Chemical mechanical polishing liquid and use thereof

Abstract

The application discloses a high-concentration chemical mechanical polishing liquid and application thereof. The polishing liquid comprises silica particles, an aminosilane compound and a non-ionic surfactant. The chemical mechanical polishing liquid can be used for polishing silica, silicon nitride and polysilicon, meets the polishing rate and selectivity ratio requirements of various materials in the polishing process, has strong correction ability for the planarization of a device surface of a silicon wafer, can realize rapid planarization, improves work efficiency and reduces production cost.

Description

Technical Field

[0001] This invention relates to the field of chemical mechanical polishing, and more particularly to a chemical mechanical polishing slurry applicable to polishing silicon dioxide, silicon nitride and polycrystalline silicon. Background Technology

[0002] In the manufacturing process of integrated circuits, thousands of structural units are often built on silicon wafer substrates. These structural units are further interconnected through multiple layers of metal to form functional circuits and components. In multilayer metal interconnect structures, silicon dioxide or silicon dioxide doped with other elements is filled between metal wires as interlayer dielectric (ILD). With the development of integrated circuit metal interconnect technology and the increase in the number of wiring layers, chemical mechanical polishing (CMP) has been widely used for surface planarization in chip manufacturing processes. These planarized chip surfaces facilitate the production of multilayer integrated circuits and effectively prevent distortion caused by dielectric layers being coated on uneven surfaces.

[0003] CMP (Chemical Mechanical Polishing) is a process that uses a mixture of abrasive particles and a polishing pad to polish the surface of integrated circuits. In a typical chemical mechanical polishing method, the substrate is placed in direct contact with a rotating polishing pad, and pressure is applied to the back of the substrate using a weight. During polishing, the pad and stage are rotated while maintaining a downward force on the back of the substrate, applying abrasive particles and a chemically active solution (often called a polishing slurry or polishing paste) to the pad. The polishing slurry reacts chemically with the film being polished, initiating the polishing process.

[0004] The method used to isolate components in semiconductor devices is called shallow trench isolation (STI) process. It typically involves forming a silicon nitride layer on a silicon substrate, creating shallow trenches within the silicon nitride layer, and filling the trenches with a deposited dielectric material (e.g., silicon dioxide). To ensure complete trench filling, excess dielectric material is typically deposited on top of the substrate. This excess dielectric material is then removed using chemical mechanical planarization (CMP) to expose the silicon nitride layer. In STI, the silicon nitride layer acts as a stop layer for CMP, requiring a high silicon dioxide (TEOS) removal rate and a low silicon nitride removal rate—a high selectivity ratio of silicon dioxide to silicon nitride removal rates. For example, CN100339420C discloses a polishing slurry comprising cerium oxide, a zwitterionic compound, a carboxylic acid polymer, and a cationic compound, which effectively improves the selectivity ratio of silicon dioxide to silicon nitride removal rates by employing the zwitterionic compound. However, the use of cerium oxide as abrasive particles in this process leads to precipitation and stratification in the polishing slurry, placing high demands on in-line equipment and increasing production costs. Furthermore, the polishing of devices such as ultra-high density dynamic memory (DRAM) and flash memory also involves the polishing of polysilicon. Particularly in the polishing process of flash memory, a low silicon dioxide / polysilicon polishing rate selectivity often results in dish-shaped depressions in the polysilicon during the final polishing process. These depressions worsen with increasing trench width between silicon dioxide particles, severely impacting device performance. Therefore, to reduce this issue, it is necessary to control the polysilicon removal rate and adjust the silicon dioxide / polysilicon removal rate selectivity to significantly improve polysilicon planarization efficiency and reduce dish-shaped depressions. For example, US2003 / 0153189A1 discloses an abrasive particle containing cerium oxide and alumina and a polycarboxylate surfactant, which can effectively improve the polishing rate of polysilicon and reduce the occurrence of dish-shaped depressions. However, this patent uses cerium oxide abrasive particles, which easily cause precipitation and stratification in the polishing slurry. Furthermore, the high hardness of alumina abrasive particles can easily cause scratches and other defects on the wafer surface. Therefore, the polishing slurry cannot achieve high polishing rates for polycrystalline silicon and reduce dish-shaped depressions while simultaneously lowering production costs. Additionally, CN104371549 discloses a chemical mechanical polishing slurry containing a silane coupling agent for polishing barrier layers containing low-k materials. The addition of the silane coupling agent can achieve high concentration and colloidal stability of the chemical mechanical polishing slurry under alkaline conditions, but the addition of the silane coupling agent has no effect on the removal rate of silicon dioxide, nor does it mention the polishing effect on silicon nitride and polycrystalline silicon.

