A review on warpage measurement metrologies for advanced electronic packaging

In the post-Moore era, advanced electronic packaging technology emerges as a prominent direction for the future evolution of semiconductor industry. Nevertheless, warpage remains a prevalent issue in this domain, capable of significantly disrupting the precision and automation operation of subsequent processes, thereby precipitating various operational challenges. Consequently, the comprehensive examination of warpage assumes paramount important in enhancing packaging assembly yield and ensuring device reliability. The rigorous measurement of warpage through experimental methodologies assumes a pivotal role in investigating warpage-related concerns. Thus, this review has succinctly encapsulated established warpage measurement metrologies that are extensively employed in advanced semiconductor packages, shedding light on the measurement capabilities, advantages and limitations inherent of each technique. Typically, warpage measurement techniques can be broadly categorized into two main classes: contact and noncontact methods. Noteworthy examples of the former category encompass moiré interferometry, digital image correlation (DIC), laser scanning measurement and optical interferometry, while the later involves stylus-based technique and the use of ruler for warpage data acquisition. Furthermore, this study encompasses a comprehensive examination of all the aforementioned measurement methods and offers insights into their comparative analysis, as well as future prospects. Notably, empirical investigations suggest that moiré-based methodologies reign supreme. This discourse delineates the technical challenges and future development trends facing each warpage measurement method. In essence, the goal of this study is to furnish concise and coherent guidelines and support for engineers and researchers seeking to navigate the realm of warpage measurement within the sphere of advanced electronic packaging.