Super-resolution laser probing of integrated circuits using algorithmic methods

Abstract

Laser probing remains invaluable to the semiconductor industry for isolating and diagnosing defects in silicon transistors in integrated circuits during electrical stress tests. However, continuous device miniaturization below the 20 nm technology node has crammed multiple transistors within the focal spot of the laser beam, resulting in signal crosstalk, poor beam positioning accuracy and degraded fault isolation capabilities. The challenge is analogous to focusing attention to a single speaker in a crowd despite the multiple simultaneous conversations in the background. Through algorithms introduced in this patented work, consisting of cross-correlations, clustering, and our previously developed combinational logic analysis, we achieved beam positioning accuracy to better than 10 nm, extracted electrooptic waveforms from a node of a group of transistors (~18 times beyond the optical resolution limit), and applied this to isolate and identify an actual fault on a defective device. While problems associated with probing with shorter wavelength lasers continue to be addressed, our approach enhances and enables the continued probing of ICs using sub-bandgap photon energies without hardware modification to existing technology at semiconductor technology nodes below 10 nm.

Inkjet-printed electrical interconnects for high resolution integrated circuit diagnostics

“…Promising approaches to further increase the optical resolution of the OBIRCH method, beyond the diffraction limit of light, include the use of a near-field optical probe (NF-OBIRCH) instead of a laser beam as the heat source, enabling a spatial resolution of 50 nm 43 , and the application of super-resolution techniques, which can provide a defect localization resolution up 18-times smaller than the diffraction limited probe spot 44 , 45 . Moreover, the very thin RDL material stack, less than 3 µm, is appealing for applications that require the laser spot to be focused several micrometres deep inside the chip.…”

Improved Target Laser Capture Technology for Hexagonal Honeycomb Scanning

“…In the medical field, research and development on technologies such as laser capture microdissection [8,9], the laser capture of individual cells in complex tissues [10], laser capture cell sampling [11], the analysis of gene expression profiles using laser capture microdissection [12], and the laser capture of blood cells [13] has demonstrated that laser capture technology has profound significance for medical progress and for the treatment of major diseases. In the engineering field, laser scanning acquisition is mainly used in laser radar, mechanical engineering, the space industry, and other fields, such as 3D nanofabrication [14], high angular resolution LiDAR [15], super-resolution laser probing [16], laser printing [17], and laser scanning [18,19]. However, in actual engineering applications, the problems of environmental complexity and spatial instability exist, posing new challenges for laser capture and tracking systems.…”