Hence, application of CMP extends to transistor formation, and importance of CMP process becomes highly underscored. Recently, sub 14 nm semiconductor scaling has developed device integration scheme to 3-dimensional transistor formation such as fin field-effect transistor, therefore device process flow becomes much more complicated than previous device node. Although CMP application had started from planarization of excessed dielectric materials, its utilization have been widely accepted in shallow trench isolation, contact and metal interconnection formation. From the abrasive perspective, abrasive-wafer contact model on removal rate has been published in many literatures which emphasize abrasive particle size (and size distribution) and shape, and abrasive hardness. With this process, fast material removal across the wafer with planarization can be achieved. Therefore, chemistry and abrasive particles in the slurry determines CMP performances. The fundamental mechanism of CMP process is : (1) Material surface becomes soften by chemical reaction with slurry, (2) Mechanical force by abrasive particle in the slurry removes soften layer and step height reduction, (3) Material surface reacts with slurry chemical to make surface soften layer again and repeat (1) – (3). Furthermore, advantages of employment of CMP in semiconductor manufacturing are : (1) elimination of step coverage burden, (2) defect removal from prior process steps, (3) surface smoothening in wafer scale, and (4) enablement of metal gate formation at sub 14 nm device. Surface topography hinders conformal deposition of photoresist, leading to distorted patterning. The role of CMP and planarized wafer associated with lithography patterning is shown in Figure 1 schematically. However, as device shrinkage continues, it has become critical process for device fabrication, and its applications play a pivotal role in semiconductor process since transistor scaling becomes beyond 14 nm. The original purpose of CMP is to planarize wafer surface both locally and globally, which enable subsequent lithographic patterning with proper depth of focus. In this chapter, CMP fundamentals, applications and challenges associated with abrasive particle technology including synthesis (up to nanoparticle scale), tribochemical reaction, abrasive surface zeta potential behavior, particle size and its distribution will be discussed.Ĭhemical mechanical polishing (CMP) has been used for several decades in semiconductor manufacturing since its development at 1980s. Hence, to achieve proper CMP performance without surface scratching, understanding and development of abrasive particles are crucially important. Surface scratching, which is generated by CMP in nature, is considered as ‘killer defect’ in semiconductor manufacturing. Moreover, semiconductor yield enhancement is sensitively influenced by CMP processing. ![]() ![]() The role of CMP is not only material removal, but also planarization, surface smoothening, uniformity control, defect reduction and more. The fundamental mechanism of CMP is to create soften surface layer by chemical reaction and then, mechanical force by abrasive particles remove soften layer. Its importance becomes highly underscored at the advanced device toward sub 14 nm scaling. Chemical mechanical polishing (CMP) is one of the most essential processes in semiconductor manufacturing.
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