WO2009070968A1

WO2009070968A1 - A chemical-mechanical polishing liquid

Info

Publication number: WO2009070968A1
Application number: PCT/CN2008/001857
Authority: WO
Inventors: Peter Weihong Song; Bob Jianxin Bao; Daisy Ying Yao
Original assignee: Anji Microelectronics (Shanghai) Co.Ltd
Priority date: 2007-11-30
Filing date: 2008-11-07
Publication date: 2009-06-11
Also published as: CN101878277B; CN101451048A; CN101878277A

Abstract

A chemical-mechanical polishing liquid is disclosed, which comprises silica doped by aluminum, mixed corrosive inhibitors, water and one or more kinds of the following rate-accelerators: organic acid, fluoride, ammonia, quaternary amine salts and the derivatives thereof. The polishing liquid has higher polishing rate for higher dielectric (such as TEOS), and can secure higher polishing rate adjustability of Cu adjusted by the concentration of oxidizer, and has better the effect of defect-correction, so it can suitably be used in controlling and adjusting the abrasion degree at different line width in semiconductor device.

Description

Chemical mechanical polishing liquid

The present invention relates to a chemical mechanical polishing liquid. technical background

In the fabrication of integrated circuits, a plurality of dielectric layers including multiple trenches are formed on a semiconductor silicon wafer. The trenches filled with metal wires are arranged in a dielectric layer to form a circuit interconnection pattern. The arrangement of the patterns usually has a damascene structure and a double Heavy metal inlay structure. These damascene structures first cover the dielectric layer with a barrier layer and then cover the barrier with metal. These metals need to be at least filled with trenches to form circuit interconnections. As integrated device devices shrink in size and wiring layers increase, copper has become a wire material for deep submicron integrated circuits because of its better resistance to electromigration and higher electrical conductivity than aluminum. The barrier layer is mainly made of tantalum or tantalum nitride to prevent copper from diffusing to the adjacent dielectric layer.

Chemical mechanical polishing (CMP) is used to planarize the surface of the chip during the fabrication of the chip. These planarized chip surfaces facilitate the production of multilayer integrated circuits and prevent distortion caused by coating the dielectric layer on uneven surfaces. The copper CMP process is usually divided into two steps: The first step is to quickly remove the interconnected metal copper with a specially designed polishing solution; the second step is to remove the barrier layer and a small amount of dielectric layer with a specially designed polishing solution to provide a flat polishing. surface.

The polishing fluid used in the first step of copper CMP typically has a high Cu polishing rate and a low barrier polishing rate to quickly remove excess copper and copper residues on the barrier surface. However, after the first step of copper CMP, the copper line region tends to form deep depressions and abrasions, so To achieve the effect of flattening the polished surface, in the second polishing process of copper CMP, the polishing liquid usually needs to have a specific selectivity, and the barrier layer and part of the dielectric layer are removed without causing excessive copper as interconnecting wires. The depression also determines that the polishing solution of the second step of the copper CMP requires a higher barrier layer and a polishing rate of the dielectric TEOS and a lower Cu polishing rate to provide better dent correction.

Semiconductor silicon wafers are constructed with a variety of structures of different widths and densities to form complex circuit interconnect patterns. These structures of different widths and densities are very sensitive to the CMP process. The CMP process flattens the structure consisting of large areas slower than the flattening of high-density small-size mosaics, thus for structures of various widths and densities. The defect correction effect is also different. An ideal polishing solution, which is expected to have similar structural defects in various widths and densities in the CMP process, and therefore requires adjustment of the polishing rate of Cu. Summary of invention

The technical problem to be solved by the present invention is to provide a higher dielectric (such as TEOS) removal rate and a higher Cu removal rate depending on the oxidant concentration in order to meet the requirements of the Cu chemical mechanical polishing process. A change in adjustability, a chemical mechanical polishing solution with better dent correction.

