Effect and Mechanism of Dual-Official Group of Ethanolamines on the Chemical Mechanical Polishing of Monocrystalline Silicon

Abstract

Chemical mechanical polishing is a key step in semiconductor technology because it is crucial to produce a defect-free and flat enough surface for further processing of microelectronic devices. Silicon (Si) wafer is widely used in integrated circuit (IC) devices, high-density information storage devices, and other advanced applications. In this paper, the effect of different pH and three ethanolamines (MEA, DEA, TEA) on the removal rate of Si was studied. The results show that the removal rate increased first and then decreased with increasing pH. Among the three ethanolamines, the effect of the removal rate is MEA>DEA>TEA. It may be related to the denser passivation film formed on the Si surface by increased hydroxyl groups in ethanolamines. The removal rate first increased and then decreased with the concentration of MEA increased and reached the peak value when the MEA concentration was 0.15 wt%. The changing trend of the removal rate is due to the Si-N bond being generated on the polished Si surface by MEA and the ionization properties of MEA, which are indicated through the X-ray photoelectron spectroscopy and the Zeta potential measurements. Si surfaces with low surface roughness and ultra-smooth with increased MEA concentration were obtained.

Mechanism Exploration of the Effect of Polyamines on the Polishing Rate of Silicon Chemical Mechanical Polishing: A Study Combining Simulations and Experiments

“…It can be observed that, during the simulations, the adsorption of polyamines resulted in the stretching of the original surface Si–Si bonds (bond lengths of about 2.10~2.18 Å) by 7~18%, facilitating the removal of surface silicon atoms through the subsequent mechanical wear action of abrasives in the CMP process. Water on the silicon surface mainly produces OH − to attack the Si–Si bonds [ 20 ], whereas simple adsorption of water molecules does not significantly affect the Si–Si bonds. In contrast, polyamines have a faster adsorption rate and the ability to stretch and weaken Si–Si bonds, making the Si atoms easier to remove; therefore, polyamines can increase the polishing rate of Si CMP.…”

“…Experiments conducted by Xie et al showed that the slurry containing 20 mmol of ammonium citrate caused a 71.6% increase in the MRR compared to the control group. Compared to the above additives, new additives with amine groups have also become popular additives for silicon wafer CMP, due to the following advantages: (1) they can achieve a higher MRR (>500 nm/min) [19,20], (2) they do not introduce contamination with metal ions such as Na + , K + , etc., and (3) they can be used as chelating agents to remove metal ions [21,22]. Polyamines are a representative class of amine additives that can achieve large MRR improvements.…”

“…Traditional MD simulations based on classical force fields can simulate the dynamic evolution of large systems with thousands or even tens of thousands of atoms, but they have the disadvantage of not being able to describe the chemical reactions. Compared to the above additives, new additives with amine groups have also become popular additives for silicon wafer CMP, due to the following advantages: (1) they can achieve a higher MRR (>500 nm/min) [19,20], (2) they do not introduce contamination with metal ions such as Na + , K + , etc., and (3) they can be used as chelating agents to remove metal ions [21,22]. Polyamines are a representative class of amine additives that can achieve large MRR improvements.…”

Effect of Polyoxyethylene-Based Nonionic Surfactants on Chemical–Mechanical Polishing Performance of Monocrystalline Silicon Wafers

“…The peaks at 285.8 eV and 284.1 eV were attributed to C-O-C and C-C [32,33], respectively, indicating the adsorption of fatty alcohol polyoxyethylene ether (AEO-9) containing ether bonds on the wafer surface during the polishing process. The binding energy at 532.4 eV was found to correspond to Si-O (Figure 13b) [34]. The peaks at 397.6 eV, 398.4 eV, and 399.8 eV corresponded to N-Si, N-H, and N-C (Figure 13c) [28].…”