Alternating-current induced thermal fatigue of gold interconnects with nanometer-scale thickness and width

Abstract

A technique for contactless measurement of water temperature using Stokes and anti-Stokes comparative Raman spectroscopy Rev. Sci. Instrum. 83, 033105 (2012) Creating a high temperature environment at high pressure in a gas piston cylinder apparatus Rev. Sci. Instrum. 83, 014501 (2012) Pressure-driven capillary viscometer: Fundamental challenges in transient flow viscometry Rev. Sci. Instrum. 82, 125111 (2011) Note: Signal conditioning of a hot-film anemometer for a periodic flow rate monitoring system Rev. Sci. Instrum. 82, 126109 (2011) Airfoil sampling of a pulsed Laval beam with tunable vacuum ultraviolet synchrotron ionization quadrupole mass spectrometry: Application to low-temperature kinetics and product detection Rev. Sci. Instrum. 82, 124102 (2011) Additional information on Rev. Sci. Instrum. With dramatic reduction in sizes of microelectronic devices, the characteristic width and thickness of interconnects in large-scale integrated circuits have reached nanometer scale. Thermal fatigue damage of so small interconnects has attracted more and more attentions. In this work, thermal fatigue of Au interconnects, 35 nm thick and 0.1-5 μm wide, is investigated by applying various alternating current densities to generate cycling temperature and strain in them. A multi-probe measuring system is installed in a scanning electron microscope and a probe-type temperature sensor is for the first time introduced into the system for real-time measuring the temperatures on the pads of the tested interconnects. A one-dimensional heat conduction equation, which uses measured temperatures on the pads as boundary conditions and includes a term of heat dissipation through the interface between the interconnect and the oxidized silicon substrate, is proposed to calculate the time-resolved temperature distribution along the Au interconnects. The measured fatigue lifetimes are presented versus current density and thermal cyclic strain, and the results show that narrower Au lines are more reliable. The failure mechanism of those Au interconnects differs from what is observed in thick interconnects with relatively larger grain size. Topography change caused by localized plasticity on the less-constrained surfaces of the interconnects have not been observed. Instead, grain growing and reorienting due to local temperature varying appear, and grain boundary migration and mergence take place during high temperature fatigue in such thin and narrow interconnects. These results seem to reflect a strain-induced boundary migration mechanism, and the damage morphology also suggests that fatigue of the interconnects with decreased grain size and film thickness is controlled by diffusive mechanisms and interface properties rather than by dislocation glide. Open circuit eventually took place by melting at a region of severely damage cross-sectional area with the grain growing and reorienting.

Characterization of micro-contact resistance between a gold nanocrystalline line and a tungsten electrode probe in interconnect fatigue testing

“…Our early experiments indicated that the temperature could reach 41 • C. 15 To investigate the effects of the contact temperature, a heating element that could heat the contact region up to 70 • C was used. The contact resistance was measured versus contact force under various temperature conditions.…”

“…Therefore, the temperature that characterizes the interconnect line degradation can be obtained from the temperature dependence relationship of the resistance, and then the temperature distribution on the interconnect line can be calculated. 15 To demonstrate the ability of the system to test for resistance changes in the Au interconnect line, a continuous laser beam was focused on the center of the Au wire to mimic localized Joule heating. The laser power was 100 mW, with a focal facular diameter of 549.9 μm.…”

“…15 To ease the measurement process, the pads are designed to lie at the end of the Au interconnect and have dimensions of 2 × 2 mm 2 . This design also allows two-wire or four-wire measurements, in which two or four W electric probes act as the electrodes to provide voltages across or currents through the interconnect lines.…”

“…Following Mönig's work, Moreau et al, 12 Zhang et al, 13 and Wang et al 14 also evaluated the thermal fatigue properties of a series of Cu and Au interconnects. Recent progress was made in 2011 by the authors 15 in their proposal of an improved fiveprobe measurement method based on a SEM stage, which could not only measure the electrical signal but could also measure the temperature response using a probe-type temperature sensor. We studied the thermal fatigue behavior of 35-nm-thick and 0.1-5 μm wide Au interconnects, which, to the best of our knowledge, were the thinnest interconnect samples available at that time.…”

<italic>In-situ</italic> high-temperature mechanical property measurement technology and its application in scanning electron microscope

“…首次在SEM环境下的高温纳米压痕测量是由Wheeler 等人 [11] 于2011年实现的, 经过几年的发展, 高温纳米压 图 1 (网络版彩图)典型商用微型高温拉伸平台. (a) Gatan; (b) MTI (c) K&W [9] ; (d) 岛津 4(a)所示), 通过在试件两端施加直流电的方式实现加 热. Sun等人 [17] 在SEM下对金纳米引线通过交流电的…”