Scratching and Brittle Fracture of Semiconductor In-Situ Scanning Electron Microscope

Abstract

The miniaturisation and the complexity of optical laser devices has been the focal centre of many industries in recent years. One key issue of the processing is the dicing of laser bars and devices. This process is constituted by the two crucial operations which are (1) the scratching and (2) the cleavage. The goal of the first operation is to create a subsurface crack aligned with a cleavage plane. This crack is required to be able to control the crack initiation and propagation, even in brittle materials such as Gallium-Arsenide (GaAs) so that atomically flat surfaces can be achieved [1]. Unfortunately, scribing semiconductors with a diamond tip does not only induce the defect needed but also some undesirable features such as radial cracks (chevrons) and particles. The purpose of the second operation is the separation of the laser bars and/or individual lasers. In order to investigate these two operations, two special apparatus, working inside a Scanning Electron Microscope (SEM), were employed. It was found that the scratching velocity and tip direction (edge first or face first) have only little influence on the onset of radial cracks and chips. However, the tip direction affects the size and number of the chips. Additionally, the depth of the initial crack, a, for subsequent cleavage, can be related to the applied load, P S , by the following power law: a 3/2 ∝ PS. PS has been found to be inversely related to PC. Finally, the scatter measured in PC is dependent on the scratching load P S . This is due to the fact that at high P S values, the median cracks are not constant throughout the scratch length and some deeper points exist which act as stress concentrations.

Dicing of gallium–arsenide high performance laser diodes for industrial applications

“…Nonetheless, so far only few tests (Wasmer et al, 2006;Solletti et al, 2005) were employed to tests this hypothesis so that no real statistics could have been performed. Fig.…”

“…The objective of this paper is to bring some lights in the micro-mechanical phenomena occurring during scratching of the GaAs based devices. This is due to the fact that in contrast to nanoindentation experiments, which have been thoroughly performed recently to investigate semiconductor mechanical properties (Bradby et al, 2001;Lloyd et al, 2001;Partiarch and Le-Bourhis, 2002;Grillo et al, 2003), much less effort has been put into understanding the effects of scratching at loads of a few mN on semiconductor surfaces (Wasmer et al, 2006;Wasmer et al, 2005;Fang et al, 2005;Solletti et al, 2005). Fig.…”

Dicing of gallium–arsenide high performance laser diodes for industrial applications

“…1. Although, cleavage of GaAs wafers has already been investigated by several authors (Rosentreter et al, 1997;Sauthoff et al, 1999), no correlation has been made with the initial defect, except some preliminary studies (Wasmer et al, 2005(Wasmer et al, , 2006. This step comes after a defect, called median crack (MC) when it is on the preferred cleavage planes, has been previously introduced by scratching (Wasmer et al, 2008).…”