Phase‐Change Logic via Thermal Cross‐Talk for Computation in Memory

• Published in: Physica status solidi. PSS-RRL. Rapid research letters 2021-03, Vol.15 (3), p.n/a
• Main Authors: Kanan, Nadim, Khan, Raihan Sayeed, Woods, Zachary, Silva, Helena, Gokirmak, Ali
• Format: Article
• Language: English
• Subjects: Amorphization; Circuits; CMOS; electrothermal modeling; Logic; Multiplexing; phase‐change logic; phase‐change memory; routers; toggle multiplexers
• ISSN: 1862-6254; 1862-6270
• DOI: 10.1002/pssr.202000422

Herein, logic function implementations are computationally demonstrated using lateral and vertical multicontact phase‐change devices integrated with complementary metal–oxide–semiconductor (CMOS) circuitry, which use thermal cross‐talk as a coupling mechanism to implement logic functions at smaller CMOS footprints. Thermal cross‐talk during the write operations is utilized to recrystallize the previously amorphized regions to achieve toggle operations. Amorphized regions formed between different pairs of write contacts are utilized to isolate read contacts. Typical expected reduction in CMOS footprint is ≈50% using the described approach for toggle‐multiplexing, JK‐multiplexing, and 2 × 2 routing. The switching speeds of the phase‐change devices are in the order of nanoseconds and are inherently nonvolatile. An electrothermal modeling framework with dynamic materials models is used to capture the device dynamics, and current and voltage requirements. Phase‐change memory devices utilize thermal processes to change state and electrical isolation for readout. At the nanoscale, thermal cross‐talk between neighboring regions can be used as a coupling mechanism to achieve logic functionality using multicontact phase‐change devices. Previously amorphized regions of these devices are crystallized during amorphization of a nearby region during write operations.