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

Abstract

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

“…The device under test (DUT) was a proprietary 28-nm-feature-size bulk silicon test device (V DD = 0.8 V, clock frequency = 50 MHz). The device was engineered to perform a logic operation, which was previously described in [8]. By controlling the supply voltage the fail rate was set to 50% and typically several hundred 2pLADA images of a region of PMOS and NMOS transistors were recorded using a pixel dwell time of 32 μs and an image size of 512  512.…”

“…We also observed single-event upset (SEU) features, typically at intensity levels below those needed for 2pLADA. More information about SEUs observed during 2pLADA imaging is provided in [8].…”

“…It was therefore essential to synchronize the laser pulse arrival with the transistor switching event occurring at [ 10 / 12 ] the 2pLADA site. The electrical-system jitter was around 10 ps [8] and the modelocked laser was phase-locked to the DUT clock with a much lower pulse-to-pulse jitter, typically of order one femtosecond. The synchronization system provided an adjustable phase between the electrical and optical pulses with a nominal resolution of 3 ps, sufficient to ensure the optical and electrical pulses were coincident in time.…”

“…We concentrate here on LADA, which is a well-established imaging/analysis technique used to isolate interaction sites of timing-critical transistors [7]. In its original form, LADA employed a continuous wave (CW) laser and therefore provided no detailed temporal information [8], however we recently showed how this limitation can be overcome by using two-photon absorption (TPA) induced by an infrared femtosecond laser [9]. In this earlier work we demonstrated how TPA, which generates electron-hole pairs within the active CMOS layer, could be synchronized with the internal clock of the device to allow a race condition to reveal speed-limiting transistor-switching evolution with a timing resolution below 10 ps [8].…”

Biofabrication of a Tubular Model of Human Urothelial Mucosa Using Human Wharton Jelly Mesenchymal Stromal Cells

“…HWJSC have been efficiently differentiated from several cell types, including epithelial cell lineages such as skin and oral mucosa keratinocytes [ 18 , 19 ], and corneal epithelial cells [ 20 ]. Although very few works focused on the urothelial differentiation potential of HWJSC, interesting preliminary reports suggest that these cells might be able to be differentiated into urothelium-like cells both ex vivo [ 21 ] and in vivo [ 22 ], at least, partially.…”