[0005] Currently, various chemical mechanical polishing (CMP) slurries are typically formulated to meet the polishing rate and selectivity requirements of different materials in various processes, thereby achieving rapid planarization, improving work efficiency, and reducing production costs. For example, CMP slurries are more effective at removing silicon dioxide than polycrystalline silicon, and more effective at removing silicon dioxide than silicon nitride. Therefore, a CMP slurry is needed that can simultaneously meet the polishing rate and selectivity requirements of different materials in different processes.

[0006] To address the aforementioned issues, this invention provides a chemical mechanical polishing slurry that can meet the requirements for removal rates and selectivity of silicon dioxide, silicon nitride, and polycrystalline silicon in different polishing processes, enabling rapid planarization, effectively improving work efficiency, and reducing production costs. Summary of the Invention

[0007] The present invention provides a chemical mechanical polishing slurry that can be used to polish silicon dioxide, silicon nitride and polycrystalline silicon, the polishing slurry comprising silicon dioxide particles, aminosilane compounds, nonionic surfactants and water.

[0008] The grinding particles are silica nanoparticles with a content of 0.5-30 wt%, preferably 2-20%; and a particle size of 20-200 nm, preferably 30-150 nm.

[0009] The structural formula of the aminosilane compound is shown below:

[0010] Where n = 1 to 12,

[0011] R1, R2 = (x = 0, 1; y = 0 ~ 11)

[0012] R3, R4, R5, R6 = H (z = 0 ~ 11)

[0013] Preferably, the aminosilane is selected from one or more of aminoethylmethyldiethoxysilane, aminoethylmethyldimethoxysilane, aminoethyldimethylmethoxysilane, aminopropylmethyldiethoxysilane, aminopropylmethyldimethoxysilane, aminopropyldimethylmethoxysilane, and aminopropyltrimethoxysilane.

[0014] The mass percentage concentration of the aminosilane compound is 0.005–0.3%, preferably 0.01–0.2%.

[0015] The nonionic surfactant is preferably selected from one or more of the following: C 10～18 Fatty alcohol polyoxyethylene (n) ether (n = 7-30), C 8～9Alkylphenol polyoxyethylene (n) ether (n = 8–200), C 12～18 Fatty amine polyoxyethylene (n) ethers (n = 10–60), Dow Chemical's Triton CF-10, Triton Chemical's Triton CF-21, Triton Chemical's Triton DF-12, Triton Chemical's Triton DF-16, and / or Dow Chemical's Triton DF-18. The preferred mass percentage concentration of the nonionic surfactant is 0.001–0.5%, more preferably 0.01–0.2%.

[0016] The chemical mechanical polishing fluid has a pH value of 3.0 to 6.0, more preferably 4.0 to 6.0.

[0017] The chemical mechanical polishing fluid of the present invention may also contain other additives in the art, such as pH adjusters and bactericides.

[0018] The chemical mechanical polishing fluid of the present invention can be prepared by concentration and diluted with deionized water to the concentration range of the present invention before use.

[0019] Compared with the prior art, the advantages of the present invention are as follows: the polishing slurry of the present invention can achieve a high removal rate of silicon dioxide and a low removal rate of silicon nitride, and can stop well on the surface of silicon nitride during the polishing process, thereby effectively improving the selectivity of silicon dioxide to silicon nitride removal rate; at the same time, the polishing slurry of the present invention can also control the removal rate of polycrystalline silicon well, effectively improving the selectivity of silicon dioxide to polycrystalline silicon removal rate, thereby meeting the requirements of different processes for the selectivity of silicon dioxide to polycrystalline silicon removal rate. Detailed Implementation

[0020] The advantages of the present invention are further illustrated below through specific embodiments, but the scope of protection of the present invention is not limited to the following embodiments. The polishing solutions of each embodiment are prepared by simply and uniformly mixing the components, with the remainder being water. Then, the pH is adjusted to a suitable level using nitric acid or potassium hydroxide.

