Chemical mechanical polishing solution

Abstract

The invention provides an alkaline chemical mechanical polishing solution. The alkaline chemical mechanical polishing solution comprises silicon dioxide grinding particles, an amino-containing compound, potassium salt, a polyhydroxy nitrogen-containing compound and water, the alkaline chemical mechanical polishing solution can significantly reduce surface defects of a chip, prolong the service life of a polishing pad and significantly improve the yield of products, and has relatively high removal speed of silicon dioxide and silicon of a dielectric layer.

Description

Technical Field

[0001] The present invention relates to the field of chemical mechanical polishing, and particularly to an alkaline chemical mechanical polishing liquid. Background Art

[0002] With the continuous development of semiconductor technology and the continuous increase of interconnect layers in large-scale integrated circuits, the planarization technology of conductive layers and insulating dielectric layers has become particularly crucial. In the 1980s, the chemical mechanical polishing (CMP) technology pioneered by IBM was considered the most effective method for global planarization currently.

[0003] Chemical mechanical polishing (CMP) is composed of chemical action, mechanical action, and the combination of these two actions. It usually consists of a polishing table with a polishing pad and a polishing head for holding the chip. The polishing head fixes the chip and then presses the front side of the chip onto the polishing pad. When performing chemical mechanical polishing, the polishing head linearly moves on the polishing pad or rotates along the same moving direction as the polishing table. At the same time, the slurry containing abrasive is dropped onto the polishing pad and spreads evenly on the polishing pad due to centrifugal force. The global planarization of the chip surface is achieved under the dual action of mechanical and chemical forces.

[0004] Currently, polishing liquids with a dielectric layer of silicon dioxide usually use fumed silica and silica sol as abrasive particles, and each of these two abrasives has its own characteristics. It is difficult to rapidly remove the dielectric layer material through chemical action. Regardless of the polishing liquid using which abrasive particles, in order to obtain a high removal rate of silicon dioxide in the dielectric layer, the solid content of the polishing liquid for silicon dioxide in the dielectric layer is relatively high, and relatively strong mechanical force is provided by the high-concentration abrasive, so that the polishing liquid has a high removal rate of silicon dioxide in the dielectric layer. The above polishing liquids have a common problem: after polishing, on the one hand, the high-solid-content abrasive particles and polishing by-products will adhere to the chip surface, causing surface defects and requiring further surface cleaning (post-CMP clean). The more abrasive and polishing by-products adhere to the chip surface after polishing, the more likely it is to directly reduce the cleaning efficiency of post-CMP clean and increase the cleaning difficulty. At the same time, the high-solid-content abrasive particles and polishing by-products cannot be rapidly removed from the polishing pad during the long-term polishing process, are prone to accumulation, and ultimately cause a significant increase in surface defects, affecting the service life of the polishing pad. On the other hand, high-solid-content liquids often cause the abrasive particles to agglomerate with each other, generating relatively large solid particles, which are extremely likely to cause a large number of scratches on the chip surface during the polishing process, resulting in open circuits and damage to components.

[0005] To solve the above problems, the alkaline chemical mechanical polishing liquid in the present invention can significantly reduce the surface defects of the chip, extend the service time of the polishing pad, significantly improve the yield of the product, and at the same time has a relatively high removal rate of silicon dioxide and silicon in the dielectric layer. Summary of the Invention

[0006] In order to overcome the above technical deficiencies, the object of the present invention is to provide a chemical mechanical polishing liquid, which can significantly reduce the surface defects of chips, extend the service life of the polishing pad, significantly improve the yield of products, and at the same time has a relatively high removal rate of silicon dioxide (Teos) and silicon.

[0007] The present invention discloses a chemical mechanical polishing liquid, comprising: silica abrasive particles, polyhydroxy nitrogen-containing compounds, amino group-containing compounds, potassium salts and water.

[0008] Further, the polyhydroxy nitrogen-containing compound is a compound having the structural formula (1), and the structural formula (1) is:

[0009]

[0010] Among them, R1 is selected from a methyl group or a 2-hydroxyethyl group, and R2 is selected from a 2-hydroxyethyl group or a straight-chain C1 to C12 saturated group.

[0011] Further, the polyhydroxy nitrogen-containing compound is selected from one or more of dodecyl bis(hydroxyethyl)methyl ammonium chloride, tris(2-hydroxyethyl)methyl ammonium hydroxide, bis(2-hydroxyethyl)dimethyl ammonium hydroxide, and tetraethanolammonium hydroxide.

[0012] Further, the amino group-containing compound is selected from one or more of ethanolamine, diethanolamine, ethylenediamine, diethylenetriamine, and triethylenetetramine.

[0013] Further, the potassium salt is selected from one or more of potassium hydroxide, potassium nitrate, potassium chloride, potassium sulfate, potassium bisulfate, potassium acetate, potassium bromate, and potassium chlorate.

