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. 2024 Aug 22;14(16):1371.
doi: 10.3390/nano14161371.

Enhancing Slurry Stability and Surface Flatness of Silicon Wafers through Organic Amine-Catalyzed Synthesis Silica Sol

Yi Xing  1   2 , Weilei Wang  3 , Weili Liu  1   3 , Zhitang Song  1   3
Affiliations

Enhancing Slurry Stability and Surface Flatness of Silicon Wafers through Organic Amine-Catalyzed Synthesis Silica Sol

Yi Xing et al. Nanomaterials (Basel). .

Abstract

The stability of slurries used for chemical mechanical polishing (CMP) is a crucial concern in industrial chip production, influencing both the quality and cost-effectiveness of polishing fluids. In silicon wafer polishing, the conventional use of commercial neutral silica sol combined with organic bases often leads to slurry instability. To address this issue, this study proposes organic amines-specifically ethanolamine (MEA), ethylenediamine (EDA), and tetramethylammonium hydroxide (TMAOH)-as catalysts for synthesizing alkaline silica sol tailored for silicon wafer polishing fluids. Sol-gel experiments and zeta potential measurements demonstrate the efficacy of this approach in enhancing the stability of silica sol. The quantitative analysis of surface hydroxyl groups reveals a direct correlation between enhanced stability and increased hydroxyl content. The application of the alkaline silica sol in silicon wafer polishing fluids improves polishing rates and enhances surface flatness according to atomic force microscopy (AFM). In addition, electrochemical experiments validate the capability of this polishing solution to mitigate corrosion on silicon wafer surfaces. These findings hold significant implications for the advancement of chemical mechanical polishing techniques in the field of integrated circuit fabrication.

Keywords: chemical mechanical polishing; monocrystalline silicon wafer; organic amine; silanol groups; silica nanoparticles.

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Conflict of interest statement

The authors Weili Liu, Zhitang Song, and Weilei Wang were employed by the company Zhejiang Xinchuangna Electronic Technology Co., Ltd. The remaining author declares that the research was conducted in the absence of any commercial or financial relationships that could be construed as potential conflicts of interest.

Figures

Figure 1
Figure 1
The variation in sol–gel time over pH in the control and experimental groups.
Figure 2
Figure 2
The variation in zeta potential over pH in the control and experimental groups.
Figure 3
Figure 3
The variation in hydroxyl content over pH in the control and experimental groups.
Figure 4
Figure 4
Thermogravimetric analysis (TGA, black line) and derivative thermogravimetry (DTG, red line) curves of SiO2 synthesized with different organic amine catalysts at pH = 10.50: (a) MEA, (b) EDA, and (c) TMAOH.
Figure 5
Figure 5
Solid-state 29Si NMR spectra of the SiO2 synthesized with different organic amine catalysts at pH = 10.50 (Q3, purple line; Q4, blue line).
Figure 6
Figure 6
Structural formulas and 3D models of different organic amines (Carbon atom, red; Oxygen atom, yellow; Nitrogen atom, blue; Hydrogen atom, white).
Figure 7
Figure 7
The adsorption between organic amine molecules and silanol groups: (a) MEA, (b) EDA, and (c) TMAOH.
Figure 8
Figure 8
Effect of the silicon polishing slurry from the control group and experimental groups on MRR and Ra at pH = 10.50.
Figure 9
Figure 9
The surface morphology and scratch performance of silicon wafer: (a) control group, (b) MEA, (c) EDA, and (d) TMAOH (the red and green lines characterized the degree of particles aggregation and the depth of scratches).
Figure 9
Figure 9
The surface morphology and scratch performance of silicon wafer: (a) control group, (b) MEA, (c) EDA, and (d) TMAOH (the red and green lines characterized the degree of particles aggregation and the depth of scratches).
Figure 10
Figure 10
Potentiodynamic polarization curve of different components in polishing slurries at pH 10.50.
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