[0021] The chemical mechanical polishing fluid of the present invention will be described in detail below through specific embodiments to provide a better understanding of the invention; however, the following embodiments do not limit the scope of the invention. All percentages of components in the embodiments are by mass.

[0022] Table 1 compares polishing slurry 1 with polishing slurries 1-15 of the present invention.

[0023]

[0024]

[0025] Example 1

[0026] In this example, the polishing performance of the above composition was studied. The prepared composition was polished under the following conditions, and the specific data are shown in Table 2: Polishing conditions: Mirra, polishing pad is IC1010 polishing pad, downward pressure is 3.0 psi, rotation speed is polishing disc / polishing head = 93 / 87 rpm, polishing fluid flow rate is 150 ml / min, and polishing time is 1 min.

[0027] Table 2 compares the removal rates of silicon dioxide (TEOS), silicon nitride (SiN), and polysilicon by polishing slurries 1-2 and polishing slurries 1-10 of the present invention.

[0028]

[0029] As shown in Table 2, compared with the comparative polishing slurry 1, the polishing slurry of the present invention can achieve a higher silicon dioxide removal rate and a lower silicon nitride removal rate, thereby effectively improving the selectivity ratio of silicon dioxide to silicon nitride removal rates. It can better stop on the surface of silicon nitride during polishing, which is beneficial for controlling the polishing process of the patterned chip and the remaining thickness of silicon nitride after polishing, and ensuring a better wafer morphology. Meanwhile, compared with the comparative polishing slurry 2, the polishing slurry of the present invention can also better control the removal rate of polycrystalline silicon, and can obtain different selectivity ratios of silicon dioxide to polycrystalline silicon removal rates, thus meeting the requirements of different processes for the selectivity ratio of silicon dioxide to polycrystalline silicon removal rates.

[0030] In summary, the chemical mechanical polishing slurry provided by this invention, comprising silica particles, aminosilane compounds, nonionic surfactants, and water, can meet the requirements for the removal rate and selectivity of silica, silicon nitride, and polysilicon during the polishing process of STI processes, DRAM and flash chips. It has wide applications, can achieve rapid planarization, effectively improve work efficiency, and reduce production costs.

[0031] It should be understood that all wt% mentioned in this invention refers to mass percentage content.

[0032] The specific embodiments of the present invention have been described in detail above, but they are merely examples, and the present invention is not limited to the specific embodiments described above. For those skilled in the art, any equivalent modifications and substitutions to the present invention are also within the scope of the present invention. Therefore, all equivalent transformations and modifications made without departing from the spirit and scope of the present invention should be covered within the scope of the present invention.

Claims

1. A chemical mechanical polishing slurry for polishing silicon dioxide, silicon nitride, and polycrystalline silicon, characterized in that, The polishing fluid is composed of silica particles, aminosilane compounds, nonionic surfactants, water, and pH adjusters. The nonionic surfactant comprises one or more of the following: C10~18 fatty alcohol polyoxyethylene ether, n=7~30; C8~9 alkylphenol polyoxyethylene ether, n=8~200; and C12~18 fatty amine polyoxyethylene ether, n=10~60. The pH value of the chemical mechanical polishing solution is 3.0~6.0; The aminosilane compounds include one or more of aminopropylmethyldiethoxysilane, aminopropylmethyldimethoxysilane, aminopropyldimethylmethoxysilane, and aminopropyltrimethoxysilane; The silica particles have a particle size of 20–200 nm; the aminosilane compound has a mass percentage concentration of 0.005–0.3%; and the nonionic surfactant has a mass percentage concentration of 0.001–0.5%. The content of the silica particles is 0.5 to 30 wt%.

2. The chemical mechanical polishing slurry as described in claim 1, characterized in that, The content of the silica particles is 2~20wt%.

3. The chemical mechanical polishing slurry as described in claim 1, characterized in that, The silica particles have a particle size of 30~150nm.

4. The chemical mechanical polishing slurry as described in claim 1, characterized in that, The mass percentage concentration of the aminosilane compound is 0.01~0.2%.

5. The chemical mechanical polishing slurry as described in claim 1, characterized in that, The nonionic surfactant has a mass percentage concentration of 0.01~0.2%.

6. The chemical mechanical polishing slurry as described in claim 1, characterized in that, The pH value of the chemical mechanical polishing fluid is 4.0~6.0.

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