A method for forming microstructure cavities in a glass substrate includes directing a first laser pulse onto the glass substrate thereby forming a first microstructure cavity having a tapered configuration. The first laser pulse may have first spot area on the surface of the glass substrate. A second laser pulse having a second spot area on the surface of the glass substrate may be directed onto the glass substrate thereby forming a second microstructure cavity having a tapered configuration. The second spot area may be substantially the same as the first spot area and may overlap the first spot area such that a portion of the sidewall disposed between first microstructure cavity and the second microstructure cavity is ablated. After the portion of the sidewall is ablated, the diameter of each of the first and second microstructure cavities may be less than the diameter of the first spot area.