Method for forming an extreme ultraviolet lithography pellicle

#The present application is a non-provisional patent application claiming priority to European Patent Application No. EP 19219382.9, filed Dec. 23, 2019, the contents of which are hereby incorporated by reference.

#The present disclosure relates to a method for forming an Extreme Ultraviolet Light pellicle.

#To enable high volume manufacturing with extreme ultraviolet (EUV) lithography (EUVL), a pellicle is utilized to protect the reticle from any fall-on particles. An EUVL pellicle comprising a carbon nanotube (CNT) membrane is a promising pellicle solution, being transparent enough to limit the imaging impact while robust enough to survive handling and capable of stopping particles. A considerable major challenge remaining for realizing a CNT-based pellicle however is to make it withstand the hydrogen plasma environment of the EUV scanner during a large number of exposures, e.g. on the order of tens of thousands or more. It has been proposed to coat a CNT membrane to make it less sensitive to exposure to hydrogen plasma. However, due to the interconnected web-like structure of CNT membranes and the relatively inert CNT surfaces, achieving a coated CNT membrane with a sufficiently maintained high and uniform EUV transmission is not trivial.

#The above, as well as additional, features will be better understood through the following illustrative and non-limiting detailed description of example embodiments, with reference to the appended drawings.

#FIG. 1 is a schematic illustration of a EUVL pellicle and a reticle system, according to an example embodiment.

#FIG. 2 is a flow chart of a method of coating a CNT pellicle membrane, according to an example embodiment.

#All the figures are schematic, not necessarily to scale, and generally only show parts which are necessary to elucidate example embodiments, wherein other parts may be omitted or merely suggested.

#Example embodiments will now be described more fully hereinafter with reference to the accompanying drawings. That which is encompassed by the claims may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided by way of example. Furthermore, like numbers refer to the same or similar elements or components throughout.

#FIG. 1 schematically illustrates the basic structures and steps for fabrication of a EUVL pellicle 20 and of a reticle system 24 comprising the pellicle 20 and a reticle 22, (i.e. a “pelliclized reticle”). The structures in FIG. 1 are shown in a schematic cross-sectional side-views.