000104953 001__ 104953
000104953 005__ 20190509132127.0
000104953 0247_ $$2doi$$a10.5075/epfl-thesis-3864
000104953 02470 $$2urn$$aurn:nbn:ch:bel-epfl-thesis3864-8
000104953 02471 $$2nebis$$a5376578
000104953 037__ $$aTHESIS 000104953 041__$$aeng
000104953 088__ $$a3864 000104953 245__$$aIndentation fracture of gallium arsenide
000104953 269__ $$a2007 000104953 260__$$bEPFL$$c2007$$aLausanne
000104953 300__ $$a167 000104953 336__$$aTheses
000104953 502__ $$aEric Le Bourhis, Johann Michler, W.J. Clegg 000104953 520__$$aThe scribe and break technique (or dicing) is a widely employed method in the industry of semiconductors to separate infrared laser diodes made from gallium arsenide (GaAs). The scribing step allows to create a precursor crack which is then propagated during the breaking step, along preferential {110} cleavage planes of GaAs. The main drawback of the scribing process is that it generates a lot of undesirable cracks and particles that degrade the performances of devices. In this dissertation, we have investigated the indentation process as a possible way to replace the scribing operation. For that purpose, we have investigated the morphology of the crack field and the cracking sequence as a function of the indenter geometry (shape, apex angle) and experimental conditions (maximal load, loading rate). Such investigations have been made with the help of a new tool: the in-situ SEM instrumented indentation which allows us to establish the cracking sequence and to correlate direct observations with the load-displacement histories. A new experimental technique has also been developed: cleavage cross-sectioning techniques allow us to determine the morphology of the crack field beneath the surface. The second research axis was focused on the interaction between deformation mechanisms and crack initiation. These investigations have been conducted with the help of Transmission Electron Microscopy (TEM) and cathodoluminescence. In the first part of the dissertation, we have shown that acute wedge indenters with an included angle of 60° promote the formation of a well defined half-penny crack, the nucleation of which is affected by load rate and indenter radius. The relation between the final half-penny crack size and the maximum indentation load was made with the help of a fracture mechanics model. The crack field has been compared for several indenter shape including conical (60° and 120° apex angles), cube corner and Vickers indenters. In the second part of this dissertation we have determined that the indenter apex angle influences the slip systems that are activated and the nature of dislocations that are found under the indenter. In particular, we have shown that below 60° wedge indenters, mainly diverging slip systems are activated whereas under obtuse wedge indenters, mainly converging slip systems are activated. The converging pattern predominant under obtuse indenters is correlated with a delayed half-penny crack formation and is so interpreted as a plastic shielding phenomenon. Some experiments have been performed on commercial devices under production conditions. Although some adjustments are needed to reduce the chipping-out effect that occurs at the indenter extremities, the results are encouraging.
000104953 6531_ $$ain-situ SEM indentation 000104953 6531_$$across-sectioning
000104953 6531_ $$ahalf-penny crack 000104953 6531_$$adislocations
000104953 6531_ $$amicrotwinning 000104953 6531_$$adivergent/convergent
000104953 6531_ $$acathodoluminescence 000104953 6531_$$aTEM
000104953 6531_ $$aindentation in-situ 000104953 6531_$$afissure semi-elliptique
000104953 6531_ $$aindenteur wedge 000104953 6531_$$adislocation
000104953 6531_ $$amicromaclage 000104953 6531_$$adivergent/convergent
000104953 6531_ $$acathodoluminescence 000104953 6531_$$aTEM
000104953 700__ $$0(EPFLAUTH)160153$$g160153$$aPouvreau, Cédric 000104953 720_2$$aGiovanola, Jacques$$edir.$$g112500$$0244720 000104953 720_2$$aBreguet, Jean-Marc$$edir.$$g104634$$0241133 000104953 8564_$$uhttps://infoscience.epfl.ch/record/104953/files/EPFL_TH3864.pdf$$zTexte intégral / Full text$$s24810810$$yTexte intégral / Full text 000104953 909C0$$xU10352$$0252350$$pLCSM
000104953 909C0 $$0252016$$pLSRO
000104953 909CO $$pDOI$$ooai:infoscience.epfl.ch:104953$$qDOI2$$qGLOBAL_SET$$pSTI$$pthesis$$pthesis-bn2018 000104953 918__$$dEDPR$$cIPR$$aSTI
000104953 919__ $$aLCSM 000104953 919__$$aLSRO2
000104953 920__ $$b2007$$a2007-8-31
000104953 970__ $$a3864/THESES 000104953 973__$$sPUBLISHED$$aEPFL 000104953 980__$$aTHESIS