The chemical mechanical polishing liquid of the present invention comprises: one or more of aluminum-doped silica, a mixed corrosion inhibitor, water, and a rate promoter: an organic acid, a fluoride, an ammonia, and a quaternary ammonium salt and a derivative thereof .

Wherein, the mixed corrosion inhibitor is preferably an azole compound such as benzotriazole, 5-aminotetrazole, 5-methyltetrazolium, 3-amino-1, 2,4-triazo A combination of two or more of azole and 1,2,4-triazole, more preferably a combination of benzotriazole and one or more of the following: 5-amino Tetrazolium, 5-methyltetrazolium, mercaptobenzothiazole, 3-amino-1,2,4-triazole and 1,2,4-triazole, said benzotriazole Good accounts for 25% to 90% of the total mass of the mixed corrosion inhibitor. The mixed corrosion inhibitor is preferably used in an amount of 0.04 to 0.6% by mass.

The aluminum-doped silica preferably has a particle diameter of 20 to 80 nm. The aluminum-doped silica is preferably used in an amount of from 1 to 20% by mass, more preferably from 3 to 15% by mass, most preferably from 3 to 10% by mass.

Wherein, the organic acid is preferably one or more of oxalic acid, butyl 'phosphonium 2-phosphonate, 2-hydroxyphosphonoacetic acid, aminotrimethylenephosphonic acid and tartaric acid. The fluoride is preferably one or more of hydrogen fluoride, ammonium fluoride, ammonium fluorosilicate and ammonium fluoroborate; the quaternary ammonium salt is preferably tetrabutylammonium hydroxide, tetrabutylammonium fluoride, tetramethyl One or more of ammonium hydroxide and tetrabutylammonium fluoroborate. The rate promoter is preferably tetrabutylammonium hydroxide and/or tetrabutylammonium fluoride. The rate promoter is preferably used in an amount of 0.05 to 1% by mass, more preferably 0.1 to 0.6% by mass.

The polishing liquid of the present invention preferably has a pH of 2 to 9, more preferably 2 to 5.

The polishing liquid of the present invention may further contain conventional additives such as an oxidizing agent, a complexing agent, a surfactant, and a pH adjusting agent in the art.

The polishing liquid of the present invention can be obtained by simply and uniformly mixing the above components, followed by adjustment to a suitable pH with a pH adjuster. The pH adjusting agent may be selected from conventional pH adjusting agents such as potassium hydroxide, ammonia water and nitric acid. In the present invention, the reagents and raw materials used are commercially available. The reagents and materials used in the present invention are commercially available.

The positive progress of the present invention is that: the polishing liquid of the present invention has a higher polishing rate of a dielectric (such as TEOS), and can increase the polishing rate of Cu with an increase in the concentration of the oxidant. It has a higher degree of adjustment and better defect correction. It is suitable for controlling and adjusting the degree of abrasion at different line widths in semiconductor devices. DRAWINGS

BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a graph comparing the removal rates of Teos in Comparative Polishing Solutions 1 and 2 and the polishing solutions 1 to 4 of the present invention.

2 is a graph comparing the removal rates of different amounts of 3⁄40 ₂ versus Cu added to the comparative polishing liquids 1 and 2 and the polishing liquids 1 to 4 of the present invention.

Fig. 3 is a graph showing the removal rate of Teos and Cu in the polishing liquids 5 to 7 of the present invention in Effect Example 2.

Fig. 4 is a view showing the comparison of the abrasion depths of the polishing liquids 5 to 7 of the present invention in the effect of Example 2 on copper wires of different line widths.

Fig. 5 is a graph showing the removal rate of Cu by the polishing liquids 8 to 12 of the present invention in Effect Example 3. Fig. 6 is a graph showing the removal rate of Teos by the polishing liquids 8 to 12 of the present invention in Effect Example 3. Fig. 7 is a graph showing the comparison of the abrasion depths of the polishing liquids 10 to 12 of the present invention in the effect of Example 3 on copper wires of different line widths.

FIG 8 is a polishing solution of the present invention results in Example 4 was added 13 ~ 16 Comparative ¾0 ₂ Cu removal rates versus different contents at different pH values.

