Design, fabrication and stress evaluation of Si electrical interconnection Air-gapped from Si interposer

In this paper, Air-gaped Si interconnection for TSV interposer is presented, it´s low stress due to having similar coefficient of thermal expansion with Si interposer and is able to provide free standing pads for stacking dies and therefore is helpful for removing stress accumulation close to stacking dies. Then process is successfully developed for fabrication of Air-gapped Si samples. Finally, stress evaluation of Air-gapped Si samples at different temperature is carried out with infrared photoelastic imaging technique and experimental results shows that stress of Si substrate of the fabricated Air-gapped Si sample keep almost the same as it rises from 25°C to 350°C except that the stress in the filled SiO2 regions change little and is less than that of the fabricated Cu TSV samples.