TWI387641B - Slurry compositions for barrier - Google Patents

Description

Chemical mechanical polishing solution for barrier layer

The present invention relates to a chemical mechanical polishing slurry, and in particular, to a chemical mechanical polishing liquid for a Tantalum (Ta) barrier layer.

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 100 processes in microelectronics processes, especially multilayer wiring, substrates, media, etc., must be fully chemically and mechanically flattened, and chemical mechanical polishing (CMP) has proven to be the best leveling. Method. In addition, large-scale integrated wiring is being converted from conventional aluminum (Al) to copper (Cu). Compared with aluminum, copper wiring has low resistivity; high resistance to electromigration; short delay time of resistor-capacitor (RC); 50% reduction in fabric layer; 30% reduction in process cost and 40% reduction in processing time. Therefore, the advantages of copper wiring have attracted widespread attention around the world.

In order to ensure the characteristics of the copper wiring and the medium, the multilayer copper wiring in the large integrated circuit wafer currently uses tantalum (Ta) or tantalum nitride (TaN) as a barrier layer. Thus, a chemical mechanical polishing liquid phase for polishing a tantalum or tantalum nitride barrier layer has been developed and applied, for example, a polishing liquid for a barrier layer disclosed in U.S. Patent No. 6,719,920, issued to U.S. Patent No. 6,503,418. A polishing liquid for a barrier layer containing an organic additive; a chemical mechanical planarization composition for tantalum and tantalum nitride disclosed in U.S. Patent No. 6,638,326, Chinese Patent No. 02116761.3 In a multi-layer copper wiring of a super large integrated circuit, a chemical mechanical whole planarizing polishing liquid of copper and tantalum is used. However, such chemical mechanical polishing fluids suffer from defects such as local and overall corrosion, high defect rates, and limited polishing selectivity of different substrates. Therefore, the development of new chemical mechanical polishing fluids for barrier layers is indeed necessary.

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

A chemical mechanical polishing liquid for a barrier layer according to a preferred embodiment of the present invention comprises an abrasive particle, an organic phosphonic acid, a tetrazolium compound, and a carrier. Due to the addition of organic phosphonic acid and tetrazolium compounds, the chemical mechanical polishing liquid has suitable polishing selectivity for different metals and oxides during polishing, which can prevent metal depression and significantly reduce organic matter and cerium oxide on the surface of the wafer. Deposition and residue of other metal ions. Moreover, various components can be referred to conventional techniques.

In a preferred embodiment of the present invention, the concentration of the abrasive particles is 1 to 10%; the concentration of the organic phosphonic acid is 0.01 to 1%; and the concentration of the tetrazolium compound is 0.01 to 0.5%; The carrier is the remaining percentage, and the above % refers to the total weight percentage of the entire chemical mechanical polishing liquid. Further, the size of the abrasive particles is preferably from 20 to 200 nm, more preferably from 30 to 100 nm, most preferably 70 nm.

The organic phosphonic acid is preferably 2-phosphonic acid butane-1,2,4-tricarboxylic acid (PBTCA), ethylenediaminetetramethylenephosphonic acid and/or diethylenetriamine pentamethylphosphonic acid. The tetrazole compound (TRA) is preferably 5-methyl-tetrazole, 5-phenyl-1-hydro-tetrazole and/or 1-hydro-tetrazole.

Further, the chemical mechanical polishing liquid for a barrier layer according to the present invention may further contain 0.001 to 1% by weight of an oxidizing agent. Further, the oxidizing agent may be various oxidizing agents in the prior art, preferably hydrogen peroxide, urea hydrogen peroxide, peracetic acid, benzammonium peroxide, potassium persulfate and/or ammonium persulfate, more preferably hydrogen peroxide.

The abrasive particles according to the present invention may also be referred to conventional techniques, preferably cerium oxide, aluminum oxide, cerium oxide and/or polymer particles such as polyethylene or polytetrafluoroethylene, more preferably cerium oxide.

Further, the pH of the chemical mechanical polishing liquid for the barrier layer according to the present invention is preferably from 2.0 to 4.0, more preferably 3.0. Further, the pH adjuster may be various acids and/or bases, preferably potassium hydroxide, nitric acid, ethanolamine, and/or triethanolamine.

Furthermore, the chemical mechanical polishing liquid for a barrier layer according to the present invention may further comprise a surfactant, a stabilizer, an inhibitor and/or a bactericide to improve the polishing performance of the substrate surface, the additives For the use, reference can be made to the prior art. Additionally, the carrier is preferably water.

The chemical mechanical polishing liquid according to the present invention can reduce the amount of abrasive particles, causing a significant decrease in defects, scratches, stains, and other residues, and reducing surface surface contaminants; and having a suitable polishing selection ratio during polishing; It prevents local and overall corrosion during metal polishing to improve product yield.

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-described technical scope and other functions of the present invention, several preferred embodiments are described as follows: Referring to Table 1, a series of embodiments according to the present invention, including implementation Examples 1 to 8 and Comparative Example 1 ⁰ .

In each of the above embodiments, the materials are in the following order: abrasive particles, half of the amount of deionized water, organic phosphonic acid, TRA, and H ₂ O _{2 are} sequentially added to the reactor and stirred uniformly, and deionized water is added, and finally Adjust to the desired pH with a pH adjuster (20% KOH or dilute HNO ₃ depending on the pH) and continue to stir to make it a homogeneous fluid. After 10 minutes of rest, the chemical mechanical polishing can be obtained. liquid. Please note that the starting materials in the examples described herein are all commercially available materials.

