TW200305715A - UV optical fluoride crystal elements for λ < 200nm laser lithography and methods therefor - Google Patents

Abstract

The invention provides a method of detecting sub-ppm lead impurity levels in a below 200 nm transmitting optical calcium fluoride crystal. The method includes providing a below 200 nm wavelength transmitting optical fluoride crystal having a crystal light transmission path length, providing a 200-210 nm spectraphotometer having a light source for producing a transmission test wavelength in the range 200 to 210 nm and a transmission detector for measuring transmission of the test wavelength, and transmitting the transmission test wavelength in the range 200 to 210 nm through the below 200 nm wavelength transmitting optical fluoride crystal light transmission path length and measuring the transmission of the 200 to 210 nm test wavelength through path length to provide a lead ppb impurity level measurement less than 500 ppb. The invention provides for improved manufacturing of below 200 nm wavelength optical elements and optical fluoride crystals such as ultralow lead contaminated calcium fluoride.

Description

200305715 V. Description of the invention (l) --------------- I. Technical field to which the invention belongs: f The invention generally relates to λ &lt; 2000m perspective optical fluoride crystal and Γ to create optical elements, and Especially for testing and manufacturing high-quality fluoride crystals and apricot lithographic / laser elements with south fluoride purity and very low levels of lead and oxygen pollution. Second, the prior art The task of improving computer performance needs lies in the use of manufacturing integrated circuit wafers lithographic printing process. Light lithography involves illuminating a mask and focusing the mask pattern through an optical low-light lithography system onto a wafer coated with a photoresist. The pattern on the mask is thus transferred to the wafer. Reducing the contour line width on known wafers will improve performance. The enhanced resolution required to achieve finer line widths is achieved by reducing the wavelength of the illumination source. The light energy used for patterning in light lithography is gradually moved deeper into the ultraviolet region. It requires optical narratives that can achieve this at these short light microlithographic lithographic wavelengths. A few materials that are highly transmissive at 193 nm and 157 nm and that do not deteriorate under intensive laser exposure are known. Fluoride crystals such as calcium fluoride and barium fluoride are possible materials that are highly transmissive at wavelengths <2000 nm. The use of projection light lithography systems with vacuum ultraviolet wavelengths below 193nm provides the advantages required to achieve smaller form factors. The low-light lithographic printing system using vacuum ultraviolet light in the wavelength range of 1 57nm has the potential to improve the integrated circuit and its manufacturing. The commercial use of 193 nm and wavelengths lower than, for example, i57nm vacuum ultraviolet has been hindered. The wavelength is caused by the transmission characteristics of the optical material. Semiconductor workers using VUV light below 175nm, such as light at 157nm

200305715 V. Description of the invention (2) The slow progress of the industry is due to the lack of optically transmissive materials for the economical manufacture of wool germs and the difficulty of manufacturing wool germs. The wool germs were identified as high quality and in line with the expectations of low-light lithographic printing Components and lasers. For the uvuv 1 57nm region deep ultraviolet light lithography, such as used to manufacture the emission spectrum of fluoro excimer lasers in integrated circuits, there is a need for transmissive optical fluoride crystals with wavelengths below 20 Onm, which have beneficial optics and high quality Characteristics including good transmission at less than 200nm and at 193nm and 157nm and being able to be manufactured, tested, evaluated, measured and economically used. The present invention overcomes the problems of the prior art and provides a way to economically provide a transmissive optical fluoride crystal with a wavelength of less than 20 nm. The quality is very low and the amount of lead contamination can be measured. Manufacturing. The present invention provides an absorption band analysis test for high-quality calcium fluoride optical fluoride crystal light lithography and excimer laser elements with a very low amount of lead concentration. 3. Summary of the Invention: The present invention includes a method for sensing low lead impurity content in transmission optical fluoride crystals below 200 nm. The method includes providing a transmissive optical fluoride crystal having a wavelength below 200 nm, which has a crystal light transmission path length of ^ 2 mm. The method includes providing a light transmission 2000—21 Onm scanning spectrum analyzer with a light source to generate a transmission test wavelength in the range of 2000 to 21 Onm and a transmission sensor to measure the transmission and retransmission of the test wavelength. The transmission test wavelength in the range of 〇 to 2100 nm is transmitted through a wavelength of less than 200 nm. The transmission path length of the optical fluoride light transmission path is measured. 〇〇ppbThe measurement of the content of impurities. priority

200305715 V. Description of the invention (3) The present invention provides that the amount of lead ppb impurities measured is less than 50 ppb, preferably 300 ppb, more preferably 100 ppb, more preferably 50 ppb, more preferably 20 ppb, and It is preferably 10 ppb. The invention comprises a method for measuring the content of lead impurities below 1 ppm in optical fluoride light lithographic printing crystals transmitting light with a wavelength of less than 200 nm. The method includes providing a transmission optical fluoride crystal having a wavelength of less than 20 nm, which has a crystal light transmission path length of 2 lcm. The method includes providing a spectrum analyzer with a 200-2 1 Onm absorption band measurement system, which has a light source to generate a test wavelength in the range of 200 to 210 nm, and a transmission sensor to calculate the absorption coefficient at the test wavelength. The transmission 200 to 21 Onm test The transmission path length of the light transmitting optical fluoride crystal at a wavelength of 200 nm ^ 1 cm and the absorption coefficient measured at a test wavelength through a path length of -1 cm to provide a lead pollution amount absorption coefficient &lt; 0 · 001 7cm-1 〇 The present invention includes a method for making a lithographic printing element with a wavelength of less than 20 nm. The method includes providing a transmission optical fluoride crystal with a wavelength of less than 20 Onm, a crystal light transmission path length of 22 ram, and providing a light transmission 2 0-21 Onm spectrum analyzer measurement system, which has a transmission test wavelength of 200 to 21 Onm. Light source and sensor for measuring transmission of test wavelength. The method includes transmitting a transmission test wavelength in a range of 200 to 21 Onm and transmitting a transmission path length of an optical fluoride crystal through a wavelength less than 20 Onm and measuring a transmittance of the test wavelength in a range of 200 to 21 Onm via a path length to provide a pollution amount. Measurements below 50 Oppb, preferably less than 300 ppb, more preferably less than 100 ppb, and re-formed optical fluoride crystals are optical elements with wavelengths below 200 nm, which have an absorption coefficient <20017CHT1 at 200 to 210 nm.

200305715 V. Description of the invention (4) The present invention includes a method for manufacturing a transmission optical fluoride crystal with a wavelength below 200 nm. The method includes providing a pre-melted fluorinated crystalline solid to form a calcium fluoride melt and growing calcium fluoride crystals from the melt to provide an optically fluorinated # 5 crystal to transmit wavelengths below 200 nm. The method includes providing a light transmission 200-2 110nm spectrum analyzer, which has a light source that generates a transmission test wavelength in the range of 200-21 Onm and a transmission sensor to measure the transmission of the test wavelength and uses a range of 200 to 2100 nm. The internal transmission test wavelength measures the amount of lead contamination in the length of the fluorinated dance path, and grows optical calcium fluoride crystals to transmit less than 200 nm wavelength, with an absorption coefficient of <0.0017 cm1 at 200 to 210 nm. The present invention includes a transmission optical fluoride crystal of calcium fluoride with a wavelength of less than 200 nm, a transmission less than 200 nm, a transmission greater than 99% / cm, a ppb value less than 50, and an absorption coefficient of <0.0017 cm-1 at 200 to 210 nm. The present invention includes a method for making a transmissive optical fluoride crystal having a wavelength below 200 nm. The method includes providing a pre-melted barium fluoride crystal solid, melting the pre-melted barium fluoride crystal solid to form a barium fluoride melt, and growing a barium fluoride crystal from the melt to provide an optical barium fluoride crystal to transmit wavelengths below 200 nm. . The method includes providing a light transmission 200-210nm spectrum analyzer having a light source to generate a transmission test wavelength in a range of 200 to 210nm and a transmission sensor to measure a barium fluoride path length using the transmission test wavelength in a range of 200 to 21 Onm. The amount of lead contaminates and grows optical barium fluoride crystals to transmit wavelengths below 200 nm, which has an absorption coefficient &lt; 0. 01 Tcnr1 at 200 to 210 nm. The present invention includes an optical fluoride crystal having a transmissive barium fluoride with a wavelength of less than 20 Onm, a transmittance of less than 200 nm greater than 99% / cm, a lead ppb value of less than 50, and an absorption coefficient at 200 to 21 Onm &lt; 0. 0017

