Patent ID: 11444053

Abstract:
The present disclosure is directed to a compact vertical oven for reflow of solder bumps for backend processes in semiconductor wafer assembly and packaging. This disclosure describes a vertical oven which uses a plurality of wafers (e.g., an example value is 50-100 wafers) in a batch with controlled injection of the reducing agent (e.g. formic acid), resulting in a process largely free of contamination. This disclosure describes controlled formic acid flow through a vertical system using laminar flow technology in a sub-atmospheric pressure environment, which is not currently available in the industry. The efficacy of the process depends on effective formic acid vapor delivery, integrated temperature control during heating and cooling, and careful design of the vapor flow path with exhaust. Zone-dependent reaction dynamics managed by vapor delivery process, two-steps temperature ramp control, and controlled cooling process and formic acid content ensures the effective reaction without any flux.