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    • 专利摘要:
    The invention relates to a method for determining the thermal expansion of a material with low thermal expansion with a very high measurement accuracy of at most +/- 3 ppb / K or less and / or a reproducibility of at most +/- 1 ppb / K or less. A measuring device based on a further developed push rod dilatometer is used to carry out the measurement.
    公开号:BE1023729B1
    申请号:E2016/5603
    申请日:2016-07-19
    公开日:2017-06-30
    发明作者:Axel Engel；Clemmens KUNISCH；Ralf Jedamzik；Gerhard Westenberger；Peter Fischer
    申请人:Schott Ag；
    IPC主号:
    专利说明:

    High-precision method for determining the thermal expansion
    description
    The present invention relates to a high-precision method for determining the thermal expansion of low-expansion materials with a low thermal expansion, such as, for example, the material Zerodur®.
    In recent years, the ever-narrower coefficient of thermal expansion ("CTE") tolerance of IC lithography component materials has required a significant advance in metrology accuracy to determine this property as required. available from the company SCHOTT AG, Mainz, Germany, is known for its extremely low CTE between 0 ° C. and 50 ° C. The measurement of the coefficient of thermal expansion is carried out using specially developed push rod dilatometer measuring systems These systems demonstrate the excellent CTE homogeneity of Zerodur® in the single-digit ppb / K range.
    The verifiable homogeneity was limited by the repeatability of the CTE (5 ° C, 50 ° C) measurement in the range of ± 1.2 ppb / K of the presently improved configuration of a push rod dilatometer, using an optical interferometer instead of an induction coil. With the material Zerodur® Tailored, a grade of material with low thermal expansion could be presented, which can be adapted to the temperature profiles of individual applications.
    The basis of this product is a model developed to better understand the thermal expansion behavior of a material at a given temperature as a function of time. It was confirmed that the CTE behavior predicted by the model is in good agreement with the data determined in the thermal expansion measurements. The measurements of the data entering the model require a dilatometer configuration with excellent stability and accuracy for long measurement times of several days.
    In recent years, great efforts have been made to push a push rod configuration-based dilatometer measurement technology to meet the ever-increasing demand for higher CTE accuracy and deeper knowledge of low thermal expansion materials such as Zerodur®.
    Field of the invention
    The thermal expansion coefficient is the most important property of low thermal expansion materials such as glass ceramics, for example Zerodur®. The material Zerodur® is an inorganic, nonporous lithium aluminum-silicon oxide glass ceramic, which is characterized by uniformly distributed nanocrystals within a residual glass matrix. The glass matrix has a positive thermal expansion coefficient of about 3 ppm / K. The crystalline phase has a negative thermal expansion coefficient. The right attitude of
    Volume content and crystal size in composition and ceramization leads to the desired thermal expansion behavior of almost zero at room temperature.
    Generally, the thermal expansion of a low-expansion material such as Zerodur® is defined by the CTE between 0 ° C and 50 ° C. This CTE (0 ° C, 50 ° C) is derived from measurements of thermal expansion at 0 ° C and at 50 ° C, after the temperature at each temperature value is held constant for 20 minutes. In between, the sample is cooled at a rate of 36 K / h. Therefore, the CTE (0 ° C, 50 ° C) is an average over the temperature range of 0 ° C to 50 ° C. The thermal expansion in the temperature range 0 ° C to 50 ° C is not linear. It is a function of temperature and time.
    Many applications, for example in lithography, use low thermal expansion materials such as Zerodur® in small temperature ranges around 20 ° C or 22 ° C.
    Astronomical telescopes use the material at lower temperatures between -10 ° C and + 20 ° C, which corresponds to the climatic conditions at the top of a mountain. Other applications also plan with temperatures in the range between 40 ° C to 60 ° C.
    For this purpose, a model was created to predict material behavior under different temperature conditions. This model is published in the document R. Jedamzik, T. Johansson, T. Westerhoff: "Modeling the Thermal Expansion Behavior of ZERODUR® at Arbitrary Temperature Profiles", Proc. SPIE Vol. 7739 (2010); R. Jedamzik, C. Kunisch, T. Westerhoff, "ZERODUR: progress in CTE characterization", Proc. SPIE. Vol. 8860 (2013)).
    The product based on this model approach is called Zerodur® Tailored. Nevertheless, it is also important to have a measuring system capable of characterizing low thermal expansion material in a flexible manner and with high accuracy under different temperature conditions. The thermal expansion is measured with dilatometer configurations based on conventional push rod dilatometer concepts, but with design changes leading to high accuracy. These changes reflect the need to measure very small changes in length over different temperature ranges and time.
    Originally, measurements were made with conventional push rod dilatometers with an induction coil for position measurement with an accuracy of ± 10 ppb / K and a reproducibility of ± 5 ppb / K. An improved dilatometer configuration using an interferometric position measurement probe resulted in an absolute accuracy of ± 6.2 ppb / K and a repeatability of ± 1.2 ppb / K, as described in the document R. Jedamzik, R. Müller, P. Hartmann, "Homogeneity of the linear thermal expansion coefficient of ZERODUR® measured with improved accuracy", Proc. SPIE Vol. 6273 (2006).
    All pushrod dilatometers are regularly calibrated with reference samples by measurements performed at the Physikalisch Technischen Bundesanstalt (PTB), the German equivalent of the National Institute of Standards and Technology (NIST) in the United States.