200305715 V. Description of the invention (5) cm1 ° IV. Implementation The present invention includes a method for measuring the content of impurities below 1 ppm in a transmission optical fluoride crystal below 200 nm. The method includes providing a transmissive optical fluoride crystal 20 at a wavelength below 200 nm. The optical crystal 20 is preferably an optical fluoride crystal having a contamination amount of less than 1 ppm. The method includes providing a light absorption band measurement system spectrum analyzer 22 having a light source 24 to generate a transmission test wavelength in the range of 200 to 21 Onm and a transmission sensor to measure the transmittance of the test wavelength. The method includes the amount of lead contamination in a gas path length 21 of a gaseous crystal with a transmission test wavelength in the range of 2000 to 2100 nm. The method includes transmitting a transmission test wavelength in a range of 20 to 21 Onm via an optical fluoride crystal 20 with a wavelength less than 2000 nm and measuring the transmission through the crystal test wavelength to provide a wrong ppb impurity content measurement value less than gooppb, preferably Ground is less than 500 ppb, more preferably less than 300 ppb, more preferably less than 1000 ppb, more preferably less than 50 ppb, more preferably less than 20 ppb, and most preferably less than 10 ppb. The light source 24 is preferably a light source with a wide band wavelength, such as a light bulb. The light source 24 preferentially provides a scannable wavelength spectrum of 200-210 nm. Compared with the laser light source, the light bulb 24 is preferably a wide-band non-homogeneous light source. Providing 200 to 21nnn test wavelengths preferentially includes the use of a wavelength selector 34, such as a monochromatic filter, to control the scanning flux and the selection of test wavelengths in the 200 to 21 Onm range. In the preferred embodiment, the 200-21 Onm scannable wavelength spectrum is provided by a deuterium bulb light source, which is filtered using a monochromatic filter. Preferentially use the spectrum analyzer to scan the 200-21 Onm spectrum. Preferentially, this method involves using a spectrum analyzer to scan the spectrum in the center wavelength range of 205 nm to identify the baseline where the 20 5 nm absorption band is located. Absorbed by total

200305715 V. Description of the invention (6) Subtract the absorption based on 205nm and get the absorption of wrong pollution amount. Scanning at the center wavelength of 2 05nm preferentially provides crystal baseline absorption, so that other absorption bands and surface optical loss (baseline) can be deducted. In a preferred embodiment for sensing very low levels of lead contamination, a scanning wavelength centered at 20 5 nm uses a scanning range of 1 95-220 nm to vary the size at the 205 nm baseline. This method provides instant measurement of lead contamination values across the crystal. Transmission 2OOnm to 210 nm Transmission test wavelengths preferentially include transmission 203 to 207nm transmission test wavelengths. Transmission of optical fluoride crystal light transmission path lengths through wavelengths below 2OOnm and measurement of 20 3 to 20 7nm test wavelengths through transmission of path lengths to provide Lead port? 1) The measured value of the impurity content is lower than 50000). Preferential transmission 2 () 0 to 21 Onm transmission test wavelength includes transmission of about 2.05 nm transmission test wavelength through optical wavelength of less than 200 nm transmission optical fluoride crystal light path length and measurement of the transmittance of 2 05 nm test wavelength through path length to Provides lead ppb impurity content measurements below 300 ppb. In the preferred embodiment of the present invention, a crystal optical transmission crystal having a wavelength of less than 200 nm with a crystal light transmission path length of $ 2 mm is provided, which includes providing a crystal light transmission path length of 2 cin and a transmission test wavelength via a -1 cffl fluoride crystal light path length. To provide lead ppb impurity content measurement value is less than 10 ppb. More preferably, the length of the crystal light transmission path is -10 cm and the transmission test wavelength is transmitted through the -10 cm fluoride crystal transmission path length to provide a lead ppb impurity content measurement value of less than 50 ppb, and more preferably less than 10. ppb. As shown in Figures 1A-B, the transmission path length of the fluoride crystal measured by the spectrum analyzer is 21. As shown in Fig. 1B, the spectrum analyzer 22 has slots 22, which have a length CL between the beam window 23 and 25 of the slot chamber, and preferably 0.5CL-the length of the fluoride crystal light transmission path. Priority Spectrum Analyzer Package

Page 11 200305715 V. Description of the invention (7) The sample holder 19 containing the chamber chamber is used to fix and stabilize the crystal sample 20 relative to the windows 23 and 25. The chamber sample holder 19 receives the long crystal sample and ensures that the light beam aligned with the transmission test wavelength is aligned in the chamber between the windows, so that the crystal sample is centered in the center of the chamber. The crystal 20 preferably has a polished surface 17. Preferentially use surface parallelism less than 1 degree, path length 21 to be at least 50mm (50-100mm) to provide the wrong ppb impurity content measurement value within a few ppb range (&lt; lOppb) ° for the tens of ppb range (i. ppb &lt; lead concentration &lt; 100ppb) For lead concentration measurement, the path length is in the range of 5-10 mm. The path length of the fluoride crystal sample is preferably at least 50mm, and more preferably at least 90mm (100mm preferred embodiment), so that the CL of the spectrum analyzer chamber is at least 100mm, more preferably CL $ 150mm, and more preferably CL2 200nm (200mm preferred embodiment). The present invention includes a method for measuring an impurity content of less than 1 ppm in an optical fluoride light lithographic printing crystal, and the crystal is a light transmitting below 200 nm, such as calcium fluoride or barium fluoride crystal20. The method includes providing a transmissive optical fluoride crystal 20 with a wavelength of less than 200 nm, a crystal light transmission path length of 21 2 lcm, and providing a spectrum analyzer 22 with a 200-21 Onm absorption measurement system with a light source 24 to generate 200 to 21 Onm. Test the wavelength in the range and the transmission sensor to calculate the absorption coefficient at the test wavelength. The method includes transmitting the test wavelength of Fan Yuan in the range of 2000 to 21 Onm through a wavelength of less than 200 nm and transmitting the optical fluoride crystal through the g 1 cm path length and measuring the absorption coefficient at the test wavelength through the g 1 cm path Length to provide lead contamination absorption coefficient <0.0017cm1. Preferentially, this method includes transmission of a test wavelength in the range of 203 to 207 nm through a wavelength of less than 20 nm and transmission of optical fluoride crystal light transmission ^ 1 ^ 11 path length and measurement of the test wavelength of 203 to 20711111.

Page 12 200305715 V. Description of the invention (8) The absorption coefficient of the g lcm path length is used to provide the absorption coefficient of lead pollution &lt; 0 · 001 6CHT1. More preferably, the method includes transmitting a test wavelength of about 205 nm through a wavelength below 20 Onm and transmitting optical fluoride crystal light through a g lcm path length and measuring an absorption coefficient through the $ lcm path length at a 205 nm test wavelength to provide lead contamination Amount of absorption coefficient &lt; 0. 0015cm1. Provides a transmission optical fluoride crystal 20 with a wavelength of less than 20 nm, which has a crystal light transmission path length of 21 Ocm to provide a lead pollution amount absorption coefficient and an impurity measurement of less than 50 ppb, preferably $ 20, more preferably $ 10, more preferably $ 5, And most preferentially $ lppb. The present invention includes a method for manufacturing an optical element E with a wavelength of less than 20 Onm to transmit light with a wavelength of less than 200 nm. 2 Excimer laser output of 157nm or ArF excimer laser of 193nm is shown in Figure 2-3. Preferentially, the method comprises manufacturing a light lithographic printing element 42 with a high optical quality of λ &lt; 200 nm, from an optical fluoride crystal 20 having a measurement value of a contamination content of less than 1,000 ppb. The method includes providing a transmission optical fluoride crystal 20 with a wavelength below 20 Onm, which has a crystal light transmission path length 21 of g 2 mm, and provides a light transmission with a rice source 24 of a 200-21 Onm spectrum analyzer 22 to produce a transmission test wavelength between 200 and 200. 21 Onm range and transmission sensor 28 to measure the transmission at this wavelength. The method includes transmitting a transmission test wavelength (200 to 21 Onm) through a light transmission path length of a transmission optical fluoride crystal below a wavelength of 200 nm to measure the transmission of a transmission wavelength through the path length of 200 to 210 nm to provide a lead pollution amount. The measured value is less than 500 ppb, preferentially &lt; 1 OOppb and the formation of optical fluoride crystals with a wavelength of less than 20 Onm optical element E, which has an absorption coefficient of lead pollution at 200 to 2 10 nm &lt; 〇 · 〇〇17cm l . Priority pollution content

