WO2011069343A1 - Chemical-mechanical polishing liquid for polishing tantalum barrier - Google Patents

Abstract

A chemical-mechanical polishing liquid for polishing tantalum barrier is disclosed. The polishing liquid comprises abrasive particles, an organic acid, polyacrylics, a metal corrosion inhibitor, a quaternary ammonium base, an oxidant and water. The polishing liquid can meet the requirement of the polishing stage for barrier layers, improve the removal rate of barrier layer (Ta or TaN), meet the selective ratio requirement of the polishing rate of an insulating layer material to that of a metallic material during the polishing process of the barrier layer, prevent the partial and overall corrosion occurred during the polishing process of the metallic material, and reduce surface defects and contaminants of a polished wafer.

Description

 Chemical mechanical polishing liquid for bismuth barrier polishing

Technical field

 The present invention relates to a chemical mechanical polishing liquid for ruthenium barrier polishing, and more particularly to a chemical mechanical polishing liquid containing abrasive particles, an organic acid, a polyacrylic acid, a metal corrosion inhibitor, a quaternary amine base, an oxidizing agent and water. technical background

 In the manufacture of integrated circuits, the standard of interconnect technology is increasing. As the number of interconnect layers increases and the size of process features shrinks, the flatness of the surface of silicon wafers is also becoming higher and higher. If there is no flattening capability, The creation of complex and dense structures on semiconductor wafers is very limited, and the chemical mechanical polishing method CMP is the most efficient way to achieve planarization of the entire wafer.

 As the feature size of the IC device shrinks, the barrier layer becomes thinner and thinner. In the process below 90 nm, the thickness of the barrier layer is only 100 to 250 A. The new insulating layer material and the capping layer are continuously applied to each. Processes, such as low-k materials, include materials such as BD (Black Diamond) and Coral that have been industrially applied. These materials have different chemical compositions and mechanical strengths. The CMP of the barrier layer gradually increases the requirements for the polishing fluid to accommodate changes in its mechanical properties. For example, the polishing selectivity of various materials (especially the selection ratio of TEOS and low-k materials), the corrosion of metal materials and the uniformity of polishing are all challenges for the new generation of barriers. There is currently no industrial polishing solution that solves all of the above problems.

An acid barrier polishing solution for increasing the TEOS removal rate using a quaternary ammonium salt is disclosed in US20050031789, which has a better barrier removal rate, a lower copper removal rate and an adjustable TEOS removal rate. Effectively control copper by adjusting the content of hydrogen peroxide In addition to the rate, the polishing fluid lacks control of the removal rate of the low-k material. CN02116761.3 discloses a chemical mechanical global planarization polishing liquid for copper and tantalum in a multi-scale integrated circuit multilayer copper wiring, the polishing liquid is alkaline, there is a problem that surface contaminants are difficult to control and a suitable oxidant is difficult to select. . U.S. Patent 6,638,326 uses ammonium nitrate or nitric acid as the oxidizing agent. Although the polishing rate selection ratio can be adjusted, there is a potential problem of metal corrosion.

 The chemical mechanical polishing liquid of the invention has high removal rate of TEOS and low-k material (BD), and the removal rate of Cu can be adjusted by increasing or decreasing the content of the oxidant, which satisfies the insulating layer material during the polishing process of the barrier layer. In combination with the metal polishing rate selection ratio, the chemical mechanical polishing liquid of the present invention can prevent local and overall corrosion problems occurring during metal polishing, and ensure that wafer surface defects and contaminants are small after polishing. Summary of invention

 The technical problem solved by the invention is to meet the requirements of the barrier layer polishing process stage, improve the removal rate of the barrier layer (or >, meet the requirements of the selection ratio of the polishing layer material and the metal material polishing rate during the barrier layer polishing process, and prevent the metal Local and overall corrosion during polishing and reduces wafer surface defects and contaminants after polishing.

 The chemical mechanical polishing liquid for bismuth barrier polishing of the present invention contains abrasive particles, an organic acid, a polyacrylic acid, a metal corrosion inhibitor, a quaternary amine base, an oxidizing agent and water.

In the present invention, the mass percentage of the abrasive particles is 1 to 10%, the mass percentage of the organic acid is 0.01 to 1%, and the mass percentage of the polyacrylic acid is 0.01~ 0.2%, the metal corrosion inhibitor has a mass percentage of 0.01% to 1%, the quaternary ammonium base has a mass percentage of 0.01 to 0.2%, and the oxidizing agent has a mass percentage of 0.001. ~1%, the balance is water. In the present invention, the abrasive particles are selected from one or more of the group consisting of silica, alumina, cerium oxide, and/or polymer particles.

 In the present invention, the abrasive particles have a particle diameter of 20 to 200 nm.

 In the present invention, the organic acid is selected from the group consisting of oxalic acid, malonic acid, succinic acid, citric acid, butyl-1,2,4-tricarboxylic acid, hydroxyethylidene diphosphate, and aminotrimethylene. One or more of a phosphatidyl acid and/or an amino acid.

