A method of etching a silicon substrate includes providing a silicon substrate including a first surface and a second surface. A plurality of grooves spaced apart from each other are etched from the first surface of the silicon substrate. A dielectric material is deposited on the first surface of the silicon substrate and into the plurality of grooves. A hole through the silicon substrate is etched from the second surface of the substrate to the dielectric material. A portion of the hole is located between the plurality of grooves.