Developing Metrology for Nondestructive Characterization of Buried Polymer Interfaces in Situ.

[摘要] Polymers are widely used in modern microelectronics as adhesives, organic substrates, chip passivation layers, insulating dielectric materials, and photoresists in microlithography. The interfacial structures of polymer materials determine the interfacial properties of the materials. Weak adhesion or delamination at interfaces involving polymer materials can lead to failure of microelectronic devices. Therefore, it is important to investigate the molecular structures of such interfaces. However, it is difficult to study molecular structures of buried interfaces due to a lack of appropriate analytical techniques. This dissertation presents the development of the nonlinear optical technique sum frequency generation (SFG) vibrational spectroscopy into a metrology tool for nondestructive characterization of molecular structures at buried polymer interfaces in microelectronic packages in situ and the elucidation of relationships between buried molecular structures and interfacial properties such as adhesion strength. Buried polymer/epoxy, copper/epoxy, and silicon/organosilicate dielectric interfaces were investigated. SFG was used to directly probe molecular structures at buried adhesive interface in situ. Plasma treatment of polymer surfaces was found to alter the molecular structure at corresponding buried interfaces prepared using the plasma treated surfaces. Hygrothermal aging treatment was found to influence hydrophobic polymer/polymer interfaces less than hydrophilic interfaces, showing that hydrophobic materials can better resist delamination during qualification testing in high humidity environments. Copper/epoxy interfaces were found to delaminate near, but not exactly at, the metal/polymer interface and silane adhesion promoters were found to modify the interfacial region near the copper surface which suggests that the interfacial layer near copper needs to be modified to improve adhesion. Quantitative data analysis methodology was developed to simultaneously characterize the surface and buried interface of silicon-supported thin low-k polymer films nondestructively before and after microelectronic processing steps which provided a molecular level understanding of the effects of the processing. The general nature of the methodology enables it to be directly utilized to elucidate structure-property relationships at buried interfaces by correlating interfacial structures to interfacial properties. Structure-property relationships elucidated using this methodology can be used to guide the rational engineering of buried polymer interfaces with optimized properties in many practical applications such as polymer composites, optical fibers, paints, and anticorrosion coatings.

[发布机构] University of Michigan

[效力级别] vibrational spectroscopy

[关键词] molecular structure;vibrational spectroscopy;Chemistry;Science;Chemistry