Chemical mechanical polishing slurry and use thereof

Abstract

The present invention provides a chemical mechanical polishing slurry comprising: cerium oxide abrasive particles having a surface potential below -30mV, and piperazine. In the described technical solution, the chemical mechanical polishing slurry significantly increases the Si removal rate; meanwhile, TEOS can also allow for a relatively high removal rate of up to 5000 Å / min or more, for example. In addition, TEOS:Si removal selectivity can be adjusted to 1:1.

Description

Chemical mechanical polishing liquid and use thereof Technical Field

[0001] The present invention relates to the field of chemical polishing, in particular to a chemical mechanical polishing liquid and application thereof. Background Art

[0002] With the rise of SoIC (System on Integrated Chips), the requirement for CMP slurry is to have similar but higher polishing rates on silicon oxide (TEOS) and silicon (Si) substrates, that is, the polishing rate of TEOS and Si is 1:1, and the polishing rate of both is as high as possible, for example, higher than or higher Common polishing solutions for polishing TEOS on the market include cerium oxide polishing solution and silicon oxide polishing solution.

[0003] Generally speaking, the TEOS polishing rate of cerium oxide polishing liquid is much higher than that of silicon oxide polishing liquid. The TEOS polishing rate of silicon oxide polishing liquid can reach Above, but difficult to achieve On the other hand, silicon oxide chemical mechanical polishing liquid can achieve a very high Si polishing rate, such as Above, even As described above (US8017524 B2), it is difficult to adjust the TEOS:Si polishing selectivity to 1:1. Summary of the Invention

[0004] In order to overcome the above technical defects, the present invention provides a chemical mechanical polishing solution, which includes cerium oxide abrasive particles with a negative zeta potential (<-30mV) and piperazine. Under alkaline conditions (pH 9-12), piperazine can effectively improve the polishing rate of Si. In addition, the polishing selectivity ratio of TEOS and Si can be adjusted to close to 1:1, and the polishing rates of both can reach Above, close to

[0005] Specifically, the present invention discloses a chemical mechanical polishing liquid, comprising piperazine and cerium oxide particles with a surface potential lower than -30 mV; the particle size of the cerium oxide abrasive particles ranges from 20 to 500 nm; and the mass percentage concentration of piperazine ranges from 10 ppm to 3000 ppm.

[0006] Preferably, the cerium oxide particles include sol-type and calcined cerium oxide.

[0007] Preferably, the concentration of the cerium oxide particles is 0.1 wt%-1.0 wt%.

[0008] Preferably, the particle size of the cerium oxide particles is 150-220 nm.

[0009] Preferably, the mass percentage concentration of the piperazine is 100 ppm to 1500 ppm.

[0010] Preferably, the chemical mechanical polishing solution further comprises a pH regulator, and the pH regulator is selected from KOH or HAc.

[0011] Preferably, the pH value of the chemical mechanical polishing solution is 9-12.

[0012] Another aspect of the present invention provides a use of a chemical mechanical polishing solution, wherein any of the above chemical mechanical polishing solutions is used to adjust the polishing selectivity of TEOS:Si to 1:1.

[0013] Compared with the existing technology, the above technical solution has the following beneficial effects:

[0014] 1. A high polishing rate can be achieved for both TEOS and Si, for example, reaching or exceeding

[0015] 2. Simultaneously adjust the TEOS:Si polishing selectivity to 1:1. DETAILED DESCRIPTION

[0016] The advantages of the present invention are further described below with reference to specific embodiments.

[0017] Exemplary embodiments will be described in detail herein, with examples illustrated in the accompanying drawings. In the following description, when referring to the drawings, identical numerals in different figures represent identical or similar elements, unless otherwise indicated. The embodiments described in the following exemplary embodiments are not intended to represent all possible embodiments consistent with the present disclosure. Rather, they are merely examples of apparatus and methods consistent with certain aspects of the present disclosure, as detailed in the appended claims.

[0018] Polishing rate detection method of the chemical mechanical polishing solution in the comparative examples and embodiments of the present invention:

[0019] TEOS and Si blank wafers were polished using a Mirra polisher. The polishing conditions included an IC1010 polishing pad, platter and carrier speeds of 93 rpm and 87 rpm, respectively, a pressure of 3 psi, and a polishing fluid flow rate of 150 mL / min. TEOS film thickness was measured using a NanoSpec film thickness measurement system (NanoSpec 6100-300, Shanghai Nanospec Technology Corporation). Blank film thickness was measured at 49 points equally spaced along the diameter starting at 3 mm from the wafer edge. The polishing rate was the average of these 49 points. Si removal was determined gravimetrically. Si wafers were weighed before and after polishing using an analytical balance with an accuracy of 0.0002 g. The total weight loss was divided by the wafer area and Si density to calculate the average thickness removed, which was then divided by the polishing time to calculate the polishing rate.

