Chemical mechanical polishing solution

Abstract

The invention provides a chemical mechanical polishing solution. The chemical mechanical polishing solution comprises silicon dioxide grinding particles, a polishing rate stabilizer, a compound containing potassium ions, a polymerization inhibitor and water, the polishing rate stabilizer is selected from one or more of a monomer with a polyol or polyol ether structure and a polymer thereof. The chemical mechanical polishing solution can obviously improve the trend that the silicon dioxide rate is gradually reduced along with the increase of the service time of a polishing pad, and has a relatively high dielectric layer silicon dioxide removal rate under the condition of ensuring the stable rate.

Description

Technical Field

[0001] The present invention relates to the field of chemical mechanical polishing fluids, and particularly to a chemical mechanical polishing fluid. 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 movement 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, for polishing fluids with a dielectric layer of silicon dioxide, fumed silica and silica sol are usually used as abrasive particles, and each of these two abrasives has its own characteristics. It is difficult to rapidly remove dielectric layer materials through chemical action. Regardless of the polishing fluid using which abrasive particles, in order to obtain a high removal rate of silicon dioxide in the dielectric layer, the solid content of the dielectric layer silicon dioxide polishing fluid is relatively high. A relatively strong mechanical force is provided by the high-concentration abrasive, so that the polishing fluid has a high removal rate of silicon dioxide in the dielectric layer. The above polishing fluids 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. The more of these abrasive agents and polishing by-products adhered after polishing, the more likely it is to directly reduce the cleaning efficiency of post-CMP clean and increase the cleaning difficulty; on the other hand, these difficult-to-clean abrasive agents and by-products will cause the continuous reduction of the polishing rate with the accumulation of polishing time, shorten the service life of the polishing medium, and affect the product yield. Summary of the Invention

[0005] In order to overcome the above technical defects, the purpose of the present invention is to provide an alkaline chemical mechanical polishing fluid, which can significantly improve the trend of the silicon dioxide rate decreasing with the increase of the polishing pad use time, and has a relatively high removal rate of silicon dioxide in the dielectric layer under the condition of ensuring a stable rate.

[0006] Specifically, the present invention discloses a chemical mechanical polishing fluid, which is characterized by comprising:

[0007] Silica abrasive particles, a polishing rate stabilizer, a potassium ion-containing compound, a polymerization inhibitor, and water;

[0008] The stabilizer is selected from one or more of monomers having a polyol or polyol ether structure and polymers thereof.

[0009] Preferably, the stabilizer is a compound having the structural formula (1), and the structural formula (1) is:

[0010] n is an integer from 1 to 50;

[0011] Wherein R is selected from hydrogen and linear or branched alkyl groups, and n is a positive integer with a value range of 1 to 50.

[0012] Preferably, the stabilizer is selected from one or more of diethylene glycol, diethylene glycol monobutyl ether, hexaethylene glycol monomethyl ether, polyethylene glycol, and dodecyl heptaethylene glycol ether.

[0013] Preferably, the stabilizer is polyethylene glycol, and the molecular weight of the polyethylene glycol is 200 to 1000.

[0014] Preferably, the mass percentage content of the stabilizer is 0.05% to 5%.

[0015] Preferably, the polymerization inhibitor is a compound having the structural formula (2), and the structural formula (2) is:

[0016]

[0017] Wherein, R1, R2, R3, and R4 are independently selected from one or more of linear or branched C2 to C15 saturated or unsaturated groups.

[0018] Preferably, the polymerization inhibitor is selected from one or more of tetraethylammonium hydroxide, tetrabutylammonium nitrate, benzyltrimethylammonium chloride, pentadecylammonium chloride, and decyltrimethylammonium chloride.

[0019] Preferably, the mass percentage content of the polymerization inhibitor is 0.01% to 1.0%.

[0020] Preferably, the average particle size of the silica abrasive particles is 45 nm to 180 nm.

[0021] Preferably, the mass percentage content of the silica abrasive particles is 10% to 40%.

[0022] Preferably, the potassium ion-containing compound is selected from one or more of potassium hydroxide, potassium nitrate, potassium chloride, potassium sulfate, potassium bisulfate, potassium acetate, potassium bromate, and potassium chlorate.

[0023] Preferably, the mass percentage content of the potassium ion-containing compound is 0.01% to 1.5%.

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

[0025] After adopting the above technical solution, compared with the prior art, the chemical mechanical polishing liquid in the present invention can significantly improve the trend that the silica rate gradually decreases with the increase of the polishing pad usage time. Under the condition of ensuring a stable rate, it has a relatively high removal rate of dielectric layer silica. Specific embodiments

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

[0027] Table 1 shows the formulations of Examples 1 - 11 and Comparative Examples 1 - 3 of the chemical mechanical polishing liquid of the present invention. According to the components and their contents listed in Table 1, the abrasive particles are all silica abrasive particles. Among them, in Comparative Example 4, Example 5, Example 7, and Example 8, fumed silica is selected, and in other comparative examples and examples, silica sol is selected. They are mixed evenly in deionized water, and water is the balance. It is adjusted to the required pH value with a pH regulator, nitric acid or potassium hydroxide, and then the chemical mechanical polishing liquid can be prepared.

