TWI452097B - A chemical mechanical polishing solution is used to reduce the removal rate of aluminum - Google Patents

Description

Use of a chemical mechanical polishing liquid for reducing the removal rate of aluminum

This invention relates to a chemical mechanical polishing fluid and its use.

With the development of microelectronics technology, the integration of large integrated circuit chips has reached several billion components, and the feature size has entered the nanometer level. Therefore, nearly one hundred processes in the microelectronics process, especially multilayer wiring, substrate, and dielectric, must be fully chemically and mechanically flattened, and chemical mechanical polishing (CMP) has proven to be the best leveling. method.

In the chemical mechanical polishing method, the polished surface of the substrate is directly contacted with the rotating polishing pad while applying pressure on the back surface of the substrate. During polishing, the polishing pad rotates with the stage while maintaining a downward force on the back side of the substrate, and a liquid composed of an abrasive and a chemically active solution (ie, a chemical mechanical polishing liquid) is applied to the polishing pad, and the polishing liquid is being polished. The chemical reaction and mechanical action of the film begin the polishing process. The polishing solution is an important factor in CMP, and a suitable polishing solution can be selected according to the needs of the process to change the polishing performance.

In typical metal chemical mechanical polishing, the defect level is usually high, especially in the presence of pitting, edge etching, corrosion, and the like. Moreover, the polishing rate is also high, and the degree of damage to the metal surface is large, which is liable to cause problems such as scratches and surface roughness. U.S. Patent Nos. 5,209,816, 6,039,891, 5,897,375, 6,749,488, and 6,520,840.

Accordingly, it is a primary object of the present invention to provide a chemical mechanical polishing liquid to solve the above problems.

One aspect of the present invention is to provide a chemical mechanical polishing fluid comprising at least one abrasive particle, a carrier, and at least one metal corrosion inhibitor. The above metal corrosion inhibitor can react with the metal surface, and the reaction product covers the metal surface to form a protective film, which can prevent corrosion and pitting of the metal surface in an acidic environment. Therefore, the above metal corrosion inhibitor can reduce the metal removal rate, reduce the defect rate, and improve the surface quality.

The chemical mechanical polishing liquid of the present invention does not contain an oxidizing agent, and a typical chemical mechanical polishing liquid for polishing a metal contains an oxidizing agent. It should be noted that the chemical mechanical polishing liquid of the present invention does not contain an oxidizing agent, and its polishing performance can also reach the polishing performance of a typical chemical mechanical polishing liquid containing an oxidizing agent. Of course, the chemical mechanical polishing liquid of the present invention may also contain an oxidizing agent, for example, for adjusting the polishing rate of a metal other than aluminum, such as copper.

Preferably, the metal corrosion inhibitor may be a mineral acid salt, and the inorganic acid salt may be an oxidizing and/or non-oxidizing inorganic acid salt. Preferably, the mineral acid salt may be a molybdate, a chromate, a permanganate, a citrate, a tungstate and/or a heteropolyacid salt, and more preferably a molybdate. Preferably, the molybdate salt described above may be ammonium molybdate. The metal corrosion inhibitor described above can form a protective film on the surface of the metal.

The abrasive particles described above may be any abrasive particles of the prior art, and may preferably be ceria, alumina, ceria, titania and/or high molecular polymer abrasive particles.

Preferably, the above carrier may be an inorganic carrier (e.g., water) or a mixture of an inorganic carrier and an organic carrier (e.g., a mixture of water and a polyol). Preferably, the above polyol may be glycerol.

Preferably, the mass concentration of the abrasive particles in the chemical mechanical polishing liquid of the present invention may be 1 to 10%, the mass concentration of the metal corrosion inhibitor may be 0.01 to 10%, and the mass concentration of the carrier is the remaining percentage. .

The chemical mechanical polishing liquid of the present invention may further comprise one or more of a film former, an oxidizing agent, a complexing agent and a pH adjusting agent, and may further comprise a surfactant to further improve the surface quality of the polished substrate.

Preferably, in the chemical mechanical polishing agent of the present invention, the mass concentration of the above complexing agent may be 0.01 to 10%, the mass concentration of the oxidizing agent may be 0 to 10%, and the mass concentration of the surfactant may be 0.001 to 10 %.

The above film forming agent may be benzotriazole, pyrazole and/or imidazole. Preferably, the film former can be benzotriazole.

