Utilizing Programmable Metallization Cells to Create Smart Interposers

Interposers have been used in the system packaging industry for years. They have advanced from basic devices used for connection to providing new opportunities for System-in-Package and System-on-Chip architectures. Currently interposers cannot be reconfigured. Systems may implement extra input-output connections for hard reconfiguration. However, programmable metallization cells (PMC) offer the opportunity to change this. PMCs offer reliable and fast switching that has the potential to be used as resistive memory cells as well. PMCs operate by growing a metal filament from the device cathode to its anode through a solid electrolyte by applying a voltage. By reversing the voltage bias, the filament will retract. The PMC’s electrolyte can also be made from a range of materials being chalcogen or oxide based, allowing for integration in a variety of systems. By utilizing PMCs in an interposer to create a “smart interposer,” it would be possible to create easily reconfigurable systems. This project investigated how PMCs function in a lab setting. By using a probe station, the current-voltage characteristics were generated for a variety of limiting current values. The PMC on and off state resistances were extrapolated for further understanding of its switch function. In addition, works-like prototypes were developed to show the function a smart interposer. In these prototypes, transistors or relays were used as the switching mechanism in place of the PMCs. The final works-like prototype demonstrated how a smart interposer might function by using a switching mechanism to swap between half adder and full adder outputs for the same inputs.