Advances in Metrology for the Determination of Young’s Modulus for low-k Dielectric Thin Films

As the semiconductor nano-electronics industry progresses toward incorporating increasingly lower dielectric constant materials as the inter layer dielectric (ILD) in Cu interconnect structures, thermo-mechanical reliability is becoming an increasing concern due to the inherent fragility of these materials. Therefore, the need for metrologies to assess the mechanical properties and elastic constants of low-k dielectric materials is great. Unfortunately, traditional techniques such as nano-indentation are being increasingly challenged as target low-k ILD thicknesses decrease below 100 nm for sub 16 nm technologies. In this light, we demonstrate the applicability of two new techniques, Brillouin Light Scattering and Contact Resonance Atomic Force Microscopy, for the determination of Young’s modulus for low-k dielectric thin films. We show that these techniques yield values that are in agreement with standard nano-indentation measurements and are capable at film thickness on the order of 100 nm or less.