Page 13 200305715 V. Description of the invention (9) The measurement is less than 100ppb, preferably &lt; 50ppb, more preferably &lt; 20ppb, and most preferably less than lOppb. Provides transmission of optical fluoride crystals with a wavelength of less than 200 nm with a crystal transmission path length of 21, including testing of transmission of optical fluoride crystals with a transmission length of l 200 cm with a crystal transmission path length of less than 200 nm, and transmission of a range of 203 to 207 nm The wavelength passes the wavelength of less than 200nm. The optical fluoride crystal transmits light through g 1 cm path length 2 1 and measures the absorption coefficient of g 1 cm path length at the test wavelength of 203 to 207 nm to provide a measurement of lead pollution less than 50 ppb. The optical fluoride crystal is formed as an optical element E having a wavelength of less than 200 nm, which has an absorption coefficient of lead contamination at 203 to 207 nm &lt; 0.00016 cm1. Preferentially, the crystal light transmission path length is $ 10 cm and the method includes transmitting about 20 5 nm test wavelength through a wavelength below 200 nm and transmitting optical fluoride crystal light transmission path length of $ 10 cm and measuring 205 nm through 2 icin path length. The absorption coefficient is to provide a measurement value of less than 20 ppb of contamination and to form an optical fluoride crystal with an optical element E having a wavelength below 200 nm, which has an absorption coefficient &lt; 0.00 16 cm-1 at 205 nm. In the preferred embodiment, the optically-transmissive optical fluoride crystal 20 having a wavelength below 2000 nm is composed of calcium fluoride CaF2. In the preferred embodiment, the wavelength below 2011111 wavelength transmitting optical fluoride crystal 20 is composed of barium fluoride 83. In the preferred embodiment, for example, as shown in FIG. 4, the optical wavelength E (by the optical element E (by Crystal formation) Absorption coefficient <200lTcnr1 from 200 to 210nm. Preferentially, the measured amount of lead contamination of the crystal 20 and the optical element 42 formed therein is less than 20 PPb, more preferably &lt; 10 ppb, and more preferably &lt; lppb. Provides transmission below 200nm

Page 14 200305715 V. Description of the invention (o) The optical optical fluoride crystal 20 preferably includes a calcium fluoride crystal so that the transmission at <200 nm is greater than 99% / cm. This method provides a light lithographic printing element 42 having a measured contamination value of less than 50 PPb and an absorption coefficient &lt; 0. 0017 cm-1 at 200 to 210 nm, and if the optical coating film is coated on the surface of the crystal, it is preferentially applied to any Measurement before film. The present invention includes a method for making a sub-200nm wavelength transmitting optical fluoride crystal 20. The method includes providing pre-melted fluorinated and crystalline solids, and melting pre-fused calcium fluoride crystalline solids to form a calcium fluoride melt and growing calcium fluoride crystals from the melt to provide optical calcium fluoride crystals for transmission below 200 nm. wavelength. The method includes providing a light transmission 200-210 nm spectrum analyzer having a light source to generate a transmission test wavelength in a range of 200 to 21 On and a transmission sensor to measure fluorination using a transmission test wavelength in a range of 200 to 210 nm. The amount of lead contamination in the length of the calcium path, and the growth of optical calcium fluoride crystals to transmit wavelengths below 200 nm, and its absorption coefficient at 200 to 210 nm is &lt; 0. 0017CHT1. In the embodiment, measuring the amount of calcium fluoride contamination with a 200-200 nm spectrometer is included in measuring the amount of lead contamination in a pre-melted calcium fluoride crystal solid. In the embodiment, 200-2 l Onro spectrum analyzer 22 is used to measure the amount of lead pollution in fluorination, and the amount of pollution is included in the fluorinated crystal grown from the melt of fluorination. In an embodiment, the amount of fluorinated # § medium contamination is measured using a 200-210 nm spectrum analyzer when the crystal is in the optical element E-form before optical coating. In the examples, the amount of lead contamination in calcium fluoride is measured before crushing into a particulate form and / or during crushing from a large solid block to a smaller volume. Measure and monitor the amount of lead contamination in the crystal during the manufacturing process of the crystal. Provide a growing fluorinated trans-crystal to transmit the wavelength below 200nm and make the amount of lead pollution less than 50ppb.

Page 15 200305715 V. Description of the Invention (li) Place &lt; 20 ppb. Optical fluoride crystals are grown preferentially, and 20 has a ship pollution amount of less than 1 Oppb, preferably &lt; lppb. Fig. 5 shows an embodiment of the present invention, in which a vacuum-controlled crystallization south temperature furnace 110 device is stacked and connected to a graphite hanging pot and a top storage crucible 100. The intermediate crucible apparatus previously melted the calcium fluoride crystal solid dense dish 80. Pre-melted calcium fluoride crystal solid dish is obtained by heating and purifying and compacting with a fluorinating agent. In the examples, the pre-fused calcium fluoride crystal solid is obtained by pre-melting and purifying and using pbF2 as a calcium fluoride fluorinating agent. It uses a controlled gas vacuum high temperature furnace operation to remove volatile lead and oxygen from the crystalline material. Thing. In an embodiment, as shown in FIG. 5, for example, a high temperature furnace can be loaded with calcium fluoride powder particles 70, which contains a fluorinating agent such as lead fluoride. The pre-fused calcium fluoride crystal solids loaded into the crystal growth high temperature furnace 11 is melted in a crucible to form a calcium fluoride melt ^ which grows by slowly cooling the melt in the crystal growth high temperature furnace ^ calcium fluoride crystal 20 For example, to reduce the thermal gradient during the growth process through StOckbarger crystals. In another embodiment shown in FIGS. 6-10 of the present invention, the I-growth collapse 62 has a seed crystal 60 that is preferentially oriented to the crystal axis in a seeder 64. The pre-dissolved fluoridium crystal solid particles 52 are loaded in oil:. A crystal growth crucible containing pre-fused calcium fluoride crystal solids = an optical fluoride growth high temperature furnace UGt, which contains a high temperature upper melting and thermally regulated wall plate 14 which provides a thermal gradient for crystal growth and solidification. 2 The fluorinated fluorene crystal solid is melted in a high temperature furnace 8 in a high temperature region 8 to form a calcium fluoride melt 66. Calcium fluoride optical crystals 20 are cured by adjusting the crystal growth of the siding plate 14. A plate, Thai &amp; u 1 &amp; domains are grown out of the melt 66 to improve the optical fluorine (transmission below 20-wavelength). Compound crystal 20. The Shaw method contains

Page 16 200305715 V. Description of the invention (12) The crystal 20 is manufactured by a 20 0-21 Onm transmission spectrum analyzer 22 to measure calcium fluoride. For example, it is a pre-fused calcium fluoride crystal solid 80, and the crystal 20 and the crystal are grown. Amount of lead pollution in species. During the entire crystal manufacturing process, 2000-21 Onm spectrum analyzer 22 is preferentially used to measure, monitor, and control the lead content of calcium fluoride, especially when lead fluoride is used as a fluorinating agent, it needs to be changed by the final The product crystal 20 and its manufactured optical element E are removed to provide high transmission and optical characteristics at wavelengths below 2000 nm. Use a 200-21 Onm spectrum analyzer to measure the amount of lead fluorinated pollution to provide a measured value below 50 PPb, preferably below 20 ppb, more preferably below 1 Oppb, and most preferably below lppb by weight. The fluorination # 5 error contamination measurement value of the 200--2 10nm spectrum analyzer can be used to identify the high error contamination area of the crystal and removed by the optical fluoride crystal optical element manufacturing process. As shown in FIG. 11, the lead pollution measurement can be used to identify the highly contaminated local crystal region 132 of the absorption coefficient &gt; 〇 〇 〇17cm-〗 at 200 to 21 Onm, and further processed into individual optics. The element blank preform crystal 20 and the optical element 42 manufactured therefrom remove the high lead contaminated area 132. For example, as shown in Figures 1 2-1 3C, measurements can be used to identify localized crystal areas 50 of high lead contamination in the pre-melted solids 52 to provide high-purity pre-production results from the use of crushers 56 and 58. Molten solid particles. High lead contaminated area 50 with an absorption coefficient of 2 0 to 2 1 0 nm> 〇 〇〇i7cnLl can be identified by a 200-210 nm transmission spectrum analyzer and removed from the low error contaminated area during crushing to produce The isolated low lead contamination pre-melts the product of solid 52. It is preferred to use a transmission measurement of 200-210 nm to provide calcium fluoride with an error of less than 10 ppb, and preferably lead of less than 50 ppb to produce a grown fluorinated dance crystal and the optical element produced therefrom, which is between 2000 and 2000. 21〇ηιη absorption

