Optical lithography solutions for sub-65-nm semiconductor devices

Abstract

In this paper we present a status update of the exposure tool developments for sub 65 nm CD's. Main development path is 157-nm lithography. ASML follows a two step approach volume will be presented.Step 1 is based on the Micrascan step and scans platform and step 2 is based on the TWINSCAN platform. The progress of the development and first results on prototypes are discussed. This includes optics, purging, and pellicle status. The impact of CaF 2 birefringence (intrinsic and stress induced) on lens performance is evaluated. Experimental data on optical path purging is presented. The pellicle status is reviewed, and results of hard pellicle testing in KrF scanners are presented. For the Micrascan system, first imaging and overlay results are presented.

New Approaches to Nanofabrication: Molding, Printing, and Other Techniques

“…To pattern still smaller features, photolithography will require further advances, such as decreasing the imaging wavelength to 157 nm , or to soft X-rays (∼13.5 nm)known in the microelectronics industry as extreme ultraviolet (EUV) light. , The shift to shorter wavelengths of light requires new photoresists to alter the wavelength sensitivity and resolution of the resist − as well as new light sources and, especially, new types of optics based on reflection rather than transmission to focus the light. − …”

Laser nanofabrication in photoresists and azopolymers

“…“Immersion lithography” , a concept borrowed from immersion microscopy that is often used with biological specimens , offers a potential route to high‐volume production of devices with sub‐50‐nm resolution. To pattern smaller features, photolithography will require further advances, such as decreasing the imaging wavelength to 157 nm to soft X‐rays ( λ = 13.5 nm) known in the microelectronics industry as extreme ultraviolet (EUV) light . There is one photolithographic method that can produce simple patterns (e.g., diffraction gratings) without using a photomask.…”

Subaperture approaches for asphere polishing and metrology

“…In another recent publication [7], SVG-Lithography, now ASML optics, reported using MRF to achieve 0.57 nm and 0.63 nm rms for <111> and <100> CaF 2 lenses respectively, i.e., tolerance tighter than lambda/1000 rms, see Figure 14. Similar or even better results have been obtained in other applications such as the improvement of thickness uniformity of SOI wafers described in Tricard, et.…”