 In the present invention, the polyacrylic acid has a molecular weight of from 1,000 to 20,000, preferably from 2,000 to 5,000. In the present invention, the metal corrosion inhibitor is an azole compound.

 In the present invention, the azole compound is selected from the group consisting of benzotriazole, methylbenzotriazole, 1,2,4-triazole, 3-amino-1,2,4-triazole, One or more of 4-amino-1, 2, 4 triazole and/or 5-methyl-tetrazole.

 In the present invention, the quaternary ammonium base is tetramethylammonium hydroxide and/or tetrabutylammonium hydroxide. In the present invention, the oxidizing agent is one or more selected from the group consisting of hydrogen peroxide, urea hydrogen peroxide, peracetic acid, benzoyl peroxide, potassium persulfate and/or ammonium persulfate.

 In the present invention, the chemical mechanical polishing liquid has a pH of 2.0 to 5.0.

 In the present invention, the chemical mechanical polishing liquid contains a surfactant, a stabilizer, and/or a bactericide. The positive effects of the present invention are:

 1. The polishing liquid of the present invention has a higher removal rate of the barrier material (Ta or TaN).

2. The polishing liquid of the present invention has a high removal rate of TEOS and low-k material (BD), and the removal rate of Cu can be increased or decreased by increasing or decreasing the content of the oxidant, thereby satisfying the barrier polishing process. Medium insulation material and metal polishing rate selection ratio requirements. 3. The polishing liquid of the present invention can prevent local and overall corrosion generated during metal polishing and improve product yield.

 After polishing with the polishing fluid of the present invention, the wafer has an intact surface topography and a low surface contamination residue. DRAWINGS

 Figure 1 is a SEM (Scanning Electron Microscope) image of the surface morphology of a wafer after polishing with a polishing solution of Comparative Example 1.

 Fig. 2 is a SEM (Scanning Electron Microscope) image of the surface morphology of the wafer after polishing with the polishing liquid of Example 1. Summary of the invention

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 the chemical mechanical polishing liquids of the present invention in Examples 1 to 16 and Comparative Example 1, according to the components listed in Table 1 and their contents, uniformly mixed in deionized water, followed by potassium hydroxide and ammonia water. The chemical mechanical polishing liquid of each example can be obtained by adjusting nitric acid to a suitable pH.

Table 1 Preparation of chemical mechanical polishing liquid of the present invention Examples 1 to 16 and Comparative Example 1

Example:

 Implemented

Example 6 I SiO ₂ (100nm) Ammonia 0.2 0.01 0.05 Oxygen

 0.3

0)

0.05 hydrogen, nitrogen, nitrogen, nitrogen, nitrogen, nitrogen, nitrogen, nitrogen, nitrogen, nitrogen, nitrogen, nitrogen, nitrogen, nitrogen, nitrogen, nitrogen, nitrogen, nitrogen, nitrogen, nitrogen, nitrogen, nitrogen, nitrogen, nitrogen, nitrogen, nitrogen, nitrogen, nitrogen, nitrogen, nitrogen, nitrogen

Limonyl carboxylic acid ric acid butyl oxalic acid diacid malonate

Implementation

^Γ I SiO ₂ (100nm) 0.5 0,2 0.01

Example 7 ^Polyene ene oxide ^ eneene polyene oxide

 3⁄4 3⁄4 5t 3t i i acid propionic acid propionate propionate propionate propionate

1 ^Al2 ° ^{3 (20nm)} 1 0.01 0.1 0.02 0.5

 Hinge hydroxide hydroxide hinge ammonium hydroxide butyl oxy ammonium hydroxide hydrogen oxyhydroxide ammonium hydroxide hydrogenation butyl tetrabutyl four four four four four

 '0) sulphur potassium peracid oxy acyl peroxide peroxybenzene hydroperoxide peracid hydrogen peroxide peroxidation

Implementation

I CeO _{2 (} 150 legs) 0.01 0.05 0.01 0.05 0.001

0)

Ammonia

 Base

Implement polymethacrylate -1,

Example Methyl ester I 10 0.05 0.1 0.05 0.1 0.005

10 (200nm)

 5000)

Ammonia

 Base

 -1 ,

SiO ₂ (100nm) 0.2 0.15 0.15 0.1

'0) Case

 Shi

 Implementation

Example I SiO ₂ (100nm)

 12

■ 4 nitrogen triazotriazole benzotriazole benzoxazole benzoxazoxazole IV

 Implementation

Example I SiO ₂ (100nm) 05

 13

 Keiki, amino, tribasic acid, hydroxyphosphoric acid, methylene sulfonate, bisphosphonate, succinic acid

Alkene β-ene oxide polyene β-polyolefin

 ϊ t

Implementation of ttt i I ii acid propionate propionic acid propionic acid propionate propionate - Example I SiO ₂ (40nm) Λ 05 • 4

 14

 5000)