Page 17 200305715 V. Description of the invention (13) Coefficient &lt; 0 · 001 7CHL !, preferentially absorption coefficient of 203 to 207nm &lt; 0.0017 CH ^, more preferably absorption coefficient at 205nm. Manufacture of optical calcium fluoride crystals and the production of optical components from them, while monitoring and measuring the amount of lead contamination, using a method of 20 0-2 1 Gnm spectrometer to provide high-quality crystals with excellent optical characteristics, which have The high transmittance is greater than 99% / cm, and more preferably the 157nm transmittance is greater than 99% / cm. The method for producing optical fluoride crystals produces fluoride crystals with lead contamination of less than 50ppb, more preferably &lt; 20ppb, more preferably &lt; 10ppb, more preferably &lt; lppb, and most preferably less than 20nm wavelength Transmission calcium fluoride elements have a weight ratio of lead contamination less than lppb. The present invention includes optical fluoride crystals with transmission wavelengths below 20 Onm. The optical fluoride crystal 20 is composed of fluorinated silicon, and its transmittance below 2000 nm is greater than 99% / (: 111, preferentially 15711111 transmittance> 99% / (: 111, and the amount of miscontamination is less than 50 ppb and absorption coefficient <200.ooncmq at 200 to 210 nm, more preferably 203 to 207 nm absorption coefficient <0.0 · 〇〇1, and preferentially 205 nm absorption coefficient <0 · OOUcrn ^. Preferential amount of lead pollution Less than IOppb, more preferably &lt; lppb. The lead analysis method of the present invention can be used in the entire optical fluoride crystal optical element manufacturing process to the final product optical element. The present invention includes a method to produce a wavelength of less than 20 nm optical transmission optical fluorine Compound crystal 20. This method includes providing a pre-melted barium fluoride crystal solid, and melting the pre-melted barium fluoride crystal solid to form a barium fluoride melt and growing the barium fluoride crystal from the melt to provide an optical barium fluoride crystal. The transmission is below 200 nm. The method includes providing a light transmission 200-210 nm spectrum analyzer with a light source to generate a transmission test wavelength in the range of 200 to 21 On and a transmission sensor to facilitate Testing the transmission wavelength range of 200 to 21 Onm

Page 18 200305715 V. Description of the invention (14) Measure the amount of lead contamination in the length of the barium fluoride path, and grow an optical barium fluoride crystal to transmit the wavelength below 200nm, and its absorption coefficient at 200 to 210nm is &lt; 〇 OOUcm-i. In the embodiment, measuring the amount of barium fluoride contamination using a 200-200 nm spectrometer is included in measuring the amount of lead contamination in a pre-melted barium fluoride crystal solid. In the embodiment, the 200-2 1 Onm spectrum analyzer 22 is used to measure the amount of lead contamination in barium fluoride, and the amount of contamination is measured in a barium fluoride crystal grown from a barium fluoride melt. In an embodiment, the amount of lead contamination in barium fluoride is measured using a 200-2 10 nm spectrometer when the crystal is in the optical element E form before optical coating. In the examples, the amount of lead contamination in barium fluoride is measured before crushing into a particulate form and / or during crushing from a large solid block to a smaller volume. It is preferred to measure and monitor the amount of lead contamination in the crystal during the crystal manufacturing process to provide grown barium fluoride crystals to transmit wavelengths below 20 nm and make the amount of miscontamination less than 50 ppb, and more preferably &lt; 20 ppb. The optical fluoride crystal 20 is preferentially grown, and has a contamination amount of less than 1 Oppb, preferably <lppb. Fig. 5 shows an embodiment of the present invention, in which a vacuum-controlled crystallization high-temperature furnace 11o device stack connects the graphite crucible g0 and the top reservoir crucible 100 interactively. The intermediate crucible device previously melted the barium fluoride crystal solid compact dish 80. Pre-melted barium fluoride crystal solid dish 80 is obtained by heating and purifying and compacting with a fluorinating agent. In the examples, the barium fluoride crystal solid was previously smelted and melted by pre-melting and purifying and using pbF2 as the fluorinating agent of barium fluoride. It uses the operation of a controlled gas vacuum high temperature furnace to remove volatile lead and oxygen from the crystalline material. Product. In an embodiment, as shown in FIG. 5, for example, a high temperature furnace can be loaded with barium fluoride powder particles 70, which contains a fluorinating agent such as lead fluoride. Loaded into a crystal growth high-temperature furnace 丨 丨 〇 Pre-melted barium fluoride crystal solids are melted in a crucible to melt barium fluoride

Article 200305715 V. Description of the invention (15), which grows into barium fluoride crystals 20 by slowly cooling the crystals to melt in the high temperature furnace, for example, to reduce the thermal gradient during the stockbarger crystal growth process. In another embodiment shown in Figs. 6 to 10 of the present invention, a seed crystal 60 having a crystallizing axis preferentially oriented to a growth crucible 62 is used in the seed crystal holder 64. Crucible 62 is loaded with solid particles 52 of barium fluoride crystals previously melted. A crystal growth crucible containing a previously melted barium fluoride crystal solid is placed in an optical fluoride growth high temperature furnace 110, which includes a high temperature upper melting region 8 and a thermally regulated wall plate 14 that provides a thermal gradient for crystal growth and solidification. The barium fluoride crystal solids placed in the crucible 62 were melted in a high temperature furnace 100 high temperature region 8 to form a barium fluoride melt 66. The barium fluoride optical crystal 20 is grown from the melt 66 by adjusting the crystal growth and solidification region of the wall plate 14 to provide an optical fluoride crystal record 20 having a transmission below 200 nm. The method includes manufacturing a crystal 20 by a 200-21 Onm transmission spectrophotometer 22 to measure barium fluoride, such as a pre-fused barium fluoride crystal solid 80, growing the crystal 20 and the amount of lead contamination in the seed. During the entire crystal manufacturing process, the 200-2 10nm spectrum analyzer 22 is preferentially used to measure, monitor, and control the lead content of barium fluoride. Especially when lead fluoride is used as a fluorinating agent, it needs to be crystallized from the final product. 20 and its manufactured optical element E are removed to provide high transmission and optical characteristics at wavelengths below 20 nm. Use 200-21 Onm spectrum analyzer barium lead pollution measurement to provide measurement values below 50ppb, preferably below 2Oppb, more preferably below lOppb, and most preferably below lppb weight ratio. It can use the measurement value of barium fluoride and lead pollution of 2000--21 Onm spectrum analyzer to identify the high lead pollution area of the crystal and remove it by the optical fluoride crystal optical element manufacturing process. As shown in Figure 11, lead pollution measurements can be used to identify 2000 to

