X-ray lithography: Status, challenges, and outlook for 0.13 μm

Abstract

X-ray lithography (XRL) has been under development since the early 1980s, and has reached a state of relative maturity. Numerous devices, including dense and complex integrated circuits, have been fabricated using XRL for one or more critical levels. While development of XRL technology itself continues, XRL is in use in several locations around the world for process development of advanced DRAM (1 Gb and beyond) and logic (0.18 μm and below) integrated circuits. Most of the tool set in use today comes from commercial vendors. Resolution using XRL has been demonstrated at dimensions down to 70 nm or below. Excellent critical dimension (CD) control results have been achieved in simple, single-layer, commercially available resists; for example, a total CD variation of 22 nm (3σ) has been achieved using a mask with a CD variation of 18 nm (3σ). Because of these capabilities, along with the experience and relative maturity of the technology, we believe that XRL is the technology best positioned to succeed optical lithography and be available for timely insertion into manufacturing for 0.13 μm ground rules, as well as to be extendible to 0.10 μm and below. In order to be accepted for manufacturing, however, significant work remains to be done. In particular, new e-beam mask writers and wafer aligners are needed, along with improved mask inspection and repair tools. Mask fabrication processes must also be advanced. The ability to satisfy these needs is not expected to be limited by fundamental physics, but rather is expected to depend on skilled engineering design and implementation.

Chemical Imaging of Photoresists with Coherent Anti-Stokes Raman Scattering (CARS) Microscopy

“…The most advanced lithographic technologies enable patterning of the resist materials with line dimensions below 100 nm, [1][2][3][4][5] which thus places new demands on measurement characterization techniques.…”

Fabrication of x-ray masks using evaporated electron sensitive layers for back patterning of membranes

“…Tantalum was chosen as the absorber for its chemical stability, making it possible to perform repeated cleaning of the mask in an industrial environment. 13 Also, it has been demonstrated by other researchers 7 that Ta has excellent mechanical properties, allowing adequate image placement for the 70 nm fabrication node of the International Technology Roadmap for Semiconductors.…”

Parametric investigation of laser nanoimprinting of hemispherical cavity arrays

“…[4][5][6] However, serial processing limits the throughput and the cost is high. X-ray lithography has high throughput 7,8 but it requires a high capital cost. UV photolithography 9,10 is a widely used method; however, its feature sizes are limited by its diffraction limit of /2 (Ref.…”