Fig. 9 is a graph showing the removal rate of Teos at different pH values of the polishing liquids 13 to 16 of the present invention in Effect Example 4.

Fig. 10 is a graph showing the comparison of the abrasion depths of the copper wires of different line widths of the polishing liquids 13 to 16 of the present invention in the effect example 4 at different pH values. Summary of the invention

The invention is further illustrated by the following examples, which are not intended to limit the invention. The following percentages are all percentages by mass.

In the following examples, the components were simply and uniformly mixed, and the water was the balance, which was then adjusted to a suitable pH using potassium hydroxide and nitric acid.

Example 1

Aluminum-doped silica (70nm) 1%, tetramethylammonium hydroxide 0.6%, benzotriazole 0.1%, 5-aminotetrazolium 0.1%, oxalic acid 0.3%, pH=3.0

Example 2

Aluminum-doped silica (80 nm) 20%, 2-hydroxyphosphonoacetic acid 0.05%, benzotriazole 0.09%, 5-aminotetrazolium 0.01%, aminotrimethylenephosphonic acid 0.05%, pH=4.0

Example 3

Aluminum-doped silica (30nm) 8%, tartaric acid 1%, benzotriazole 0.1%, 5-aminotetrazolium 0.1%, pH=2.0

Example 4

Aluminum-doped silica (60nm) 6%, ammonium fluoride 0.05%, benzotriazole 0.1%, 5-aminotetrazolium 0.1%, pH=5.0

Example 5

Aluminum-doped silica (60nm) 5%, ammonium fluorosilicate 0.1%, tetrabutyl fluoroborate 0.1%, benzotriazole 0.1%, 5-aminotetrazolium 0.1%, pH=5.0

Example 6

Miscellaneous aluminum silica (70nm) 4%, ammonium fluoroborate 0.5%, benzotriazole 0.1%, 5-amino Tetrazolium 0.1%, pH=5.0

Effect embodiment 1

Contrast polishing solution 1 : Miscellaneous aluminum silica (70nm) 10%, benzotriazole 0.2%, 2-phosphonic acid Butane -1, 2, 4-tricarboxylic acid 0.3%, pH=3.0

Contrast polishing solution 2: aluminum-doped silica (70nm) 10%, tetrabutylammonium hydroxide (TBAH)

0.3%, benzotriazole 0.2%, 2-phosphonium butane -1, 2, 4-tricarboxylic acid 0.3%, H=3.0

Polishing solution 1: aluminum-doped silica (70nm) 10%, TBAH 0.3%, benzotriazole 0.1%, 5-aminotetrazolium 0.1%, 2-phosphonium bromide-1, 2, 4-tricarboxylate Acid 0.3%, pH=3.0

Polishing solution 2: yttrium aluminum silica (70 nm) 10%, TBAH 0.3%, benzotriazole 0.1%, 5-methyltetrazolium 0.1%, 2-phosphonium butyl hydrazine-1, 2, 4-three Carboxylic acid 0.3%, pH=3.0

Polishing solution 3: aluminum-doped silica (70 nm) 10%, TBAH 0.3%, benzotriazole 0.1%, 3-amino-1, 2, 4-triazole 0.1%, 2-phosphonate butane-1 , 2, 4-tricarboxylic acid 0.3%, pH=3.0 Polishing solution 4: aluminum-doped silica (70nm) 10%, TBAH 0.3%, benzotriazole 0.1%,

1, 2, 4-triazole 0.1%, 2-phosphonium butane -1, 2, 4-tricarboxylic acid 0.3%, pH=3.0

Polishing conditions: 2.0 psi under pressure, polishing pad Politex, polishing plate speed 70 rpm, polishing fluid flow rate 100 ml/min, polishing machine Logitec PM5.

