Study On The Characterization Measurement Of Excimer Laser

As the key equipment of microlithography system, some properties of the excimer lasercentered at193nm are closely related to the Cost of Ownership, lithographic quality,yield, throughput and equipment utilization of lithography, which need to be measuredprecisely before being used and monitored during operation. Therefore, high-precisionmeasurement methods for the characterization of excimer laser have been performed inthis paper. And the accuracy as well as feasibility of the measurement equipments hasbeen analysis through experiments and data processing.The spectra of excimer laser are measured with a high-resolution Echelle spectrometer,the resolution of the spectrometer is0.02pm (FWHM) and0.1pm (E95), which isenhanced by using deconvolution. In addition, the accuracy of absolute centerwavelength and stability are better than0.1and0.01respectively aftercalibration with the spectra of Fe lamp. In order to obtain the spectrum of one pulse ofhigh repetition rate excimer laser, an equipment and synchronization control method isproposed.The pulse energy, energy stability, dose energy stability and integrated pulse length aremeasured with photodetector, which is calibrated by using pyroelectric energymeter.According to the measurement results in different test conditions, a test program isproposed.The beam characterizations of excimer laser are analyzed based on the internationalstandards ISO11146and ISO11670. The beam width and position stability aremeasured with large area UV camera and UV to visible fluorescence converter. Theresults indicate that the method by using UV camera is better than another method. Thepolarization of excimer laser is measured with Brewster window method and Rochonprism polarizer. And the Brewster window is Calcium fluoride substrate in this paper.The measurement accuracy of both methods is better than1%.Transmission measurement, laser calorimetry technique and fluorescence measurement are used for analysis of durability of synthetic fused silica and CaF2at193nmirradiation. Repetition rate-dependent absorptance measurements of synthetic fusedsilica were performed with an ArF laser calorimeter. By measuring the laserfluence-dependent absorptance of fused silica samples with different thickness indifferent repetition rate to separate the surface absorption and bulk absorption, and thesurface absorptance, effective single-and two-photon absorption coefficients weredetermined in different repetition rate. In addition, the repetition independent single-and two-photon absorption coefficients are obtained by measuring therepetition-dependent absorptance of fused silica sample with different laser fluence. Theeffective linear absorptance and nonlinear absorption coefficient of CaF2are alsodetermined with an ArF laser calorimeter.193nm laser induced fluorescence of fused silica and CaF2materials are measured byusing fluorescence spectrometer. Combine with the aborption measurement results andsome published papers, the reasons and mechanisms of absorption of fused silica underlong term or high energy irradiation at193nm have been given. These results provideuseful information for the development of high performance deep UV components.