Mask Technologies for Soft X-ray Projection Lithography at 13nm

Imaging systems using soft X-ray reflective optics can be configured with either a transmission [1] or reflection mask [2] to print onto resist coated wafers. Transmission masks are well suited for high contrast and high resolution imaging. However, thin membranes are needed for such masks which can be fragile and sensitive to heating effects. Ultimately it is therefore desirable to take advantage of the robust nature of a thick reflecting mask. Practical reflective masks intended for use at λ=13 nm require Mo/Si multilayer reflective coatings with minimum features sizes from 2.0 to 0.1 μm in order to demonstrate a 0.1 μm printing capability with systems designed mask to wafer reduction from 20X to 1X, respectively. In this work we compared a variety of technologies for patterning transmissive and reflective masks containing features on this size scale. Transmissive masks which are reported consist of patterned absorbers on silicon membranes with features as small as 0.1 μm. Reflective masks patterned using various methods including; absorbing layers formed on top of multilayer reflectors; reflective coating removal by reactive ion etching (RIE); and ion damage of multilayer regions by ion implantation are also reviewed [2]. With a view to the future,we have begun to assess these reflective masks in a number of areas. Of principal interest are the reflectance contrast; resolution; process complexity; and repairability.</jats:p

Effects of Absorption on Resist Performance in Soft X-Ray Projection Lithography

Projection x-ray lithography has been proposed as a possible candidate for the delineation of integrated circuit features below 0.25µm (1). Recently it was demonstrated that near diffraction limited imaging could be achieved at several soft x-ray wavelengths (2) (3). Using 0.06pm thick films of PMMA, features of 0.2µm nd 0.1µm were printed at 37.5 and 14nm respectively. Figure 1 shows a scanning electron micrograph of these features. Note that the resist sidewalls exposed at 14nm are significantly more vertical than those printed at 37.5nm. The purpose of this work is to investigate the reasons for this difference by developing a simulation tool that would accurately model resist profiles in the soft x-ray regime (5 to 40nm).</jats:p

Extreme Ultraviolet 1:1 Ring-Field Lithography Machine

A 1X Offner Ring Field Extreme Ultraviolet lithography machine has been fabricated for use with 13.4nm radiation. Initial imaging results printed 75nm features but with low modulation. This initial work indicates that the optics suffer from a range of problems that we are trying to identify. These problems are typical of what a realistic EUV lithography machine will face.</jats:p

Achieving fast high-resolution 3D imaging by combining synchrotron x-ray microCT, advanced algorithms, and high performance data management

Synchrotrons like the Advanced Light Source (ALS) at Lawrence Berkeley National Laboratory (LBNL) are an extremely bright source of X-rays. In recent years, this brightness has been coupled to large increases in detector speeds (including CMOS and sCMOS detectors) to enable microCT 3D imaging at unprecedented speeds and resolutions. The micro-CT Beamline at the ALS has been used by geologi