Contact Behavior and Chemical Mechanical Polishing (CMP) Performance of Hole-Type Polishing Pad

Abstract

A polishing pad plays an essential role in determining the chemical mechanical planarization (CMP) performance such as removal rate, planarization, and defectivity. Further, it is important for the polishing pad to maintain good CMP performance throughout its lifespan. In order to achieve high performance and durability, a hole-type pad was suggested as an alternative to the conventionally used pore-type pad. In this study, the effect of the hole density on the CMP performance was examined for a hole-type pad. Surface characterization of the hole-type pad showed that the hole density corresponded to the contact ratio between the pad and the wafer, and therefore, the contact characteristics could be controlled by a hole fabrication process. The experimental results showed that the number of holes play a key role in determining CMP performances. The removal rate decreased with an increase in the hole density. The level of dishing showed an increase with the hole density. The number of CMP scratches decreased at higher hole densities. Higher contact ratio and the presence of large particle trap sites explain the lower trend of the micro-scratch observed. An important advantage of the hole-type pad is that it retains the surface structure as CMP continues, which implies contact behavior is maintained.

Mechanisms of Local Planarization Improvement Using Solo Pad in Chemical Mechanical Polishing

“…This difference can explain the above result, that is, the lower compressibility of IC1000 causes better planarity as in the case of ILD planarization [19][20][21] and also causes a lower RR because of the less contact of the pad with the wafer due to the lower flexibility, which cannot compensate for the pad surface waviness. 25) However, as will be discussed later, the mechanism of local planarization such as STI or Cu damascene CMP must be different from that of global planarization such as that of ILD CMP, and other factors are considered to dominate the mechanism. One possible factor is the temperature during polishing.…”

A statistical characterization model of the microscale contact state of polishing pads

“…Some scholars have developed parametric analyses and even statistical models for microscale contact states [3]. Kim et al [4] found that increasing the pore density increased the contact rate and thus reduced the number of scratches. Lee et al [5] and Khanna et al [6] described microscale contact states through parameters such as polishing pad height distribution and deflection angle, smoothness, and gap coefficient.…”

Development of Novel Conditioning Method Using Thermal Shape Memory Characteristics of Polyurethane CMP Pad

“…4,8,9 In particular, the CMP pad plays a key role in CMP performance because it is in direct contact with the wafer during polishing. 10,11 Mechanical abrasion is supplied by the mechanical friction between pad asperities, abrasive, and the chucked wafer. Therefore, the roughness of the CMP pad surface and its recovery from deformation are crucial.…”