It can be seen from Figures 1 and 2 that, compared with the comparative polishing liquid 1, the contrast polishing liquid 2 is added with yttrium, the TEOS polishing rate is increased, and the Cu polishing rate is decreased, but the polishing rate of Cu is increased with the increase of the oxidant concentration. . However, the polishing liquids 1 to 4 of the present invention employ a rate accelerating agent and a mixed corrosion inhibitor system, and the polishing rate of TEOS is still high, the polishing rate of Cu is lowered, and the polishing rate of Cu increases with the increase of the concentration of the oxidant. Higher, ensuring the adjustability of Cu polishing rate. Effect Example 2 Removal rate of polishing solution containing mixed corrosion inhibitors in different ratios

Slurry 5: aluminum-doped silica (70 nm) 3%, HF 0.027%, TBAH O.15%, benzotriazole 0.15%, 5-aminotetrazolium 0.05%, 2-phosphonate butane-1, 2, 4-tricarboxylic acid 0.15%, pH=3.0, H ₂ 0 ₂ 0.3%

Polishing solution 6: aluminum-doped silica (70 nm) 3%, HF 0.027%, TBAH 0.15%, benzotriazole 0.1%, 5-aminotetrazolium 0.1%, 2-phosphonate butane-1, 2, 4-tricarboxylic acid 0.15%, pH=3.0,

H ₂ 0 ₂ 0.3%

Polishing solution 7: aluminum-doped silica (70 nm) 3%, HF 0.027%, TBAH O.15%, benzotriazole 0.05%, 5-aminotetrazolium 0.15%, 2-phosphonic acid butane-1, 2, 4-tricarboxylic acid 0.15%, pH=3.0, H ₂ 0 ₂ 0.3%

It can be seen from Figures 3 and 4 that the polishing rate of the TEOS is substantially unchanged by changing the ratio in the mixed corrosion inhibitor. However, at the same concentration of 3⁄40 ₂ , as the ratio of benzotriazole increases, the polishing rate of Cu decreases, the depth of defects decreases, and the difference in the depth of abrasion at different line widths is small, so the benzotriazole in the mixed inhibitor is mixed. The higher the ratio, the polishing performance of the polishing liquid is favorable.

Effect Example 3. Polishing performance of polishing solution containing mixed anti-corrosion agent in different amounts

Polishing solution 8: aluminum-doped silica (70 nm) 10%, TBAH 0.3%, benzotriazole 0.02%, 5-aminotetrazolium 0.02%, 2-phosphonate butane-1, 2, 4-tricarboxylate Acid 0.3%, pH=3.0

Polishing solution 9: aluminum-doped silica (70 nm) 10%, TBAH 0.15%, benzotriazole 0.05%, 5-aminotetrazolium 0.05%, 2-phosphonic acid butane-1, 2, .4-three Carboxylic acid 0.3%, pH=3.0

Polishing solution 10: aluminum-doped silicon dioxide (70 nm) 10%, TBAH 0.15%, benzotriazole 0.1%, 5-aminotetrazolium 0.1%, 2-phosphonium butane-1, 2, 4-tricarboxylic acid 0.3%, pH=3.0 Polishing solution 11: aluminum-doped silica (70 nm) 10%, TBAH 0.15%, Benzotriazole 0.15%, 5-aminotetrazolium 0.15%, 2-phosphonate butane-1, 2, 4-tricarboxylic acid 0.3%, pH=3.0

Polishing solution 12: aluminum-doped silica (70 nm) 10%, TBAH 0.15%, benzotriazole 0.3%, 5-aminotetrazolium 0.3%, 2-phosphonium bromide-1, 2, 4-tricarboxylate Acid 0.3%, pH=3.0

As can be seen from Figures 5 and 6, the concentration of the mixed inhibitor is preferably between 0.04% and 0.6%, and the TEOS polishing rate is not much different. Add 3⁄40 ₂ to adjust the polishing rate of Cu. As can be seen from Fig. 7, in the above range, it is advantageous to use a large amount of the mixed corrosion inhibitor because the defects are small and the degree of abrasion at different line widths is small.

