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With the demand for manufacturing large (e.g., 450 mm) wafers, problems arise due to temperature increases associated with the chemical mechanical polishing (CMP) process. Various methods have been employed to stabilize the in-situ polishing temperature. The use of a high-temperature slurry can improve the removal rate, but a degradation in surface morphology occurs during the copper CMP procedure. To explain this mechanism, the effects of temperature on the slurry, CMP pad, and copper wafer were separately investigated. A temperature of approximately 40 °C was demonstrated to be a suitable choice when considering polishing efficiency and quality, thereby facilitating the rapid production of semiconductors. Particle aggregation was also observed with a rise in temperature. The work presented here may allow for a reduction in defects during low-hardness material polishing.

In this paper, tribological effects on the material removal rate (MRR) are investigated using two types of slurry abrasives (i.e., ceria and silica) and three types of pads. From a micro to macro viewpoint, the physico-chemical interaction between the pad-wafer interface and abrasive was studied based on multi-asperity contact. First, the relative contact pressure in high or low proportions among all asperities was calculated using a contact mechanics model. The results indicate that for the commercial slurry used in the semiconductor industry, relatively high contact pressure due to the asperities can be transferred to the ceria abrasives, and only a low contact pressure can be supported by these silica abrasives. Furthermore, it was confirmed that the two different slurry abrasives showed opposite behaviors according to the real contact area of the pad asperities. That is, as the pad texture changed from ‘Desired pad’ to ‘Smoothed pad’, the MRR of the ceria increased by 47%, while the MRR of the silica decreased 59%. Lastly, the Stribeck curve, which is suitable for the CMP process, was re-analyzed to clarify the abrasion mechanism under the pad asperity scale. The results showed that two-body abrasion may be maintained for the ceria CMP, and transition is possible from two-body to three-body abrasion at the silica CMP as the contact area increases. The present paper is expected to clarify the tribological mechanism of the oxide CMP and can provide further insight into optimizing and selecting consumables such as conditioner, pad, and slurry.

Chemical mechanical planarization (CMP) is a planarization technique that combines mechanical and chemical factor for enhanced polishing and finishing. CMP process reduces the surface roughness to meet the requirements of semiconductors. The characteristics of CMP, such as material removal rate (RR), thickness uniformity and surface quality, are determined by various mechanical and chemical factors. CMP has many consumables. Slurry, conditioner, and pad are typically used in CMP process. These consumables’ interaction is very important in CMP process. The reason why, the other can affect each other. These factors are known to significantly affect the results of CMP. During the process time, the lack of conditioner will block the pore and glazing on the pad surface. The longer process time, the lower pad cut rate is occurred because of poor conditioner performance [1]. And then pad glazing is occurred. When the pad glazing occurred, RR is changed [2]. At this point, the RR has different value according to abrasive. The number of particles that can act on the wafer depends on the pad surface changed. This affects the local pressure acting on the wafer. As the amount of abrasive acting on the wafer increases, the local pressure on the wafer is decreased. As briefly think about the situation, reduction of local pressure should result in decreasing removal rate. However, when the pad glazing situation, the RR has difference phenomenon according to abrasive types. Normally, Fig.1 (a) shows RR using ceria abrasive. It has higher RR after pad glazing. Fig.1 (b) shows RR using silica abrasive. It has lower RR after pad glazing. In this research, the difference in RR according to abrasive types generated during pad glazing was investigated. Based on these phenomena, I present the optimum pad land area each abrasive. Reference [1] C. Shin, H. Qin, S. Hong, S. Jeon, A. Kulkarni, and T. Kim, Journal of Mechanical Science and Technology, pp. 5659-5665, (2016). [2] H. Kim et al., Wear, pp. 93-98, (2017). Figure 1