MT

M. Taouil

info

Please Note

150 records found

Why Faulty Chips are Escaping the Fab and Crashing in the Field

Conference paper (2026) - Mottaqiallah Taouil, Shawn Blanton, Phil Nigh, Adit D. Singh, Said Hamdioui
The increasing complexity of semiconductor technologies is exposing limitations in traditional manufacturing test methodologies. Although fault-model-based testing has enabled efficient production screening for decades, growing evidence from advanced logic and memory technologies indicates that many realistic defect mechanisms are insufficiently represented by conventional fault abstractions, leading to test escapes and in-field failures. This paper examines three directions for improving outgoing product quality. First, we discuss the growing mismatch between fault models and actual silicon behavior and emphasize the need for silicon-informed assessment of defect coverage. Second, we investigate timing failures caused by process-variation-induced delay marginalities, which increasingly evade conventional scan-based delay testing. Finally, we present Device-Aware Test (DAT), a defect-centric methodology that derives fault models and test solutions directly from physical defect behavior. Examples from STT-MRAM, RRAM, and FeFET memories demonstrate how DAT enables the detection of realistic defect mechanisms beyond the reach of conventional approaches. Together, these directions support a transition toward defect-aware, data-driven testing for future semiconductor systems. ...
Instruction Set Architecture (ISA) extensions, particularly scalar cryptography extensions (Zk), combine the performance advantages of hardware with the adaptability of software, enabling the direct and efficient execution of cryptographic functions within the processor pipeline. This integration eliminates the need to communicate with external cores, substantially reducing latency, power consumption, and hardware overhead, making it especially suitable for embedded systems with constrained resources. However, current scalar cryptography extension implementations remain vulnerable to physical threats, notably power side-channel attacks (PSCAs). These attacks allow adversaries to extract confidential information, such as secret keys, by analyzing the power consumption patterns of the hardware during operation. This paper presents an optimized and secure implementation of the RISC-V scalar Advanced Encryption Standard (AES) extension (Zkne/Zknd) using Domain-Oriented Masking (DOM) to mitigate first-order PSCAs. Our approach features optimized assembly implementations for partial rounds and key scheduling alongside pipeline-aware microarchitecture optimizations. We evaluated the security and performance of the proposed design using the Xilinx Artix7 FPGA platform. The results indicate that our design is side-channel-resistant while adding a very low area overhead of 0.39% to the full 32-bit CV32E40S RISC-V processor. Moreover, the performance overhead is zero when the extension-related instructions are properly scheduled. ...
Conference paper (2026) - Soyed Tuhin Ahmed, Krishnendu Chakrabarty, Jin Fu Li, Mottaqiallah Taouil, Fouwad Jamil Mir, Said Hamdioui, Mehdi Tahoori, Martin Keim, Jongsin Yun
Compute-in-Memory (CiM) devices have several attributes that make them of interest especially for accelerating artificial intelligence workloads and, at the same time, reduce power consumption. Both are critical aspects of edge computing. This paper summarizes a 3-topic special session held at the European Test Symposium 2026 on the topic of CiMs: (a) concerning the reliability of CiMs, (b) the testing of CiMs, and finally (c) on the security of CiMs. ...
Efficient generation of high-quality Gaussian random numbers remains a key challenge for enabling differential privacy (DP) and security primitives on resource-constrained edge devices. Existing hardware-based solutions rely on lookup tables or complex transformations, making them ill-suited for tightly integrated computation-in-memory (CIM) architectures. This work proposes a Gaussian random number generator (GRNG) based on a digital 8T SRAM-CIM array that leverages intrinsic memory periphery to generate and transform entropy. The design exploits voltage underscaling and stochastic readpath failures to produce in-situ uniform randomness, which is then aggregated through a lightweight central limit theorem (CLT)-based datapath with digital recentering to synthesize N0, σ2) samples. By reusing existing periphery, the proposed approach eliminates the need for dedicated random number generation hardware. Experimental evaluation demonstrates that the generated distribution closely follows an ideal normal curve, achieving low tail error and strong goodness-of-fit across standard statistical tests. The design sustains ≈ 2 Gsamples s throughput at an energy of ≈ 11.2 fJ/ sample, with no additional area overhead beyond standard CIM periphery. ...
Resistive Random Access Memory (RRAM) has emerged as a promising candidate to succeed conventional memory technologies, offering advantages such as low energy operation and scalable storage density. As different manufacturers continue to advance RRAM toward large-scale production and commercial deployment, the demand for accurate and efficient testing methodologies becomes increasingly critical. This paper investigates interconnect and contact defects in RRAM arrays, with particular attention to the influence of the Data Background (DB), and proposes corresponding test strategies. A comprehensive defect space covering interconnect and contact defects is formulated for a layout-independent RRAM design. Systematic defect injection and circuit-level simulations are conducted to derive fault models, encompassing not only single-cell and two-cell coupling faults but also multi-cell faults strongly affected by DBs. The analysis identifies previously unreported 3-cell and 4-cell faults, which originate from defect-related sneak paths in the array. Conventional RRAM test schemes are unable to detect such faults. To address this limitation, a DB-aware test generation scheme is presented, capable of efficiently identifying all the aforementioned fault types and thereby enhancing the overall fault and defect coverage in RRAM devices. ...
Computation-in-Memory (CIM) architectures address the rising demand for energy-efficient artificial intelligence (AI) solutions, by minimizing costly data movements between memory and processor. Within such architectures, SRAM-based digital CIM is especially attractive as it preserves the advantages of CIM while avoiding analog complexity. Recent studies have revealed potential weaknesses in these architectures, particularly to power side-channel attacks (SCA) capable of extracting sensitive model parameters (e.g., neural network (NN) weights), which represent the intellectual property of CIM-based neural network systems. In this study, we propose and evaluate two countermeasures to secure SRAM-based CIM architectures against power attacks: (1) Balanced Obfuscated-path countermeasure, and (2) Glitch Aware countermeasure. To validate their effectiveness, we conducted a comprehensive power analysis that successfully demonstrated attacks against an unprotected implementation. Our experimental results demonstrate that both countermeasures significantly improve resistance to power attacks. Although the Balanced Obfuscated-path offers better area overhead and run-time performance, the Glitch Aware approach achieves higher protection against advanced attacks, making each suitable for different design constraints. ...
Mapping Binary Neural Networks (BNNs) on computation-in-memory (CIM) architectures enables a highly efficient approach for energy-constrained edge computing. In-memory processing significantly reduces critical performance bottlenecks in conventional architectures. Despite their efficiency, current optimized CIM implementations remain vulnerable to IP theft via side-channel analysis. This work investigates the side-channel leakage of a digital BNN-CIM accelerator that employs popcount-based accumulation. A range of circuit-level modifications in counter implementations are proposed and evaluated, exploring their impact on security metrics and design overhead. Results demonstrate that the Hamming weight (HW) and Hamming distance (HD) equalizing techniques combined with power equalization through duplication perform better than traditional dual-rail countermeasures. The findings provide practical guidance for designing secure and efficient peripheral components for popcount-based BNN accelerators. ...

