Quantitative Study of Photoelectric Laser Stimulation for Logic State Imaging in Embedded SRAM

The use of optical techniques for attacking integrated circuits (ICs) at the silicon level is increasingly being reported. Although these attacks can be complex to set and require skilled attacker that can access expensive equipment, they are nonetheless very powerful. Among the different applications described in literature, there has been a focus on extracting data directly from embedded SRAM. Such attacks can provide access to highly sensitive information such as encryption keys and bypass various security strategies. An attacker usually exploits one of the several interactions that exist between light and semiconductor to generate an image where content can be directly qualified by the data in memory (Logic State Image – LSI). Thermal laser stimulation (TLS) and laser probing (EOFM-Electro-Optical Frequency Mapping) have been reported in the literature recently but Photoelectric Laser Stimulation (PLS) did not get as much attention. Considering the potential advantages of PLS over other techniques (e.g. lower power requirements to generate current/voltage change, effect can be triggered at shorter wavelength which may lead to an improved spatial resolution), we investigate in this paper if logic state images can be generated with PLS on a variety of devices and do a comparative assessment with state-of-the-art technologies to assess potential benefits and limitations.

High Spatial and Energy Resolution Fault Isolation by Electron Beam Probing for Advanced Technology Nodes

On older semiconductor technology, electron-beam probing (EBP) for active voltage contrast and waveform on frontside metal lines was widely utilized. EBP is also being extended to include the well-known optical techniques such as signal mapping imaging (SMI) with the use of a lock-in amplifier in the signal chain and e-beam device perturbation. This paper highlights some of the achievements from an Intel in-house built e-beam tool on current technology nodes. The discussion covers the demonstration of fin and contact resolution on the current technology nodes by EBP and the analysis of the SRAM array with EBP and EBP of metal lines. By utilizing EBP, it has been demonstrated that logic state imaging, SMI, and waveform have significantly improved spatial resolution compared to the current optical fault isolation analogues.

Tunable Intermediate-Logic Ternary Circuits based on MoSe2-WSe2 Heterojunction

Van der Waals (vdW) heterojunctions, which consist of p-type and n-type semiconductors, have provided new features for transition metal dichalcogenides (TMDs). In this work, a negative differential transconductance (NDT) transistor based on a MoSe2-WSe2 heterojunction (MoSe2-WSe2 H-TR) is proposed. The MoSe2-WSe2 H-TR provides desirable device characteristics for ternary circuit operation with a switching behavior of off-state / p-type turn-on / NDT region / p-type turn-on. As a result, a 100% output voltage (VOUT) swing inverter can be achieved in a ternary inverter, which consists of the proposed MoSe2-WSe2 vdW-H-TR and a MoS2 floating-gate transistor. Furthermore, a tunable intermediate-logic ternary circuit operation is demonstrated by controlling the threshold voltage (VTH) in a pull-down n-type MoS2 floating-gate transistor. We also investigated that a light-induced operation on the MoSe2-WSe2 vdW-H-TR offers control of the VOUT amplitude at the intermediate-logic state. Based on the proposed MoSe2-WSe2 vdW-H-TR, this work suggests a strategy to obtain a tunable ternary circuit, thus providing a new concept of heterojunction electronics using layered TMDs.

The logic of non-enforcement: Entanglements between state and non-state law in Bangladesh

This article investigates the ways in which state and non-state laws become intricately intertwined in practices of conflict resolution in rural Bangladesh. Instead of inhabiting separate legal universes, I show how state and non-state laws become entangled in what I call the logic of non-enforcement. People in rural Bangladesh frequently appeal to state courts—yet they frequently do so not in order to get binding and enforceable verdicts, but to alter the outcomes of a non-state justice institution like the shalish in their favour. This leads to unexpected patterns of political accountability: people expect local elected politicians to intervene in the state courts, stop pending cases and bring them back to community-based resolution in non-state fora. Elected politicians are thus held accountable according to their ability to prevent the enforcement of state laws. At the same time, state agencies frequently bring legal cases to trial in non-state courts. I conceptualise this blurring between state and non-state laws, its underlying social dynamics as well as its normative justifications as a distinct ‘logic of non-enforcement’. According to this logic, state courts decisively affect the outcomes of processes of conflict resolution in rural Bangladesh while state laws nonetheless are systematically not enforced.

Electron Beam Probing of Active Advanced FinFET Circuit with Fin Level Resolution

This paper shows for the first time chip level electron beam probing on fully functional 10nm and 14nm node FinFET chips with sub-fin level resolution using techniques developed in house. Three novel electron beam probing techniques were developed and used in the debug and fault isolation of advanced node semiconductor devices. These techniques were E-beam logic state imaging, electron-beam signal image mapping, and E-beam device perturbation. Two tools that can offer all three techniques were constructed and used in production. The techniques have been successfully applied to real case chip debug and fault isolation on advanced 10nm and 14nm FinFET on production tools developed in-house. Sub-fin level resolution was achieved for the first time.