Dielectric Barrier, Etch Stop, and Metal Capping Materials for State of the Art and beyond Metal Interconnects

Abstract

Over the past decade, the primary focus for improving the performance of nano-electronic metal interconnect structures has been to reduce the impact of resistance-capacitance (RC) delays via utilizing insulating dielectrics with ever lower values of dielectric permittivity. The integration and implementation of such low dielectric constant (i.e. low-k) materials has been fraught with numerous challenges. For intermetal and interlayer (ILD) low-k dielectrics, these challenges have been largely associated to integration with metal interconnect fabrication processes and well documented and reviewed in the literature. Although equally important, less attention has been given to other low-k dielectrics utilized in metal interconnect structures that are commonly referred to as low-k dielectric barriers (DB), etch stops (ES), and/or Cu capping layers (CCL). These materials present numerous challenges as well for integration into metal interconnect fabrication processes. However, they also have more stringent integrated functionality requirements relative to low-k ILD materials that serve only a basic purpose of electrically isolating adjacent metal lines. In this article, we review the integration challenges and associated integrated functionality requirements for low-k DB/ES/CCL materials with a focus on the current status and future direction needed for these materials to facilitate both Moore's law (i.e. More Moore) and More than Moore scaling.

Review—Investigation and Review of the Thermal, Mechanical, Electrical, Optical, and Structural Properties of Atomic Layer Deposited High-kDielectrics: Beryllium Oxide, Aluminum Oxide, Hafnium Oxide, and Aluminum Nitride

“…118 In CMOS logic, memory, NEM and other microelectronic device applications, a-SiN:H is instead more commonly utilized either as a dielectric diffusion barrier, etch stop, or hermetic encapsulation layer. 119,120 To compare and contrast the above materials, their full spectrum of thermal, mechanical, electrical, optical, and chemical properties was measured. The thermal properties investigated include thermal conductivity (κ) and interfacial thermal resistance, as measured by time domain thermoreflectance (TDTR), and coefficient of thermal expansion (CTE) as determined by heated wafer curvature and X-ray reflectivity (XRR) thickness measurements.…”

Review—Silicon Nitride and Silicon Nitride-Rich Thin Film Technologies: Trends in Deposition Techniques and Related Applications

“…It was found that this effect is driven primarily by the plasma gas residence time, with a shorter residence time leading to a reduction in re-deposition effects and yielding films of higher purity and improved quality. A report of note 96 incorporated ab initio techniques into theoretical models to examine the effects of PE-ALD reaction mechanisms on precursor adsorption and decomposition pathways for a variety of inorganic and organic Si precursors, including SiH 4 , SiH 2 Cl 2 , SiH 2 (CH 3 ) 2 , (Si 3 N 4 ) 4 (NH 3 ) 12 , and SiN 2 C 8 H 22 . The techniques employed realistic cluster models of aminecovered surfaces to derive the configurations and energies of chemisorption and reaction of these Si sources via functional groups removal.…”

Non-Heat Assistance Plasma-Enhanced Chemical Vapor Deposition of SiCxNyOzFilm Using Monomethylsilane, Nitrogen and Argon

“…Particularly, the formed film could fill the non-flat aluminum surface. The existence of nano-pores 4 should be evaluated, when this film is expected for the low k applications. The grain boundary was not observed in this figure.…”

“…Additionally, the SiC x N y O z film is widely studied for developing the highly functional films of low k, diffusion barrier, cupper capping layer and etch stop, for the advanced electronics device fabrication. [4][5][6][7] Its demand is expected to increase further. For producing the SiC x N y O z film at room temperature, the plasmaenhanced CVD (PECVD) process developed in our previous study 8 is expected to be useful, because it forms a silicon carbide (SiC) film from the monomethylsilane (MMS) gas without any heating assistance.…”