Specific embodiment 1

In each embodiment described above in Example 1 to 8 and a chemical mechanical polishing liquid ¹⁰ controls embodiment, gaps of tantalum (Ta), copper (Cu) and silicon dioxide (SiO ₂₎ wafers were polished, the same polishing conditions, the polishing parameters As follows: polishing pad manufactured by Logitech.; downward pressure 2 psi; turntable speed / polishing head speed 60/80 rpm; polishing time 120 s; chemical mechanical polishing liquid flow rate 100 mL / min. See Table 2 for polishing results.

Obviously, as compared to Comparative Example ^10, and can adjust the removal rate of tantalum, copper and silicon dioxide, and through the addition of an organic acid species tetrazole chemical mechanical polishing solution of the present invention. Also, when the concentrations of the abrasive particles, the organic acid, and the tetrazole are adjusted, a suitable polishing selectivity can be obtained; when the concentration of the oxidizing agent is adjusted, a better polishing selectivity can be obtained.

Referring to FIG. 1 and FIG. 2, FIG. 1 is a surface microscopic image of a blank germanium wafer before polishing using the chemical mechanical polishing liquid of Example 1, and FIG. 2 is a blank after polishing using the chemical mechanical polishing liquid of Example 1. Surface microscopic image of the tantalum wafer. Comparing Fig. 1 and Fig. 2, it can be found that the chemical mechanical polishing liquid according to the present invention can significantly reduce defects at a lower abrasive particle concentration, and can prevent local and overall corrosion generated during metal polishing, and reduce the surface of the substrate. Contaminants, the surface of the tantalum wafer after polishing using the chemical mechanical polishing liquid of the present invention is significantly less pitting, thereby improving product yield.

Specific embodiment 2

For the ceria-impregnated/electroplated copper ceria test wafer, the copper was polished and then polished with the chemical mechanical polishing liquids of the above Examples 2, 3 and 5, respectively, and the polishing conditions were the same, and the polishing parameters were as follows: Logitech. Polished pad manufactured; downward pressure 2 psi; turntable speed / polishing head speed 60/80 rpm; polishing time 120 s; chemical mechanical polishing liquid flow rate 100 mL / min. See Table 3 for polishing results.

It will be apparent that the chemical mechanical polishing fluid according to the present invention can reduce the size of the depressions on the surface of the test wafer and test the surface of the wafer free of corrosion, contaminants and other residues. After polishing using the chemical mechanical polishing liquid of Example 2, no contamination was found after the surface of the test wafer was magnified 250 times by the microscope (see Fig. 3). Further, after polishing using the chemical mechanical polishing liquid of Example 3, the surface of the test wafer was not significantly found to be contaminated, corroded, etc. after being magnified 5000 times by a scanning electron microscope (SEM) (see FIG. 4).

In summary, the chemical mechanical polishing liquid for the barrier layer according to the present invention can reduce the amount of abrasive particles, causing a significant decrease in defects, scratches, stains and other residues, thereby reducing surface surface contaminants; The polishing process has a suitable polishing selectivity; in addition, the chemical mechanical polishing solution can prevent local and overall corrosion during metal polishing and improve product yield.

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

11. . . TEOS

13. . . Cu

Figure 1 is a surface microscopy image of a blank tantalum wafer before polishing.

Figure 2 is a surface microscopy image of a blank tantalum wafer after polishing.

Figure 3 shows the microscopic image of the wafer surface after polishing (magnification 250 times) (TEOS refers to SiO _{2 in the} figure).

Figure 4 is a scanning electron microscope image (magnification 5000 times) of the surface of the test wafer after polishing (TEOS refers to SiO _{2 in the} figure).

Claims (10)

A chemical mechanical polishing liquid for a barrier layer comprising: an abrasive particle; an organic phosphonic acid; a tetrarazole compound; and a carrier liquid Wherein the concentration of the abrasive particles is from 1 to 10% by weight; the concentration of the organic phosphonic acid is from 0.01 to 1% by weight; the concentration of the tetrazolium compound is from 0.01 to 0.5% by weight; and the carrier is the remaining percentage. The chemical mechanical polishing liquid according to claim 1, wherein the abrasive particles have a size of 20 to 200 nm. The chemical mechanical polishing liquid according to claim 2, wherein the abrasive particles have a size of 30 to 100 nm. The chemical mechanical polishing liquid according to any one of claims 1 to 3, wherein the organic phosphonic acid is butane-1,2,4-tricarboxylic acid and ethylenediamine 2-phosphonate. Tetramethylphosphonic acid and/or diethylenetriamine pentamethylphosphonic acid. The chemical mechanical polishing liquid according to any one of claims 1 to 3, wherein the tetrazole compound is 5-methyl-tetrazole, 5-phenyl-1-hydrogen-tetra Azole and/or 1-hydro-tetrazole. The chemical mechanical polishing liquid according to any one of claims 1 to 3, further comprising 0.001 to 1% of an oxidizing agent. The chemical mechanical polishing liquid as described in claim 6, wherein the oxidizing agent is hydrogen peroxide, urea hydrogen peroxide, peracetic acid, benzammonium peroxide, potassium persulfate, and/or ammonium persulfate. The chemical machine according to any one of claims 1 to 3 An abrasive slurry, wherein the abrasive particles are cerium oxide, aluminum oxide, cerium oxide, and/or polymer particles. The chemical mechanical polishing liquid according to any one of claims 1 to 3, wherein the chemical mechanical polishing liquid has a pH of 2.0 to 4.0. The chemical mechanical polishing liquid according to any one of claims 1 to 3, further comprising a surfactant, a stabilizer and/or a bactericide.