Preferably, the complexing agent may be a compound containing a hydroxyl group, a carboxyl group, a sulfate group, a sulfonic acid group, a phosphoric acid group, a hydroxylamine group, an amine salt and/or an amine group, and more preferably, it may be succinic acid, oxalic acid, citric acid, Cyclohexanediaminetetraacetic acid, diethylenetriaminepentaacetic acid, ethylenediaminetetraacetic acid and/or tannic acid.

Preferably, the pH adjusting agent may be potassium hydroxide, ammonium hydroxide, sulfuric acid or nitric acid, and the oxidizing agent may be hydrogen peroxide, iron nitrate, organic peroxide and/or inorganic peroxide. The surfactant may be a cationic, anionic, nonionic surfactant and/or a polymeric surfactant, and more preferably a fatty alcohol polyoxyethylene ether, polyvinyl alcohol, polyoxyethylene alkylamine and/or an alkane. Alcoholamine.

Another scope of the present invention is to provide a chemical mechanical polishing liquid of the present invention for polishing a metal, wherein the polished metal may be aluminum, copper, tantalum, tantalum nitride, titanium, titanium nitride, silver or gold, or the like. Preferably, the metal can be aluminum.

Therefore, the chemical mechanical polishing liquid according to the present invention can not only suppress pitting corrosion and corrosion of the metal, but also reduce the metal removal rate, thereby improving the quality of the metal surface.

The advantages and spirit of the present invention will be further understood from the following detailed description of the invention.

In order to achieve the above-mentioned technical scope and other functions of the present invention, several preferred embodiments are described as follows: First Embodiment: In this embodiment, the chemical mechanical polishing liquid 1 of the present invention comprises 5 wt% of cerium oxide particles, 0.1% by weight of benzotriazole, 0.5% by weight of succinic acid, 0.01% by weight of ammonium molybdate and the other component are water, wherein the pH is 4.25.

Second Embodiment: In this embodiment, the chemical mechanical polishing liquid 2 of the present invention comprises 5 wt% of cerium oxide particles, 0.1% by weight of benzotriazole, 0.5% by weight of succinic acid, and 0.1% by weight of molybdic acid. Ammonium and other ingredients are water with a pH of 4.25.

Third Embodiment: In this embodiment, the chemical mechanical polishing liquid 3 of the present invention comprises 5 wt% of cerium oxide particles, 0.5% by weight of succinic acid, 0.5% by weight of ammonium molybdate, and the other component is water, wherein The pH is 4.25.

Fourth Embodiment: In this embodiment, the chemical mechanical polishing liquid 4 of the present invention comprises 1 wt% of cerium oxide particles, 10% by weight of potassium permanganate, 10% by weight of hydrogen peroxide, and 0.001% by weight of polyvinyl alcohol. 10% by weight of succinic acid, 5% by weight of glycerol, and the other component are water, wherein the pH is 3.

Fifth Embodiment: In this embodiment, the chemical mechanical polishing liquid 5 of the present invention comprises 10% by weight of alumina particles, 1% by weight of sodium citrate, 1% by weight of iron nitrate, 10% by weight of fatty alcohol ethoxylate, 0.1 wt% of ethylenediaminetetraacetic acid, and the other component is water, wherein the pH is 5.

Sixth Embodiment: In this embodiment, the chemical mechanical polishing liquid 6 of the present invention comprises 2 wt% of titanium oxide particles, 5 wt% of potassium chromate, 0.5 wt% of hydrogen peroxide, and 0.05 wt% of alkyl decylamine. 0.5 wt% citric acid, 10 wt% glycerol, and other components are water, wherein the pH is 6.

Seventh Embodiment: In this embodiment, the chemical mechanical polishing liquid 7 of the present invention contains 5 wt% of cerium oxide particles, 1% by weight of ammonium molybdate, and the other component is water, wherein the pH is 7.

Eighth Embodiment: In this embodiment, the chemical mechanical polishing liquid 8 of the present invention comprises 5 wt% of cerium oxide particles, 0.1% by weight of benzotriazole, 0.5% of ethylenediaminetetraacetic acid, and 0.1% by weight. Ammonium molybdate, 1% by weight of hydrogen peroxide, and other components are water, wherein the pH is 3.

