Process for making low dielectric constant hollow chip structures by removing sacrificial dielectric material after the chip is joined to a chip carrier

摘要

Disclosed is a multilayer integrated circuit structure joined to a chip carrier, and a process of making, in which the area normally occupied by a solid dielectric material in the IC is at least partially hollow. The hollow area can be filled with a gas, such as air, or placed under vacuum, minimizing the dielectric constant. Several embodiments and processing variants are disclosed. In one embodiment of the invention, the wiring layers, which are embedded in a temporary dielectric, alternate with via layers, also embedded in a temporary dielectric, in which the vias, besides establishing electrical communication between the wiring layers, also provide mechanical support for after the temporary dielectric is removed. Additional support is optionally provided by support structures though the interior levels and at the periphery of the chip. The temporary dielectric is removed subsequent to joining by dissolution or by ashing in an oxygen-containing plasma.