    Object of the invention
    The goal for a measuring device, especially for a further developed push rod dilatometer, based on the improved dilator configuration, is to achieve an improved absolute CTE measurement accuracy of <± 3 ppb / K along with a reproducibility of <± 1 ppb / k.
    In order to achieve the high demands on measurement accuracy and reproducibility, the measuring device must have a very good long-term stability (no or a controllable creep behavior of the measuring device in the nm range over long periods). At the same time, the measuring device should be robust and allow adequate throughput in a production laboratory environment. A key objective is also to determine the limits of the push rod dilatometer concept for the CTE measurement of low thermal expansion materials such as Zerodur®.
    This further developed push rod dilatometer is then used to perform a homogeneity measurement, in particular a homogeneity measurement of the material Zerodur®.
    State of the art
    Many different dilator concepts are known in the literature. Their use depends on the application and the required accuracy. For small and very thin samples, capacitive dilatometers are often used. The sample is placed between the parallel plates of a capacitor. The change in length changes the distance between the moving plates and thus the capacity. The achievable thermal
    Expansion accuracy depends on the thermal expansion of the cell material and the change in the capacity of the empty dilatometer cell (empty cell effect). This influence can be reduced by the use of quartz glass as the cell material.
    The Physikalisch Technische Bundesanstalt uses an ultraprecision interferometer for the high-precision measurement of absolute measurements of prismatic bodies. The samples are polished at the ends and twisted onto a larger polished plate. The interferometer uses three stabilized lasers at 780 nm, 633 nm and 532 nm, which provide high accuracy in measuring absolute lengths in an environment whose temperature is tightly monitored. Between 10 ° C and 50 ° C, this configuration achieves a length inaccuracy of 0.22 nm, as disclosed by R. Schödel, A. Walkov, M. Zenker, G.
    Bartl, R. Meess, D. Hagedorn, C. Gaiser, G. Thummes and S. Heltzel, "A new ultra-precision interferometer for absolute length measurements of cryogenic temperatures", Meas. Sci. Technol. 23 (2012) shows.
    In an industrial laboratory environment, capacitive and interferometric dilatometry seem to have disadvantages in terms of long and complex sample and measurement preparation. Ideally, the thermal expansion measurements should be completed within a few hours of measurement time to allow for short feedback times.
    Therefore, the pushrod dilatometer design is the most commercially used configuration for measuring the thermal expansion of materials. The sample is fixed in a fork-like construction that mechanically separates the probe from the furnace part where the sample must be placed and the temperature profile is applied. A push rod transmits the change in length of the sample to the measuring head. Such standard push rod dilatometers are commercially available, such as the company Netsch or Linseis.
    The DIL 402 Expedis Select / Supreme, available from Netzsch, is a horizontal push rod dilatometer and achieves a CTE measurement reproducibility of ± 10 ppb / K and an absolute accuracy of ± 100 ppb / K.
    The L75 Laser Dilatometer, available from Linseis, is a blend of the optical concept and the push rod dilatometer. It provides an accuracy of ± 50 nm and a reproducibility of ± 10 nm. For a sample with a length of 100 mm this means an accuracy of ± 0.5 ppm (500 ppb).
    All of these types of push rod dilatometers are designed to measure thermal expansion over large temperature differences, while measurements for low thermal expansion materials such as Zerodur® are typically made in the temperature range 0 ° C to 50 ° C or -50 ° C to 100 ° C as maximum become.
    The required maximum measuring range for measuring the thermal expansion of such materials as Zerodur® is in the range of ± 15 ppm or 1.5 gm and the reproducibility of the length measurement should be in the range of
    Temperature range between 0 ° C and 50 ° C be better than 0.05 ppm, which calls for a comprehensive improvement of the concept.
    The basic construction of the push rod dilatometer used to measure the thermal expansion of the low thermal expansion material, such as Zerodur®, is based on the instrument presented by Plummer and Hagy, which is described in the publication W.A. Plummer, H.E. Hagy, "Precision Thermal Expansion Measurements on Low Expansion Optical Materials", Applied Optics, Vol. 5 (1968).
    However, the dilatometer according to the invention has the difference that the sample holder and the push rod are made of a titanium silicate glass. The system is optimized for a sample length of 100 mm and a sample diameter of 6 mm. The temperature is measured using a platinum resistance thermometer (PT 100) mounted near the sample. An electromechanical transformer (inductor) or a linear variable differential transformer (LVDT) was used as the probe in the first configuration. For an improved dilator configuration, the measurement system has been replaced by an interferometric measurement system. The resolution of the interferometer probe is better by a factor of 50 compared to the standard LVDT configuration. It also offers a higher reproducibility of the measurement. For the measurement, the sample and the sample holder are immersed in a gas cooling system. A thermostat is programmed to heat and cool the gas according to a defined procedure. When the temperature is changed, the sample changes its length and the rod moves a prism within the
    Interferometer head, which changes the length of the optical path. Therefore, the push rod dilatometer is a relative length measuring system. The absolute accuracy depends on the accuracy of a reference sample needed to compensate for the thermal expansion of the measuring system itself. The change in the optical path and the temperature of the gas system are recorded and used to calculate the CTE (see Fig. 1).
    Such a design of the head of the laser interferometer has some advantages and disadvantages.
    Due to the use of a pentaprism reflector on the push rod, the cosine deviation is small. The lengths of the optical path are small but still significant to be affected by humidity and pressure of the environment. The biggest drawback is the "non-monolithic" design of the configuration, all the optical components and also the frame are interconnected by means of a low thermal expansion resin, its performance impact is low, but it limits the possibility of increasing stability and performance the accuracy of the system.
