Collaborative Research: CMOS+X: 3D integration of CMOS spiking neurons with AlBN/GaN-based Ferroelectric HEMT towards artificial somatosensory system

通过先进的封装工艺将硅技术与新兴设备相结合的三维异质集成方法可以利用先进电子/光电子学的独特半导体组合。特别是，硅基人工神经元和人工突触的集成将使传感器、计算和执行单元之间的数据传输最小化，从而实现能效高的近传感器计算。我们的神经形态阵列将允许对各种传感器获取的数据进行现场处理，并将为驱动提供必要的控制信号，这些信号可以普遍用于读取和处理外部刺激并做出相应的反应，例如原位视觉处理和机械响应。具体地说，3D集成神经形态单元将实现高频和高功率操作，实现机器人、自动车辆和医疗设备的简化感知到动作系统。因此，我们提出的异质集成系统为从中央处理器(CPU)和图形处理单元(GPU)分散的紧凑型神经形态边缘计算系统提供了一种创新的范例。为了实现上述目标，该提案旨在设计并演示一种芯片上的人工体感系统，该系统可以通过3D集成基于互补金属氧化物半导体(CMOS)的棘神经元和基于GaN铁电高电子迁移率晶体管(FeHEMTs)的人工突触来模拟生物体感系统。设计的神经形态芯片将能够用一维时间序列向量调制微小的感觉信号。原始的时间序列感官信号可以通过基于CMOS的尖峰神经网络(SNN)进行能量高效的时空编码来有效地处理，以克服冯·诺依曼瓶颈。设计的神经形态芯片提供一次性计算，类似于中枢神经系统(CNS)的生物计算。此外，铜-铜互连将实现基于CMOS的SNN与基于宽带隙半导体的铁电晶体管的高密度3D集成，用于原位处理输入刺激以触发机械致动。图像传感器捕获的时间序列数据将通过前端基于CMOS的神经形态芯片在尖峰域进行编码。编码后的输出信号将直接传输到基于FeHEMT纵横制组合阵列的后端神经形态芯片，对其权值进行编程。通过AlBN/gan HEMT交叉棒阵列的解码输出电流可以超过一个安培的数量级，使其能够驱动机械驱动以进行系统宏观运动，如机械目标跟踪。我们相信，拟议的混合信号神经形态阵列将允许对时间序列感觉数据进行现场处理，从而实现超低功耗人工体感系统，该系统为包括AIoT和机器人在内的广泛应用提供从传感和数据处理到反应的高能效和自发计算。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

Three-dimensional heterogeneous integration approaches that combine silicon technology with emerging devices via advanced packaging processes can leverage unique semiconductor combinations for advanced electronics/optoelectronics. In particular, the integration of Si-based artificial neurons and artificial synapses will enable energy-efficient near-sensor computing by minimizing data transfer between sensor, computing, and actuation units. Our neuromorphic array will allow for the in-situ processing of data acquired by various sensors and will provide necessary control signals for actuation that can be universally used to read and process external stimuli and respond accordingly, such as in-situ vision processing and mechanical response. Specifically, 3D integrated neuromorphic unit will enable high-frequency and high-power operation, realizing a simplified sensing-to-action system for robots, autonomous vehicles, and medical devices. Thus, our proposed heterogeneously integrated system provides an innovative paradigm for a compact neuromorphic edge-computing system that is decentralized from central processing units (CPUs) and graphic processing units (GPUs). To achieve the above goal, the proposal aims to design and demonstrate an on-chip artificial somatosensory system that can emulate the biological somatosensory system via 3D integration of complementary metal-oxide-semiconductor (CMOS)-based spike neurons and GaN ferroelectric high electron mobility transistors (FeHEMTs) based artificial synapses. The designed neuromorphic chip will be able to modulate small sensory signals with a one-dimensional time-series vector. The raw time-series sensory signals can be efficiently processed with a CMOS-based Spiking Neural Network (SNN) for energy-efficient and spatiotemporal encoding to overcome the Von Neumann bottleneck. The designed neuromorphic chips provide one-shot computation, analogous to the biological computing in the central nervous system (CNS). Furthermore, Cu-Cu interconnection will enable the high density 3D integration of the CMOS-based SNN with ferroelectric transistors based on wide-bandgap semiconductors for in-situ processing of the input stimulus to trigger mechanical actuation. The time-series data captured by the image sensor will be encoded through the front-end CMOS-based neuromorphic chip in a spiking domain. The encoded output signals will be directly transmitted to the back-end neuromorphic chip based on the FeHEMT crossbar-based synpatic array to program its weight value. The decoded output current through the AlBN/GaN HEMT crossbar array can exceed an order of mangitude of an ampere, allowing it to drive mechanical actuation for system macro-motion, such as mechanical object tracking. We believe the proposed mixed-signal neuromorphic array will allow for the in-situ processing of time-series sensory data, leading to the realization of an ultra-low-power artificial somatosensory system that provides power-efficient and spontaneous computing from sensing and data processing to reaction for widespread applications including AIoT and robotics.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.