USE OF DIFFRACTED LIGHT FROM LATENT IMAGES IN PHOTORESIST FOR EXPOSURE CONTROL

摘要

In microelectronics manufacturing, an arrangement for monitoring and control of exposure of an undeveloped photosensitive layer on a structure susceptible to variations in optical properties in order to attain the desired critical dimension for the pattern to be developed in the photosensitive layer. This is done by ascertaining the intensities for one or more respective orders of diffracted power for an incident beam of radiation corresponding to the desired critical dimension for the photosensitive layer as a function of exposure time and optical properties of the structure, illuminating the photosensitive layer (43) with a beam of radiation (45) of one or more frequencies to which the photosensitive layer is not exposure-sensitive, and monitoring (51a) the intensities of the orders of diffracted radiation (51) due to said illumination including at least the first order of diffracted radiation thereof, such that when said predetermined intensities for the diffracted orders are reached during said illumination of photosensitive layer, it is known that a pattern having at least approximately the desired critical dimension can be developed on the photosensitive layer.