Page 20 200305715 V. Description of the invention (16) Absorption coefficient at 210nm &gt; 0. 0017CHT1 Highly-contaminated local crystal region 132, and further processing steps for individual optical element blank preform crystals 20 and manufactured therefrom The optical element 42 removes the high-lead contaminated area 132. For example, as shown in Figure 12-1 3C, measurements can be used to identify high lead contamination local crystal regions 50 in the pre-melted solid 52 to provide high-purity pre-melted solids produced by the crusher 56 and 58 crushing processes. Particles. The high lead pollution area 50 with an absorption coefficient of 200-210nm &gt; (K〇〇i7cm_1) can be identified by a 200-210nm transmission spectrum analyzer and removed from the low lead pollution area during crushing to produce separated low lead pollution The amount of the product of the pre-melted solid 52. Preference is given to using 200-210 ηη transmission measurements to provide barium fluoride with lead less than 10 ppb, and preferably lead less than 50 ppb to produce growing barium fluoride crystals and optical components produced there , Its absorption coefficient at 200 to 2100 nm &lt; 0. 0017cm1, preferentially at 203 to 207nm absorption coefficient &lt; 0.017 cir1, more preferably at 205nm absorption coefficient <0.0017cm1. Manufacturing optical barium fluoride crystals and Optical elements are generated from it, and the amount of lead contamination is monitored and measured at the same time. The method of 200-200 nm spectrometer is used to provide high-quality crystals with excellent optical characteristics. It has a high transmittance of more than 99% / cm at 200 nm. Preferentially, the transmission at 157nm is greater than 99% / cm. The method of producing optical fluoride crystals has a lead pollution amount of less than 5Oppb, more preferably &lt; 20ppb, more preferably &lt; 10ppb, more Preferentially &lt; lppb and most preferentially below 200nm wavelength transmission barium fluoride elements have a weight ratio of lead contamination less than ippb. The present invention includes wavelengths below 20nm wavelength transmission optical fluoride crystals. Optical fluoride crystal 20 is made of barium fluoride The composition has a transmittance of less than 20 nm and a transmittance of more than 99% / cm, preferably a transmittance of 157 nm &gt; 99% / cm, and a lead pollution amount of less than

Page 21 200305715 V. Description of the invention (17) 50 ppb and absorption coefficient <0.007 cm-1 at 200 to 21 Onm, more preferably 203 to 20711111 absorption coefficient <0.000017〇1〇-1, And preferentially 205 | 1111 absorption coefficient &lt; 0 · 01616cm-1. The amount of lead contamination is preferably less than 10 ppb, and more preferably &lt; lppb. The error analysis method of the present invention can be used in the entire optical fluoride crystal optical element manufacturing process to the final product optical element. The present invention includes measuring the impurity of lead in optical fluoride crystals by measuring the crystal transmittance at a known wavelength in the range of 20 Onm to 21 Onm, preferably in the range of 203 nm to 207 nm, and more preferably in the wavelength of 205 nm. The length of the measuring beam passing through the crystal is preferably longer than 2 mm and preferably longer than 1 cm, and the length of the crystal passing through the measuring beam preferentially is at least 10 cm. In this test, in order to control the purity of the crystal, the method includes comparing the measured transmission value or the absorption coefficient calculated from the measured transmission value with a reference value, and preferentially comparing the final absorption coefficient of the crystal with 0. 0017 cm1. This method involves quantifying the crystalline lead content under test. The crystals are preferably selected from alkali metal fluoride crystals, earth metal fluoride crystals, and a mixture of the fluoride crystals such as NaF, KF, LiF, CaF2, BaF2, MgF2, and SrF2 and mixtures thereof. In a preferred embodiment, a crystal having a light transmission path length of at least 9 mm (approximately 100 mm) is measured, and this method is used to provide an optical fluoride crystal, which is 200 to 210 nm (preferably 203 to 207 nm, and more preferably 205 nm). ) Lead pollution amount absorption coefficient &lt; 0.0017CBT1, preferentially &lt; 0.016CHT1, preferentially &lt; 0.015cm1, preferentially &lt; 0.0010cm1, preferentially &lt; 0.0084 cm1, preferentially &lt; 0 0007cm1, preferentially &lt; 〇 · 〇〇〇〇65CHT1, preferentially &lt; 0, 0004cm1, preferentially &lt; 0.003cm-1, preferentially &gt; 0, 0002cm_1, preferentially &gt; 0.00025cm1, preferentially Between 0.0025cm1 and 0.00Scnr1.

Page 22 200305715 V. Description of the invention (18) Figure 17 shows the absorption spectrum of the optical fluoride crystal in the A-absorption band (200nm-210nm) of the Pb of the present invention. The optical fluoride crystal sample of Fig. 17 is a calcium fluoride crystal sample having a light transmission path length of 50 mm. Figure 丨 8 Optical fluoride crystal sample is a fluorinated trans-crystalline sample with a light transmission path length of 10 cm. Figure 18 shows how to use the baseline to sense very low-error contamination values according to the present invention, using the scan center to be within the range of 1 95-220 nm of the 205 nm wavelength to identify the baseline size at 205 nm. It can be seen in Figure 18 that the misabsorption is close to 10 times smaller than the baseline size at 205 nm. The baseline in Figure 18 contains surface loss as well as some other internal absorption, so scanning 195-200nm helps to measure 205nm lead absorption correctly. Based on the signal-to-noise ratio, it can be seen that lead absorption is approximately 0 · 0 02 2 as the minimum absorption. As an example, the light transmission path length J 0 cm can be measured with a minimum absorption coefficient of 0.0 · 02 / i0cm = 0. 〇〇〇2_1. Considering the disappearance coefficient e = 0 · ZScm ^ / ppb, the absorption coefficient is relative to a lead concentration of about 1 ppb. In FIG. 18, the transmission path length for a 10 cm light is 2.005 at an absorption of 2.065 to produce an absorption coefficient of 0.00065 ^ 1 ^ (0.065 / 1 0 cn ^ O.OOOeScnr1). The wrong concentration with an absorption coefficient of 0.0065c nr1 is 2. 6 ppb [(0. OOOeScmKlppm wrong / 25 CHT1) = 2. 6 ppb wrong]. Examples: The invention is further illustrated by the following examples. In implementing the present invention, a 200-2100 nm spectrum analyzer 22 such as a Perkin-Elmer Lambda-900 spectrum analyzer (Perkin Elmer Analysis Instruments, 710 Bridgeport Avenue Shelton, CT 06484-4794 USA) is used. In the embodiment, the light source 24 is constituted by a gas arc light bulb. In the preferred embodiment, the light source 24 is constituted by a deuterium bulb. Preferably the invention is provided as non-destructive

Page 23 200305715 V. Description of the invention (19) Non-dissolving non-destructive testing (compared with loss-destructive stimuli such as wet chemical steps and ICP-AES). In an embodiment, the present invention includes removing a crystal sample from a larger crystal block object to have a polished surface (preferably at least 50 mju long with parallel planes, and its parallelism is better than 1 degree). The size of the specimen is cut, polished, and inserted into the 200-21 Onm spectrum analyzer for measurement. The present invention provides that the calcium fluoride crystal has an error concentration of less than 100 ppb, preferably less than 1 ppb, measured according to a transmission measurement of 200-210 nm. Preferentially, the present invention provides an optical fluoride crystal having a transmissive calcium fluoride with a wavelength of less than 200 nm, which has a transmittance of less than 200011111 at 157 11111 is greater than 99% / 〇: 111, "the impurity weight ratio is less than 0. OOlTcnr1 · 5ppm, the weight ratio of K impurities is less than 0.5ppm, and the weight ratio of lead impurities is less than 10Ppb, measured by a 200-21 Onm spectrometer at 200 to 21 Onm. The crystal quality of fluoride crystals is controlled by measuring the absorption error of fluoride crystals in the range of 200 to 210 nm for use in wavelength &lt; 2000 nm applications. Fluoride crystals are used as wavelength &lt; 2000 nm optics The material exhibits very good characteristics due to its high transmittance. However, it only exists when the crystal does not contain oxygen impurities. In particular, when the oxygen species exists at the crystal's ten-wavelength 193 and 157nm (equivalent to ArF and " 2Laser) The transmittance of fluoride crystals will be significantly reduced. In order to obtain fluoride crystals with excellent transmittance, it is preferred to add a scavenger such as lead fluoride scavenger to remove oxygen species from the crystal raw material. Lead fluoride Scavenger It is effective to remove oxygen, but the halogen will remain in the crystal after removal. Lead impurities will have a negative effect on the crystal wavelength &lt; 2000 nffl transmittance. In particular, when lead impurities are present in the crystal 5 7nm transmittance will be seriously deteriorated.

