Oxidation film polishing solution and preparation method thereof

Abstract

The invention relates to an oxide film polishing solution and a preparation method thereof, and the oxide film polishing solution comprises the following raw materials in percentage by mass: 96.9-99.969 wt% of silica sol, 0.01-1 wt% of an organic acid additive, 0.01-1 wt% of a pH regulator, 0.01-1 wt% of a dispersant and 0.001-0.1 wt% of a bactericide. Through reasonable formula design of the oxidation film polishing solution, the prepared oxidation film polishing solution solves the problem that a traditional CMP oxidation film polishing solution is low in polishing rate, the chip manufacturing cost is reduced, and the number of defects generated after polishing is low; meanwhile, the oxidation film polishing solution has the characteristic of wide polishing rate range, different polishing rates can be customized according to requirements, and diversified market requirements are met.

Description

Technical Field

[0001] The invention relates to the technical field of chemical mechanical polishing, and in particular to an oxide film polishing liquid and a preparation method thereof. Background Art

[0002] In the mid-1960s, most semiconductor substrates were polished by mechanical polishing, which resulted in extremely severe damage to the mirror surface. In the 1970s, chemical mechanical polishing (CMP) technology represented by silica sol gradually replaced traditional mechanical polishing. Since the 1990s, with the development of the electronics industry, the demand for silica sol, a raw material for silicon wafer polishing liquid, has increased sharply.

[0003] Silica sol is a polishing material for CMP technology with excellent performance. It can be used for rough polishing, fine polishing of silicon wafers and IC processing, and is particularly suitable for planarization of multi-layered films of large-scale integrated circuits. Silica sols of different particle sizes will produce different removal rates, providing a variety of options for the planarization process of chip manufacturing. For example, CN106978088A discloses a method for preparing a silica sol polishing liquid, comprising the following steps: S1, mixing silica sol with a particle size of 100-120nm and a solid content of 43-45% and silica sol with a particle size of 20-30nm and a solid content of 43-45% in a molar ratio of 7:3; S2, adding 0.3-0.5% KCl or NaCl solution to the mixed silica sol solution at a rate of 10-20kg / h, stirring with a stirring rod at a speed of 60-80r / min, and standing for 1-2h after adding; S3, adding a 10% KOH or NaOH solution at a speed of 10-20kg / h until the pH of the mixed solution is adjusted to 10.0-10.5. The silica sol polishing liquid prepared by this method has the advantages of high polishing rate and good polishing surface quality for sapphire polishing.

[0004] The polishing liquid used for polishing the oxide film on the surface of the wafer also uses silica sol as a raw material, but the current oxide film polishing liquid is expensive, and the polishing rate of ordinary oxide film polishing liquid is low, which does not have product advantages. CN109401630A discloses an aluminum alloy anodic oxide film mirror polishing liquid and a preparation method thereof. The aluminum alloy anodic oxide film mirror polishing liquid is prepared from high-purity aluminum oxide micropowder, dispersant, wetting agent, surfactant, buffer, and pure water as raw materials. The mass percentage of each raw material of the aluminum alloy anodic oxide film mirror polishing liquid is: aluminum oxide micropowder: 1-30%, dispersant: 5-30%, wetting agent: 0.1-10%, surfactant: 0.1-5%, buffer: 0.1-5%, pure water: 20-93.7%. The average particle size of the α-type aluminum oxide micropowder used in the invention is between 0.5-2.0μm. However, the polishing rate range of the polishing liquid is relatively narrow, and it does not involve whether the number of defects on the oxide film surface after polishing can meet the requirements.

[0005] Therefore, in view of the shortcomings of the prior art, it is necessary to provide an oxide film polishing liquid with low cost, high polishing rate and low number of defects after polishing. Summary of the invention

[0006] The purpose of the present invention is to provide an oxide film polishing liquid and a preparation method thereof, which solves the problem of low polishing rate of traditional oxide film polishing liquid and has the advantage of low cost.

[0007] In order to achieve the purpose of the invention, the present invention adopts the following technical solutions:

[0008] In the first aspect, the present invention provides an oxide film polishing liquid. Based on the total mass percentage of 100wt%, the raw materials of the oxide film polishing liquid include: 96.9-99.969wt% of silica sol, 0.01-1wt% of organic acid additive, 0.01-1wt% of pH adjuster, 0.01-1wt% of dispersant, and 0.001-0.1wt% of bactericide.