    The goal for a further developed
    Push rod dilatometer with even better accuracy is therefore to provide an improved absolute CTE
    Accuracy of <± 3 ppb / K together with a reproducibility of <± 1 ppb / k.
    Another goal of the new dilator configuration is to increase the long term stability, reproducibility, and accuracy of the push rod dilatometer system. Retaining the design of the push rod dilatometer allows for faster measurement cycles and shorter ones
    Downtime, compared to a non-contact optical solution typically available from universities or scientific organizations, is needed for metrology to control production processes. Solution to the Problem Surprisingly, this object is achieved by a method and a device for determining the thermal expansion of a material with low thermal expansion and a use of this device according to one of the independent claims. Preferred embodiments and further developments of the invention are to be taken from the respective subclaims.
    Accordingly, in a first aspect, the invention relates to a method for determining the thermal expansion of a material with low thermal expansion with a measurement accuracy of at most, that is not worse than +/- 3 ppb / K or less and / or a reproducibility of at most +/- 1 ppb / K or less.
    In a preferred embodiment, the method is characterized in that the measurement accuracy is at most 1 ppb / K or less, preferably at most 0.6 ppb / K (2 sigma, 95% confidence level) or less CTE (0 ° C, 50 ° C).
    The measurement is carried out using a pushrod dilatometer. In this case, the so-called further developed push rod dilatometer is preferably used.
    The method is further characterized in that with a repeatability of at most, that is not worse than + / - 5 ppb / K, preferably at most +/- 3 ppb / K, more preferably at most +/- 1 ppb / K is measured.
    The temperature of a sample of the material with low thermal expansion takes place in a tempering, preferably an oven, wherein the sample is tempered in the temperature control unit with a gas, preferably with helium. For the measurement, a temperature range from a temperature range of -50 to + 100 ° C can be selected, for example, a temperature range of 40 ° C to 70 ° C, from -10 ° C to + 20 ° C, or from 19 ° C to 24 ° C.
    The existing configuration of the push rod dilatometer has been redesigned in many ways and includes the term "further developed
    The following improvement points were made: 1. The fork was redesigned to allow a monolithic design without any connected parts 2. Implementation of a high-precision incremental linear encoder LIP382 available from Heidenhahn This linear encoder uses laser diffraction read out at incremental scale intervals with a resolution better than 0.25 nm 3. The length change of the sample is transferred from a push rod to the measuring head The push rod is at the fork by means of springs, in particular a newly designed resilient attachment, with low thermal expansion 4. The sample is cooled and heated by means of a furnace with helium as the heat transfer medium.The design of the furnace is FEM-optimized.The position of the temperature measurement has also been optimized 5. A cryostat was installed to allow very reproducible temperature profiles during the measurement the whole Temperature range from -50 ° C to + 100 ° C. The reproducibility is better than 0.2 ° C, depending on the temperature range. 6. The measuring device, in particular the entire push rod dilatometer, shall be placed in an air-conditioned laboratory, with a variation of the temperature within the measuring range below ± 0,2 ° C and a stability of the humidity better than ± 2%. 7. New titanium silicate reference specimens measured at the Physikalisch Technische Bundesanstalt (PTB) with a temperature-dependent length accuracy between ± 0.06 and ± 0.003 ppm are used to guarantee the highest absolute accuracy of measurement.
    Table 1 below summarizes the achievable accuracies of the various push rod dilatometer configurations.
    Table 1: CTE measurement: Accuracy and reproducibility of differently configured push rod dilatometers based on CTE (0 ° C, 50 ° C) measurements
    The term CTE (0 ° C, 50 ° C) measurements is understood as meaning those measurements which serve to determine the CTE over the temperature interval from 0 ° C up to 50 ° C.
    Thus, in a second aspect, the present invention comprises an apparatus for measuring the linear expansion of a low thermal expansion sample comprising a pushrod dilatometer, preferably a more advanced pushrod dilatometer, with a push rod, fork, and springs for holding the push rod within the fork.
    The further developed push rod dilatometer is characterized by the fact that the fork and the push rod are monolithic. Accordingly, the fork and the push rod are made of a single workpiece, preferably a low-expansion material such as Zerodur® or titanium silicate, so that it is possible to dispense with organic compounds, for example adhesives or plastic connecting parts, for joining the elements. This is of great importance, since the different thermal expansion behavior of the organic compounds or the plastic parts on the one hand and the material for the fork and / or the push rod on the other hand, adversely affect the accuracy of measurement.
    This is particularly useful if, for the CTE measurements, a sample of a material with low thermal expansion inserted in the push rod dilatometer is subjected to the appropriate temperature, regions of the measuring device or of the
    Push rod dilatometer are subjected to this temperature, whereas other areas are not exposed to this temperature. Therefore, the smallest possible and most homogeneous thermal expansion of the measuring device, in particular the push rod dilatometer and the associated components, is generally desired.
    Therefore, according to the invention, the spring for holding the push rod in the fork made of a material with low thermal expansion, also to the expansion behavior of the device during the
    Temperature control does not affect. As a spring material, for example, the material Invar® can be used.
    Furthermore, in the context of the invention, a cryostat for the temperature range from -50 ° C to + 100 ° C with a reproducibility of at least 0.5 ° C, more preferably at least 0.3 ° C, most preferably at least 0.2 ° C. , used, so that a high-precision tempering of the inserted sample is given.
