Double layer method for fabricating a rim type attenuating phase shifting mask

摘要

A method of forming a rim type attenuating phase shifting mask which requires only one resist layer and developing the resist using a single developing solution. A transparent mask substrate has a layer of attenuating phase shifting material, a layer of opaque material, and a layer of resist material formed thereon. The layer of resist is exposed to a first pattern using a first exposure dose and a second pattern using a smaller second exposure dose. The resist is developed for a first time forming the first pattern in the entire layer of resist and the second pattern in the top portion of the layer of resist. The first pattern is then etched in the layer of opaque material using the first pattern in the layer of resist as a mask. In one embodiment the first pattern is then etched in the layer of attenuating phase shifting material, the resist is partially etched using an O2 plasma etch leaving the second pattern in the lower part of the resist, the second pattern is etched in the layer of opaque material, and the resist is stripped. In a second embodiment the layer of resist is developed for a second time in the same solution forming the second pattern in the entire resist layer, the first pattern is etched in the layer of attenuating phase shifting material, the second pattern is etched in the layer of opaque material, and the resist is stripped.