A new method of anisotropic etching an amorphous bulk material is proposed in this paper. Laminar flow is employed in this method to mask the flow of an etchant and is termed as "liquid etch mask". Since this mask has the physical properties of a liquid, it brings several advantages that could not be achieved by any kind of other etch mask in the solid phase. As a consequence, the aspect ratio of the glass channel could be improved to approximately 1 while in an inexpensive and convenient manner.