Phase-change materials (PCM) are capable of transforming from a crystalline phase to an amorphous phase. These two solid phases exhibit differences in electrical properties, and semiconductor devices can advantageously exploit these differences. Given the ever-increasing reliance on radio frequency (RF) communication, there is particular need for RF switching devices to exploit phase-change materials. However, the capability of phase-change materials for phase transformation depends heavily on how they are exposed to thermal energy and how they are allowed to release thermal energy. For example, in order to transform into an amorphous phase, phase-change materials may need to achieve temperatures of approximately seven hundred degrees Celsius (700° C.) or more, and may need to cool down within hundreds of nanoseconds.
Heating elements in PCM RF switches often contribute to parasitics, such as parasitic capacitors, associated with RF frequencies and result in performance tradeoffs. Additionally, the performance of an RF switch using PCM depends heavily on how contacts to the PCM are made. Fabricating contacts to the PCM without significant RF performance tradeoffs becomes complex, especially where the RF switch is designed primarily around thermal performance. Fabrication techniques applicable to conventional semiconductor devices may not be suitable for fabricating PCM RF switches. Accordingly, accommodating PCM in RF switches can present significant manufacturing challenges. Specialty manufacturing is often impractical, and large scale manufacturing generally trades practicality for the ability to control device characteristics and critical dimensions.
Thus, there is a need in the art to reliably manufacture PCM RF switches having low parasitics and improved thermal performance.