[0014] Further, the mass percentage content of the polyhydroxy nitrogen-containing compound is 0.01% to 2.0%.

[0015] Further, the mass percentage content of the amino group-containing compound is 0.01% to 5.0%.

[0016] Further, the mass percentage content of the potassium salt is 0.01% to 1.5%.

[0017] Further, the average particle size of the silica abrasive particles is 30 nm to 170 nm.

[0018] Further, the mass percentage content of the silica abrasive particles is 10% to 40%.

[0019] Further, the chemical mechanical polishing liquid further includes a polymerization inhibitor, and the polymerization inhibitor is a compound having the structural formula (2), and the structural formula (2) is:

[0020]

[0021] Among them, R1, R2, R3, and R4 are selected from: linear or branched C2-C15 saturated or unsaturated groups.

[0022] Furthermore, the inhibitor is selected from one or more of tetraethylammonium hydroxide, tetrabutylammonium nitrate, and benzyltrimethylammonium chloride.

[0023] Furthermore, the mass percentage content of the inhibitor is 0.01% - 1.0%.

[0024] Furthermore, the pH value of the chemical mechanical polishing liquid is 9.5 - 12.0.

[0025] The chemical mechanical polishing liquid in the present invention can significantly reduce the surface defects of the chip, extend the service life of the polishing pad, significantly improve the yield of the product, and at the same time has a relatively high removal rate of dielectric layer silicon dioxide and silicon. Detailed implementation manners

[0026] The advantages of the present invention are further elaborated below in combination with specific embodiments.

[0027] Table 1 shows the formulations of Examples 1 - 14 and Comparative Examples 1 - 4 of the chemical mechanical polishing liquid of the present invention. According to the components and their contents listed in Table 1, they are mixed uniformly in deionized water and adjusted to the required pH value with nitric acid or potassium hydroxide to obtain the chemical mechanical polishing liquid.

[0028] Table 1 Formulations of Examples 1 - 14 and Comparative Examples 1 - 4

[0029]

[0030]

[0031]

[0032] Polish silicon dioxide (Teos) and silicon wafers according to the formulation in Table 1 under the following experimental conditions.

[0033] The specific polishing conditions are as follows:

[0034] The polishing machine is the AMAT (USA) LK type, with an IC1000 polishing pad, a 12-inch wafer (Wafer), a polishing pressure of 3.5 psi, a polishing table rotation speed of 110 revolutions per minute, a polishing head self-rotation speed of 108 revolutions per minute, and a polishing liquid droplet acceleration of 200 ml / minute.

[0035] Use a Surface SP2 surface defect scanner to scan the surface defects of the silicon dioxide (Teos) wafer after polishing.

[0036] Defect collection experiment process: Under the action of the disk, the polishing pad is cleaned, and the clean silicon dioxide (Teos) wafer is polished under the above polishing conditions, and the defect results of the initial surface are collected. Without cleaning the polishing pad, 50 silicon dioxide (Teos) wafers are continuously polished under the above conditions, and then the clean silicon dioxide (Teos) wafer is polished to collect the defect results on the surface.

[0037] The test results are listed in Table 2.

[0038] Table 2 Comparison of removal rates and defect conditions of Examples 1-14 and Comparative Examples 1-4

[0039]

[0040] Comparative Example 1 and Comparative Example 3 show that when an amine compound is added to the polishing liquid, the rate of silicon can be significantly increased.

[0041] Comparative Example 3 and Comparative Example 4 show that when a potassium salt is added to the polishing liquid, the potassium salt can significantly increase the removal rate of silicon dioxide (Teos).

[0042] Comparative Example 4 and Examples 1-14 show that when the polyhydroxy nitrogen-containing compound mentioned in the present invention is not added to the polishing liquid, the number of defect particles on the surface of the silicon dioxide (Teos) wafer is significantly large, and since the polishing by-products cannot be removed from the polishing pad in time, they accumulate on the polishing pad. As 50 silicon dioxide (Teos) wafers are continuously polished, the defects on the surface of the silicon dioxide (Teos) wafer increase from 14,057 to 26,735, showing an obvious upward trend. However, when the polyhydroxy nitrogen-containing compound mentioned in the present invention is added to the polishing liquid, the number of defect particles on the surface of the silicon dioxide (Teos) wafer is significantly reduced, and at the same time, the problem of defect increase caused by continuous polishing is also improved. And the higher the concentration of the polyhydroxy nitrogen-containing compound, the fewer the initial defect numbers, and the gentler the upward trend of continuous polishing defects.

[0043] When the polyhydroxy nitrogen-containing compound provided by the present invention is added, the removal rates of silicon dioxide and silicon do not decrease significantly and still maintain a relatively fast removal rate.