Orienting to SPICE and Circuit Design

Journal article (2026) - Changhao Wang, Sicong Yuan, Nicolo Bellarmino, Danyang Chen, Hanzhi Xun, Lin Wang, Mottaqiallah Taouil, Moritz Fieback, Said Hamdioui, More Authors
Physics-based compact models for emerging non-volatile memories (NVMs) are often limited by the complex interactions of microscopic domains and defects that are difficult to capture analytically, resulting in reduced accuracy and simulation efficiency. To address this challenge, a machine learning (ML)-based approach is proposed using artificial neural networks (ANNs) trained entirely on device measurement data, enabling a direct translation of fabrication characteristics into SPICE-compatible circuit models. The resulting models achieve high accuracy (MSE: 0.724, adjusted R2 : 0.998), significantly outperforming physics-based baselines with an 18× lower MSE for polarization and a two-order-of-magnitude precision improvement in FeFET current simulation, while accurately capturing the wake-up process. Furthermore, the model demonstrates robust out-of-distribution (OOD) extrapolation to unseen ferroelectric thicknesses and a 33.7% improvement in simulation speed. These results validate the ML-based approach as a highly efficient, SPICE-compatible solution for next-generation memory. ...
RRAM-based compute-in-memory (CIM) AI accelerators integrate memory cells with mixed-signal peripherals to enable energy-efficient, low-latency edge computing. These architectures require novel test techniques for unique electrical defects. Current system-level functional tests cannot guarantee defect-free circuits, while accurate circuit-level techniques remain non-scalable to Deep Neural Networks (DNNs). To bridge this gap, we present the first structural test methodology for CIM DNNs, unifying system-level analysis with circuit-level precision. We accurately model RRAM crossbar defects to formulate test patterns, and then propagate results across layers for comprehensive structural testing. Generated test patterns are optimized either for 96% defect coverage or test time reduction by a factor of three while covering all unique defects and maintaining over 73% defect strength coverage. ...

