TW201412963A - Chemical mechanical polishing slurry - Google Patents

Abstract

The present invention relates to a chemical mechanical polishing slurry. The slurry includes at least one of water, cerium oxide abrasive particle, oxidant and water-soluble cyclic oligosaccharides. The slurry could lead a relatively high polishing rate of SiO2, high selectivity of the polishing rate for SiO2 to Si3N4 and high polishing rate of Ta. Meanwhile, the slurry is independently packaged, and convenient to use. And excellent polishing performance could be maintained for a long time.

Description

Chemical mechanical polishing liquid

The present invention relates to a chemical mechanical polishing liquid.

As part of the integrated circuit fabrication process, wafer packaging technology has also evolved with the development of Moore's law. Among them, 3D-packaging technology has developed rapidly since the end of the last century, and has been applied to industrial production processes such as data storage, photosensitive digital chips and the like. The three-dimensional package has the characteristics of small size, high efficiency of use of the chip, short signal delay, etc., and makes some special circuit designs impossible in the conventional two-dimensional package possible.

Chemical Mechanical Polishing (CMP) is an essential part of 3D packaging. Through-silicon via (TSV) fabricated on the back side of the wafer by etching, deposition, and chemical mechanical polishing is the key to achieving 3D-stacking between wafers. The size of the vias is an order of magnitude different from the size of the transistors in the wafer - for example, the size of the transistors in current mainstream circuits has been reduced to less than 100 nanometers, while the size of the vias is typically between a few microns and tens of Micron - - Therefore, the through-hole chemical mechanical polishing process has different requirements than the conventional chemical mechanical polishing process. For example, since various dielectric layers in the via structure have a large thickness, a high removal rate is required for chemical mechanical polishing.

On the other hand, industrial production requires that the polishing liquid used must be easy to use and stable in performance. If the polishing solution contains unstable components or chemical reactions occur between the components, it will have a serious impact on its performance stability. In this case, it is usually necessary to use a separate packaging method to separate the unstable components separately, or to separately package the components that react with each other, and then mix and form the polishing liquid before use and use it as soon as possible. For example, if it is necessary to use hydrogen peroxide which is easily decomposed as an oxidizing agent in the polishing liquid, it is usually only possible to prepare a polishing liquid precursor containing no hydrogen peroxide, and hydrogen peroxide is added before use, and it must be used as soon as possible after the addition.

Another example is WO 2006/001558 A1, which uses a saccharide compound as a Si ₃ N ₄ polishing inhibitor, but the polishing liquid is an A+B type package, and A and B must be mixed before use, which is inconvenient to use.

The present invention provides a polishing liquid which has a higher SiO ₂ , Ta removal rate and a higher SiO ₂ /Si ₃ N ₄ removal rate selection ratio in order to solve the problem that the polishing liquid has a lower abrasive particle content.

The chemical mechanical polishing liquid of the present invention comprises: abrasive particles, water, an oxidizing agent, and a Si ₃ N ₄ inhibitor.

In the present invention, the Si ₃ N ₄ inhibitor is a water-soluble cyclic oligosaccharide. Preferably, the water-soluble cyclic oligosaccharide is β -cyclodextrin.

In the present invention, the abrasive particles are selected from the group consisting of ceria and/or ceria.

In the present invention, the oxidizing agent is selected from one or more of hydroxylamine, KBrO ₃ and KIO ₃ .

In the present invention, the abrasive particles are contained in an amount of 0.1 to 2% by weight, the oxidizing agent is contained in an amount of 0.1 to 0.5% by weight, and the Si ₃ N ₄ inhibitor is contained in an amount of 0.04 to 0.3% by weight. Water is the balance. Wherein the content of the abrasive particles is preferably from 0.3 to 1.0% by weight.

In the present invention, the abrasive particles have a particle diameter of 60 to 250 nm; preferably, the abrasive particles have a particle diameter of 100 to 220 nm; more preferably, the abrasive particles have a particle diameter of 110 to 213 nm. .

In the present invention, the polishing liquid further contains a corrosion inhibitor containing copper. Wherein the corrosion inhibitor of copper is selected from the group consisting of benzotriazole and/or 3-amino-1,2,4-triazole.

In the present invention, the copper is inhibited in an amount of from 0.01 to 0.1% by weight.

In the present invention, the polishing liquid has a pH of 5.7-12.1; preferably, the polishing liquid has a pH of 9 to 12, and more preferably, the polishing liquid has a pH of 10 to 11.

The reagents, materials and products used in the present invention are commercially available.

