Effect of the Lapping Platen Groove Density on the Characteristics of Microabrasive-Based Lapping.

Taekyung Lee,Haedo Jeong,Hyoungjae Kim,Doyeon Kim,Sangjik Lee

doi:10.3390/mi11080775

Taekyung Lee, Haedo Jeong + Show 3 more

Open Access

https://doi.org/10.3390/mi11080775

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Abstract

Microabrasive-based lapping is widely used in the manufacturing of single-crystal substrates such as sapphire, SiC, and GaN. Although many studies have been conducted to improve the lapping process characteristics, most of them focused on process conditions or consumables. In this study, the effect of the lapping platen groove density on the lapping characteristics was studied using a sapphire substrate. Groove density was defined as the ratio of groove width to groove pitch, and the displacement of the lapping head was measured to calculate the oil film thickness. It was confirmed that, for groove densities below 0.30, hydroplaning occurs when the oil film thickness increases. When the oil film thickness is larger than the abrasive particle size, the material removal rate is low because the abrasive does not participate in the lapping process. When the oil film was developed, the experimental results showed a high surface roughness and poor flatness of the substrate, as only large abrasive particles participated in the lapping process. Therefore, to improve the lapping characteristics, it is important to reduce the groove density by reducing the groove pitch, which prevents the development of the oil film.

Highlights

Lapping using microabrasives improves the flatness of the substrate being machined and reduces the thickness of the subsurface damaged layer in the manufacturing of single-crystal substrates such as sapphire, SiC, and GaN, which in turn reduces the post processing time of chemical mechanical polishing (CMP) [1,2,3,4]
The lapping characteristics are represented by the material removal rate (MRR), the substrate surface roughness, and the flatness of the substrate
Change of Oil Film Thickness According to Groove Density 3.1

Summary

Introduction

Lapping using microabrasives improves the flatness of the substrate being machined and reduces the thickness of the subsurface damaged layer in the manufacturing of single-crystal substrates such as sapphire, SiC, and GaN, which in turn reduces the post processing time of chemical mechanical polishing (CMP) [1,2,3,4]. To address this knowledge gap, in this study, the effect of groove density on the state of the contact surface between the substrate and the platen, i.e., the magnitude of the oil film thickness and frictional force, were investigated and the effect of the change in the oil film thickness on lapping characteristics, including MRR, surface roughness, and substrate flatness, was studied.

Results

Conclusion