    To perform CTE measurements, the device is preferably in an air-conditioned room with a constant, predetermined temperature, for example 22 ° C, at most +/- 0.2 ° C deviation and / or with a constant predetermined humidity of at most + / - 2 % Deviation operated.
    This makes it possible to obtain a device for CTE measurement with very good long-term stability, ie a very low drift ("creep"), in the nm range, which drift is preferably at most 0.1 nm / h (1.4 nm / day) ), more preferably at most 0.08 nm / h, most preferably at most 0.06 nm / h.
    After probing an inserted sample at the intended temperature, the position of the push rod is determined relative to the fork by means of an optical interferometer as a detector. For this purpose, preferably the linear incremental encoder is used.
    In a preferred embodiment, this interferometric measuring head has an absolute accuracy of at least +/- 10 ppb / K, preferably at least +/- 8 ppb / K, more preferably + / - 7 ppb / K and / or a repeatability of at most +/- 2 ppb / K on.
    Finally, in a third aspect, the invention relates to the use of the above-mentioned method for the characterization of materials or samples with low thermal expansion, in particular for measuring the thermal expansion behavior of such materials or samples with low thermal expansion, which in astronomy, LCD lithography, microlithography and the measurement technology can be used.
    According to the invention, the above-described further developed push rod dilatometer is used for this purpose.
    In this way, the thermal expansion of substrate materials for microlithography, for example for Waferstages, and in EUV lithography in particular for substrates for mask blanks (masks) and mirrors for EUV lithography can be measured.
    Preferably, the substrate materials are selected from the group comprising ceramic, glass ceramic, and glass, for example quartz glass with low thermal expansion, for example Ti-doped quartz glass, which is also called titanosilicate or titanium silicate glass, such as ULE®, or LAS glass ceramic with low thermal expansion, in particular Zerodur®, Clearceram®, SITAL®, or generally low thermal expansion ceramics, such as Codierit.
    The substrate material may have a zero crossing of the CTE / T curve at the application temperature and the
    Use temperature may for example be selected from 22 ° C, 40 ° C, 60 ° C, 70 ° C or 80 ° C, or another value in the temperature range from 0 ° C to 80 ° C.
    The invention will be described in more detail below with reference to preferred embodiments and with reference to the accompanying figures.
    The drawings show:
    Fig. 1: the basic construction of the improved
    Configuration of the push rod dilatometer,
    2 shows the further developed push rod dilatometer,
    3 shows results of the measurement of a calibration sample from the PTB,
    4: the measurement of the thermal expansion of a
    Titanium silicate reference sample over a small temperature range,
    5 shows a drift measurement,
    6 shows the reproducibility of the length measurement (sigma dl / l) as a function of the temperature,
    7 shows a representation of the reproducibility of CTE (0 ° C., 50 ° C.) measurements of the further developed dilatometer,
    8 shows a two-dimensional contour plot of the CTE
    Homogeneity,
    9 shows the CTE homogeneity of a 1200 mm × 1200 mm test plate made of Zerodur® material at y = 202 mm in the x direction,
    10 shows the CTE homogeneity of the 1200 mm x 1200 mm test plate made of Zerodur® material at x = 200 mm in the y direction, and FIG
    11 is a schematic view of a push rod dilatometer.
    Detailed description of preferred embodiments
    In the following detailed description of preferred embodiments, for the sake of clarity, like reference numerals designate substantially similar parts in or on these embodiments. For better clarity of the invention, however, the preferred embodiments shown in the figures are not always drawn to scale.
    In Fig. 1 the basic structure of a device for measuring the thermal expansion behavior (CTE measurement) by means of a push rod dilatometer is shown schematically. The push rod dilatometer 1 comprises a fork 20 and a push rod 30 springs for holding the push rod in the fork are not shown for clarity.
    The temperature control device comprises an oven 10, a heat transfer medium supply device 11, in the example of helium, and a temperature sensor 12, in the example a Pt 100 platinum resistance thermometer, for temperature measurement and monitoring. Between the head end of the push rod 30 and the uncovered by the push rod 30 open portion of the fork 20, a sample 50 of a material with low thermal expansion, in the example of Zerodur®, inserted, which is engaged with the head end of the push rod.
    At the opposite end of the push rod 30, a laser interferometer 60 for measuring the relative position of the foot end of the push rod 30 to the fork 20 is arranged. This measuring range is surrounded by an insulation 62, wherein a thermostat 61 is provided to maintain a predetermined temperature.
    The thermocouple 12 is connected via a voltmeter 41 to a central processing unit 43. Furthermore, a control unit 42 is provided to control the measurements and to store the measured values in the arithmetic unit 43.
    To perform a CTE measurement, the sample 50 to be measured is inserted into the opening of the fork 20. So then the sample is subjected to the desired temperature. The reaching of the temperature can be detected by means of the thermocouple 12, after which the measurement of the expansion of the sample can be carried out. For this purpose, the sample 50 is scanned with the push rod 30 and the position of the foot end of the push rod 30 relative to the fork 20 measured. The measured values are stored in the computer unit 43. Thereafter, the temperature is changed according to a predetermined temperature curve, and after the temperature is reached, the measurement is repeated.
