Development Of EUV Lithography Research Articles

Progresses and Challenges of EUV Lithography Materials

In the last years the continuous efforts on the development of EUV lithography has allowed to push the lithographic performances of the EUV photoresists on the ASML NXE:3100 full field exposure tool at imec. The latest chemically amplified photoresists can reach an ultimate resolution of 16 nm and 24 nm for line-space (L/S) and dense contacts (CH), respectively, but the major issue on EUV photoresists remains to simultaneously meet resolution, sensitivity, line-edge roughness (LER) for LS and local CD uniformity (LCDU) for CH, suggesting that the desired performance characteristics of EUV photoresists may require the development of new EUV materials. Aiming to this, imec has recently started a new project to look into novel materials for EUV lithography to explore alternative approaches that can offer superior characteristics in photoresist imaging: improved LER and line collapse, high sensitivity and high etch resistance. In this paper we report the first results from the exploration of new EUV alternative materials and the latest results from the conventional EUV photoresist evaluation and process optimization at imec towards the ASML NXE:3300 full field exposure tool.

EUV Lithography Development and Research Challenges for the 22 nm Half-pitch

For the 32 and 22 nm half-pitch nodes of the International Technology Roadmap for Semiconductors, the industry will face the challenge of introducing new lithography technologies into manufacturing. Some can build on the extension of current optical lithography technologies. However, others require a tool, optics, mask, and resist infrastructure quite different from those supporting today's manufacturing. Developing new technology solutions for use in manufacturing takes a long time and the final stages of infrastructure development and commercialization are very costly. The readiness of lithography technologies needs to be assessed based on development progress, but it also needs to consider whether a technology receives the necessary support to intersect a given technology node. In addition to being technically challenging, enabling an infrastructure capable of supporting pilot line and then high volume manufacturing insertion on an aggressive timeline is also a significant business challenge. To share the risk and cost, the industry must consider new business models for efficient collaboration with tool and infrastructure suppliers on the one side and device manufacturers on the other.

Design freedom gets the brush-off [chip design

Various techniques have been used to push processes this far past the point where diffraction effects kick in. These have included using phase-shift masking to turn diffraction to the designers' advantage, and optical proximity correction (OPC) techniques, such as adding 'ears' to the corners of layout elements so that they are printed as right angles. The problem is that chipmakers are applying ever more Byzantine combinations of these techniques to keep up with shrinking process dimensions, and getting diminishing returns. Device characteristics are varying wildly as more aggressive OPC techniques are pressed into action. The chip equipment industry has been working to solve this for years, but couldn't persuade its customers that moving to 157nm illumination sources was worth the development costs given the marginal advantages it would bring over 193nm light. Unfortunately, the development of EUV lithography is fraught with difficulties. The solution to the 65 nm and 45 nm design for manufacture is new DFM routers. As they are DFM-aware they can run the rule-based checks and ensure that around 80 percent of the DFM problems are avoided. The layout team can then use model- based DFM to take care of the remaining 20 percent.

The EUV metrology program of PTB

The development of EUV lithography (EUVL) is critically based on the availability of a suitable metrology. The industrial demand for high accuracy characterization of EUV components is met at the laboratory of the Physikalisch-Technische Bundesanstalt (PTB) operated at the electron storage ring BESSY II. Using stable and well-characterized synchrotron radiation, PTB performs – in cooperation with industry – the characterization of optical components (reflectometry), the calibration and characterization of EUV radiation detectors and sources and lifetime characterization of optics and sensors. Recent examples from either of these working areas are presented.

EUV multilayer optics

According to the optics requirements of an EUVL tool, the accurate deposition of high reflective and laterally graded multilayers on ultraprecise polished substrates can be regarded as one of the major challenges of EUV lithography development today. To meet these requirements, a new dc magnetron sputtering system NESSY and technologies to coat laterally graded EUV multilayers on curved optics were developed. The major characteristics of the deposition tool and results of sputtered multilayer optics are presented in this paper.

Current Status and Perspective of EUV Lithography

The EUV lithography (EUVL) utilizes 13-nm photons as a light source. Because of the short wavelength, it provides a very high resolution and is applicable to the fabrication of multiple generations of semiconductor devices from 45 nm hp down to 32 and even 22 nm hp. This makes EUVL the most promising next-generation lithography, which will follow ArF immersion lithography. However, because the wavelength is so short, bringing EUVL to the level of a practical production tool involves many difficult challenges, such as the development of a high-power light source, high-precision reflective optics, low-defect multilayer masks, a high-resolution high-sensitivity resist, and so on. To overcome the technical difficulties and accelerate the development of EUVL, various projects have been launched and are currently running under the management of SEMATECH (US), NEDEA+ (Europe), and ASET and EUVA (Japan). These activities have produced great advances in EUVL technology in the past several years. A full-field exposure tool for process development (α tool) will be delivered in 2006, and an exposure tool for mass production (γ tool) will be delivered two or three years after that. This presentation gives an overview of recent progress in EUVL.