NADIA · Novel approach to Area selective Deposition for BEOL Interconnect Applications

Novel approach to Area selective Deposition for BEOL Interconnect Applications

Area selective deposition has been hailed as the next paradigm shift in nanoscale patterning as we continue the down scaling trend of Moore’s Law. As feature sizes get smaller, traditional “top-down” photolithography steps are struggling to fabricate the critical dimensions needed in devices. ASD has been proposed as a “bottom-up” technique which could see Moore’s Law continue for several more technology nodes and even into new 3D device architectures. In an ASD process a material is preferentially deposited, usually by atomic layer deposition (ALD), on a specific area on the surface while the remainder is left uncoated, giving control over the deposited thin film in the horizontal plane. One approach being adopted to achieve ASD is through the use of self- assembled monolayers (SAMs), which can assist in the patterning of microscale and nanoscale features. The adaptability of the SAM chemistry makes them a prime candidate for selectively adhesion to particular sections of the surface, allowing them to block any subsequently deposited material. The primary goal of the NADIA project was to develop a fully self-aligned (ASD) concept based on Dielectric-on-Dielectric (DoD) or Dielectric-on-Metal (DoM) without involving hard mask or resist steps and to downscale the concept to features with critical dimensions below 50 nm. In other words, a particular SAM was deposited on a metal surface, where deposition would be blocked, leaving the dielectric free for deposition. This is the called the DoD scheme. In the DoM scheme a SAM was deposited that would passivate the dielectric area, leaving the metal free for deposition. The project has achieved most of its objectives, milestones, and deliverables within the planned period with relatively minor deviations. The main focus of the NADIA project was to deepen our understanding of the fundamentals of ASD processing and to use this understanding to improve upon the state-of-the-art. There were four main objectives in NADIA which were grouped into three work packages: (i) Establish a method for sample preparation (WP1) (ii) Characterising the functionalization of the metal and dielectric surfaces (WP2) (iii) Dielectric on Dielectric and Dielectric on Metal nanometre patterning using ASD (WP3) (iv) Adaption to industry fabrication process (WP3)

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