Chemical mechanical polishing solution

Abstract

The invention provides a chemical mechanical polishing solution. The chemical mechanical polishing solution comprises grinding particles, an accelerant, a pH regulator and water. The chemical mechanical polishing solution provided by the invention can obviously reduce the defects generated on the surface of silicon dioxide in the polishing process and promote the polishing speed of silicon at the same time.

Description

Technical Field

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

[0002] The rapid development of modern chip technology has greatly promoted the miniaturization process of integrated circuit components. To ensure the normal distribution and effective operation of circuit components at the nanoscale, the planarization degree of the wafer surface must also reach the corresponding level. Currently, the most effective method to achieve this goal is chemical mechanical polishing (CMP) technology.

[0003] A semiconductor wafer typically includes a substrate on which a plurality of transistors have been formed, such as silicon (Si) or gallium arsenide (GaAs). The transistors are chemically and physically connected to the substrate by patterning regions in the substrate and layers on the substrate. The transistors and metal layers are separated by an interlayer dielectric (ILD) mainly containing a certain form of silicon dioxide (SiO2). The transistors are interconnected with each other by using well-known multi-level interconnections. A typical multi-level interconnection includes a stacked thin film composed of one or more of the following materials: titanium (Ti), titanium nitride (TiN), tantalum (Ta), aluminum-copper (Al-Cu), aluminum-silicon (Al-Si), copper (Cu), tungsten (W), doped polysilicon (poly-Si), and various combinations thereof. In addition, transistors or groups of transistors are usually isolated from each other by using trenches filled with insulating materials such as silicon dioxide, silicon nitride, and / or polysilicon.

[0004] Chemical mechanical polishing involves both chemical and mechanical actions. Generally, the wafer is fixed to a polishing head, and its front surface is brought into contact with a polishing pad in a CMP device. Under a certain pressure, the polishing head linearly moves on the polishing pad or rotates along the same movement direction as the polishing table. At the same time, a polishing composition ("slurry") is injected between the wafer and the polishing pad at a certain flow rate, and the slurry is evenly spread on the polishing pad due to centrifugal force. Thus, under the dual action of chemistry and mechanics, the surface of the wafer is polished and global planarization is achieved.

[0005] Although many known CMP slurry compositions are suitable for limited uses, they all tend to use one or several additives to reduce the defects on the silicon dioxide surface, and there is relatively little research on the influence of abrasives on the defects of the silicon dioxide surface. Summary of the Invention

[0006] In order to overcome the above technical defects, the purpose of the present invention is to provide a chemical mechanical polishing liquid, comprising: abrasive particles, a compound containing a polycyclic ring and an amino group, a pH regulator, and water.

[0007] Preferably, the abrasive particles are two or three of alumina, cerium oxide, and silicon dioxide.

[0008] Preferably, the abrasive particles are a composition of silica and nano-silica.

[0009] Preferably, the mass percentage concentration ratio of the silica to the nano-silica is 1:1 to 1:10.

[0010] Preferably, the mass percentage concentration ratio of the silica to the nano-silica is 1:5 to 1:10.

[0011] Preferably, the mass percentage concentration of the abrasive particles is 1 wt% to 40 wt%.

[0012] Preferably, the particle size of the abrasive particles is 50 nm to 150 nm.

[0013] Preferably, the compound containing a polycyclic ring and an amino group is piperazine.

[0014] Preferably, the mass percentage concentration of the accelerator is 0.01 wt% to 2 wt%.

[0015] Preferably, the mass percentage concentration of the accelerator is 0.05 wt% to 1 wt%.

[0016] Preferably, the pH regulator is one or more of ammonium hydroxide, potassium hydroxide, sodium hydroxide, nitric acid, and hydrochloric acid.

[0017] Preferably, the pH value of the chemical mechanical polishing liquid is 8.5 to 11.5.

[0018] After adopting the above technical solution, compared with the prior art, it has the following beneficial effects:

[0019] The present invention provides a polishing composition with mixed abrasives. By adjusting the ratio of abrasives with different particle sizes in the mixed abrasives, the defects generated on the surface of silica during the polishing process can be significantly reduced, and at the same time, the polishing speed of silicon can be promoted. Detailed Embodiments

[0020] The advantages of the present invention are further elaborated below in conjunction with specific embodiments.

[0021] For the specific embodiments and the comparative examples, according to the formulas given in Table 1, all components are dissolved and mixed evenly, and the mass percentage is made up to 100% with water. The pH is adjusted to the desired value with a pH regulator. Nano-silica is used in both the comparative examples and the embodiments, but the particle sizes used are different. For specific data, please refer to Table 1.

