Novel Surface Finish for Next Generation Wafer Level Packaging Applications

Wafer level packaging (WLP) in the semiconductor industry continues to grow especially in the areas of IOT, high speed/mobility, sensors, wearables, automotive and other critical applications. The requirements of the products from these markets include smaller footprint, perform optimally-electrically, cost-effective and reliable. WLP materials/chemistries are critical components in helping semiconductor manufacturers, OEMs to attain these requirements to achieve the best performance. One of the most important materials include surface finish on the copper features to support interconnect integration. The selection criteria of surface finish for high frequency, high density next generation WLP applications involve minimal insertion loss, long shelf life, cost-effective and high reliability. There are few options (ImAg, EPIG, EPAG, DIG, OSP, etc.) available in the market; however, there are concerns over fulfilling all the requirements for next generation applications. An innovative nickel-less approach involving a proprietary nano-engineered barrier designed to coat copper contacts, finished with an outermost gold layer has shown superior benefits over contemporaries. Reliability testing results will be discussed comparing performance benefit of novel surface finish.