Probing molecular structures at buried solid/solid interfaces involving low-k materials or polymers in situ nondestructively: a review

Background: With the development of three-dimensional (3D) integration technology including extreme ultraviolet (EUV) lithography, more and more buried interfaces are involved in a device. It is important to probe such buried solid/solid interfaces in situ, but due to the lack of appropriate metrology, it is difficult to do so.Aim: This review aims to introduce sum frequency generation (SFG) vibrational spectroscopy to researchers and engineers in the research fields related to 3D integration technology including EUV lithography. SFG can probe buried solid/solid interfaces in situ nondestructively.Review Approach: This review presents the SFG technique and the recent results obtained from SFG studies on a variety of solid/solid interfaces, including porous low-k material/silicon interfaces, plasma treated polymer/epoxy interfaces, flux treated metal/epoxy interfaces, chemical reactions at buried solid/solid interfaces, and structures of buried solid/solid interfaces in multilayered thick device.Conclusions: SFG has been successfully applied to elucidate molecular structures and molecular interactions at buried solid/solid interfaces in situ nondestructively. SFG has great potential to probe buried interfaces in devices based on 3D integration technology.