[0020] The Zeta potential of the cerium oxide particle surface is measured as follows:

[0021] The surface charge of cerium oxide particles is characterized by zeta potential. The cerium oxide polishing solution is diluted to a 0.2% cerium oxide particle concentration and then placed in a quartz cuvette. Zeta potential is measured using a Malvern instrument.

[0022] Effect embodiment 1:

[0023] To demonstrate the effectiveness of piperazine in enhancing the polishing rate of silicon (Si) in a polishing slurry, a series of amino-containing molecules were tested in a polishing slurry containing 0.5 wt% sol-type cerium oxide particles (referred to as Type-1). Type-1 cerium oxide particles are negatively charged (zeta potential less than -30 mV) and approximately 150 nm in size.

[0024] According to the proportions of the components in Table 1, each component was dissolved in deionized water, the pH was adjusted to 12 with KOH, and the weight percentage was supplemented with deionized water to 100%, thereby obtaining the chemical mechanical polishing solutions of Comparative Examples 1-6 and Example 1 of the present invention. The polishing rates of Si and TEOS measured according to the above test method are shown in Table 1.

[0025] Table 1 Components and contents of chemical mechanical polishing liquids and polishing performance of comparative examples 1-6 and embodiment 1

[0026] According to the data in Table 1, at a pH of 12, the silicon removal rate of Comparative Example 1 containing only cerium oxide particles is Taking this as a standard, the Si polishing rates of Comparative Examples 2-5, which added methylguanamine, triethylamine alcohol, salicylic acid hydrazide, and carbohydrazide, respectively, were all reduced by more than 20%; 1,2,4-triazole had almost no effect on the silicon polishing rate. In contrast to the above compounds, the addition of piperazine increased the silicon polishing rate by 20%. In summary, when the surface of cerium oxide particles is negatively charged, under high pH conditions (12), the addition of piperazine can effectively increase the polishing rate of silicon by the polishing liquid. This may be because the addition of piperazine promotes the breaking of Si-Si bonds under chemical mechanical action. In addition, after the addition of piperazine, due to the significant increase in the Si polishing rate, the removal rate of TEOS and Si can be adjusted to 1:1.

[0027] Effect embodiment 2:

[0028] To investigate the effect of piperazine concentration on Si polishing rates, cerium oxide polishing solutions containing varying concentrations of piperazine were prepared based on Comparative Example 1. As shown in Table 2, the components were dissolved in deionized water according to the ratios listed in Table 2. The pH was adjusted to 12 with KOH, and the weight percentage was supplemented with deionized water to 100%. This yielded the chemical mechanical polishing solutions of Comparative Example 1 and Examples 1-4 of the present invention. The corresponding polishing data are shown in Table 2.

[0029] Table 2 Components and contents of chemical mechanical polishing liquids and polishing performance of Examples 1-6 and Comparative Example 1

[0030] The components and contents of Comparative Example 1 and Example 1 are identical to those in Table 1. The polishing rates show slight fluctuations, falling within the normal range. The results in Table 2 demonstrate that piperazine concentrations ranging from 10 ppm to 3000 ppm can improve the Si polishing rate of the polishing solution, reaching a maximum at 3000 ppm. Compared to Comparative Example 1, which lacks piperazine, the polishing rates of Examples 3-6 all increase Si polishing rates by at least 20%.

[0031] Effect Example 3

[0032] To further examine the pH range required for piperazine to improve the Si polishing rate, piperazine was added to a dispersion containing negatively charged cerium oxide particles at a concentration of 0.1 wt %. The pH of the polishing solution was adjusted to 11, 9, and 5, respectively, using potassium hydroxide or acetic acid. The pH was then adjusted to 100% by weight using water. The components and amounts of the chemical mechanical polishing solutions for Examples 5-6 and Comparative Examples 7-10, as well as their polishing performance, are shown in Table 3.

[0033] Table 3. Components, contents, and polishing performance of chemical mechanical polishing solutions of Examples 7-8 and Comparative Examples 7-10

[0034] Comparative Example 7 contains Type-2 sol-type cerium oxide particles, which, like Type-1 cerium oxide particles, have a negative zeta potential (<-30 mV) and a particle size of approximately 150 nm. The difference lies in the different dispersions used. Example 4 adds 1000 ppm of piperazine to Comparative Example 7. Comparative Example 8 lowers the pH to 9 based on Comparative Example 7. Example 5 further adds 1000 ppm of piperazine to Comparative Example 8. Further lowering the pH in the Type-2 cerium oxide system would destabilize the cerium oxide colloidal particles, causing particle agglomeration and precipitation. Therefore, to prevent particle precipitation, Comparative Example 9 uses calcined cerium oxide particles (Type-3) with a negative zeta potential (<-30 mV) and a particle size of approximately 220 nm, which are stable at a pH of 5. Comparative Example 10 adds 1000 ppm of piperazine to Comparative Example 9. Based on the test data in Table 3, it can be seen that in the alkaline range, such as at pH 9 and 11, the addition of piperazine can increase the polishing rate of Si in the polishing solution. However, when the pH is adjusted to 5, the effect of piperazine on the polishing rate of Si disappears. In summary, piperazine can increase the polishing rate of Si in the pH range of 9-12.

