Towards traceable bidirectional optical size measurements for optical coordinate measuring machine metrology
Towards traceable bidirectional optical size measurements for optical coordinate measuring machine metrology
复制标题
实现光学坐标测量机计量的可追溯双向光学尺寸测量
DOI：
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发表时间：
2011
期刊：
影响因子：
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通讯作者：
H. Bosse
中科院分区：
文献类型：
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作者：
R. Köning;B. Bodermann;D. Bergmann;E. Buhr;W. Häßler;J. Flügge;H. Bosse
双向测量将用于光学坐标测量机（CMM）性能的校准和再验证。国家计量研究所面临的挑战是，在100 nm的所需不确定度水平上提供国际公认的适当标准校准。此外，大多数用户不知道这些测量的具体困难。由于光学成像过程是基于干涉和衍射的，因此测量取决于它们的所有影响参数。第一个必要条件是使用正确的阈值，通常需要通过模拟显微图像来确定。光学线宽测量的比较，这是双向测量的一个例子，和扫描电子线宽测量同意下降到纳米级。这些结果验证了建议的测量程序和相关的不确定度计算。在工业实验室的认证过程中获得的经验表明，为了能够实现约100 nm的所需测量不确定度，成像系统需要具有单色Koehler照明、大于0.6的数值孔径、大于50的放大率以及将焦点位置的偏差控制到优于100 nm的能力。
Bidirectional measurements are to be performed for the calibrations and the reverification of the performance of optical coordinate measurement machines (CMMs). The national metrology institutes are challenged to provide internationally recognized calibrations of suitable standards at the required uncertainty level of 100 nm. Furthermore most users are not aware of the specific difficulties of these measurements. Because the optical image formation process is based on interference and diffraction the measurements depend on all of their influence parameters. The first requisite is the use of the correct threshold value, which usually needs to be determined by a simulation of the microscopic image. A comparison of optical linewidth measurements, which are one example of bidirectional measurements, and scanning electron linewidth measurement agreed down to the nanometer level. These results validate the proposed measurement procedure and the related uncertainty calculations. The experience obtained within the accreditation process of industrial labs shows that, in order to be able to achieve the desired measurement uncertainties of about 100 nm, the imaging system needs to have a a monochromatic Koehler illumination, numerical aperture lager than 0.6, a magnification greater than 50 and the ability to control the deviation of the focus position to better than 100 nm.