Effect of implementation 4 polishing performance of different pH polishing liquid

Polishing solution 13: aluminum-doped silica (70 nm) 10%, tetrabutylammonium fluoride (TBAF) 0.3%, benzotriazole 0.1%, 5-aminotetrazolium 0.1%, 2-phosphonate butane- 1, 2, 4-tricarboxylic acid 0.3%, pH=2.0 Polishing solution 14: aluminum-doped silica (70 nm) 10%, TBAF 0.3%, benzotriazole 0.1%, 5-aminotetrazolium 0.1%, 2-phosphonate butane-1, 2, 4-tricarboxylic acid 0.3%, pH=3.0

Polishing solution 15: aluminum-doped silica (70 nm) 10%, TBAF 0.3%, benzotriazole 0.1%, 5-aminotetrazolium 0.1%, 2-phosphonate butane-1, 2, 4-tricarboxylate Acid 0.3%, pH=5.0

Slurry 16: Aldo-doped silica (70nm) 10%, TBAF 0.3%, benzotriazole 0.1%, 5-aminotetrazolium 0.1%, 2-phosphonate butane-1, 2, 4-tricarboxylate Acid 0.3 ° /. , pH=9.0

Polishing conditions: 2.0 psi down pressure, polishing pad Politex, polishing plate speed 70 rpm, polishing fluid flow rate 100 ml/min, polishing machine Logitec PM5. As can be seen from Fig. 8 and Fig. 9, the pH of the polishing liquid containing the mixed corrosion inhibitor system is preferably from 2 to 9, more preferably from 2 to 5. It can be seen from Fig. 10 that when the pH of the polishing liquid is low, the abrasion of different line widths is small.

Claims

Rights request

A chemical mechanical polishing liquid characterized by comprising: one or more of a disastrous aluminum silica, a mixed corrosion inhibitor, water, and a rate promoter: an organic acid, a fluoride, an ammonia, and a season Ammonium salts and their derivatives.

2. The chemical mechanical polishing liquid according to claim 1, wherein: the mixed corrosion inhibitor is benzotriazole, 5-aminotetrazole, 5-methyltetrazole, 3-amino- A combination of two or more of 1, 2, 4-triazole and 1,2,4-triazole.

3. The chemical mechanical polishing liquid according to claim 1, wherein: the mixed corrosion inhibitor is a combination of benzotriazole and one or more of the following: 5-aminotetrazolium, 5 -methyltetrazolium, mercaptobenzothiazole, 3-amino-1,2,4-triazole and 1,2,4-triazole.

The chemical mechanical polishing liquid according to claim 3, wherein the benzotriazole accounts for 25% to 90% of the total mass of the mixed corrosion inhibitor.

The chemical mechanical polishing liquid according to claim 1, wherein the mixed corrosion inhibitor is used in an amount of 0.04 to 0.6% by mass.

The chemical mechanical polishing liquid according to claim 1, wherein the aluminum-doped silicon dioxide is used in an amount of from 1 to 20% by mass.

The chemical mechanical polishing liquid according to claim 6, wherein the aluminum-doped silica is used in an amount of from 3 to 10% by mass.

The chemical mechanical polishing liquid according to claim 1, wherein the organic acid is selected from the group consisting of oxalic acid, 2-phosphonic acid butane-1, 2, 4-tricarboxylic acid, and 2-hydroxyphosphonoacetic acid. And one or more of aminotrimethylenephosphonic acid and tartaric acid; the fluoride is selected from one or more of hydrogen fluoride, ammonium fluoride, ammonium fluorosilicate and ammonium fluoroborate; The ammonium salt is selected from the group consisting of tetrabutylammonium hydroxide, One or more of tetrabutylammonium fluoride, tetramethylammonium hydroxide, and tetrabutylammonium fluoroborate.

9. The chemical mechanical polishing liquid according to claim 1, wherein the rate promoter is used in an amount of 0.05 to 1% by mass.

The chemical mechanical polishing liquid according to claim 1, wherein the polishing liquid has a pH of 2 to 9.