[0009] The oxide film polishing liquid provided by the present invention is prepared through a reasonable oxide film polishing liquid formula design, which solves the problem of low polishing rate of traditional CMP oxide film polishing liquid, reduces chip manufacturing costs, and has a lower number of defects after polishing; at the same time, the oxide film polishing liquid has the characteristics of a wide polishing rate range, and different polishing rates can be customized according to needs to meet diversified market demands.

[0010] The mass percentage of silica sol in the raw material of the oxide film polishing liquid is 96.9-99.969wt%, for example, it can be 96.9wt%, 97.5wt%, 98wt%, 99wt% or 99.969wt%, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0011] The mass percentage of the organic acid additive in the raw materials of the oxide film polishing liquid is 0.01-1wt%, for example, it can be 0.01wt%, 0.05wt%, 0.1wt%, 0.5wt% or 1wt%, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0012] The mass percentage of the pH adjuster in the raw materials of the oxide film polishing liquid is 0.01-1wt%, for example, it can be 0.01wt%, 0.05wt%, 0.1wt%, 0.5wt% or 1wt%, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0013] The mass percentage of the dispersant in the raw materials of the oxide film polishing liquid is 0.01-1wt%, for example, it can be 0.01wt%, 0.05wt%, 0.1wt%, 0.5wt% or 1wt%, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0014] The mass percentage of the bactericide in the raw materials of the oxide film polishing liquid is 0.001-0.1wt%, for example, it can be 0.001wt%, 0.005wt%, 0.01wt%, 0.05wt% or 0.1wt%, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0015] Preferably, the solid content of the silica sol is 10-20%, for example, 10%, 12%, 15%, 18% or 20%, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0016] Preferably, the average particle size of the particles in the silica sol is 40-100 nm, for example, 40 nm, 50 nm, 60 nm, 80 nm or 100 nm, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0017] In the present invention, by selecting the appropriate solid content and average particle size of the silica sol, the oxide film polishing liquid can have a higher dilution ratio and a faster polishing rate.

[0018] Preferably, the organic acid additive comprises any one of malonic acid, maleic acid or acetic acid or a combination of at least two thereof, and typical but non-limiting combinations include a combination of malonic acid and maleic acid, a combination of maleic acid and acetic acid, or a combination of malonic acid, maleic acid and acetic acid.

[0019] Preferably, the pH adjuster comprises any one of nitric acid, aqueous ammonia or tetramethylammonium hydroxide or a combination of at least two thereof. Typical but non-limiting combinations include a combination of nitric acid and aqueous ammonia, a combination of aqueous ammonia and tetramethylammonium hydroxide, or a combination of nitric acid, aqueous ammonia and tetramethylammonium hydroxide.

[0020] Preferably, the dispersant comprises any one of polyacrylic acid, polyvinyl pyrrolidone or polyethylene glycol, or a combination of at least two thereof. Typical but non-limiting combinations include a combination of polyacrylic acid and polyvinyl pyrrolidone, a combination of polyvinyl pyrrolidone and polyethylene glycol, or a combination of polyacrylic acid, polyvinyl pyrrolidone and polyethylene glycol.

[0021] Preferably, the fungicide comprises an isothiazolinone.

[0022] In a second aspect, the present invention provides a method for preparing the oxide film polishing liquid as described in the first aspect, the preparation method comprising the following steps:

[0023] The formulated raw materials are weighed, and the silica sol and the dispersant are first uniformly mixed, and then the organic acid additive is added and mixed continuously, and then the pH adjuster is added and mixed continuously, and finally the bactericide is added and mixed uniformly to obtain the oxide film polishing liquid.

[0024] The method for preparing an oxide film polishing liquid provided by the present invention controls the order of adding the raw material components and adjusts the mixing rotation speed, so that the prepared oxide film polishing liquid has a high polishing rate and a low number of defects after polishing, and can meet the process requirements of different processes in a wafer fab.

[0025] Preferably, the mixing rotation speed is 5-300 r / min, for example, it can be 5 r / min, 50 r / min, 100 r / min, 200 r / min or 300 r / min, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0026] Preferably, the bactericide is added and mixed evenly before filtering and filling.

[0027] As a preferred technical solution of the preparation method of the present invention, the preparation method comprises the following steps:

[0028] Weigh the formulated raw materials, first uniformly mix the silica sol and the dispersant at a speed of 5-300 r / min, then add the organic acid additive and continue mixing, then add the pH adjuster and mix, finally add the bactericide and mix evenly, and obtain the oxide film polishing liquid after filtering and filling.

