. Further, the polishing liquid further contains a nonionic surfactant such as a homopolymer or a copolymerization product of ethylene glycol or propylene glycol. CN101497765A significantly improves the polishing speed of tantalum by utilizing the synergistic action of biguanide and azole materials.

The polishing of copper is usually carried out under acidic conditions, using a high oxidation potential of an oxidizing agent (hydrogen peroxide) under acidic conditions, and copper is easily coordinated and dissolved under acidic conditions to achieve a high polishing rate. For example, CN 1705725 A discloses a polishing liquid for polishing a copper metal surface having a pH between 2.5 and 4.0, and removing the surface of the copper metal under the action of an oxidizing agent (hydrogen peroxide, etc.), a chelating agent and a passivating agent. CN1787895A discloses a CMP composition comprising a fluid agent together with an oxidizing agent, a chelating agent, an inhibitor, an abrasive, and a solvent. Under acidic conditions, such a CMP composition advantageously increases the material selectivity in the CMP process and can be used to polish the surface of a copper component on a semiconductor substrate without creating depressions or other unfavorable planarization in the polished copper. defect. CN01818940A discloses a copper polishing slurry which can be formed by further combining with an oxidizing agent such as hydrogen peroxide, and/or a corrosion inhibitor such as benzotriazole to increase the copper removal rate. This higher polishing rate is achieved while maintaining local pH stability and significantly reducing overall and localized corrosion.

Polishing of copper is sometimes carried out under alkaline conditions, for example: CN 1644640 A discloses an aqueous composition for polishing copper under alkaline conditions, the composition comprising 0.001% to 6% by weight of non-ferrous Metal inhibitor, 0.05% to 10% by weight of the metal complexing agent, 0.01% to 25% by weight of copper remover for accelerating copper removal, 0.5% to 40% by weight of abrasive Etc., the copper removal rate is increased by the interaction of the copper remover imidazole and BTA. CN1398938A discloses a chemical mechanical global planarization polishing liquid for multi-layer integrated circuit copper wiring, which is used for improving the removal rate of copper. The composition of the polishing liquid is as follows: the weight percentage of the abrasive is 18% to 50%, and the weight of the chelating agent The percentage is from 0.1% to 10%, the weight percent of the complexing agent is from 0.005% to 25%, the weight percent of the active agent is from 0.1% to 10%, the weight percent of the oxidizing agent is from 1% to 20%, and deionized water.

In the prior art, polishing under acidic conditions, although a high copper polishing speed can be obtained, the polishing speed for tantalum is generally low. The reason is that under acidic conditions, the oxidant oxidizes the surface of the elemental cerium to cerium oxide, which is more difficult to remove than cerium. Polishing under alkaline conditions, if no oxidizing agent is applied, although a very high polishing speed can be obtained, the polishing speed for copper is generally low. The reason is that copper needs to be oxidized before it is easily removed. However, if an oxidizing agent, such as hydrogen peroxide, is added, the hydrogen peroxide will oxidize the surface of the elemental cerium to cerium oxide, which is more difficult to remove. In addition, under alkaline conditions, oxidants such as hydrogen peroxide are very unstable and will rapidly decompose and fail.

The technical problem solved by the present invention is that while the polishing speed of copper in an alkaline polishing environment is improved, the polishing rate of tantalum can be remarkably improved.

The chemical mechanical polishing liquid of the present invention comprises: abrasive particles, an oxidizing agent, an amino acid, a quaternary ammonium base and water, and the pH of the chemical mechanical liquid is alkaline.

In the present invention, the abrasive particles are selected from one or more of SiO ₂ , Al ₂ O ₃ , ZrO ₂ , CeO ₂ , SiC, Fe ₂ O ₃ , TiO ₂ and/or Si ₃ N ₄ . The abrasive particles have a mass percentage of 1 to 30%.

In the present invention, the oxidizing agent is selected from one or more of a bromate, a chlorate, an iodate, a periodic acid, and/or a periodate. The bromate is potassium bromate, the chlorate is potassium chlorate, the iodate is potassium iodate, and the periodate is ammonium periodate. The oxidizing agent has a mass percentage content of 0.5 to 4%.

In the present invention, the amino acid is selected from the group consisting of glycine and/or L-glutamic acid. The amino acid has a mass percentage of from 1 to 8%.

In the present invention, the quaternary ammonium base is tetramethylammonium hydroxide. The quaternary ammonium cerium has a mass percentage of 5 to 12%.

In the present invention, the chemical mechanical polishing liquid has a pH of 8.00 to 13.00.

