Enhanced Reliability of Ultra-low-k Dielectric with Columnar Pores Using hBN Capping Layer

This work demonstrated the use columnar porous dielectric together with hBN capping layer to achieve ultra-low-k value, high porosity, and enhanced reliability in terms of reduced surface roughness, better surface adhesion, and resistance to moisture uptake. The use of hBN capping layer is shown to reduce the surface roughness caused by the columnar structure. In addition, metal adhesion as well as hydrophobicity can be improved beyond that of the commonly used <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">Si₃N₄</tex> . capping layer. Measurement results show that an effective k-value of 1.8 with flat, adhesive, and hydrophobic surface can be achieved.