Amorphous Silicon Spikes

Amorphous Silicon Spikes

Material Name: Silicon
Record No.: 175
Primary Chemical Element in Material: Si
Sample Type: Wafer
Uses: No data
Etchant Name: None
Etching Method: No data
Etchant (Electrolyte) Composition: No data
Procedure (Condition): No data
Note: In order to understand the origin of this NB-TLS signature, physical analysis of the ESD stressed protection structure was undertaken. A SEM image of the silicon surface obtained after silicon oxide removal by plasma etching is shown in Figure 1. In this case, several holes could be observed in the Si substrate. The presence of these holes is explained by preferential etching of the ESD induced defects by the plasma due to the presence of oxygen in the silicon. Upon ESD stressing, the oxygen from the silicon oxide is introduced into the ESD molten silicon spikes. The thermocouple created by this amorphous silicon layer with the crystalline silicon substrate explains the observed NB-TLS signal.
Reference: Félix Beaudoin, et al., Laser Beam Based ESD Defect Localization in ICs, ISTFA 2002, Proceedings of the 28th International Symposium for Testing and Failure Analysis, 3-7 November 2002, Phoenix Civic Center, Phoenix, Arizona, pp. 543-551.

Figure 1: SEM images of the silicon substrate after plasma etching of the oxygen containing amorphous silicon spikes.