Page 24 200305715 V. Description of the invention (20) The measurement of the quality of the manufactured crystal by measuring the internal transmittance of 1 93nm and 1 57nm is a complicated process, which requires a moisture-free spectrum analyzer, which is performed by flushing. Or vacuum extraction and special cleaning of the sample surface. This process increases the cost of crystal manufacturing. We propose to measure the Pb absorption value above 200nm to control the transmittance of fluoride crystals with wavelengths below 200nm and preferentially between 200 and 210nm. When the path length of the sample is at least 100min, The sensing limit is 1 ppb. Fluoride crystals, especially Pb-doped alkaline earth fluorides, mainly have three absorption bands (AC200-21 0nm), B (1 60-1 70nm) and C (1 50-1 60nm). These band characteristics are excited from the Pb2 + ion ground state 1SQ to the states 3Pi, 3P2, and 1k, respectively. According to the present invention, we control fluoride crystals by measuring the quality of Pb absorption / transmission to its A-absorption band (200-21 Onm). We found that the maximum absorption coefficient (155nra) in the C-band is 2.5 times higher than the maximum absorption coefficient in the A-band (205nm). Due to this relationship, we can obtain the zero-band disappearance coefficient at 155nm, which is ε (155) = 6. 25 * 10-knrVppb. For comparison, Pb can also be analyzed by iCp-AES. However, this method requires a "wet chemistry" step, which contaminates the sample, and the method's sensing limit value does not exceed 1 P P. It is preferable to provide the transmittance &lt; 99.0% / cm of the fluoride crystal 157njn of the optical element, and the absorption coefficient of Pb in the range of 200 to 210 nm should be <o.ooncnr1. The present invention provides information on optical fluoride crystals with an average pb concentration along the path length. The present invention provides a method for testing and manufacturing high-quality optical fluoride crystals with high purity and excellent optical characteristics below 200 nm and low lead content. The present invention provides the manufacture of optical fluoride crystals such as calcium fluoride, which

Page 25 200305715 V. Description of the invention (21) It has low lead content and low oxidative pollutants, and manufactures less than 20nm transmission optical fluoride crystal elements to transmit ArF and F2 laser wavelengths (193nm and 157nm respectively), preferably Manufactured using lead fluoride as a fluorinating agent oxide scavenger while still producing optical fluoride crystals and optical components with low lead pollution. The optical fluoride crystal of the present invention has a transmittance of less than 20 nm (for example, 193 nm and 157 nm) with a transmittance of more than 99% / cm and is preferably used as an optical element below 20 nm, such as light lithography and laser optical elements, prisms, projection systems, and Lighting system. The optical fluoride crystals of the present invention preferably include LiF, NaF, CaF2, SrF2, BaF2, and MgF2 crystals and their composition crystals, especially CaF2 and SrF2 mixed crystals, and most preferably CaF2 4BaF2 or 8 ^ 2 unmixed crystals. . In a preferred embodiment of the present invention, a fluorinating agent oxide scavenger compound such as PbF2 is used in the manufacture of optical fluoride crystals to reduce the number of sites containing oxygen in the crystals. Although lead fluoride is beneficial for removing oxygen and improving optical components below 20 Onm, lead is an impurity, especially for fluoride crystals with wavelengths less than 200 nm, which is particularly undesirable. Lead-contaminated crystals in particular have a reduced transmittance of 1 57nra and they absorb wavelengths of less than 2000 nm when exposed to light emitted by ArF and F2 excimer lasers. A test method is proposed to evaluate the purity of crystals containing errors. This method involves measuring the transmission caused by absorption at a wavelength of 157 nm and / or 193 nm, which is the wavelength used by the crystal. These measurements are difficult to implement. At this wavelength of less than 200 nm, the sample must be protected from air and moisture. Therefore, a tank containing the sample is required, and the tank is flushed with gas or maintained in a high vacuum state, or the test device should be kept in a place free of air and moisture.

Page 26 200305715 V. Description of Invention (22) ----- Environment. The previous method for testing the robustness of lasers is expensive because the excimer laser device itself and the operation and maintenance costs of excimer lasers below 200 nm are not suitable for economical use in the manufacture of optical gas crystals. Device in the system. Nikon's Japanese Patent No. Jp—A—2000 1 9098 has described some proposals to analyze lead content by a method that analyzes trace elements by inductively coupled plasma (ICP) technology. However, this method requires a wet chemical step, which may contaminate the sample. Measuring instruments must be calibrated using inductively coupled plasma technology, which also suffers from the possibility of being contaminated and deteriorating the quality of the measurement. In any case, a large number of steps will create room for operator error and instrument drift because lead is distributed throughout the crystal and must be analyzed at several points. With this method, the limit of false impurity sensing is not greater than 1 ppm. The present invention provides a novel method for testing the purity of lead crystals with respect to fluoride crystals. This method is particularly useful for the manufacture of optical fluoride crystals and the manufacture of optical elements therefrom. The present invention provides a reliable and easy-to-implement test. The present invention includes shifting away from the used wavelength (157nm and / or I93nm) toward a wavelength in the range of 200nm to 210nm, preferably in the range of 203nm to 207 run, and more preferentially. It was 205 nm. The manufacturing of a 20 Onm transmissive optical fluoride crystal element according to the present invention includes measuring the transmittance of an optical fluoride crystal in a range of 20 Onm to 210. The measured transmittance is related to the transmittance below the wavelength of 2011111 (15711111 and / or 193111〇). The measured wavelength itself is not measured and is preferentially avoided. This is due to the cost of excimer laser irradiation below 20Onm and Complexity. It has been found that transmission at 200 nm21 Onm wavelength may detect the presence of lead and quantify crystals

Page 27 200305715 V. Description of the invention (23) The content of lead in the body is very accurate and accurate. According to the present invention, FIG. 14 is a transmission spectrum of a lead-doped BaF2 crystal in a range of 120 nm to 220 nm. This spectrum shows that the absorption coefficient of lead-contaminated crystals at 157nm is approximately three times greater than that measured in the range of 20nm to 210nm. Generalizing the ratio of the absorption coefficient measured for gaseous crystals at 157 nm to the contaminated crystals in error and the absorption coefficient measured at lead crystals in the range of 20 Onm to 21 Onm, we found that the ratio was between 2.5 and 5 3 range. This value provides a correlation between the transmittance of the optical fluoride crystal at the measurement wavelength (200nm to 21 Onm) and the transmittance of the crystal at the use wavelength (157nm and / or 1.93nm). The transmittance of the two is the same. grade. Considering the case of poor calculation use (the ratio is set to 2.5), according to the present invention, it is necessary to obtain an absorption coefficient with a wavelength in the range of 200 nm to 21 Onm less than 0.07cnr1 to obtain a transmission at 157 nm of greater than 9 9% / cm (Crystals are tested under light lithography / laser conditions). The test of the present invention has the advantage that it is suitable for testing in the ultraviolet operating region in a standard spectrum analyzer measurement device in the air ° Unexpectedly, the present invention may also provide the accuracy of measuring lead impurities and be able to produce high Quality optical fluoride crystal element, which has a low lead content and an absorption coefficient in the range of 200 nm to 21 Onm is less than 0.001 Tcnr1. In order to obtain the proportionality coefficient between the transmittance obtained at the test wavelength (in the range of 20 Onm to 21 Onm) and the transmittance obtained using the wavelength (157nm and 193nm), we use 2 05nm to measure CaFz containing different concentrations of wrong impurities Crystal absorption (Figure 15). These measurements show that the lead disappearance coefficient is about 30 ppm of lead of 30cnri / caF2 crystal. The sensing limit level of the present invention is light

Page 28 200305715 V. Description of the invention (24) Learn lead ppb in fluoride crystals. At I57nm, lppb is equivalent to an absorption value of 0.0000 3CIT1, which is equivalent to 0.1% / cm transmittance, and the loss is sensed by a standard spectrum analyzer. We have found that the sensing limit of the amount of miscontamination in an optical fluoride crystal is improved by increasing the path length of the beam through the optical fluoride crystal sample. In the preferred embodiment of the present invention, for a transmission absorption coefficient test at a test wavelength in the range of 200 nm to 21 Onm, it uses at least 2 mm optical fluoride crystal path length, preferably greater than iCffl, and more preferably greater than 10 cm.

