EcoFlash?: Next level of enhanced isotropic etchants

With the trend towards miniaturization IC-manufacturers are permanently requested to increase the density of interconnects generating conductors featuring finer lines and spaces. Advanced manufacturing technologies such as Semi-Additive-Processing (SAP) and advanced Modified-Semi-Additive-Processing (aMSAP) were devised, realized and implemented in order to meet the requirements.i According to the roadmaps of the major Original Equipment Manufacturers, line and space requirements of copper conductors become increasingly finer and will be below 5/5μm for the future packaging substrates.ⁱⁱSAP as well as aMSAP processes are based on pattern plating the desired circuitry on a thin conductive copper seed layer and finalizing the circuit formation afterwards by removal of the respective seed layer using so called flash/differential etching solutions. Herein we report about the performance of the new developed ferric sulfate based EcoFlashTM process for SAP and aMSAP application with the focus on performance and fine line capability in comparison with hydrogen peroxide etchants.