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

Abbas Salhab (1) , Julien Carlier (1, 2) , Malika Toubal (1, 3) , Pierre Campistron (1, 2) , Marc Neyens , Bertrand Nongaillard (1, 2) , Vincent Thomy (1, 4)

1 IEMN - Institut d’Électronique, de Microélectronique et de Nanotechnologie - UMR 8520
2 MAMINA - IEMN - Matériaux et Acoustiques pour MIcro et NAno systèmes intégrés - IEMN
3 UPHF - Université Polytechnique Hauts-de-France
4 BIOMEMS - IEMN - Bio-Micro-Electro-Mechanical Systems - IEMN

Removing contaminants from silicon wafers surface is an important part in the semi-conductors industry. Wet cleaning processes are essential steps as they are used after each operation (lithography, etching, etc…) in order to remove contaminations like metals, organic impurities and dopants that could potentially damage the silicon wafers. A drying process is also necessary after each wet operation 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). As a reminder, we have already published a paper on the matter at wetting characterization using liquid flow on surface of Deep Trench Isolation (DTI) structures used in STMicroelectronics image sensors. 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.

Domaines: Acoustique [physics.class-ph]

Abbas Salhab, Julien Carlier, Malika Toubal, Pierre Campistron, Marc Neyens, et al.. 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. 16ème Congrès Français d'Acoustique, CFA2022, Société Française d'Acoustique; Laboratoire de Mécanique et d'Acoustique, Apr 2022, Marseille, France. ⟨hal-03714740v1⟩