Electron Beam Absorbed Current Research Articles

One-Probe Nanoprobing of Power Devices and Electronic Packages

Results involving the use of a single nanoprobing contact are presented, on both a SiC planar MOSFET device, and a small system-in package. In both cases, mechanical polished samples were prepared, and then probed with a single contact. For the SiC MOSFET, the depletion zones were imaged while the samples were mounted on a 45 ° stub. Discussion of the different signals generated from Passive Voltage Contrast (PVC) and Electron Beam Induced Current (EBIC), as well as possible artifacts of sample grounding, are provided. For the package, Electron Beam Absorbed Current (EBAC) provided indication of connected features within the sample. The experiment showed the capability of measuring features across three orders of magnitude in size.

Electrical resistivity mapping of potassium-doped few-layer CVD graphene by EBAC measurements

The electron beam absorbed current (EBAC) method identifies the open and/or short points in various semiconductor devices, which can be applied to characterize the current path and local resistance in graphene. In this study, potassium (K)-doped few-layer graphene with inhomogeneous K atoms seemed to be one of the appropriate materials to characterize the current path by EBAC. Nonuniform contrast in the EBAC image due to inhomogeneous local resistances is observed, which is explained by the variation of the Fermi level in the graphene channel from the G-band peak shifts from Raman spectroscopy. The changes in the contrast of the EBAC images are obtained by applying a gate voltage. These changes are attributed to the modulation of the local carrier densities by applying the gate voltage. For comparison, uniform contrast in EBAC images and uniform G-band peak positions of undoped few-layer graphene field effect transistors are confirmed. The obtained results suggest that homogeneous Fermi level leads to a uniform current path. EBAC enables us to evaluate the uniformity of local resistance and current through a pass in the graphene channel, which can be applied to other two-dimensional materials, such as transition metal dichalcogenides, graphene oxide, and hexagonal boron nitride.

Localization of NVM Inter-Poly Defects using nanoprobing techniques

The continuous growth and advancements of semiconductor devices for automotive applications and internet-of-things drive the demand and scaling of embedded non-volatile memories (eNVM). Existing eNVM landscape in 40 nm and 28 nm advanced processes is dominated by split-gate flash memory devices (Do, 2016) where inter-poly oxide (IPO) defect is one of the most challenging types of defect to localize (Tan et al., 2019). IPO defects typically surface as full or partial row NVM failures due to globally shared polysilicon select gate, control gate or erase gate among thousands of NVM cells. Conventional NVM bitmap is not effective to isolate these failures. In this paper, a systematic 2 steps isolation approach using nanoprobing techniques is proposed to effectively localize IPO defects. The first step involves the inter-poly leakage characterization to isolate the smallest failure sub-block. The next step utilizes Electron Beam Absorbed Current (EBAC) analysis to effectively localize IPO defect in nanoscale resolution subsequent TEM analysis. Two case studies of split-gate automotive grade eNVM suffering from read/write cycling failure were described to demonstrate the usefulness of the proposed techniques for accurate and precise localization on the NVM IPO defect.

Method of Precise Positioning for Defect Failure Analysis Based on Nano-Probing and EBAC

Failure analysis (FA) becomes increasingly crucial for semiconductor industries with the scale-down and larger integration of devices. In order to overcome the limitation of traditional optical resolution for FA techniques, this article proposed an effective method of precise positioning of circuit defect based on localized probing technique, nano-probing and electron beam absorbed current (EBAC). Open circuit, short circuit and gate/capacitor oxide defects were the most common failures in IC manufactures, therefore representative examples based on these failures were employed to illustrate the analysis procedure and effectiveness of the proposed method. Scanning electron microscope (SEM), focused ion beam (FIB) and transmission electron microscope (TEM) results were presented to verify the accuracy of the positioning. It was demonstrated that the proposed precise positioning method was able to accurately locate the defect position, and was useful for determining the failure mechanism as well. The method showed great potential for improving the success rate of FA for semiconductor devices.

Apply DFT Integrated Enhanced EBAC Methodology on Defect Isolations

Design for test (DFT) has been widely applied to digital circuit failure analysis (FA) in semiconductor industries. The FA methods based on DFT involve layer-by-layer checks using a polisher and an SEM for defect identification and localization. Yet these methods have limitations with high risks of sample damages. Besides, they are highly dependent on the technical proficiencies of operators and, thus, they are not effective for precise defect isolations. This problem has been aggravated, especially at advanced nodes. The nano-probing electron beam absorbed current (EBAC) has significant advantages on precisely locating defects. This technique is to directly identify specific defects without layer-by-layer checks. Therefore, it can minimize sample damages during sample pretreatment. EBAC is an efficient technique to isolate the defects when the circuit is at the floating condition. Because the ground lines exist almost everywhere in a chip and they are for, e.g., electronic static discharge charge releases or connecting with sources for pickup, EBAC becomes a natural option for us. However, due to poor EBAC images, EBAC’s applications are restricted when the circuits under test have grounding paths. In this paper, we propose two enhanced EBAC analysis methods, based on the DFT and EBAC integrated system, for the defect isolations with grounded connections. It is the first time the DFT and EBAC integrated system is reported, and we successfully demonstrated EBAC applicability by real FA cases.