[0044] Examples 2 and 11 show that after adding the inhibitor, the removal rate of silicon dioxide (Teos) increases to a certain extent.

[0045] Furthermore, the stability of the polishing liquid is tested. Select the formulations of Example 2, Example 5, Example 11 and Example 12, and prepare 1 kg of polishing liquid. The stability of the average particle size of the abrasive is observed by placing the polishing liquid in an oven at 55 degrees. The test results are listed in Table 3.

[0046] Table 3 Comparison of the Stability of the Abrasive Particle Size in the Polishing Liquid

[0047]

[0048] As shown in Table 3, Examples 2, 5, 11 and 12 indicate that for the polishing liquid without the addition of inhibitor, after being placed in the oven for 20 days, the average particle size shows an increasing trend. However, when the inhibitor mentioned in the present invention is added to the polishing liquid and it is placed in the oven for 20 days, the average particle size of the abrasive does not increase. This shows that the polishing liquid with the added inhibitor has a more stable system than the polishing liquid without the added inhibitor, further indicating that the inhibitor can disperse the abrasive well, making it not easy to agglomerate, and can extend the service life of the polishing liquid.

[0049] Based on the above test results, it can be seen that the alkaline chemical mechanical polishing liquid in the present invention can significantly reduce the surface defects of the chip, extend the service life of the polishing pad, significantly improve the yield of the product, and at the same time has a relatively high removal rate of silicon dioxide (Teos) and silicon, and has broad application prospects.

[0050] It should be noted that the embodiments of the present invention have good implementability and are not in any form of limitation to the present invention. Any person skilled in the art may use the disclosed technical content to change or modify it into an equivalent effective embodiment. However, as long as it does not depart from the technical solution of the present invention, any modification, equivalent change or modification made to the above embodiments based on the technical essence of the present invention still falls within the scope of the technical solution of the present invention.

Claims

1. A chemical mechanical polishing liquid, characterized in that, Comprising: silica abrasive particles, polyhydroxy nitrogen-containing compounds, amino group-containing compounds, potassium salts, and water.

2. The chemical mechanical polishing liquid according to claim 1, wherein, The polyhydroxy nitrogen-containing compound is a compound having the structural formula (1), and the structural formula (1) is: Wherein, R1 is selected from a methyl group or a 2-hydroxyethyl group, and R2 is selected from a 2-hydroxyethyl group or a straight-chain C1 to C12 saturated group.

3. The chemical mechanical polishing liquid according to claim 2, wherein The polyhydroxy nitrogen-containing compound is selected from one or more of dodecyl bis(hydroxyethyl)methylammonium chloride, tris(2-hydroxyethyl)methylammonium hydroxide, bis(2-hydroxyethyl)dimethylammonium hydroxide, and tetraethanolammonium hydroxide.

4. The chemical mechanical polishing liquid according to claim 1, characterized in that, The amino group-containing compound is selected from one or more of ethanolamine, diethanolamine, ethylenediamine, diethylenetriamine, and triethylenetetramine.

5. The chemical mechanical polishing liquid according to claim 1, wherein The potassium salt is selected from one or more of potassium hydroxide, potassium nitrate, potassium chloride, potassium sulfate, potassium bisulfate, potassium acetate, potassium bromate, and potassium chlorate.

6. The chemical mechanical polishing liquid according to claim 1, wherein The mass percentage content of the polyhydroxy nitrogen-containing compound is 0.01% to 2.0%.

7. The chemical mechanical polishing liquid according to claim 1, characterized in that, The mass percentage content of the amino group-containing compound is 0.01% to 5.0%.

8. The chemical mechanical polishing liquid according to claim 1, characterized in that, The mass percentage content of the potassium salt is 0.01% to 1.5%.

9. The chemical mechanical polishing liquid according to claim 1, wherein The average particle size of the silica abrasive particles is 30 nm to 170 nm.

10. The chemical mechanical polishing liquid according to claim 1, wherein The mass percentage content of the silica abrasive particles is 10% to 40%.

11. The chemical mechanical polishing liquid according to claim 1, characterized in that, It further includes an inhibitor, and the inhibitor is a compound having the structural formula (2), and the structural formula (2) is: Wherein, R1, R2, R3, and R4 are selected from: straight-chain or branched-chain C2 to C15 saturated or unsaturated groups.

12. The chemical mechanical polishing liquid according to claim 11, wherein The inhibitor is selected from one or more of tetraethylammonium hydroxide, tetrabutylammonium nitrate, and benzyltrimethylammonium chloride.

13. The chemical mechanical polishing liquid according to claim 11, wherein The mass percentage content of the inhibitor is 0.01% to 1.0%.

14. The chemical mechanical polishing liquid according to claim 1, characterized in that, The pH value of the chemical mechanical polishing liquid is 9.5 - 12.0.

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