Amphibian XIS: an immersion lithography microstepper platform

Abstract

Recent advances in immersion lithography have created the need for a small field microstepper to carry out the early learning necessary for next generation device application. Combined with fluid immersion, multiple-beam lithography can provide an opportunity to explore lithographic imaging at oblique propagation angles and extreme NA imaging. Using the phase preserving properties of Smith Talbot interferometry, the Amphibian XIS immersion lithography microstepper has been created for research and development applications directed toward sub-90nm patterning. The system has been designed for use at ArF and KrF excimer laser wavelengths, based on a fused silica or sapphire prism lens with numerical aperture values up to 1.60. Combined with a chromeless phase grating mask, two and four beam imaging is made possible for feature resolution to 35nm. The approach is combined with X-Y staging to provide immersion imaging on a microstepper platform for substrates ranging up to 300mm. The Amphibian system consists of single or dual wavelength sources (193nm and 248nm), a 2mm exposure field size, stage accuracy better than 1 um, polarization control over a full range from linear polarization to unpolarized illumination, full control of exposure dose and demodulation (to synthesize defocus), and the ability to image both line patterns as well as contact features. A fluid control system allows use of water or alternative fluids, with the ability to change fluids rapidly between wafers. The Amphibian system is fully enclosed in a HEPA and amine controlled environment for use in fab or research environments.

Fundamental Optical Properties of Linear and Cyclic Alkanes: VUV Absorbance and Index of Refraction

“…While the transmittance of methyldinorbornane at 193 nm is too low for use in immersion lithography manufacturing, imaging through a thin layer of this fluid is possible with interference immersion lithography 42 and can be used to demonstrate the patterning of 32 nm features with immersion lithography using n 2 -1 n 2 + 2 ) 4π 3…”

Effects of beam pointing instability on two-beam interferometric lithography

“…. Equation [5][6][7][8][9][10][11][12][13][14][15][16][17] If the standard deviation σ of beam direction fluctuation is known, that is, P(δ) is known, it allows us to numerically evaluate the fringe contrast in the absence of laser beam direction fluctuation. An example is shown in Figure 9.…”

“…The resemblance of projection imaging to interference imaging in the cases analyzed in the preceding paragraph has stimulated studies of optical projection systems using an interferometric setup. [4][5][6][7][8] Although those are special cases, they represent a system's resolution limits, which mostly define the system's capability. An advantage of using an interferometric setup is that the costly lenses are not needed.…”

Achieving interferometric double patterning through wafer rotation

“…[3][4][5] Interferometric imaging systems such as the Amphibian XIS microstepper serve as an ideal platform for developing novel double patterning materials and processes. 6 Two-beam interference lithography produces the highest possible contrast grating of any optical lithography, while eliminating both the mask and projection optics. High index lens materials such as sapphire and LuAG, which are hard to produce in large diameter high precision projection optics, are once again viable.…”