TW201311840A - Chemical mechanical polishing liquid - Google Patents

Abstract

The present invention relates to a chemical mechanical polishing liquid containing: grinding particles, halogen-containing oxidant, organic amine, ethylene diamine tetraectic acid (EDTA) and pH adjuster. The chemical mechanical polishing liquid has an alkaline pH and can realize having a very high polishing rate for silicon and copper in the alkaline polishing condition. In addition, amino acid can be further added into the polishing liquid to keep the removal rate of silicon and cooper stable.

Description

Chemical mechanical polishing fluid

The present invention relates to a chemical mechanical polishing liquid.

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 polishing at the same time, and has a very high polishing speed for both tantalum and copper materials.

Polishing of the crucible is usually carried out under alkaline conditions, and a higher polishing speed can be obtained. 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 fluid for increasing the removal rate of polysilicon comprising from 4.25% to 18.5% by weight of abrasive and from 0.05% to 1.5% by weight of additives. 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.

Patent 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, the patent CN 1705725 A discloses a polishing liquid for polishing a copper metal surface, the polishing liquid being between 2.5 and 4.0, and removing the surface of the copper metal by the action of an oxidizing agent (hydrogen peroxide, etc.), a chelating agent and a passivating agent.

Patent 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.

Patent CN01818940A discloses that a copper polishing slurry 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: Patent CN 1644640 A discloses an aqueous composition for polishing copper under alkaline conditions, the composition comprising 0.001% to 6% by weight of non- Iron 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.

Patent CN1398938A discloses a chemical mechanical global planarization polishing liquid for a multi-layer integrated circuit copper wiring 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 chelating agent The weight 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 to provide a chemical mechanical polishing liquid which can significantly improve the polishing rate of tantalum while improving the polishing speed of copper in an alkaline polishing environment.

The chemical mechanical polishing liquid of the present invention comprises: abrasive particles, a halogen-containing oxidizing agent, an organic amine and ethylenediaminetetraacetic acid (EDTA), and the chemical mechanical polishing liquid has an alkaline pH.

In the present invention, the abrasive particles are 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 , preferably SiO ₂ . The abrasive particles have a mass percentage of 1% to 30%, preferably 1% to 15%.

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

In the present invention, the organic amine is ethylenediamine, pyridazine or a combination thereof. The ethylenediamine has a mass percentage of 0.2% to 0.8%. The content of the pyridazine is from 0% to 4% by mass.

In the present invention, the ethylenediaminetetraacetic acid (EDTA) has a mass percentage of 0.01% to 6%, preferably 1% to 4%.

In the present invention, the chemical mechanical polishing liquid further comprises: a pH adjusting agent, wherein the pH adjusting agent is a quaternary ammonium base, an inorganic base or a combination thereof. The quaternary ammonium hydrazine is tetramethylammonium hydroxide (TMAH). The inorganic base is potassium hydroxide (KOH).

In the present invention, the pH of the chemical mechanical polishing liquid is 8 to 13, preferably 10 to 12.

In the present invention, the chemical mechanical polishing liquid further contains: an amino acid, and the amino acid is glycine or L-glutamic acid, preferably glycine. The amino acid has a mass percentage of 1% to 8%, preferably 1% to 4%.

The positive progress of the present invention is that the polishing rate of the copper in the alkaline polishing environment is improved, and the polishing speed of the crucible can be remarkably improved. After the amino acid is continuously added to the polishing liquid, the chemical mechanical polishing liquid of the present invention maintains a stable removal rate of bismuth and copper, and does not cause a significant decrease in the removal rate of bismuth and copper due to the prolongation of time.

Preparation example

Table 1 shows the formulations of the chemical mechanical polishing liquids of Examples 1 to 28 and Comparative Examples 1 to 5 of the present invention, which are uniformly mixed in deionized water according to the components and contents thereof listed in Table 1, and adjusted with a pH adjusting agent. A chemical mechanical polishing solution can be prepared at the desired pH.

