The Lyot coronagraph can achieve significant on-axis starlight suppression when equipped with a notch filter image mask. Notch filter masks are placed in the focal plane and have small intricate features. They must be manufactured using nanofabrication techniques, when designed for coronagraphs operating at visible or near infrared wavelengths. This process often involves depositing an opaque material onto a glass substrate whereby a pattern is then etched. The substrate however can be a source of internal reflections and chromatic aberrations that limit the coronagraph's dynamic range and broadband performance. We present theoretical and experimental work on a new series of image masks that do not require the support of a glass substrate. We show that by adding periodic bar structures of appropriate spacing, it may be possible to manufacture a Silicon binary notch filter mask that is “free-standing”.