Side-Channel Weakness Evaluation and Enhanced Mitigation for DREAM-CIM

Computation-in-memory (CIM) accelerators offer energy and area efficiency gains but remain vulnerable to power side-channel leakage. This paper presents a comprehensive security analysis of a pipelined digital SRAM-based CIM accelerator named DREAM-CIM. We first identify leakage mechanisms through pre-silicon modeling and gate-level simulation, and then confirm their presence on a 22 nm post-silicon prototype. Moreover, to mitigate leakage, we introduce a Globally Synchronous and Locally Asynchronous (GSLA) countermeasure approach that desynchronizes immediate-pipeline-update registers and randomizes local activity while preserving functional correctness. Security is evaluated using post-silicon power traces under standard side-channel analyses, demonstrating effective leakage suppression. The countermeasure incurs ≈ 53% area and ≈ 74% energy overhead relative to the baseline design. Compared to masking-based countermeasures, GSLA achieves a reduction of ≈ 8.9 × and ≈ 9.2 × in area and energy overhead, respectively. ...
Journal article (2026) - Hassen Aziza, Hanzhi Xun, Moritz Fieback, Mottaqiallah Taouil, Said Hamdioui
Vector–matrix multiplication (VMM), implemented through multiply–accumulate (MAC) operations, represents the dominant computational primitive in many artificial intelligence (AI) workloads. When executed on conventional von Neumann architectures, VMM operations suffer from important energy consumption and latency due to the separation between memory and processing units. To overcome these limitations, crossbar arrays built from Resistive Random Access Memory (RRAM) cells have been proposed for accelerating VMM computations. In this work, we investigate the key optimization trade-offs associated with implementing RRAM-based neural networks for classification applications. A simple two-layer neural network is first defined and trained in software to generate the weight matrices and bias parameters. Next, three hardware implementation scenarios are evaluated depending on whether negative floating-point numbers are used: Positive Weights Only (PWO), Positive and Negative Weights Only (PNWO), and Positive and Negative Weights with Biases (PNWB). The different implementations are analyzed at the hardware level by examining classification accuracy, energy efficiency, latency, and area overhead. The study further incorporates important RRAM limitations, including restricted conductance range and device variability. Hardware results show that the PWO scenario offers the lowest energy consumption (189 fJ/MAC) and area overhead but results in the lowest accuracy. PNWO and PNWB significantly improve accuracy (+177% and +180%) but increase energy consumption (+63% and +87%) and area (×2 and ×2.1). Under variability effects, PWO achieves better accuracy (94.65%), followed by PNWO (93.11%) and PNWB (92.11%). ...
Binary Neural Networks (BNNs) have obtained a strong foothold in the field of machine learning at the edge due to their minimal hardware requirements. However, their energy and performance efficiency remain hindered by frequent data transfer between memory and processors. Computation-in-memory (CIM) architectures address this problem by embedding processing units within the memory. Unfortunately, current implementations of CIM are susceptible to IP piracy attacks through side channels. This paper presents a novel secure periphery scheme for NN accelerators with sequential accumulation that conceals IP information by obscuring the power consumption of the counter responsible for the leakage. This is achieved by combining two innovative techniques: operand schedule randomization and an always-count Gray code counter. The results demonstrate that the proposed design effectively resists power side channel attacks (SCAs). Moreover, Signal-to-Noise Ratio (SNR) and Test Vector Leakage Assessment (TVLA) show safe leakage levels. Compared to the state-of-the-art, our countermeasure reduces area and power overheads by up to 12.7× and 13.3×, achieving only 37% area and 51.2% power overhead with the added protection logic. Notably, this enhanced security comes with zero latency overhead, maintaining the performance of the baseline design. ...