[0022] In the embodiments, the % in the concentration refers to the mass concentration.

[0023] Table 1 Components and Contents of the Chemical Mechanical Polishing Liquid in Embodiments 1-16 and Comparative Examples 1-3

[0024]

[0025]

[0026] Further detect the polishing properties of the polishing fluids in the examples and comparative examples. Conduct experiments according to the following experimental conditions:

[0027] Specific polishing conditions: pressure 234 HPa, rotational speeds of the polishing pad and polishing head 110 / 108 rpm, polishing pad IC1000, polishing fluid flow rate 200 mL / min, polishing machine Ebara, polishing time 1 min. Defect number measuring instrument: patternless wafer defect detection system SP2, scan threshold 160 nm.

[0028] The test results are shown in Table 2:

[0029] Table 2 Polishing test results of the chemical mechanical polishing fluids of Examples 1-16 and Comparative Examples 1-3

[0030]

[0031]

[0032] Based on the above test results, it can be seen that Comparative Example 1 shows that under the condition of not containing a promoter, the polishing rate of silica abrasive on silicon under alkaline pH condition is 3042 Å / min. Compared with Examples 1-7, after adding piperazine, the polishing rate of silicon increases by nearly 20%, while the number of defects and removal rate on the surface of silica basically remain unchanged. Comparative Example 2 shows that when the ratio of the two grinding particles remains unchanged, increasing the total concentration of the grinding particles will simultaneously increase the removal rates of both silica and silicon. Comparative Example 3 shows that when the concentration and ratio of the grinding particles remain unchanged, decreasing the concentration of piperazine will cause the removal rate of silicon to decrease by 15%, while the number of defects and removal rate on the surface of silica basically remain unchanged. From Examples 1-12, it can be seen that when the total concentration of the grinding particles remains unchanged, increasing the ratio of the two abrasives will cause a significant increase in the number of defects on the surface of silica. Whether reducing the total concentration of the grinding particles or increasing the ratio of the two abrasives, it will reduce the removal rates of both silica and silicon under alkaline pH conditions.

[0033] In summary, the silicon promoter proposed in this patent can significantly increase the polishing rate of silica abrasive on silicon under alkaline pH conditions while keeping the removal rate of silica unchanged. The mixed silica abrasive proposed in this patent can significantly reduce the number of defects on the surface of silica and simultaneously increase the removal rates of both silica and silicon at a certain ratio.

[0034] It should be noted that the embodiments of the present invention have better implementability and do not impose any form of limitation on the present invention. Any person skilled in the art may use the technical content disclosed above to modify or transform it into equivalent effective embodiments. However, as long as it does not depart from the content of 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: Abrasive particles, a compound containing a polycyclic ring and an amino group, a pH regulator, and water.

2. The chemical mechanical polishing liquid according to claim 1, wherein The abrasive particles are two or three of alumina, cerium oxide, and silica.

3. The chemical mechanical polishing liquid according to claim 2, wherein The abrasive particles are a composition of silica and nano-silica.

4. The chemical mechanical polishing liquid according to claim 3, wherein The mass percentage concentration ratio of the silica and nano-silica is: 1:1 to 1:

10.

5. The chemical mechanical polishing liquid according to claim 4, wherein The mass percentage concentration ratio of the silica and nano-silica is: 1:5 to 1:

10.

6. The chemical mechanical polishing liquid according to claim 3, wherein The mass percentage concentration of the abrasive particles is 1 wt% to 40 wt%.

7. The chemical mechanical polishing liquid according to claim 1, wherein The particle size of the abrasive particles is 50 nm to 150 nm.

8. The chemical mechanical polishing liquid according to claim 1, wherein The compound containing a polycyclic ring and an amino group is piperazine.

9. The chemical mechanical polishing liquid according to claim 1, wherein The mass percentage concentration of the accelerator is 0.01 wt% to 2 wt%.

10. The chemical mechanical polishing liquid according to claim 9, wherein The mass percentage concentration of the accelerator is 0.05 wt% to 1 wt%.

11. The chemical mechanical polishing liquid according to claim 1, wherein The pH regulator is one or more of ammonium hydroxide, potassium hydroxide, sodium hydroxide, nitric acid, and hydrochloric acid.

12. The chemical mechanical polishing liquid according to claim 1, wherein The pH value of the chemical mechanical polishing liquid is 8.5 to 11.5.

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