The positive effect of the present invention is that it is possible to achieve a very high polishing speed for both tantalum and copper in an alkaline polishing environment.

Preparation example

The invention is further illustrated by the following examples, but the invention is not limited thereto. In the following examples, the percentages are all by mass.

Table 1 shows the formulations of Examples 1 to 23 and Comparative Examples 1 to 4 of the chemical mechanical polishing liquid of the present invention, which are uniformly mixed in deionized water according to the components listed in Table 1 and their contents, and a pH adjusting agent ( A chemical mechanical polishing solution can be prepared by adjusting the desired pH to 50% potassium hydroxide.

Effect embodiment

In order to further investigate the polishing condition of the chemical mechanical polishing liquid of the present invention, the present invention employs the following polishing conditions: the polishing machine is a Logitech (UK) 1PM52 type, a polytex polishing pad, a 4 cm x 4 cm square wafer (Wafer), and a grinding pressure of 3 psi. The rotation speed of the polishing table was 70 rpm, the rotation speed of the polishing head was 150 rpm, and the polishing liquid droplet acceleration was 100 ml/min. The results are shown in Table 2.

It was shown by Comparative Examples 1-4 that the removal rates of copper and cerium were low in the presence of only the abrasive and under alkaline conditions.

By comparison of Examples 1-2 and Comparative Example 1, the removal rate of copper and cerium was significantly increased by adding our specific oxidizing agent, amino acid and quaternary ammonium base to the alkaline solution with the same concentration of the abrasive.

By comparison of Examples 3-10 and Comparative Example 2, the addition rate of copper and cerium was significantly increased by adding our specific oxidizing agent, amino acid and quaternary ammonium base to the alkaline solution at the same concentration of the abrasive.

By comparison of Example 11 and Comparative Example 3, the removal rate of copper and cerium was significantly increased by adding our specific oxidizing agent, amino acid and quaternary ammonium base to the alkaline solution at the same concentration of the abrasive.

By comparison of Examples 12-13 and Comparative Example 4, the addition rate of copper and cerium was significantly increased by adding our specific oxidizing agent, amino acid and quaternary ammonium base to the alkaline solution at the same concentration of the abrasive.

By comparison of Example 1 and Example 2, Example 4 and Example 5 are compared, and Example 7 and Example 8 are compared. When the concentration of the amino acid is constant, the concentration of the oxidizing agent is changed in the alkaline solution, and it is found that Increasing the concentration of the oxidant significantly increases the removal rate of copper, and at the same time, there is no significant inhibition of the removal rate of ruthenium.

Comparison of Examples 3 and 4, after comparison of Examples 9 and 10, found that increasing the concentration of amino acids can increase the removal rate of copper and bismuth.

Comparison between Example 7 and Example 11 revealed that increasing the concentration of the abrasive can increase the removal rate of copper and bismuth.

Claims (11)

A chemical mechanical polishing liquid comprising: abrasive particles, an oxidizing agent, an amino acid, a quaternary ammonium base and water, and the pH of the chemical mechanical liquid is alkaline. The chemical mechanical polishing liquid according to claim 1, characterized in that the abrasive particles are selected from the group consisting of SiO ₂ , Al ₂ O ₃ , ZrO ₂ , CeO ₂ , SiC, Fe ₂ O ₃ , TiO ₂ and/or Si. One or more of ₃ N ₄ . The chemical mechanical polishing liquid according to claim 1, wherein the abrasive particles have a mass percentage of from 1 to 30%. The chemical mechanical polishing liquid according to claim 1, wherein the oxidizing agent is one or more selected from the group consisting of a bromate, a chlorate, an iodate, a periodic acid, and/or a periodate. The chemical mechanical polishing liquid according to claim 4, wherein the bromate is potassium bromate, the chlorate is potassium chlorate, the iodate is potassium iodate, and the high iodine is The acid salt is ammonium periodate. The chemical mechanical polishing liquid according to claim 1, wherein the oxidizing agent has a mass percentage of 0.5 to 4%. The chemical mechanical polishing liquid according to claim 1, wherein the amino acid is selected from the group consisting of glycine and/or L-glutamic acid. The chemical mechanical polishing liquid according to claim 1, wherein the amino acid has a mass percentage of from 1 to 8%. The chemical mechanical polishing liquid according to claim 1, wherein the quaternary ammonium base is tetramethylammonium hydroxide. The chemical mechanical polishing liquid according to claim 1, wherein the quaternary ammonium base has a mass percentage of 5 to 12%. The chemical mechanical polishing liquid according to claim 1 has a pH of from 8.00 to 13.00.