    The construction of the new, more advanced push rod dilatometer is shown in FIG. A key feature of the new, advanced push rod dilatometer is its accuracy and reproducibility for CTE (0 ° C, 50 ° C) measurement. The absolute accuracy of measurement is limited by the measurement accuracy of a reference sample from the material
    Titanium silicate, which was measured at the Physikalisch Technische Bundesanstalt (PTB). The measurements were carried out on PTB ultra-precision interferometer (UPI), the most recent of which is published in R. Schödel, A. Walkov, M. Zenker, G. Bartl, R. Meeß, D. Hagedorn, C. Gaiser, G Thummes and S. Heltzel: "A new ultra-precision interferometer for absolute length measurements of cryogenic temperatures", Meas. Sci. Technol.23 (2012).
    Three highly stabilized lasers are used consecutively in the measurements. The length values resulting from the use of the two J2-stabilized lasers at 532 nm and 633 nm were averaged. The Rb-stabilized laser at 780 nm was used only for a coincidence test. The measurements were carried out under vacuum conditions. The temperature near the samples was measured by temperature sensors.
    Fig. 3 shows the measurement results of a CTE measurement between 0 ° C and 50 ° C with the associated inaccuracies of the length measurement. The estimated inaccuracy for the CTE (5 ° C, 50 ° C) measurement is 0.6 ppb / K (2 sigma, 95% confidence interval). The inaccuracy of the length measurement varies depending on the temperature range between ± 0.003 and ± 0.06 ppm. Error bars in Fig. 3 show the various accuracy ranges. The calibration sample allows extremely accurate correction of the inherent thermal expansion of the rest of the system design.
    The advanced push rod dilatometer is optimized for better measurement stability over time. Therefore, for measurements of thermal expansion for a longer time over narrow temperature ranges, i. Temperature ranges smaller than areas of a width of 50 ° C, for example, areas of a width of at most 20 ° C, preferably of at most 10 ° C, according to certain embodiments of at most 5 ° C, are used.
    FIG. 4 shows a temperature profile for measuring the thermal expansion of a titanium silicate reference sample around 22 ° C. The temperature is lowered in steps of 2 ° C from a temperature of 24.5 ° C down to a temperature of 14.5 ° C, followed by 2 hours at a constant temperature. The total measuring time adds up to 23 hours. In addition, Fig. 4 shows the measurement of a titanosilicate reference sample under the given temperature profile. Due to the high resolution of the measuring head, the measurement shows an excellent resolution of the new refined
    Thrust dilatometer with a low noise level. For long term measurements it is important that the push rod dilatometer shows a very low and predictable drift. The solid line indicates the reference sample, the dotted line indicates the temperature.
    Fig. 5 shows the drift behavior of the further developed dilatometer, measured over a period of 80 hours. The observed drift is nearly linear and very small on the order of only <0.06 nm / h = 1.44 nm / day. It is important to check if the repeatability of the measurement changes with temperature. The continuous thicker line indicates the temperature, the dotted line shows the reference sample.
    Fig. 6 shows the reproducibility of the length measurement (Sigma dl / 1) as a function of temperature using the example of the standard pushrod dilatometer (triangular points) and the further developed pushrod dilatometer (circular points). As a result, the improved push rod dilatometer improved by almost a factor of 10 over the standard push rod dilatometer.
    In particular, Figure 6 shows the change in standard deviation of a length measurement over a temperature range of 0 ° C to 50 ° C with the more advanced push rod dilatometer compared to the change in standard deviation of a length measurement with the standard push rod dilatometer. It can be seen that the change of the more developed
    The push rod dilatometer at a value below 0.03 ppm (3 nm with a sample length of 100 mm) is nearly constant over the temperature, whereas with the standard push rod dilatometer the repeatability seems to decrease with the temperature. The standard deviation of the standard push rod dilatometer is about a factor 10 greater than the more advanced push rod dilatometer.
    The repeatability of the improved
    For a period of 7 days, the push rod dilatometer was described in the publication R. Jedamzik, R. Müller, P. Hartmann: Homogeneity of the linear thermal expansion coefficient of ZERODUR® measured with improved accuracy.
    Proc. SPIE Vol. 6273 (2006). This is a time frame that is greater than the typical time required for a homogeneity measurement and is about 2 to 3 days. During this time, the push rod dilatometer must be as stable as possible. The standard deviation over all measurements with the improved push rod dilatometer is ± 0.6 ppb / K, resulting in a short-term reproducibility of ± 1.2 ppb / K for the improved push rod dilatometer based on a 95% confidence interval.
    Fig. 7 shows the reproducibility of a CTE (0 ° C, 50 ° C) measurement with the more advanced push rod dilatometer. The measurement shows a repeatability of less than 1 ppb / K for a 95% confidence interval over a period of 50 days.
    Specifically, Figure 7 shows the results of weekly CTE (0 ° C, 50 ° C) measurements on the reference sample performed with the new enhanced push rod dilatometer for a 50 day timeframe. The standard deviation is 0.47 ppm / K and therefore the reproducibility 2 * σ (95% confidence interval) is better than 1 ppb / K. Measurements with the further developed push rod dilatometer already show a higher reproducibility of the measurements over a much longer period compared to the older improved push rod dilatometer.
    With the more advanced push rod dilatometer, the short to medium time repeatability is better than ± 1 ppb / K. The absolute measuring accuracy is due to the high degree of calibration standard and the low drift tendency due to the many realized design
    Improvements were excellent. Therefore, an absolute measurement accuracy of ± 3 ppb / K can be achieved.