The outstanding technical effects of the present invention are:

1. Compared with the polishing liquid phase using cerium oxide as the abrasive particles, by using cerium oxide as the abrasive particles, the polishing liquid has a higher removal rate of SiO ₂ and Ta at a lower abrasive particle content. And there is a higher SiO ₂ /Si ₃ N ₄ removal rate selection ratio.

2. By using a Si ₃ N ₄ inhibitor with higher stability, the polishing solution maintains a high SiO ₂ /Si ₃ N ₄ removal rate selection ratio and maintains performance in the aging experiment.

3, the polishing liquid has a lower solid content; has a higher SiO ₂ removal rate, and has a higher SiO ₂ /Si ₃ N ₄ removal rate selection ratio; has a higher tantalum (Ta) removal rate, and Ta The /Cu removal rate selection ratio is greater than 1; the polishing solution is one-pack, and no additional components or pre-mixing are required before use, which is convenient to use and stable in performance.

The advantages of the present invention are further illustrated by the following specific examples, but the scope of the present invention is not limited only to the following examples.

Preparation example

Table 1 shows the chemical mechanical polishing liquid formulations of the present invention. The percentage contents described below are all percentage by mass. The chemical reagents used in the formulation are all commercially available.

Effect Example 1

Table 2 Polishing data of the polishing liquid and the comparative polishing liquid of the present invention

Comparative experiments show that the use of cerium oxide as abrasive particles and the addition of β -cyclodextrin as a Si ₃ N ₄ inhibitor can achieve higher SiO ₂ , Ta removal rates and higher at lower abrasive particle content. The SiO ₂ /Si ₃ N ₄ selection ratio.

Effect Example 2

As can be seen from the comparison, the use of β -cyclodextrin as a Si ₃ N ₄ inhibitor enables the polishing liquid to have more stable performance.

Effect Example 3

Table 4 lists the polishing effects of some of the specific examples. It can be seen that β -cyclodextrin as a Si ₃ N ₄ inhibitor can maintain its performance over a wide range of pH applications and is compatible with different oxidants (such as hydroxylamine, potassium bromate, potassium iodate). .

It should be understood that the wt% of the present invention refers to the mass percentage content.

The specific embodiments of the present invention have been described in detail above, but are merely exemplary, and the invention is not limited to the specific embodiments described above. Any equivalent modifications and substitutions to the invention are also within the scope of the invention. Accordingly, equivalents and modifications may be made without departing from the spirit and scope of the invention.

Claims (16)

A chemical mechanical polishing liquid comprising: abrasive particles, water, an oxidizing agent, and a Si ₃ N ₄ inhibitor. The polishing liquid according to claim 1, wherein the Si ₃ N ₄ inhibitor is a water-soluble cyclic oligosaccharide. The polishing liquid according to claim 2, wherein the water-soluble cyclic oligosaccharide is β-cyclodextrin. The polishing liquid according to claim 1, wherein the abrasive particles are selected from the group consisting of cerium oxide and/or cerium oxide. The polishing liquid according to claim 1, wherein the oxidizing agent is one or more selected from the group consisting of hydroxylamine, KBrO ₃ and KIO ₃ . The polishing liquid according to claim 1, wherein the abrasive particles are contained in an amount of 0.1 to 2% by weight, the oxidizing agent is contained in an amount of 0.1 to 0.5% by weight, and the Si3N4 inhibitor is contained in an amount of 0.04 to 0.3% by weight. The water is the balance. The polishing liquid according to claim 6, wherein the abrasive particles are contained in an amount of from 0.3 to 1.0% by weight. The polishing liquid according to claim 1, wherein the abrasive particles have a particle diameter of 60 to 250 nm. The polishing liquid according to claim 8, wherein the abrasive particles have a particle diameter of 100 to 220 nm. The polishing liquid according to claim 9, wherein the abrasive particles have a particle diameter of 110 to 213 nm. The polishing liquid of claim 1, wherein the polishing liquid further comprises a corrosion inhibitor containing copper. The polishing liquid according to claim 11, wherein the corrosion inhibitor of copper is selected from the group consisting of benzotriazole and/or 3-amino-1,2,4-triazole. The polishing liquid according to claim 11, wherein the copper is inhibited in an amount of from 0.01 to 0.1% by weight. The polishing liquid according to claim 1, wherein the polishing liquid has a pH of 5.7-12.1. The polishing liquid of claim 14, wherein the polishing liquid has a pH of 9-12. The polishing liquid according to claim 15, wherein the polishing liquid has a pH of 10 to 11.