Powerlase has made significant steps forward in developing reliable and cost-effective, kilowatt-class laser modules with short pulse duration and small footprint, for use as EUV drivers. These characteristics in parallel to EUV target requirements are essential for the generation of 115W of in-band EUV power at the intermediate focus. These laser modules can be coupled to the EUV target by using our flexible spatial and temporal multiplexing approach in order to scale up the laser average power on target. The multiplexing method developed by Powerlase is modular and optimised for maximum EUV collection angle. To further this goal we are currently evaluating target materials such as xenon in various phases and forms and also have a programme in place to investigate suitable tin targets.
Laser milling of diverse materials has been demonstrated with short pulse lasers ranging from microsecond to femtosecond pulse durations, and with wavelengths from the far infrared to vacuum ultra-violet. In all cases a balance between quality, throughput and cost of ownership must be struck in order to determine commercial relevance. Latest generation Q-switched Diode Pumped Solid State Lasers offer the potential to enable the industrial uptake of laser milling for a wide variety of materials including aerospace alloys, thermal barrier coatings, tool steels, diamond and diamond substitutes. This paper will investigate these practical applications of laser milling with reference to comparative laser and non-laser processes.
Powerlase has made significant advances towards making the LPP EUV source the most likely choice for a full production EUV lithography machine. Our main achievement was enhancing the performance of the LPP driver and particularly increasing the average power per laser module. This was achieved by increasing the electrical to optical conversion efficiency of our gain modules. In order to increase the conversion efficiency of the in-band EUV, we are currently using cryogenic solid xenon, as well as other target materials. The combination of an efficient and cost effective laser driver with appropriate choice of target material significantly lowers the Cost of Ownership (CoO) of the LPP EUV source, including day to day running, making it comparable to the cost of Discharge Produced Plasma (DPP) sources.
Laser milling of a variety of substrates is investigated with the intention of achieving high quality material removal to create three-dimensional shapes in the material. A high power Q-switched Diode Pumped Solid State Nd:YAG Laser at 1064nm is used in all cases. Materials investigated include Nickel Superalloys, Thermal Barrier Coatings, Steels, Tungsten Carbide and Polycrystalline Diamond. Multi-layer substrates are also considered. The effects of laser intensity, plasma formation, pulse duration, material properties, and resulting removal rate, recast and surface finish are explored for this process. This paper defines the findings of this study within the context of commercial imperatives.
We have recently made significant advances in the performance of our laser driver module employed in our laser produced plasma (LPP) EUV source. We increased the average power output from the laser whilst minimising the overall Cost of Ownership (CoO) and footprint of the system. In addition to minimising the CoO of the laser solution, it is necessary to choose an appropriate target that can attain the overall requirements of EUVL. We are currently investigating xenon in its various phases, as well as other target materials, in order to increase the conversion efficiency of the source and therefore further drive down its CoO. We have prepared a source roadmap in response to industry demands, and it shows that the combination of our demonstrated laser technology with available targets will meet the objectives for a production level source.
Widely tunable laser sources are desirable for many experiments and applications. The goal of this work is to develop sources of high frequency stability, low frequency noise, and tunability through the entire gain bandwidth of the diode laser without mode hops. Mode hops are discrete jumps in both amplitude and phase that are detrimental in many tunable laser applications. Tuning performance and analysis of grazing incidence external cavity lasers are emphasized in this paper. The external cavity diode laser studied in this work is an effective low noise platform for accessing a wide range of elements from the periodic table for atomic absorption experiments such as process control and monitoring. Frequency doubling can be used to reach many elements not accessible at the diodes fundamental wavelength range. Vapor deposition, wavelength division multiplexing, coherent communications, and fundamental research are additional applications for widely tunable external cavity diode lasers.