Fast and Fault-Resilient PMP Reconfiguration for RISC-V

Conference paper (2026) - Christian Larmann, Abdullah Aljuffri, Adrian Marotzke, Alejandro Garza, Said Hamdioui, Mottaqiallah Taouil
This paper presents a Physical Memory Protection Snapshot Engine (PSE), a lightweight hardware extension for RISC-V that addresses both performance and security challenges of Physical Memory Protection (PMP) reconfiguration. By storing and restoring full PMP configurations in a single cycle, the PSE drastically reduces the overhead of context switches typically used in Trusted Execution Environments (TEEs) and secure real-time systems. At the same time, the redundant storage and two-dimensional parity protection provide an efficient and effective defense against fault injection attacks that target PMP registers. In 100k randomized trials, our experimental results demonstrate that the PSE can reliably detect and prevent FI-induced privilege escalations, while incurring only 11.7% area overhead. This makes it a practical solution for embedded devices where both efficiency and trustworthiness are essential. ...

Layout-Aware Pre-Silicon Side-Channel Analysis

Power side-channel attacks pose a serious threat to cryptographic hardware implementations. To avoid deploying insecure implementations, it is essential to perform side-channel leakage assessments at the pre-silicon stage. Register Transfer Level (RTL)-level or gate-level power traces-generated, for example using SpyGlass, can be produced very efficiently but suffer from limited accuracy. In contrast, post-layout simulations provide a much higher accuracy but are prohibitively time-consuming. In this work, we propose a hybrid approach that extracts layout information, including timing and parasitic effects, and augments the gate-level netlist with this data. This approach enables fast pre-silicon power trace generation that accurately embeds post-layout parasitics. Our results show that power traces generated from gate-level and transistor-level simulations, both augmented with layout information, perform similarly in key-ranking anlysis and have a low Euclidean distance, while the gate-level simulations are 19 x-125 x faster to generate. ...
Conference paper (2025) - Hanzhi Xun, Moritz Fieback, Sicong Yuan, Changhao Wang, Erbing Hua, Hassen Aziza, Rajendra Bishnoi, Mottaqiallah Taouil, Said Hamdioui, More Authors...
Addressing non-idealities in Resistive Random Access Memories (RRAMs) is crucial for their successful commercialization. For example, the inherent resistance drift that occurs during consecutive read operations can induce Read Disturb Faults (RDF), leading to functional errors. This paper analyzes and characterizes the resistance drift and the RDF based on data measurements and presents a physics-based RRAM compact model that incorporates these non-idealities. Additionally, an in-field mitigation scheme is proposed, leveraging bidirectional read operations to balance the resistance. The scheme is implemented and validated through circuit simulations, both for RRAM used as memory and for RRAM-based computation-in-memory microarchitectures for deep neural networks. The results demonstrate that RRAM without any mitigation scheme can start failing after 8,000 consecutive reads, while our mitigation scheme ensures that the memory remains functional even after 106 consecutive reads. Furthermore, the results indicate that using the MNIST dataset as a case study, the accuracy can drop significantly from 86% to as low as 12.5% without any mitigation scheme. In contrast, the proposed mitigation scheme improves this accuracy up to 84.2%. ...
Conference paper (2025) - Changhao Wang, S. Yuan, More Authors..., N Kolahimahmoud, H. Xun, Nicolo Bellarmino, Danyang Chen, Chujun Yin, M. Taouil, M. Fieback, S. Hamdioui
Ferroelectric Field-Effect Transistors (FeFETs) are promising candidates for non-volatile memory (NVM) technologies, especially in embedded systems and edge computing. However, due to their physical characteristics, FeFETs exhibit unique defects—such as Threshold Voltage Shifting (TVS) caused by trap charges in the oxide layer—that are not captured by conventional defect models. This study adopts the Device-Aware Test (DAT) methodology to model these defects by incorporating their impact into the electrical parameters, calibrated using measurement data. Defect injection, circuit-level simulations, and fault analysis are performed to derive realistic fault models. Finally, the March algorithm and Design-for-Test (DfT) techniques are proposed to effectively detect these defects. ...