We found that in CaFz samples containing more than 1 ppb of Pb, the Pb concentration can be determined based on 200-210 nm absorption data. We confirmed this result with the data in Figure η, which shows the curve of Cat-group samples' TPb absorption and pb content (chemical analysis data) at 205 nm. From the slope of this linear correlation we get ε (205) = 2. SnOkn ^ / ppb. It should be noted that in order to evaluate the Pb content in the range of 1 to 10 ppb, the length of the sample passing along the optical path is preferably not less than 100 mm. This novel test method is implemented to screen fluoride crystals for transmission quality at 1 57nm and / or 1 93Π1Π using wavelengths (by comparing quantities ^

Value, or calculate the absorption coefficient by comparing the measured transmission value with a reference value). The screening is performed in the wavelength range of 200 nm to 2100 nm and the final absorption / beneficial comparison with 1. 7 X 1 0 V cm; if the measured value is less than this value, the transmission under the body 157 is greater than 99%. The test method used in accordance with the present invention is to manufacture transmission optical elements below 200 nm and optical fluoride crystals = control. This test method of the present invention is further implemented as an economical method to measure the presence of lead impurities in the entire crystal of the optical fluoride crystal material.

200305715 V. Description of the invention (25) Content. The present invention can be used to measure error concentrations as low as a few ppb in optical fluoride crystals. This quantification is performed by measuring the transmittance of the crystal at a wavelength in the range of 200 nm to 210 nm, with the central wavelength being more preferably at 205 nm (205 ± 1 nm, more preferably 205 ± 0.5 nm). It is possible to measure transmittances above 200 nm by using the appropriate reference tables to determine the error content. The test method of the present invention is particularly suitable for optical fluoride crystals selected from alkali metal fluoride crystals, alkaline earth metal fluoride crystals, and a mixture of fluoride crystals thereof. This test method is preferentially implemented on the crystals of NaF, KF, LiF, CaF2, BaF2, MgF2, MgF2, and Sr and mixtures thereof. For example, the molecular formula of the mixed composition is) x (Mg) 1-XF2, wherein the chemical formula and% are independently selected by Ba, Ca, or Sr and wherein X is O ^ x ^ l, and the composition may have a molecular formula of. 8 卜} ^ 35 ^ 1 ^^ 2, where 7 and 7 will make 〇 $ and $ 1 and 〇 $ 7 ^ 1, and the composition can also have the molecular formula MRF3, where M can be selected from Li, Na, K, and R Can be selected from Ca, Sr, Ba, or Mg. The present invention has been described with reference to the accompanying drawings, wherein FIG. 14 shows the transmission spectrum of BaF2 contaminated by lead (in the range of 120 nm to 220 nm); and FIG. 15 shows the passivation of CaI containing different amounts of Pn (ppm units) at 20 5 nm. The absorption (cm1) of? 2 crystal changes. Those skilled in the art will understand that the present invention can make various changes and modifications without departing from the spirit and scope of the present invention. The present invention covers these changes and modifications, all of which fall within the scope of the following patent applications and their equivalents.

Page 30 200305715 Brief description of the drawings Brief description of the drawings: The first figures A-B show embodiments of the present invention. The second to twelfth figures show embodiments of the present invention. The thirteenth figure A-C shows an embodiment of the present invention. The fourteenth figure shows the transmission spectrum (transmission / 10 mm and 120 to 220 wavelengths) of the optical fluoride crystal of the present invention. The fifteenth figure is a graph of Pb absorption (cm1) and Pb concentration (ppb) of the optical fluoride crystal of the present invention at 250 nm. The sixteenth figure is a graph of the absorption (cm 1) and Pb concentration (ppb) of the optical fluoride crystal of the present invention at 205 nm. The seventeenth figure is the absorption spectrum of the optical fluoride crystal in the A-absorption band (200nm-210nm) of Pb in the present invention. Figure 18 shows the absorption spectrum of a spectrometer for an optical fluoride crystal. Description of figures and symbols: high temperature upper melting region 8; thermally regulated wall plate 14; polished surface 17; sample holder 19; optical crystal 20; crystal path length 21; spectrum analyzer 22, Vision® 23, 25; light source 24; Cell chamber 27; transmission sensor 28; wavelength selector 34; light lithographic printing element 42; local crystal area with high lead pollution; calcium crystal solid particles 52; crusher 56, 58; seed 60; growth affected by " 4; gasification radon 66; fluoride powder ΛΊ graphite hanging pot 90; the top storage rack is exhausted 100, 1, 2, and 10 furnaces; daily high-contamination local crystal area 32.

Claims (1)

