Silicon grisms are suitable optical devices that allow for a spectroscopic mode able to effectively complement the natural
imaging mode of IR cameras, providing high spectral resolution
(R>5000) in the near infrared. We present a review of the fabrication process aimed to produce IR grisms with high refractive index. Such devices are intended to implement a high resolution mode in the Near IR Camera-Spectrograph, NICS, the user instrument at the focal plane of the Italian national telescope Galileo. Litho masking and anisotropic etching techniques have been employed to get, firstly, silicon gratings of suitable size for astronomical use, then warm bonding techniques have been used to obtain the final grisms in echelle configuration. The results and the problems encountered in the bonding procedure are presented along with a future implementation of silicon grisms in space instrumentation.© (2003) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.