A method of removing at least a portion of a layer of material from over a semiconductor substrate that can include dispensing an etching solution over the semiconductor substrate to form a pool of etching solution on the layer of material, wherein a footprint of the pool of etching solution is less than a footprint of the semiconductor substrate. The pool of etching solution and the semiconductor substrate can be moved with respect to each other. A pool boundary of the pool of etching solution can be defined on the semiconductor substrate with at least one air-knife such that the pool of etching solution etches the layer of material over the semiconductor substrate within the footprint of the pool of etching solution. The etching solution and at least a portion of the layer of material etched by the etching solution can be removed with the at least one air-knife.