Executive Summary : | Alumina, a substrate with excellent electrical insulation, mechanical stiffness, and thermal conductivity, can be used for packaging electrical components in harsh environments like automotive and space. However, the fabrication of alumina interposers has been challenging due to the difficulty in machining hard and brittle alumina. This project aims to demonstrate the fabrication of Alumina interposer technology using cost-effective, cleanroom-free steps in India. A novel ultrasonic machining technique will create multiple through-holes and embedded redistribution lines simultaneously, with the target etches rate being over 10 times higher than plasma etching. An electroless technique will deposit a conductive seed layer in through-holes without using any additional adhesion layer, and local roughening will be used instead of expensive chemical treatment. A proprietary bottom-up electroplating technique will fill through-holes and embedded RDLs, and post-deposition annealing will be investigated for stress-free metal layers. Direct Cu-Cu bonding will ensure air-tight packaging, aligning with the Indian semiconductor Mission (IsM) for high-performance integrated passive devices (IPDs), inductors, MIM capacitors, and thin film resistors. |