Effects of ultra-smooth surface atomic step morphology on chemical mechanical polishing (CMP) performances of sapphire and SiC wafers

Zhou, Yan; Pan, Guoshun; Shi, Xiao‐Lei; Zhang, Suman; Gong, H.; Luo, Guihai

doi:10.1016/j.triboint.2015.02.013

Cited by 90 publications

(32 citation statements)

References 27 publications

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“…6. Zhou and Pan [29] observed an atomic-scale smooth surface after a CMP process in their experiments. Therefore, it can be assumed that only one atomic layer is removed in a single adhesion process.…”

Section: Removal Rate By Adhesive Wearmentioning

confidence: 95%

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Mechanical model of nanoparticles for material removal in chemical mechanical polishing process

2016

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Chemical mechanical polishing (CMP) is the most effective method for surface planarization in the semiconductor industry. Nanoparticles are significant for material removal and ultra-smooth surface formation. This research investigates the mechanical effects of the material removal in the CMP process. The various contact states of pad, individual particle, and wafer caused by the variations of working conditions and material properties are analyzed. Three different mechanical models for the material removal in the CMP process, i.e., abrasive wear, adhesive wear, and erosive wear are investigated, with a focus on the comparison of the results for different models. The conclusions and methods obtained could potentially contribute to the understanding and evaluation of the CMP process in further work.

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Section: Removal Rate By Adhesive Wearmentioning

confidence: 95%

“…The real contact area ratio varies from 0.00001 to 0.15 [11,29]. The number of trapped particles depends on the ratio of the real contact area to the cross-sectional area of a particle.…”

mentioning

confidence: 99%

Mechanical model of nanoparticles for material removal in chemical mechanical polishing process

2016

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“…In all of these applications, high surface quality of sapphire substrates is critical, as well as in relation to subsurface damage. Currently, chemical mechanical polishing (CMP) with the help of an alkaline slurry is still the main planarization machining method for realizing the precision requirement of sapphire substrates [6][7][8]. Owing to its intrinsic nature such as great hardness, high mechanical strength, and chemical resistance, sapphire substrates are extremely difficult to polish with regard to simultaneously obtaining both a high material remove rate (MRR) and a perfect polished surface.…”

Section: Introductionmentioning

confidence: 99%

Pollution-Free Approaches for Highly Efficient Sapphire Substrate Processing by Mechanical Chemical Polishing

2019

Catalysts

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In this study, two pollution-free approaches were used to improve the processing efficiency of mechanical chemical polishing (MCP) for sapphire substrates. The first was dedicated to polishing using synthetic silica abrasives with high reactivity as soft abrasives, and the second was dedicated to polishing using organic acids and bases as catalysts on the polishing pad and coolant, including citric acid, theophylline, green tea, and coffee. The results showed that the rate of material removal of MCP with highly reactive silica abrasives was more than 187.5% larger than that of pristine silica abrasives with low reactivity, and surface roughness was 21% smaller than that of pristine silica abrasives. Meanwhile, in case of citric acid, the removal mass of sapphire was more that 29.2% larger than that of an original polishing method, and surface roughness was about 15.2% smaller than that of original polishing method. However, theophylline, green tea, and coffee affected processing efficiency negligibly or negatively, due to a limited effect on increasing the pH level of the coolant, and the powder residue in the coolant obstructing the contact between the nano-silica abrasive particles and sapphire surface. These results indicate that highly reactive nano-silica abrasives and citric acid show good catalytic activity towards the sapphire processing efficiency of MCP. The promoting mechanism of highly active silica abrasives and citric acid for the processing efficiency of MCP is also discussed in detail in this study.

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“…The final surface roughness after CMP is usually less than 0.5 nm, thus enabling an atomic-scale smoothness to be achieved [5]. However, owing to the extremely high hardness (Mohs' scale of 9.5) and chemical inertness, the polishing rate of SiC with conventional CMP methods [6,7] using slurry containing silica alumina or ceria colloids under harsh alkaline conditions is low [8][9][10][11]. At the same time, surface scratches are inevitable owing to a rather high hardness of polishing colloid particles.…”

Section: Introductionmentioning

confidence: 99%

Marrying medicine and materials: artemisinin (Qinghaosu) particle is soft enough for scratching hard SiC wafer in water

Zhu

Zhang

Gan

et al. 2016

ScienceOpen Research

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Silicon carbide (SiC) single crystals, along with sapphire and silicon, are one of the most important substrates for highbrightness light-emitting diode fabrications. Owing to extremely high hardness (Mohs' scale of 9.5) and chemical inertness, the polishing rate of SiC with conventional chemical mechanical polishing methods is not high, and surface scratches are also inevitable because of using slurry containing hard abrasives such as silica particles. Here artemisinin (Qinghaosu) crystals, very soft molecular solids, were found, for the first time to the best of our knowledge, to effectively polish SiC wafers even in pure water as demonstrated by proof-of-concept scratching experiments using atomic force microscopy. The underlying mechanism is attributed to activated oxidation of SiC by mechanically released reactive ·OH free radicals from the endoperoxide bridges. The preliminary results reported here have important implications for developing novel alternative green and scratch-free polishing methods for hard-brittle substrates including SiC, diamond, and others.

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Effects of ultra-smooth surface atomic step morphology on chemical mechanical polishing (CMP) performances of sapphire and SiC wafers

Cited by 90 publications

References 27 publications

Mechanical model of nanoparticles for material removal in chemical mechanical polishing process

Mechanical model of nanoparticles for material removal in chemical mechanical polishing process

Pollution-Free Approaches for Highly Efficient Sapphire Substrate Processing by Mechanical Chemical Polishing

Marrying medicine and materials: artemisinin (Qinghaosu) particle is soft enough for scratching hard SiC wafer in water

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