New Industrial Selective Processing Technique for Solar Cell

A new industrial selective processing technique based on a confined dynamic liquid drop\meniscus is presented. This approach is based on localized wet treatment of silicon wafers using confined and dynamic liquid drop that while in contact with the wafer forms a dynamic liquid meniscus. The concept of dynamic meniscus is inherited from the static meniscus, i.e. the liquid bridge that is formed when a liquid is confined between two surfaces. The difference between the static meniscus and the dynamic one is that the shape is defined by the surface tension, contact angles and gravity in the former, and by the equilibrium between fluid speed and the confinement vacuum in the latter. Such new technique allows to touch in specific defined positions the silicon wafer (front and/or back) in order to perform any kind of wet processing (e.g. etching, cleaning and/or plating) without the need of any protective photo-resist. The main scientific innovation and relevance introduced by this work can be easily applied to industrial solar cell production. Due to jet impingement of the liquid, the diffusion layer is reduced and high deposition rate of metal is obtained (i.e. Cu > 2 μm/s) offering high throughput in small equipment footprint.