[0029] Compared with the prior art, the present invention has the following beneficial effects:

[0030] The oxide film polishing liquid provided by the present invention is prepared through a reasonable oxide film polishing liquid formula design, which solves the problem of low polishing rate of traditional CMP oxide film polishing liquid, reduces chip manufacturing costs, and the number of defects generated after polishing is as low as 21; at the same time, the oxide film polishing liquid has the characteristics of good polishing effect and a wide range of polishing rates, and different polishing rates can be customized according to needs to meet diversified market demands. DETAILED DESCRIPTION

[0031] The technical solution of the present invention is further described below by specific implementation methods. It should be understood by those skilled in the art that the embodiments are only to help understand the present invention and should not be regarded as specific limitations of the present invention.

[0032] Example 1

[0033] This embodiment provides an oxide film polishing liquid, and the raw materials of the oxide film polishing liquid include: 98wt% of silica sol, 0.5wt% of malonic acid, 0.5wt% of nitric acid, 0.5wt% of polyacrylic acid, and 0.5wt% of isothiazolinone, based on the total mass percentage of 100wt%.

[0034] The solid content of the silica sol is 15%; the average particle size of the particles in the silica sol is 60nm.

[0035] The preparation method of the oxide film polishing liquid comprises the following steps:

[0036] Weigh the formulated raw materials, first uniformly mix the silica sol and polyacrylic acid at a speed of 100 r / min, then add malonic acid to continue mixing, then add nitric acid to mix, and finally add isothiazolinone to mix uniformly, and obtain the oxide film polishing liquid after filtering and filling.

[0037] Example 2

[0038] This embodiment provides an oxide film polishing liquid, and the raw materials of the oxide film polishing liquid include: 96.9wt% of silica sol, 1wt% of maleic acid, 1wt% of ammonia water, 1wt% of polyvinyl pyrrolidone, and 0.1wt% of isothiazolinone based on the total mass percentage of 100wt%;

[0039] The solid content of the silica sol is 20%; the average particle size of the particles in the silica sol is 100 nm.

[0040] The preparation method of the oxide film polishing liquid comprises the following steps:

[0041] Weigh the formulated raw materials, first uniformly mix the silica sol and polyvinyl pyrrolidone at a speed of 5 r / min, then add maleic acid to continue mixing, then add ammonia water to mix, and finally add isothiazolinone to mix evenly, and obtain the oxide film polishing liquid after filtering and filling.

[0042] Example 3

[0043] This embodiment provides an oxide film polishing liquid, and the raw materials of the oxide film polishing liquid include: 99.969wt% of silica sol, 0.01wt% of acetic acid, 0.01wt% of nitric acid, 0.01wt% of polyethylene glycol, and 0.001wt% of isothiazolinone, based on the total mass percentage of 100wt%.

[0044] The solid content of the silica sol is 10%; the average particle size of the particles in the silica sol is 40nm.

[0045] The preparation method of the oxide film polishing liquid comprises the following steps:

[0046] Weigh the formulated raw materials, first uniformly mix the silica sol and polyethylene glycol at a speed of 300 r / min, then add acetic acid to continue mixing, then add nitric acid to mix, and finally add isothiazolinone to mix uniformly, and obtain the oxide film polishing liquid after filtering and filling.

[0047] Example 4

[0048] This embodiment provides an oxide film polishing liquid, which is different from the embodiment 1 in that, except that the solid content of the silica sol is adjusted to 5%, the rest is the same as the embodiment 1.

[0049] Example 5

[0050] This embodiment provides an oxide film polishing liquid, which is different from the embodiment 1 in that, except that the solid content of the silica sol is adjusted to 25%, the rest is the same as the embodiment 1.

[0051] Example 6

[0052] This embodiment provides an oxide film polishing liquid, which is different from Embodiment 1 in that, except that the average particle size of the particles in the silica sol is adjusted to 30 nm, the rest is the same as Embodiment 1.

[0053] Example 7

[0054] This embodiment provides an oxide film polishing liquid, which is different from Embodiment 1 in that, except that the average particle size of the particles in the silica sol is adjusted to 110 nm, the rest is the same as Embodiment 1.

[0055] Comparative Example 1

[0056] This comparative example provides an oxide film polishing liquid, which is different from Example 1 in that polyacrylic acid is not added to the raw materials of the oxide film polishing liquid, the mass percentage of silica sol is adaptively adjusted to 98.5wt%, and the rest is the same as Example 1.

[0057] Comparative Example 2

[0058] This comparative example provides an oxide film polishing liquid, which is different from Example 1 in that the raw materials of the oxide film polishing liquid are adjusted to: 96wt% silica sol, 1.2wt% malonic acid, 1.3wt% nitric acid, 1.2wt% polyacrylic acid, 0.3wt% isothiazolinone, and the rest are the same as Example 1.