 Ammonium hydroxide ammonium hydroxide based ammonium hydroxide butyl butyl ammonium hydroxide ammonium hydroxide tetrabutyl four four four four

Implementation hydrogen oxyhydrogen hydrogen peroxide hydrogen peroxide sulfur peroxide peroxidation peracid

 Example I SiO2 (100nm) | 10 ,02 05

 15

3-ammonia

 Base

 -1 ,

 SiO2 (100nm) 10 05 05

 0)

Effect embodiment 1

The polishing liquid of Comparative Example 1 and the polishing liquids of Examples 1 to 6 of the present invention were polished under the following conditions for Ta, TEOS, BD and Cu. Polishing conditions: polishing pad is Politex 14, lower pressure is 1.5 psi, rotation speed is polishing disk / polishing head = 70/90 rpm, polishing liquid flow rate is 100 ml / minute, polishing time is 2 minute. The results are shown in Table 2.

 Table 2 Comparative Example 1 and Examples 1 to 6 for the removal rates of Ta, TEOS, BD and Cu

从表 2中可以看出， 与对比例 1抛光液相比， 本发明的化学机械抛光液 可以获得较高的 Ta、 TEOS和 BD的去除速率， 通过调节氧化剂的浓度可以 调节铜的抛光去除速率， 满足了阻挡层抛光过程中 TEOS、 BD和 Cu的抛光 速率选择比的要求。 效果实施例 2

As can be seen from Table 2, the chemical mechanical polishing liquid of the present invention can obtain a higher removal rate of Ta, TEOS and BD than the polishing liquid of Comparative Example 1, and the polishing removal rate of copper can be adjusted by adjusting the concentration of the oxidizing agent. , meets the requirements of the polishing rate selection ratio of TEOS, BD and Cu during the barrier polishing process. Effect Example 2

 Polishing material: Sputtered germanium barrier/copper-plated silicon dioxide test wafer; Polishing conditions: Polishing pad is Politex l4', downforce is 1.5 psi, rotation speed is polishing disk / polishing head = 70/90 rpm, polishing fluid flow rate For 100 ml/min, the polishing time is 2 minutes.

 1 and 2 are SEM images of the surface morphology of the test wafer after polishing with the polishing solution of Comparative Example 1 and the polishing liquid of Example 1, respectively, as can be seen from the comparison of FIG. 1 and FIG. 2, after polishing with the polishing liquid of the present invention. The surface of the test wafer was smooth and flat, and no contaminating particles remained.

Claims

Claims: A chemical mechanical polishing fluid for tantalum barrier polishing, containing abrasive particles, organic acids, polyacrylates, metal corrosion inhibitors, quaternary ammonium bases, oxidants and water. . The chemical mechanical polishing fluid according to claim 1, the mass percentage of the abrasive particles is 1 to 10%, the mass percentage of the organic acid is 0.01 to 1%, and the polyacrylic acid The mass percentage content of the metal corrosion inhibitor is 0.01~0.2%, the mass percentage content of the metal corrosion inhibitor is 0.01%~1%, the mass percentage content of the quaternary ammonium base is 0.01~0.2%, the The mass percentage of the oxidant is 0.001~1%, and the balance is water. . The chemical mechanical polishing liquid according to claim 1, wherein the abrasive particles are selected from one or more types of silicon oxide, aluminum oxide, cerium oxide and/or polymer particles. . The chemical mechanical polishing fluid according to claim 1, the particle size of the abrasive particles is 20~200nm. , the chemical mechanical polishing liquid according to claim 1, the organic acid is selected from oxalic acid, malonic acid, succinic acid, citric acid, 2-phosphonic acid butyl-1,2,4-tricarboxylic acid , one or more of hydroxyethylene diphosphate, aminotrimethylene phosphate and/or amino acids. . The chemical mechanical polishing fluid according to claim 1, the molecular weight of the polyacrylic acid is 1000-20000 . The chemical mechanical polishing fluid according to claim 1, wherein the metal corrosion inhibitor is an azole compound. . The chemical mechanical polishing liquid according to claim 7, the azole compound is selected from benzotriazole, methylbenzotriazole, 1, 2, 4-triazole, 3-amino-1 , one or more of 2, 4-triazole, 4-amino-1, 2, 4-triazole and/or 5-methyl-tetrazole. 9. The chemical mechanical polishing fluid according to claim 1, wherein the quaternary ammonium base is tetramethylammonium hydroxide and/or tetrabutylammonium hydroxide. 10. The chemical mechanical polishing fluid according to claim 1, the oxidizing agent is selected from hydrogen peroxide, urea hydrogen peroxide, peracetic acid, benzoyl peroxide, potassium persulfate and/or ammonium persulfate. one or more. 11. The chemical mechanical polishing liquid according to claim 1, the pH value of the chemical mechanical polishing liquid is 2.0~5.0. 12. The chemical mechanical polishing fluid according to claim 1, containing surfactant, stabilizer and/or bactericide.