Analysis of Wetting Transition and Pattern Collapse During the Drying Process of Deep Trench Isolation Structures Using Ultra-high Frequency Acoustic Waves and SEM Imaging

Archive ouverte : Communication dans un congrès

Salhab, Abbas | Carlier, Julien | Toubal, Malika | Campistron, Pierre | Neyens, Marc | Nongaillard, Bertrand | Thomy, Vincent

Edité par HAL CCSD

International audience. Removing contaminants from silicon wafers surface is an important part in the semiconductors industry. Thus through wet cleaning processes, after each operation (lithography, etching, etc…), contaminants like metals, organic impurities and dopants need to be removed. A drying process is also necessary after each of these wet operations in order to remove the cleaning chemicals used. These two processes (wet cleaning and drying) are critical when dealing with micro / nanoscale geometries that have high aspect ratio, making removal of small particles a tedious task that can create several problems (inefficient cleaning and surface modification). Wetting characterization using liquid flow on surface of Deep Trench Isolation (DTI) structures used in STMicroelectronics image sensors has already been studied. The dynamic study was carried out using ultra-high frequency (#GHz) acoustic waves and micro-fluidic channel made of PolyDimethylSiloxane (PDMS), in which we observed some surface modification of the DTI during the drying process. In this paper we examine in depth the drying phenomenon of the DTI, and we show the wetting state transition of the DTI from partial wetting to quasi-complete and sometimes complete wetting state. Also, we analyze the effect of capillary forces on micro / nano-structures deformation known as pattern collapse. This study is based on the correlation of a set of acoustic measurements with electron microscopy (SEM) images.

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