[0035] Effect Example 4

[0036] The effect of piperazine on the Si rate in cerium oxide dispersions of varying concentrations was further verified. According to the component ratios listed in Table 4, each component was dissolved in deionized water, the pH was adjusted to 12 with KOH, and the weight percentage was made up to 100% with deionized water to produce the chemical mechanical polishing solutions of the comparative example and the example. Polishing data measured using the above test method is shown in Table 4.

[0037] Table 4 Components, contents and polishing test results of Comparative Examples 1, 11-12 and Examples 1, 9-10

[0038] The results in Table 4 show that at a cerium oxide concentration of 0.1%, Comparative Example 11 exhibited almost no polishing rate for Si, whereas the addition of piperazine significantly improved the Si polishing rate. Similarly, the addition of 1000 ppm of piperazine to polishing solutions with 0.5% and 1% cerium oxide concentrations significantly increased the Si polishing rate.

[0039] Effect Example 5

[0040] To further verify the influence of the surface charge of cerium oxide particles, the polishing performance of a polishing solution using positively charged cerium oxide (Type-4 cerium oxide particles, zeta potential >30 mV) was tested. According to the ratios in Table 5, the components were dissolved in deionized water. The pH was adjusted to 5 with HAc (since positively charged cerium oxide particles tend to aggregate and precipitate under alkaline pH conditions, the pH was set at 5 to stabilize the particles). Deionized water was then added to the final weight percentage of 100%, yielding the chemical mechanical polishing solutions of Comparative Examples 13 and 14 of the present invention. The corresponding polishing data are shown in Table 5.

[0041] Table 5. Components, contents, and polishing performance of chemical mechanical polishing solutions of Comparative Examples 13-14

[0042] As shown in Table 4, regardless of the addition of piperazine, the Si polishing rate of the polishing solution is very low, approaching the measurement limit of silicon weight loss. Therefore, the addition of piperazine to the polishing solution containing positively charged cerium oxide particles does not increase the Si polishing rate.

[0043] Effect Example 6

[0044] To further verify the influence of cerium oxide particle size, the polishing performance of cerium oxide polishing solutions with different particle sizes was tested. According to the component ratios listed in Table 6, each component was dissolved in deionized water, the pH was adjusted to 12 with KOH, and the weight percentage was made up to 100% with deionized water to produce the chemical mechanical polishing solutions of the comparative example and the example. The polishing data measured according to the above test method is shown in Table 6.

[0045] Table 6. Component content, polishing performance, and particle size of Comparative Examples 1, 15-16, and Examples 1, 11-12

[0046] Type 5 is a sol-type cerium oxide particle with a negative zeta potential (<-30mV) and a particle size of approximately 20nm. Type 6 is a calcined cerium oxide particle with a negative zeta potential (<-30mV) and a particle size of approximately 500nm. Table 6 shows that piperazine improves the polishing rate of Si for cerium oxide particles with a particle size distribution of 20-500nm.

[0047] It should be noted that the embodiments of the present invention have better practicability and do not impose any form of limitation on the present invention. Any technician familiar with the field may use the technical content disclosed above to change or modify it into an equivalent effective embodiment. However, any modification or equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solution of the present invention are still within the scope of the technical solution of the present invention.

Claims

1. A chemical mechanical polishing liquid, characterized in that: include: Cerium oxide abrasive particles and piperazine having a surface potential below -30 mV; The particle size of the cerium oxide abrasive particles ranges from 20 to 500 nm; The mass percentage concentration of piperazine is 10 ppm to 3000 ppm.

2. The chemical mechanical polishing solution according to claim 1, characterized in that: The cerium oxide abrasive particles include sol-type and calcined cerium oxide particles.

3. The chemical mechanical polishing solution according to claim 1, characterized in that: The concentration of the cerium oxide particles is 0.1 wt%-1.0 wt%.

4. The chemical mechanical polishing solution according to claim 1, characterized in that: The particle size of the cerium oxide particles is in the range of 20-500 nm.

5. The chemical mechanical polishing solution according to claim 1, characterized in that: The mass percentage concentration of the piperazine is 10ppm to 3000ppm.

6. [Corrected 20.12.2024 in accordance with Rule 26] The chemical mechanical polishing liquid according to claim 1, characterized in that: The polishing liquid includes a pH adjuster.

7. The chemical mechanical polishing composition according to claim 6, wherein The pH regulator is KOH or HAc.

8. The chemical mechanical polishing solution according to claim 1, characterized in that: The pH value of the chemical mechanical polishing liquid is 9-12.

9. Use of a chemical mechanical polishing solution, wherein the chemical mechanical polishing solution according to any one of claims 1 to 8 is used to adjust the polishing selectivity of TEOS:Si to 1:1.

Images