Phase-shift masked zone plate array lithography

#The present invention is directed to lithography using an array of Fresnel zone plates. More particularly, the present invention to lithography using a combination of a phase-shift mask and an array of Fresnel zone plates.

#Lithography is conventionally performed by a variety of systems and methods. Optical projection lithography employs a reticle (also called a mask) which is then imaged onto a substrate using either refractive or reflective optics, or a combination of the two. The reticle or mask contains the pattern to be created on the substrate, or a representation thereof. Often, but not always, the optics produces a reduction of the reticle image by a factor between 4 and 10. In other cases there is no reduction of magnification, often referred to as 1-to-1 imaging.

#X-ray lithography employs a mask held in close proximity (e.g., a gap of zero to 50 micrometers) to the substrate. By passing x-ray radiation through the mask, the pattern on the mask is replicated in a radiation-sensitive film on the substrate. This film is commonly called a “resist.”

#The present invention may take form in various components and arrangements of components, and in various steps and arrangements of steps. The drawings are only for purposes of illustrating a preferred embodiment or embodiments and are not to be construed as limiting the present invention, wherein:

#FIG. 1 is a perspective view of an array of Fresnel zone plates configured on a silicon substrate in accordance with the invention;

#FIG. 2 is a cross-sectional schematic view of an exemplary embodiment illustrating the focusing of incident beamlets onto a resist-coated substrate;

#The present invention will be described in connection with preferred embodiments; however, it will be understood that there is no intent to limit the present invention to the embodiments described herein. On the contrary, the intent is to cover all alternatives, modifications, and equivalents as may be included within the spirit and scope of the present invention as defined by the appended claims.

#For a general understanding of the present invention, reference is made to the drawings. In the drawings, like reference numbering has been used throughout to designate identical or equivalent elements. It is also noted that the various drawings illustrating the present invention may not have been drawn to scale and that certain regions may have been purposely drawn disproportionately so that the features and concepts of the present invention could be properly illustrated.

#As noted above, it is desirable to provide a zone plate array lithography system that provides control of the size and phase profile of the point-spread function. To realize such a system, the present invention utilizes a phase-shift mask in conjunction with the zone plate array lithography system. In the system of the present invention, the phase-shift mask used to control the size and phase profile of the point-spread function so as to optimize the lateral shape of the point-spread function in terms of narrowness or depressed side-lobes.