[0028] Table 1 Compositions and Contents of Examples 1 - 11 and Comparative Examples 1 - 4 of the Present Invention

[0029]

[0030]

[0031] The results of the polishing liquid for polishing dielectric layer silica are further tested. The specific polishing conditions are as follows:

[0032] The polishing machine is the AMAT (USA) Mirra type, Politex Reg polishing pad, 8-inch wafer, polishing pressure 1.6 psi, polishing table rotation speed 63 revolutions per minute, polishing head rotation speed 57 revolutions per minute, polishing liquid droplet acceleration 100 ml / min, polishing time is one minute, and the polishing pad usage time ends at 250 pieces. The test results are listed in Table 2.

[0033] Table 2 Silica Polishing Rates of Examples 1 - 11 and Comparative Examples 1 - 4 at Different Polishing Pad Usage Times

[0034]

[0035] The test results of Comparative Examples 1 - 3 show that the selection of the type and content of silica abrasive particles and the addition of potassium salts can significantly improve the polishing rate of silica.

[0036] Comparisons between Comparative Examples 1-4 and Examples 1-11 show that: the addition of stabilizers and inhibitors does not significantly affect the rate of silica, while without the addition of surfactants, the polishing rate of silica shows a very obvious downward trend with the increase in the use time of the polishing pad. After adding the stabilizer, this trend is significantly changed, and the increase or decrease range of the rate returns to the range of systematic error.

[0037] It can be seen from Examples 1-11 and Comparative Examples 1-4 that the components of the chemical mechanical polishing liquid in the present invention are not limited to the use system of silica sol. The silica can be silica sol or fumed silica. That is, the technical solution in the present invention is applicable to silica prepared by different methods.

[0038] Furthermore, the stability of the chemical mechanical polishing liquid was tested. The formulations of Comparative Example 4 and Example 7 were selected to prepare 200 ml of polishing liquid, which were both placed in an oven environment at 55 °C for a stability experiment. The agglomeration of abrasives was judged by measuring the change in the average particle size of the polishing liquid over time. The test results are listed in Table 3.

[0039] Table 3 Comparison of the average particle size of the polishing liquid

[0040] Chemical mechanical polishing liquid Initial average particle size (nm) Average particle size after 10 days of storage (nm) Comparative Example 4 130 197 Example 7 130 131

[0041] From the data in Table 3, it can be seen that Comparative Example 4 and Example 7 show that the average particle size of the polishing liquid in Comparative Example 4 increased from 130 nm to 197 nm after being placed in an oven at 55 °C for 10 days, while in Example 7, with the addition of an inhibitor, the average particle size basically did not change under the same environment and placement time. Obviously, the stability of Example 7 is much greater than that of Comparative Example 4, indicating that the inhibitor can well disperse the abrasives, making them not easily agglomerate and extending the storage time of the polishing liquid. Therefore, even though the polishing rate of the polishing liquid in Comparative Example 4 can remain stable during the polishing test, its stability is poor and the particle size increases, which is not conducive to storage and actual use.

[0042] It should be noted that the embodiments of the present invention have better implementability and are not 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 equivalent effective embodiments. 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 belongs to the scope of the technical solution of the present invention.

Claims

1. A chemical mechanical polishing liquid, characterized in that, Comprising: Silica abrasive particles, a polishing rate stabilizer, a potassium ion-containing compound, a polymerization inhibitor, and water; The polishing rate stabilizer is selected from one or more of monomers having a polyol or polyol ether structure and their polymers.

2. The chemical mechanical polishing liquid according to claim 1, characterized in that The stabilizer is a compound having the structural formula (1), and the structural formula (1) is: n is an integer from 1 to 50; wherein R is selected from hydrogen and linear or branched alkyl groups, and n is a positive integer with a value range of 1 to 50.

3. The chemical mechanical polishing liquid according to claim 2, characterized in that The stabilizer is selected from one or more of diethylene glycol, diethylene glycol monobutyl ether, hexaethylene glycol monomethyl ether, polyethylene glycol, and dodecyl heptaethylene glycol ether.

4. The chemical mechanical polishing liquid according to claim 3, characterized in that The stabilizer is polyethylene glycol, and the molecular weight of the polyethylene glycol is 200 to 1000.

5. The chemical mechanical polishing liquid according to claim 1, characterized in that The mass percentage content of the stabilizer is 0.05% to 5%.

6. The chemical mechanical polishing liquid according to claim 1, characterized in that The polymerization inhibitor is a compound having the structural formula (2), and the structural formula (2) is: wherein, R1, R2, R3, and R4 are independently selected from one or more of linear or branched C2 to C15 saturated or unsaturated groups.

7. The chemical mechanical polishing liquid according to claim 6, characterized in that The polymerization inhibitor is selected from one or more of tetraethylammonium hydroxide, tetrabutylammonium nitrate, benzyltrimethylammonium chloride, pentadecylammonium chloride, and decyltrimethylammonium chloride.

8. The chemical mechanical polishing liquid according to claim 1, characterized in that The mass percentage content of the polymerization inhibitor is 0.01% to 1.0%.

9. The chemical mechanical polishing liquid according to claim 1, characterized in that The average particle size of the silica abrasive particles is 45 nm to 180 nm.

10. The chemical mechanical polishing liquid according to claim 1, characterized in that 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 The potassium ion-containing compound is selected from one or more of potassium hydroxide, potassium nitrate, potassium chloride, potassium sulfate, potassium bisulfate, potassium acetate, potassium bromate, and potassium chlorate.

12. The chemical mechanical polishing liquid according to claim 1, characterized in that The mass percentage content of the potassium ion-containing compound is 0.01% to 1.5%.

13. 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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