Effect Example 1

Polishing conditions: Polishing machine is Logitech (UK) 1PM52 type, polytex polishing pad, 4cm × 4cm square wafer (Wafer), grinding pressure 3psi, grinding table rotation speed 70rev / min, grinding head rotation speed 150 rev / min, polishing The droplet acceleration is 100 ml/min.

It was shown by Comparative Examples 1-5 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 1-18 and Comparative Examples 1-5, a halogen-containing oxidizing agent, an organic amine, ethylenediaminetetraacetic acid (EDTA), a pH adjusting agent, an alkaline polishing solution for copper and bismuth were added to the polishing liquid. The removal rate is significantly improved.

By comparing Examples 1-18 with each other, it was found that increasing the concentration of one or more of the halogen-containing oxidizing agent, organic amine, EDTA, and pH adjusting agent in the alkaline polishing liquid is advantageous for increasing the removal rate of copper and bismuth. .

Effect Example 2

Polishing conditions: Polishing machine is Logitech (UK) 1PM52 type, polytex polishing pad, 4cm × 4cm square wafer (Wafer), grinding pressure 3psi, grinding table rotation speed 70rev / min, grinding head rotation speed 150 rev / min, polishing The droplet acceleration is 100 ml/min.

From the comparison of Examples 2 and 3 in Table 3, it was found that when there is an amino acid, the removal rate of copper and cerium can be kept stable under alkaline conditions and does not decrease with time.

Claims (16)

A chemical mechanical polishing liquid comprising: abrasive particles, a halogen-containing oxidizing agent, an organic amine and ethylenediaminetetraacetic acid (EDTA), said chemical mechanical polishing liquid having an alkaline pH. The chemical mechanical polishing liquid according to claim 1, wherein the abrasive particles are in SiO ₂ , Al ₂ O ₃ , ZrO ₂ , CeO ₂ , SiC, Fe ₂ O ₃ , TiO ₂ and/or Si ₃ N ₄ One or more. According to the chemical mechanical polishing liquid of claim 1, the abrasive particles have a mass percentage of 1% to 30%. The chemical mechanical polishing liquid according to claim 1, wherein the halogen-containing oxidizing agent is one or more selected from the group consisting of potassium bromate, potassium iodate, potassium chlorate, periodic acid and/or ammonium periodate. The chemical mechanical polishing liquid according to claim 1, wherein the halogen-containing oxidizing agent has a mass percentage of 0.5% to 4%. The chemical mechanical polishing liquid according to claim 1, wherein the organic amine is ethylenediamine, pyridazine or a combination thereof. According to the chemical mechanical polishing liquid of claim 6, the ethylenediamine has a mass percentage of 0.2% to 0.8%. The chemical mechanical polishing liquid according to claim 6, wherein the pyridazine has a mass percentage of 0% to 4%. According to the chemical mechanical polishing liquid of claim 1, the ethylenediaminetetraacetic acid (EDTA) has a mass percentage of 0.01% to 6%. The chemical mechanical polishing liquid according to claim 1, further comprising: a pH adjusting agent, wherein the pH adjusting agent is a quaternary ammonium base, an inorganic base or a combination thereof. According to the chemical mechanical polishing liquid of claim 10, the quaternary ammonium hydrazine is tetramethylammonium hydroxide (TMAH). The chemical mechanical polishing liquid according to claim 10, wherein the inorganic base is potassium hydroxide (KOH). According to the chemical mechanical polishing liquid described in claim 1, the pH is 8 to 13. The chemical mechanical polishing liquid according to claim 1 further comprising: an amino acid. The chemical mechanical polishing liquid according to claim 14, wherein the amino acid is glycine or L-glutamic acid. The chemical mechanical polishing liquid according to claim 14, wherein the amino acid has a mass percentage of from 1% to 8%.