An Approximate Digital SRAM-Based CIM Accelerator for Edge AI

Conference paper (2025) - A. El Arrassi, C. Yu, M. Taouil, R.V. Joshi, S. Hamdioui
With the increasing demand for energy-efficient solutions in smart edge applications, there is a pressing need for computing architectures that can effectively manage di-verse and computation-intensive workloads. To address this, we propose APX-DREAM-CIM, an approximate digital SRAM-based Computation-In-Memory (CIM) accelerator specifically designed to maximize energy and area efficiency with minimal impact on accuracy by investigating cross-layer optimizations. The architecture uses, on the one hand, quantized models and, on the other hand, integrates a range of approximate adder designs, each offering distinct trade-offs between hard-ware efficiency and computational precision. To further enhance resilience to approximation-induced errors, we introduce a novel Approximate-Aware Training (AAT) methodology, which models the approximate behavior of the hardware during training, enabling the network to adapt accordingly. We evaluate APX-DREAM-CIM using the MNIST and CIFAR-10 datasets with LeNet-5 and ResNet-20 topologies. Experimental results show that APX-DREAM-CIM achieves up to 17% energy and 16% area reduction compared to the exact baseline architecture. Moreover, AAT enables the system to retain, and in some cases, even exceed, the accuracy of standard quantized models. ...
Edge AI accelerators have revolutionized intelligent information processing, enabling applications, such as self-driving cars and low-power IoT devices. Design efforts prioritize computational power and energy efficiency. Nevertheless, testability is also critical for in-field, reliable operation, especially for novel architectures such as memristive, analog Computation-in-Memory (CIM) cores. These structures combine emerging Resistive Random Access Memory (RRAM) with CMOS peripherals to efficiently implement vector-matrix-multiplication (VMM) operations for inference. Current research on AI Accelerator testing relies on functional test patterns, derived from abstract and unrealistic fault models. This paper presents a novel structural testing methodology for CIM VMM circuits. The methodology utilizes device-level defect models and defines new fault models for CIM VMM. The resulting test patterns are optimized to maximize defect coverage and minimize test time, since they require only a single write operation per victim cell. ...

An Anniversary Snapshot

Conference paper (2025) - M. Jenihhin, J. Raik, A. Jutman, S. Mir, M. Taouil, M. Fieback, R. Bishnoi, S. Hamdioui, K. Ma, More Authors...
The IEEE European Test Symposium (ETS) has been facilitating progress in electronic systems testing since its launch in 1996. On the occasion of its 30th anniversary, this collaborative paper gathers sections by 21 ETS teams to outline their influential ideas and milestones. Each team's section highlights historical perspective, current research, frameworks and projects as well as forward-looking research agendas in the area of electronic-based circuits and systems testing, reliability, safety, security and validation. This anniversary summary documents how research of various ETS teams, exemplifying the test community, has been evolving and transitioning from concepts to practical standards and Electronic Design Automation (EDA) tools and flows. This legacy is a strong base to drive the next generation of advances in electronic systems testing. ...
Conference paper (2025) - N. Moeskops, A. Aljuffri, S. Hamdioui, M. Taouil
In this paper, we introduce a novel passive physical anti-tampering Physical Unclonable Function (PUF) based on glitters that can protect an entire Integrated Circuit (IC) and/or Printable Circuit Board (PCB). A prototype of the proposed glitter based PUF has been developed. The glitters are dropped randomly in a resin layer during its formation and their positioning is used as the basis of a PUF. The PUF response is created by taking a picture inside the coating layer. To get a stable response resilient against noise and different temperature cycles, the picture is processed using filtering, image processing, and error correction. Using actual drill measurements, our findings indicate that even drilling with a 0.1mm diameter drill can be detected and lead to a wrong PUF response. ...