The trend in semiconductor packaging is moving toward thinner and thinner packages. Likewise, chip profile is moving toward thinner and thinner chips. Presented here is a technique used to obtain a semiconductor package containing chips as slim as one micron in thickness. The ELO Packaging Process yields ultrathin chips for applications such as advanced heat sinking, high-efficiency optoelectronics, multiple stacked chips in a single package, and thin mechanically flexible semiconductor circuits. This technology is being developed around both the fab and packaging house so as not to interfere with the conventional semiconductor fabrication process flow.
Through a combination of back-grinding and chemical etch techniques, chips have been thinned to as little as 1 µm and bonded to a variety of new host substrates. Several bonding methods have been utilized – including thin solder or epoxy layers – to bond these functional chips to a variety of new substrates. Ultrathin microwave power amplifiers have been bonded to heat sinks and optoelectronic devices have been bonded to transparent substrates. In both cases, the ultrathin chip configuration coupled with the desired substrate can increase performance of the chip by a factor of 10X.