200305715 VI. Application Patent Scope 1 · A method for sensing the content of low-error impurities in transmissive optical fluoride crystals below 200 nm, the method comprising: providing a transmissive optical fluoride crystal below 20 Onm wavelength, which has crystal light Transmission path length, the transmission path length of the light-transmitting optical fluoride crystal below 2Onm wavelength—2 mm, providing a light transmission spectrometer with a light source to generate a transmission test wavelength in the range of 2000 to 2100 nm, and The transmission sensor measures the transmittance of the test wavelength, and transmits the transmission test wavelength in the range of 200 to 21 Onm through the light transmission path length of the transmissive optical fluoride at a wavelength below 200 nm and measures the path length The transmittance at a test wavelength of 2000 to 21 Onm is provided to provide a measurement of lead ppb impurity content below 900 ppb. 2. The method according to item 1 of the scope of patent application, wherein the light source is a light bulb. 3. The method according to item 1 of the scope of patent application, in which the transmission test wavelength in the range of 2000 to 2101 is transmitted. The transmission test wavelength includes transmission of 203 to 207 nm. The transmission test wavelength passes through the optical fluoride crystal with a wavelength less than 20 nm. The length of the transmission path and the transmission through the test wavelength of 203 to 207 nm are measured to provide a measurement of less than 500 ppb of impurity content. 4. The method according to item 1 of the scope of patent application, wherein the transmission test wavelength in the range of 200 to 2100 nm includes the transmission of 205 nm. The transmission test wavelength passes the length of the light transmission path of the optical fluoride crystal that is less than 200 nm in wavelength. And measure the transmittance through the test wavelength of 205 nm of the path length to provide a measurement of less than 30Oppb lead impurity content. 5. The method according to item 1 of the scope of patent application, in which crystal light transmission is provided Page 32 200305715 VI. Patent Application Range Path length g2mm Transmissive optical fluoride crystals with wavelengths below 20 Onm include providing crystal light transmission path length g 1 cm and transmitting the transmission test wavelength through the gl cm fluoride crystal. Path length is measured to provide less than 10 Oppb impurity content. 6. The method according to item 1 of the scope of patent application, wherein providing a crystal optical transmission path length of -2 ram with a wavelength of less than 200 nm and a transmissive optical fluoride crystal includes providing a crystal transmission path length of $ 100 cm and transmitting the transmission test wavelength The length of the light transmission path through the Ocm fluoride crystal is measured to provide a lead impurity content of less than 50 ppb. 7 · —A method for measuring the content of lead impurities below 丨 ppm in optical fluoride crystals, the optical fluoride crystals are used to transmit light with a wavelength less than 2000 n] n, the method includes: providing less than 200 nm A wavelength-transmitting optical fluoride crystal having a crystal light transmission path length. The light-transmitting path length of the wavelength-transmitting optical fluoride crystal below 200 nm is −1 cm, and f is for a transmission spectrum of 200 to 20 nm. With a light source to generate a test wavelength in the range of 2000 to 2100 nm and a sensor to calculate the absorption coefficient at the test wavelength, the transmission of the test wavelength in the range of 200 to 2100 nffl is less than 200 njn Wavelength, the transmission path length of the ray optical vapor of -1 cm, and the absorption coefficient measured through the path length at the test wavelength to provide the absorption coefficient &lt; 〇〇〇〇17cnrl of the lead pollution content. 82. The method according to item 7 of the patent application range, wherein the transmission wavelength in the range of 200 to 2njn includes the transmission wavelength in the range of 203 to 207 nm. Page 33 200305715 VI. Application for patents Passing the optical transmission path length of iCH1 below 20 Onm wavelength and the transmission path length of iCH1 and measuring the absorption coefficient through the $ lcin path length at the test wavelength of 203 to 207 nm to provide lead pollution The absorption coefficient of the content &lt; 0.016 cm 1 〇9. The method according to item 7 of the patent application range, wherein the test wavelength in the range of 200 to 2100 nm includes the test wavelength of 205 nm in transmission through less than 200. The light transmission path length of the nm wavelength transmissive optical fluoride cm and the absorption coefficient measured through the -1 cjq path length at a test wavelength of 20 5nm to provide an absorption coefficient &lt; 0.001 5cm1 of the lead pollution content. 10. The method according to item 7 of the scope of patent application, wherein providing a crystal light transmission path length of $ lcm below 200 nm is a wavelength-transmissive optical fluoride crystal including providing a crystal light transmission path length gl0 cm to provide less than 50 ppb lead impurities Content measurement. U · —A method for manufacturing an optical element with a wavelength below 200 nm, the method comprising: providing a transmissive optical fluoride crystal with a wavelength below 200 nm, which has a crystal light transmission path length, and the transmissive optical with a wavelength below 200 nm The transmission path length of the fluoride crystal is -2mm, and a 200-210 nm transmission spectrum analyzer is provided, which has a light source to generate a test wavelength in the range of 200 to 21 nm and a transmission sensor to measure the transmission at the test wavelength. The transmission wavelength of the test wavelength in the range of 20G to 210nm is transmitted through the optical transmission path length of the optical fluoride below 200nm, and the transmittance of the test wavelength of 2000 to 210nm through the path length is measured. Measure that the content of miscontamination is less than 100 ppb, and the optical fluoride crystal is formed to be less than 2000njn wave. Page 34 200305715 6. The optical element with a long patent application scope, the optical element absorption coefficient &lt; 0.001 Tcnr1. 1 2. The method according to item 11 of the scope of patent application, wherein the crystal optical transmission path length g2mm is less than 20 Onm wavelength transmissive optical fluoride crystal includes providing a crystal optical transmission path length g lcm of less than 20 Onm wavelength transmission optical Fluoride crystals and transmission wavelengths in the range of 203 to 207 nm. Transmit optical path lengths of -1 cm through wavelengths below 200 nm. Transmit optical path lengths of -1 cm and form optical elements whose optical fluoride crystals have wavelengths below 200 nm. The absorption coefficient of the optical elements &lt; 0.016cm1. 1 3. The method according to item 11 of the scope of patent application, wherein the crystal light transmission path length is provided-a wavelength of less than 20 Onm wavelength transmissive optical fluoride crystal of 2 mm includes providing a wavelength transmission of crystal light transmission path length glcin below 200 nm wavelength Optical fluoride crystals and transmission wavelengths in the range of 205 nm are transmitted through a wavelength of less than 200 nm, the transmission path length of the optical fluoride $ 100 cm, and the absorption coefficient measured at 205 nm through a path length of -10 cm is provided. Measured with a contamination content of less than 20 ppb, and formed an optical element with an optical fluoride crystal having a wavelength of less than 20 Onm. The optical element has an absorption coefficient <0.0017 cm1 at 205 nm. 14. The method according to item 11 of the scope of patent application, wherein providing a wavelength-transmissive optical fluoride crystal below 2 QQnffl includes providing a calcium fluoride crystal. 15. The method according to item 11 of the patent application scope, wherein providing a wavelength-transmissive optical fluoride crystal below 200011111 comprises providing a barium fluoride crystal. 16. · A method of manufacturing a transmission optical fluoride crystal having a wavelength below 200 nm, the method comprising: providing a pre-fused solid of calcium fluoride crystal; Page 35 200305715 VI. Applying for a patent Fan Yuan Melt the calcium fluoride crystal solids in advance to form a calcium fluoride melt and grow calcium fluoride crystals from the melt to provide optical calcium fluoride crystals to transmit wavelengths below 20 nm; provide Light transmission spectrum analyzer having a light source to generate a transmission test wavelength in the range of 2000 to 2101 and a transmission sensor to measure the transmittance of the test wavelength and to measure using the transmission test wavelength in the range of 20G to 21 Onm The amount of contamination in the two-way length of fluorination is wrong, and the grown optical calcium fluoride crystal has a transmission wavelength below 200 nm, and its absorption coefficient at 200 to 210 nm &lt; 0.007 cm-1 ° 17 · The method according to item 16 of the patent application, wherein measuring the amount of lead pollution in the path length of calcium fluoride by using a light transmission 200 to 21 Onm spectrum analyzer includes measuring the amount of lead pollution in the solids of pre-melted fluorinated horn crystals. 1 · 8. The method according to item 6 of the scope of patent application, wherein the transmission of light through a 20 to 21 Onm spectrum analyzer is used to measure the amount of lead contamination in calcium fluoride. Wrong amount of pollution. 19. The method according to item 16 of the patent application range, wherein an optical calcium fluoride crystal having a wavelength of less than 2000njn is grown and an absorption coefficient &lt; 0. 001 Tcnr1 at 200 to 21 Onm. 20. The method according to item 16 of the scope of patent application, wherein the growth of the optical calcium fluoride crystal having a wavelength below 20 Onm has an absorption coefficient &lt; 0.0017 cm-1 at 20 3 to 20 7 nm. 21 · The method according to item 16 of the scope of patent application, wherein an optical calcium fluoride crystal having a wavelength of less than 200 nm is grown and the absorption coefficient at 20 5 nm &lt; 0,0171 cm'1. Page 36 200305715 6. Application patent scope 22 · —A kind of transmissive optical fluoride crystal with a wavelength of less than 20 nm. The optical fluoride crystal is composed of calcium fluoride, which has a transmittance below 200 nm greater than 99% / cm and lead. 0017cm1。 Contamination value content is less than 50ppb and lead pollution absorption coefficient &lt; 0. 0017cm1 at 200 to 21 Onm. 23. The optical fluoride crystal according to item 22 of the scope of the patent application, wherein the calcium fluoride crystal has an absorption coefficient of lead pollution at 203 to 207 nm &lt; 0.017 cm1. 24. The optical fluoride crystal according to Item 22 of the patent application park, wherein the calcium fluoride crystal has an absorption coefficient of lead pollution at 205 nm of <0.0016 cm1. 25. A method of manufacturing a transmission optical fluoride crystal with a wavelength below 200 nm, the method comprising: providing a pre-melted barium fluoride crystal solid; melting the pre-melted barium fluoride crystal solid to form a barium fluoride melt; and Grow barium fluoride crystals to provide optical barium fluoride crystals to transmit wavelengths below 20 nm; provide a light transmission spectrometer with a light source to generate transmission test wavelengths and transmission sensors within a range of 200 to 2100 nm By measuring the transmittance of the test wavelength and measuring the amount of median contamination in the path length of the barium fluoride using the transmission test wavelength in the range of 200 to 210 nm, the grown optical barium fluoride crystal has a transmission below 200 nm, Absorption coefficient at 200 to 210 nm <0.001? Cm'1 ° 2 6 · The method according to item 25 of the scope of patent application, wherein the measurement of the amount of miscontamination in the path length of barium fluoride using a light transmission spectrum analyzer includes measurement of pre-melting Amount of miscontamination in gasification lock crystal solids. 27. Method according to item 25 of the scope of patent application, in which light transmission is used Page 37 200305715 6. Scope of patent application The spectrum analyzer for measuring the amount of lead pollution in barium fluoride includes measuring the amount of wrong pollution in the gasification lock crystals grown from the barium fluoride melt. 28. The method according to item 25 of the scope of patent application, wherein the growth of the optical barium fluoride crystal having a wavelength of less than 2000 nm has an absorption coefficient &lt; 0.0017 7CJIT1 at 200 to 2100 nm. 29. The method according to item 25 of the scope of patent application, in which the growth of optical barium fluoride crystals with transmission below 20 Onm wavelengths has an absorption coefficient at 203 to 207 nm &lt; 0 · 001 7cm-1 〇30 · according to the patent application The method of the 25th item, in which the growth of optical barium fluoride crystals with transmission wavelengths below 200 nm has an absorption coefficient at 0.05 nm &lt; 0 · 0017 cm1 ° 31 ·-a transmission optical fluoride crystal with a wavelength below 20 nm, The optical fluoride crystal is composed of barium fluoride, which has a transmittance of less than 200 nm, a transmittance of more than 99% / cm, a content of miscontamination value of less than 50 ppb, and an absorption coefficient of lead pollution at 200 to 21 Onm &lt; 0.017CHT1. 32. The optical fluoride crystal according to item 31 of the scope of the patent application, wherein the barium fluoride crystal has an absorption coefficient of lead pollution at 203 to 207 nm &lt; 0,017 cm1. 33. The optical fluoride crystal according to item 31 of the patent application park, wherein the barium fluoride crystal has an absorption coefficient of lead pollution at 205 nm &lt; 〇e〇16cm-i. Page 38