    Generally, the performance of push rod dilatometers is limited by the mechanics of the design. Nevertheless, in the case of a purely optical design of the contact higher accuracies can be realized.
    However, the effort to achieve the necessary stability and the time to prepare the samples will be much higher.
    Publication R. Jedamzik, T. Döhring, T. Johansson, P. Hartmann, T. Westerhoff: "CTE characterization of ZERODUR® for the ELT century", Proc. SPIE Vol. 7425 (2009) shows the CTE homogeneity in the single-digit ppb range per Kelvin for circular and rectangular blanks made of the material Zerodur® with diameters in the range of 1.5 m.
    The term CTE homogeneity here means the homogeneity of the CTE of different samples of the same material, which are therefore separated and analyzed at different points from this same material. This suggests the homogeneity of the CTE of larger bodies. Similar results were obtained for mirror blanks with dimensions in the range of 4 m (so-called 4m class), wherein the excellent CTE homogeneity was at the same level as in the publication T. Westerhoff, S. Gruen, R. Jedamzik, C. Klein, T. Werner, A. Werz: "Progress in 4m class ZERODUR® mirror production", Proc. SPIE. Vol. 8126 (2011).
    Measurements were also taken at smaller physical dimensions on a 1,200 mm x 1,200 mm test plate made of Zerodur® material. Fig. 8 shows a two-dimensional contour plot of CTE homogeneity. A number of 64 samples were cut equally distributed from this test plate. The distance between these samples was about 100 mm. The difference between the individual measurements and the mean value of the blank is displayed in the contour plot. The two vertical and horizontal lines in FIG. 8 show the position of the sample cutout with a distance of 7.5 mm.
    The CTE average of the blank is determined using the improved dilatometer and is 12.2 ppb / K for the blank. The total CTE homogeneity of the blank has a variation of 5 ppb / K. In order to calculate the CTE homogeneity on a spatial scale between 100 and 150 mm, a part of the plate was cut into many samples, which lay directly next to each other. The CTE sample geometry, which is at least required for a high accuracy of the CTE measurement, is 100 mm by 5 mm × 5 mm in cross section. Due to typical losses during cutting, the minimum achievable distance between the samples is therefore 7 to 8 mm.
    At this scale, 14 samples were cut horizontally in the y-direction at a total height of 110 mm. Twenty-one samples were cut vertically in the x-direction at a total height of 150 mm. The results based on the so-called improved push rod dilatometer can be found in the publication R. Jedamzik, C. Kunisch, J. Nieder, T. Westerhoff: "Glass ceramic ZERODUR enabling nanometer precision", Proc. SPIE Vol. 9052 (2014).
    This measurement was repeated using the configuration of the advanced push rod dilatometer and the same set of samples.
    Figure 9 shows the results of CTE homogeneity for the samples cut horizontally in the y direction as measured by the improved push rod dilatometer and the more advanced push rod dilatometer. The maximum peak-to-valley variation in CTE homogeneity observed with the old push rod dilatometer was 4 ppb / K leads to a fluctuation of 2 ppb / K.
    The mean absolute value of the measurement with the more advanced push rod dilatometer is lower by about 3 ppb / K. This is still within the difference in absolute measurement accuracy of 6.2 ppb / K for the improved push rod dilatometer and 3 ppb / K for the more advanced pushrod dilatometer. The error bars (± 1.2 ppb / K for the improved and ± 1 ppb / k for the more advanced pushrod dilatometer) show the reproducibility of the measurements. Comparing the change in results from sample to sample between the two measurements, it is difficult to find any trend. It seems that the deviation only reflects the accuracy / repeatability of the measurement.
    This has already been described in the publication R. Jedamzik, C. Kunisch, J. Nieder, T. Westerhoff: "Glass ceramic ZERODUR enabling nanometer precision", Proc. SPIE Vol. 9052 (2014) and appears to have been verified in this comparison. Similar results can be found when comparing the results of the vertically cut samples in FIG. 10. The maximum peak-to-valley fluctuation of homogeneity observed with the improved push rod dilatometer is 3 ppb / K. The homogeneity observed with the newly developed push rod dilatometer is only 2 ppb / K. The offset between the two measurements is in the range of 2 to 3 ppb / K and is therefore in agreement with the observations in the horizontal measurement Again, there is no comparable trend behavior from sample to sample along the measuring points.
    Therefore, these results seem to emphasize that the observed changes are measurement noise and not small scale changes of the Zerodur® test plate. With the new developed push rod dilatometer the very good results of the homogeneity measurement can be confirmed. Both sets of 36 total samples are within a variation of 2 ppb / K CTE homogeneity of the Zerodur® material.
    Finally, FIG. 11 schematically shows a measuring device for measuring the linear dimension of a sample in a predeterminable temperature range on the basis of the further developed pushrod dilatometer 1. The pushrod dilatometer 1 comprises an elongate fork 20 and a likewise elongate pushrod 30. For the sake of clarity, this illustration is shown the
    Springs for holding the push rod in the fork not shown.
    The fork 20 comprises a measuring area 21, which is preferably designed to be connected to the measuring device or the measuring apparatus, in particular the position transducer, preferably to the linear incremental encoder (not shown), a tapering elongated, central area 22 with two symmetrical fork-like parallel arranged legs and a measuring range 21 opposite sample receiving area 25. The reference numeral 18, the zero line of the fork 20 is indicated.
