Gongxue Hua

Advanced F2 lasers for microlithography

According to the SIA-Roadmap, the 157 nm wavelength of the F2 laser emission will be used for chip production with critical dimensions of 100 nm down tot eh 70 nm node. Currently al basic technologies for 157 nm lithography are under investigation and development at material suppliers, coating manufacturers, laser suppliers, lens and tool manufacturers, mask houses, pellicle manufacturers, and resist suppliers.

Advanced F2-lasers for 157-nm lithography

According to the SIA-Roadmap, the 157 nm wavelength of the F2 laser is the most likely solution to extend the optical lithography for chip production from the critical dimensions of 100 nm down to the 50 nm node. The introduction of the 157 nm lithography for high volume mass production requires high power, high repetition rate F2 lasers operating in the power range of more than 40 W or at repetition rates of more than 4 kHz. These leading specifications are combined with other challenging laser specifications on dose stability and bandwidth which must be realized within a very aggressive time line for the introduction of the full-field scanner systems in the year 2003. According to this roadmap of the tool suppliers Lambda Physik has now introduced a 2 kHz lithography-grade F2 laser F2020 for further pilot scanner systems. In this report we present basic performance data of this single line 2 kHz F2 laser and some typical results on key laser parameters which had been measured with new and improved metrology equipment. We demonstrate for the first time precise measurements on the correlation of the natural bandwidth versus pressure which had been performed with an ultrahigh resolution VUV spectrometer. In addition a new compact and transportable high resolution VUV spectrometer was used for analyses of spectral purity and line suppression ratio of the laser emission. The experimental setup and result of an absolute calibration of a power meter, for the first time directly performed at the true 157 nm wavelength, are presented.

Sub-0.25-pm 50-W amplified excimer laser system for 193-nm lithography

We report performance parameters of a robust, 50 W, high repetition rate amplified ArF excimer laser system with FWHM bandwidth of less than 0.25 pm, 95% energy content bandwidth of less than 0.55 pm, and ultra-low ASE level. Proprietary design solutions enable stable operation with a substantial reliability margin at this high power level. We report on characterization of all the key parameters of importance for the next generation microlithography tools, such as spectrum and dose control stability, in various operating modes.

High-power high-repetition-rate F2 lasers for 157-nm lithography

According to the ITRS-Roadmap, the 157nm wavelength of the F2-laser is the most likely solution to extend the optical lithography for production of ICs with critical dimensions below 70nm down to the 50nm node. The introduction of the 157nm lithography for high volume mass production requires high power, high repetition rate F2-lasers operating in the power range of more than 40W or at repetition rates of more than 4kHz. To meet the narrow time gap for an introduction of the full-field 157nm-scanner systems for real production in the year 2004/5 the community have to solve several challenging issues even in the laser section. F2-laser systems are needed which completely fulfill all specifications of a lithography light source, either for a refractive or a catadioptic projection optics. Verification and precise measurement of the key laser parameters in the VUV usually requires a specific development of the metrology, necessary for this task. In this report we present the progress which had been achieved in the development of high repetition rate high power single-line F2 lasers for catadioptic lithography application. The key features of a F2-laser > 4kHz will be demonstrated. We will also review the main parameters and the performance data from the field of the standard lithography-grade F2020 a 2kHz system which is already applied for pilot scanner tool design. Some improvements of these systems with regard to single line power, dose stability, polarization and gas life will be shown and reliability data from the field will be reviewed. Critical dependence of the spectral properties of the F2-laser emission at 2 kHz and 4 kHz will be discussed. Some new investigations on the coherence properties of the Fluorine laser are also implemented.

High-power excimer lasers for 157-nm lithography

According to the ITRS-Roadmap, the 157 nm wavelength of the F2-laser is the most likely solution to extend the optical lithography for production of ICs with critical dimensions below 70 nm down to the 50 nm node. This requires high power, high repetition rate F2-lasers with highest reliability, operating in the power range of more than 40 W at repetition rates of at least 4 kHz. In the recent three years strong efforts have been done in order to investigate and develop all kind of materials, technologies and devices which are necessary to introduce the 157 nm lithography for high volume mass production in the year 2004/5. Towards this road Lambda Physik has developed a 4 kHz line selected F2-laser with an output power of 20 W meeting the spectral performance requirements and therefore suitable for pilot 157 nm scanner. In order to reach an output power of 40 W under retention of the required spectral performance, we are now concentrating on the output power increase which comprises a new tube design, a modified discharge and charging circuit. In this paper the laser performance data which has been verified and measured by existing and improved 157 nm metrology as well as new findings on general F2-laser properties at high repetition rate, high power operation will be discussed. The prototype 4 kHz line selected F2-laser gains benefit from the outstanding long term reliability of the resonator optics. The field proven NovaLine F2020 optics modules are only slightly modified for 4 kHz operation. Lambda Physik will present appropriate reliability data which had been confirmed from field application showing laser tube and optical modules life times passing 5 Bio shots at 2 kHz repetition rate operation.

Development and characterization of advanced F2 laser source for 157-nm lithography

The 157 nm F2 laser is becoming the workhorse for lithography tools for the 70 nm technology node. In this paper we review our recent advances in technology and reliability of 157 nm lasers. We discuss the improved lifetimes of main laser components and their impact on Cost of Ownership (CoO) of the F2 laser. The typical lifetime of Lambda Physik Novaline laser discharge tube, coated CaF2 optics, and energy monitors exceeds 3 billion, 2 billion, and 2.5 billion respectively. The CoO of the F2 lasers reaches that of ArF lasers. We also report the results of our very thorough studies on the various line-narrowing arrangements, and feasibility of amplification at 157 nm, in the context of our recent studies of the fundamental spectral properties of F2 lasers.