Stress-buffer and passivation processes for Si and GaAs IC's and passive components using photosensitive BCB: process technology and reliability data

Polymer coatings are applied to chips and passive components to provide stress relief between the device/component and the plastic package and/or to provide mechanical and environmental protection. The semiconductor industry is actively pursuing a one mask, photosensitive dielectric process for stress-buffer and secondary passivation of memory die. A one mask photo-benzocyclobutene (BCB) process is compared to traditional two mask wet etch processes. This new one mask process reveals 1/3 the total wafer processing time and equivalent reliability (traditional MIL 883C testing) for passivated 100 lead static random access memory components (SRAMs). Reliability data are also presented for GaAs chips, and NiCr and TaN resistors which have been passivated by BCB.