    The fork 20 forms a hollow, elongated interior 29 for receiving an elongate sample (not shown) and the push rod 30 from. The sample is inserted into the test receiving space 28 provided for this purpose, which comprises a section of the elongated inner space 29 lying in the sample receiving area 25. In this case, the symmetry axis of the sample is preferably at the zero line 18.
    The fork 20 is monolithic in order to be able to dispense with connection and joints. Thus, it is free of splices or other plastic parts, as they may have an undesirable high thermal expansion.
    The sample receiving portion 25 of the fork 20 is intended to allow the sample to be charged at a certain temperature, hence heating or cooling. For this purpose, the corresponding area 25 of the receiving device in a
    Tempering device such as a cooling chamber or a furnace (not shown) are introduced.
    The measuring area 21 of the fork 20 is designed to allow easy connection to the measuring apparatus. For this purpose, suitable receptacles, recesses or holes are provided, which allow a high-precision, positive connection of the fork 20 with the measuring apparatus.
    The elongated push rod 30 is equally spaced within the fork 20 from the two legs and can be moved longitudinally in the interior while being held by springs. The movement takes place along the symmetry line and parallel to the measuring direction, which is denoted by "X".
    As well as the fork 20 and the push rod 30 is monolithically formed to dispense with connection and joints can. Glue or other parts made of plastic is omitted, since they have an undesirable high thermal expansion and thus can affect the intrinsic expansion of the device unfavorable.
    The push rod 30 is held by springs (not shown) which are connected thereto on one side with portions of the legs and on the other side with the push rod 30.
    The push rod 30 is configured to engage a sample placed in the sample receiving space at the desired temperature. For this purpose, it can be equipped at its head end with a feeler, which is designed for the high-precision and defined probing of a sample inserted in the interior. The probing is preferably carried out with very low pressure in order not to deform the inserted sample.
    权利要求:
    Claims (19)
    [1]
    claims
    A method of determining the thermal expansion of a low thermal expansion material using a pushrod dilatometer with a push rod, fork and springs to hold the push rod within the fork, with a measurement accuracy of at most +/- 3 ppb / K or less and / or a reproducibility of at most +/- 1 ppb / K or less.
    [2]
    2. The method according to claim 1, characterized in that the measurement accuracy is at most 1 ppb / K or less, preferably at most 0.6 ppb / K (2 sigma, 95% confidence interval) or less, preferably for the "coefficient of thermal expansion" CTE (0 ° C, 50 ° C).
    [3]
    3. The method according to any one of the preceding claims, characterized in that the measurement is carried out using a push rod dilatometer, preferably a further developed push rod dilatometer.
    [4]
    4. The method according to any one of the preceding claims, characterized in that with a repeatability of at most + / - 5 ppb / K, preferably at most +/- 3 ppb / K, more preferably at most + / - 1ppb / K (1.2ppb) measured becomes.
    [5]
    5. The method according to any one of the preceding claims, characterized in that the sample is tempered in an oven with a heat transfer medium, preferably with helium.
    [6]
    6. The method according to any one of the preceding claims, characterized in that the measuring in a predeterminable temperature range, selectable from a temperature range of -50 to + 100 ° C, for example from 40 ° C to 70 ° C, from -10 ° C to + 20 ° C, or from 19 ° C to 24 ° C, takes place.
    [7]
    7. A device for measuring the linear expansion of a sample with low thermal expansion, comprising a further developed push rod dilatometer with a push rod, a fork and springs for holding the push rod within the fork for carrying out the method according to any one of the preceding claims.
    [8]
    8. Apparatus according to claim 7, wherein the fork and the push rod are monolithic and / or no organic compounds or plastic parts are used to connect these components.
    [9]
    9. Device according to one of the two preceding claims 7 or 8, wherein the spring comprises a material with low thermal expansion, preferably the material Invar®.
    [10]
    10. Device according to one of the preceding claims 7 to 9, wherein a cryostat for the temperature range -50 ° C to + 100 ° C with a reproducibility of at least 0.5 ° C, more preferably at least 0.3 ° C, most preferably at least 0.2 ° C, is used.
    [11]
    11. Device according to one of the preceding claims 7 to 10, wherein the device in an air-conditioned room with a constant predetermined temperature with at most + / - 0.2 ° C deviation and / or with a constant predetermined humidity of at most +/- 2% Deviation is located.
    [12]
    12. Device according to one of the preceding claims 7 to 11, wherein the device a "drift" of preferably at most 0.1 nm / h (1.4 nm / day), more preferably at most 0.08 nm / h, most preferably less than 0.06 nm / h.
    [13]
    13. Device according to one of the preceding claims 7 to 12, wherein an optical interferometer is used as a detector for determining the position of the push rod relative to the fork.
    [14]
    14. Device according to the preceding claim, wherein the interferometric measuring head an absolute accuracy of at least +/- 10 ppb / K, preferably at least +/- 8 ppb / K, more preferably + / - 7 ppb / K and / or a repeatability of at most +/- 2 ppb / K.
    [15]
    Use of a method according to any one of claims 1 to 6 for the characterization of low thermal expansion materials or samples for use in astronomy, LCD lithography, microlithography and metrology.
    [16]
    16. Use of a method according to the preceding claim using a device according to one of the preceding claims 7 to 15.
    [17]
    17. Use of a method according to one of claims 15 or 16 for determining the thermal expansion of substrate materials for EUV lithography, in particular for substrates for mask blanks (masks) and mirrors for EUV lithography.
