Laser Assisted Device Alteration Research Articles

Dynamic optical beam induced current variation mapping: A fault isolation technique

In this paper, we describe the concept and applications of a dynamic laser stimulation technique based on optical beam-induced current (OBIC) variation mapping for global fault localization. A production tester exercised the chip dynamically while a 1064 nm wavelength laser interrogates the devices in the region of interest from the chip backside. OBIC variations at different test cycles are recorded for every scanned pixel and translated into a current profile. A post-processing scheme then determines the suspected defect location. Unlike laser-assisted device-alteration (LADA) which uses the same laser, this technique applies to hard defects localization. Five case studies will be presented as proof of concept.

Take a Closer Look at Electrically-Enhanced LADA: Setup

Abstract This article explains how hardware and software enhancements bring new capabilities to one of the most widely used soft-defect localization techniques. It discusses the basic concept of electrically enhanced laser-assisted device alteration (EeLADA) and demonstrates its use on different types of soft and hard defects. It also discusses the relative advantages of hardware and software implementations.

Two-photon laser-assisted device alteration in CMOS integrated circuits using linearly, circularly and radially polarized light

The rapidly developing semiconductor industry demands constant innovations in optoelectronic imaging of semiconductor integrated circuits to keep up with continuing device scaling. It was recently shown that two-photon laser-assisted device alteration (2pLADA) can deliver precision fault isolation. Here we describe an investigation into the influence of the incident light polarization on the 2pLADA spatial resolution. Linear polarization provides a highly confined but elliptical focal spot, while circular polarization diminishes the lateral resolution but benefits from a symmetrical focal spot. Radially polarized light potentially provides the highest lateral imaging resolution in all directions at the expense of the longitudinal resolution. By comparing 2pLADA results obtained using linear, circular and radial polarizations we show that certain polarizations have advantages in particular applications. Therefore a polarization optimized 2pLADA tool can achieve a sufficiently high performance to isolate faults of transistors separated by as little as 100nm and maybe smaller.

Two-photon laser-assisted device alteration in silicon integrated-circuits

Optoelectronic imaging of integrated-circuits has revolutionized device design debug, failure analysis and electrical fault isolation; however modern probing techniques like laser-assisted device alteration (LADA) have failed to keep pace with the semiconductor industry's aggressive device scaling, meaning that previously satisfactory techniques no longer exhibit a sufficient ability to localize electrical faults, instead casting suspicion upon dozens of potential root-cause transistors. Here, we introduce a new high-resolution probing technique, two-photon laser-assisted device alteration (2pLADA), which exploits two-photon absorption (TPA) to provide precise three-dimensional localization of the photo-carriers injected by the TPA process, enabling us to implicate individual transistors separated by 100 nm. Furthermore, we illustrate the technique's capability to reveal speed-limiting transistor switching evolution with an unprecedented timing resolution approaching <10 ps. Together, the exceptional spatial and temporal resolutions demonstrated here now make it possible to extend optical fault localization to sub-14 nm technology nodes.

Two-photon absorption laser assisted device alteration using continuous wave 1,340 nm laser

We report several cases of two photon absorption (TPA) laser assisted device alteration (LADA) using continuous wave (CW) 1,340 nm laser in Si Complimentary Metal-Oxide Semiconductor (CMOS) Integrated Circuits (IC). Two photon absorption using CW 1,340 nm laser in Si was confirmed by photon beam induced photocurrent measurements. TPA LADA showed greater than two times better resolution in critical timing circuit defect localization and debug application, when compared with traditional single photon absorption (SPA) LADA with CW 1,064 nm laser. A simplified analysis on the resolution improvements presented here showed in good agreement with our experimental observations. Further enhancements of this technology are outlined, which we believe will enable this technology for critical timing circuit debug capabilities well into the future generations of Si CMOS Debug applications.