[0059] Comparative Example 3

[0060] This comparative example provides an oxide film polishing liquid, which is different from Example 1 in that the raw materials of the oxide film polishing liquid are adjusted to: 99.98wt% silica sol, 0.005wt% malonic acid, 0.005wt% nitric acid, 0.005wt% polyacrylic acid, 0.005wt% isothiazolinone, and the rest are the same as Example 1.

[0061] The oxide film of the wafer was mechanically chemically polished using the oxide film polishing liquid provided in Examples 1-7 and Comparative Examples 1-3, and the polishing rate of the oxide film polishing liquid was tested. The results are shown in Table 1. The number of defects on the polished surface was detected using a wafer defect particle detection system, and the results are shown in Table 1.

[0062] Table 1

[0063]

[0064]

[0065] It can be seen from Table 1 that the oxide film polishing liquid provided by the present invention has a high polishing rate and a low number of defects, and can meet the process requirements of different processes in wafer factories;

[0066] From the comparison between Example 1 and Examples 5-7, it can be seen that the solid content and average particle size of the silica sol have a certain influence on the polishing rate of the oxide film polishing liquid. When the polishing rate exceeds the specified range, the polishing rate decreases and the defects generated increase.

[0067] By comparing Example 1 with Comparative Example 1, it can be seen that not adding a dispersant has an adverse effect on the polishing effect of the oxide film polishing liquid; by comparing Example 1 with Comparative Examples 2 and 3, it can be seen that when the raw material ratio range specified in this application is exceeded, the number of defects generated increases significantly.

[0068] In summary, the oxide film polishing liquid provided by the present invention is prepared through a reasonable oxide film polishing liquid formula design, which solves the problem of low polishing rate of traditional CMP oxide film polishing liquid, reduces chip manufacturing costs, and has a lower number of defects after polishing; at the same time, the oxide film polishing liquid has the characteristics of a wide polishing rate range, and different polishing rates can be customized according to needs to meet diversified market demands.

[0069] The above description is only a specific implementation mode of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily thought of by those skilled in the art within the technical scope disclosed by the present invention are within the protection scope and disclosure scope of the present invention.

Claims

1. An oxide film polishing liquid, characterized in that: Taking the total mass percentage as 100wt%, the raw materials of the oxide film polishing liquid include: 96.9-99.969wt% of silica sol, 0.01-1wt% of organic acid additive, 0.01-1wt% of pH regulator, 0.01-1wt% of dispersant, and 0.001-0.1wt% of bactericide.

2. The oxide film polishing liquid according to claim 1, characterized in that: The solid content of the silica sol is 10-20%.

3. The oxide film polishing liquid according to claim 1 or 2, characterized in that: The average particle size of the particles in the silica sol is 40-100 nm.

4. The oxide film polishing liquid according to any one of claims 1 to 3, characterized in that: The organic acid additive includes any one of malonic acid, maleic acid or acetic acid, or a combination of at least two thereof; Preferably, the pH adjuster includes any one of nitric acid, ammonia water or tetramethylammonium hydroxide, or a combination of at least two thereof.

5. The oxide film polishing liquid according to any one of claims 1 to 4, characterized in that: The dispersant includes any one of polyacrylic acid, polyvinyl pyrrolidone or polyethylene glycol, or a combination of at least two of them.

6. The oxide film polishing liquid according to any one of claims 1 to 5, characterized in that: The fungicide includes isothiazolinone.

7. A method for preparing an oxide film polishing liquid as claimed in any one of claims 1 to 6, characterized in that: The preparation method comprises the following steps: The formulated raw materials are weighed, and the silica sol and the dispersant are first uniformly mixed, and then the organic acid additive is added and mixed continuously, and then the pH adjuster is added and mixed continuously, and finally the bactericide is added and mixed uniformly to obtain the oxide film polishing liquid.

8. The preparation method according to claim 7, characterized in that: The mixing speed is 5-300r / min.

9. The preparation method according to claim 7 or 8, characterized in that: The bactericide is added and mixed evenly, and then filtered and filled.

10. The preparation method according to any one of claims 7 to 9, characterized in that: The preparation method comprises the following steps: Weigh the formulated raw materials, first uniformly mix the silica sol and the dispersant at a speed of 5-300 r / min, then add the organic acid additive and continue mixing, then add the pH adjuster and mix, finally add the bactericide and mix evenly, and obtain the oxide film polishing liquid after filtering and filling.

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