    [18]
    18. Use of a method according to any one of claims 15 to 17, wherein the substrate materials are selected from a group comprising ceramics, glass ceramics, and glasses, such as quartz glass with low thermal expansion, for example, Ti-doped silica, such as ULE®, or LAS glass ceramics with low thermal expansion, in particular Zerodur®, Clearceram®, SITAL®, or low thermal expansion ceramics, such as Codierit.
    [19]
    19. Use of a method according to any one of claims 15 to 17, wherein the application temperature may be selected from 22 ° C, 40 ° C, 60 ° C, 70 ° C or 80 ° C.
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    引用文献:
    公开号 | 申请日 | 公开日 | 申请人 | 专利标题
    DE10317792A1|2003-04-16|2004-11-11|Schott Glas|Blank mask for use in EUV lithography and process for its manufacture|
    DE102012110177A1|2012-10-24|2014-04-24|Schott Ag|Method for determining time delayed change in temperature or voltage-dependent physical quantities of glass ceramic, involves determining reference temperature and weighting factors of glass ceramic at several relaxation times|
    DE255060C|
    US3680357A|1970-09-21|1972-08-01|Gerhard R Clusener|Dilatometer|
    US3805589A|1972-11-15|1974-04-23|Theta Ind Inc|Quenching dilatometer|
    US3898836A|1974-04-08|1975-08-12|Theta Ind Inc|Differential dilatometer|
    US3919879A|1974-09-03|1975-11-18|Theta Ind Inc|Electrical zeroing means for a dilatometer|
    FR2468902B1|1979-11-05|1983-10-21|Vettori De Almeida Rodrigues C|
    US4618274A|1984-04-16|1986-10-21|Clusener Gerhard R|Dilatometer housing|
    US4548515A|1984-04-23|1985-10-22|Clusener Gerhard R|Multiple sensor dilatometer|
    US4636090A|1985-05-22|1987-01-13|Theta Industries, Inc.|Low temperature dilatometer|
    US4762424A|1985-05-22|1988-08-09|Theta Industries, Inc.|Low temperature dilatometer|
    DE3714988C2|1987-05-06|1989-03-23|Mtu Muenchen Gmbh|
    US5121987A|1989-03-02|1992-06-16|Honeywell Inc.|Method and apparatus for measuring coefficient of thermal expansion|
    JPH03154856A|1989-11-10|1991-07-02|Shinku Riko Kk|Thermal expansion measuring instrument|
    US5287749A|1990-10-11|1994-02-22|Seiko Instruments, Inc.|Thermomechanical analyzer|
    TW527526B|2000-08-24|2003-04-11|Asml Netherlands Bv|Lithographic apparatus, device manufacturing method, and device manufactured thereby|
    US6724488B1|2002-05-07|2004-04-20|Paul L. Guilmette|Interferometer for length measurement|
    US7350715B2|2003-03-10|2008-04-01|Hewlett-Packard Development Company, L.P.|Tracking electronic devices|
    US7104680B2|2003-10-31|2006-09-12|Sii Nanotechnology Inc.|Thermal analyzer with gas mixing chamber|
    US7239397B2|2003-12-31|2007-07-03|Corning Incorporated|Device for high-accuracy measurement of dimensional changes|
    US7224475B2|2004-04-29|2007-05-29|Battelle Energy Alliance, Llc|Methods and apparatus for measurement of a dimensional characteristic and methods of predictive modeling related thereto|
    US7635092B2|2004-08-04|2009-12-22|Waters Technologies Corporation|Humidity-controlled chamber for a thermogravimetric instrument|
    JP2007040715A|2005-07-29|2007-02-15|Ulvac-Riko Inc|Michelson optical interferometer, thermal expansion meter using optical interferometer, and thermal expansion amount measuring method|
    EP2095065A4|2006-11-15|2010-11-24|Zygo Corp|Distance measuring interferometer and encoder metrology systems for use in lithography tools|
    US20080262391A1|2007-04-23|2008-10-23|Mark Peter Ottensmeyer|Instrument for measuring the mechanical properties of vocal tissues|
    US7999912B2|2007-05-08|2011-08-16|Asml Netherlands B.V.|Lithographic apparatus and sensor calibration method|
    RU2593917C1|2012-10-24|2016-08-10|Шотт Аг|Method of determining time-delayed changes of physical values depending on temperature or mechanical stress for glass or glass-ceramic|
    DE102014102077A1|2014-02-19|2015-08-20|Netzsch-Gerätebau GmbH|Apparatus and method for measuring a change in length of a sample and / or for measuring a deformation force on a sample|
    TWI585363B|2015-12-01|2017-06-01|國立清華大學|Double ball-bar system and errors compensation method thereof for measurement|
    US10458936B2|2016-05-11|2019-10-29|Corning Incorporated|Apparatus and method for the determination of the absolute coefficient of thermal expansion in ultralow expansion materials|CN107655931B|2017-08-09|2020-06-09|北京空间机电研究所|High-precision barrel linear expansion coefficient measuring device and method|
    DE102018104309A1|2018-02-26|2019-08-29|Leibniz-Institut für Werkstofforientierte Technologien - IWT|Dilatometer for the automated examination of samples and methods for the automated dilatometric examination of samples|
    法律状态:
    优先权:
    申请号 | 申请日 | 专利标题
    DE102015112150|2015-07-24|
    DE102015112150.6|2015-07-24|
    DE102015113548.5A|DE102015113548A1|2015-07-24|2015-08-17|High-precision method for determining the thermal expansion|
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