Ferroelectric Hafnia-Based M3D FeTFTs Annealed at Extremely Low Temperatures and TCAM Cells for Computing-in-Memory...

Area of Science:

• Materials Science
• Electrical Engineering
• Computer Engineering

Background:

• The von Neumann architecture faces bottlenecks in processing speed and energy efficiency.
• Advancing artificial intelligence (AI) demands high-density memory solutions for storing billions of parameters.
• Monolithic three-dimensional (M3D) stacked ferroelectric thin-film transistors (FeTFTs) offer a promising path for high-density computing-in-memory (CIM).

Purpose of the Study:

• To develop a low-temperature fabrication process for M3D-integrated FeTFTs suitable for CIM applications.
• To address the thermal challenges associated with high-temperature annealing in M3D integration.
• To demonstrate the performance and potential of M3D-stacked FeTFTs in CIM devices.

Main Methods:

• Utilized focused microwave annealing (FMA) for M3D integration of oxide FeTFTs at 250 °C.
• Fabricated metal-ferroelectric-metal-insulator-semiconductor (MFMIS) FeTFTs.
• Employed multifrequency capacitance-voltage measurements and nucleation-limited-switching model analysis to characterize device properties.

Main Results:

• Achieved a large memory window of 3.2 V, endurance exceeding 10^6 cycles, and retention time of 10^5 s in FMA FeTFTs.
• Successfully analyzed the electrical characteristics of FeTFTs in both top and bottom layers of the M3D structure.
• Demonstrated the first vertical stacked FeTFTs-based ternary-content-addressable memory (TCAM) cell for CIM.

Conclusions:

• Focused microwave annealing is an effective low-temperature method for M3D integration of FeTFTs.
• The developed M3D-stacked FeTFTs exhibit excellent memory characteristics suitable for CIM.
• This technology enables the development of high-density, energy-efficient memory and CIM solutions for AI.