The invention further provides a set of comparative examples, wherein the chemical mechanical polishing liquid 1' comprises 5% by weight of cerium oxide particles, 0.1% by weight of benzotriazole, 0.5% by weight of succinic acid, and the other component is water, wherein pH The value is 4.25. In other words, the chemical mechanical polishing liquid 1' of the comparative example does not have a component of a metal corrosion inhibitor.

The above chemical mechanical polishing liquids 1' and 1 to 3 were used to polish a metal aluminum film on a wafer. The parameters for polishing were set as follows: downforce: 2 psi, polishing disc speed: 102 rpm, polishing head speed: 110 rpm, and slurry flow rate: 100 ml/min. The experimental results are shown in Table 1 below.

As shown in Table 1, the chemical mechanical polishing liquid containing the metal corrosion inhibitor of the present invention can reduce the removal rate of aluminum (all below 200 A/min), and the polished metal surface has no defects, thereby greatly improving the quality of the metal surface. .

The above chemical mechanical polishing liquids 1' and 1 were used to polish a metal aluminum film on a wafer. The parameters for polishing were set as follows: downforce: 2 psi, polishing disc speed: 102 rpm, polishing head speed: 110 rpm, and slurry flow rate: 100 ml/min.

Referring to FIG. 1 and FIG. 2, FIG. 1 is an optical microscope bright field diagram of pitting of aluminum metal surface after polishing by the chemical mechanical polishing liquid of the present invention. Figure 2 is an optical microscope bright field diagram of pitting of aluminum metal surface after polishing of chemical mechanical polishing liquid without metal corrosion inhibitor. The black spots in the figure are pitting corrosion. The experimental results show that after polishing with the chemical mechanical polishing liquid containing the metal corrosion inhibitor of the present invention, the surface of the aluminum metal is not pitting, as shown in FIG. After polishing with a chemical mechanical polishing solution that does not contain a metal corrosion inhibitor, there is a large amount of pitting on the surface of the aluminum metal, as shown in FIG. Therefore, the use of the chemical mechanical polishing liquid containing the metal corrosion inhibitor of the present invention can greatly improve the surface quality of the aluminum metal.

The above chemical mechanical polishing liquids 1' and 1-3 were respectively polished with a pattern of a pattern composed of aluminum and cerium oxide. The parameters for polishing were set as follows: downforce: 2 psi, polishing disc speed: 102 rpm, polishing head speed: 110 rpm, and slurry flow rate: 100 ml/min. The experimental results are shown in Table 2 below.

Table II

As shown in Table 2, the chemical mechanical polishing liquid of the present invention can polish not only a metal wafer but also a wafer containing a pattern such as aluminum, copper or a pattern composed of ruthenium and ruthenium dioxide.

Compared with the prior art, the chemical mechanical polishing liquid according to the present invention can not only inhibit pitting and corrosion of metals, but also reduce the metal removal rate, thereby improving the quality of the metal surface.

The features and spirit of the present invention will be more apparent from the detailed description of the preferred embodiments. On the contrary, the intention is to cover various modifications and equivalents within the scope of the invention as claimed. Therefore, the scope of the patented scope of the invention should be construed as broadly construed in the

Figure 1 is an optical microscope bright field diagram of pitting of aluminum metal surface after polishing by chemical mechanical polishing liquid of the present invention.

Figure 2 is an optical microscope bright field diagram of pitting of aluminum metal surface after polishing of chemical mechanical polishing liquid without metal corrosion inhibitor. The black spots in the figure are pitting corrosion.

Claims (7)

A chemical mechanical polishing liquid for reducing the removal rate of aluminum, the chemical mechanical polishing liquid comprising molybdate, chromate, permanganate, silicate, tungstate and/or heteropoly acid salt and at least An abrasive particle, a carrier liquid. The use of claim 1, wherein the molybdate is ammonium molybdate. The use of claim 1, wherein the carrier is water. The use of claim 1, wherein the carrier is water and a polyol. The use according to claim 1, wherein the molybdate, chromate, permanganate, citrate, tungstate and/or heteropolyacid salt has a mass concentration of 0.01 to 10%. The use of the first aspect of the invention, wherein the abrasive particles have a mass concentration of 1 to 10%, the molybdate, chromate, permanganate, silicate, tungstate and/or miscellaneous The mass concentration of the polyacid salt is 0.01 to 10% and the mass concentration of the carrier is the remaining percentage. The use as described in claim 1 is further used together with one or more of a film former, a binder, an oxidizing agent, and a pH adjusting agent.