Sub-half Micron Lithography Research Articles

New negative tone resists for subhalf micron lithography

Abstract New crosslinking type resist systems are described which use benzylic carbocation precursors carrying phenolic hydroxy group. The special feature of the new resists is the versatility of applications, ease of synthesis, high sensitivity, high contrast and a large process window. One such resist system has been used successfully in the back-end-of-the-line personalization for manufacturing advanced bipolar devices which required an exceptionally large process window. The new resist system is a promising candidate for surface imaging as well as for I-line, DUV and X-Ray applications.

Focal plane determination for sub-half micron optical steppers

In this paper the determination of optimal focus using a unconventional method as a function of common lithographic variables such as exposure wavelength, resist thickness, resist contrast, and numerical operture (NA) will be studied. The determination of the focal plane in resist with now widely used high NA lenses have shown to be problematic due to the asymmetric nature of the depth of focus range (1). In sub-half micron lithography, the usable depth of focus has shrunk to about 1 micron because of the relatively high NA lens used. For this reason, having the focus set at the center of the usable depth of focus is very critical. An updated application of a previously reported focus determination technique will be studied as a function of stepper and resist variables 2.

New silicon containing positive resist and its applications for sub-half micron lithography

New silicon containing photosensitive polymers have been synthesized using poly(phydroxybenzylsilsesquioxane-co-p-methoxybenzylsilsesquioxane) resins as starting materials and partially replacing the available -OH groups with 2,1-diazonaphthoquinone sulfonyloxy moiety. Bilayer resist formulations derived from these polymers have higher sensitivity and contrast as compared to the resists based on silicon resins/PAC mixtures for sub-micron and sub-half micron I-line, DUV, and g-line lithography.

High resolution lithography using synchrotron radiation

This paper reviews the current state of X-ray lithography (XRL) with special emphasis on the exposure equipment, the resolution limitations and on the expected overlay accuracy. Recent developments in mask technology will also be considered consisely. In order to take full advantage of XRL (high throughput, ultimate resolution), one has to use the parallel high-intensity synchrotron radiation. The compact storage ring “COSY” being built at BESSY presently shows all the features concerning cost and physical dimensions required for a semiconductor fabrication environment. The same holds for the low-cost beam line equipped with an X-ray mirror for the illumination of large areas on the wafer. The wobbling of the electron beam within the storage ring has also been investigated for the enlargement of the exposure area. The first X-ray stepper suitable for synchrotron sources being operated in the lithography laboratory in Berlin shows an alignment accuracy which meets the requirements of a sub-half micron lithography. Experimental and theoretical results show that a structure resolution down to 0.2 μm is achievable and that an exposure field of several cm 2 can probably be used even at a feature size well below 0.5 μm.