Key Engineering Materials Vols. 381-382

Abstract: Your 32nm is different from my 32nm! The paradoxical statement reflects one of the most essential debates in the field of nanoscale dimension metrology for process control in the modern nanoelectronic manufacturing industry. This baffling debate is all about accuracy and traceability of dimension measurement systems used on production floors. As the circuit geometry and density continues to scale to the 45nm node and below, the metrology bias and uncertainty play a more significant role, and the characterization becomes more difficult. This article assesses the capability of atomic force microscope (AFM) as an accurate inline calibration metrology tool and the correlation of AFM measurement to NIST traceable standards. It introduces the methodology of adopting AFM as a traceable reference tool for CD SEM and optical scatterometry used in inline process control. The focus is on height, linewidth, and pitch calibrations due to their critical but challenging roles for process control in today’s nanoelectronic manufacturing. Care must be taken to minimize the impact from factors that affect the traceability and accuracy in the AFM system, including tip width calibration, tip wear, tip shape effect, contamination, and linewidth roughness.

Abstract: To ensure the reliability of the measurement results with optical digitizers, it is necessary that the instruments are verified under proper protocols with traceably calibrated artefacts. The requirement for test artefacts is being calibrated with small uncertainty. In addition, it is needed that the optical characteristics of the artefacts' surface are suitable for the measurement with optical sensors because optical digitizers adopt different measuring methods. In this research, the concept, structure and feature of the test artefacts are reported.

Abstract: In this paper a Kalman filter algorithm for estimating a linear regression model wıth account of the regression vector error is presented. That approach has been applied to calibrating measuring instruments and gives a rigorous derivation of a recurrent algorithm for estimating the parameters of the calibration curve with the incorporation of the errors in reproducing the inputs. Calibration of the differential pressure gauge by the standard pressure setting devices (piston gauges) is demonstrated in the paper as an example.

Abstract: The next generation GPS standard system is based on operation/operator. One of the most important motivations of the next generation GPS is to reduce specification uncertainty. This paper analyzes the origination of specification uncertainty and the relationship between specification uncertainty and other two important uncertainties in the next generation GPS, correlation uncertainty and measurement. And then the procedure for management of Specification uncertainty is proposed in the paper. Finally, a method on evaluation of specification uncertainty and the general formula for this method is proposed. The embodied formula for estimation of specification uncertainty on the diameter example is deduced in the paper.

Abstract: The today’s nanometrology limits the accuracy of the precision engineering. These limits are based on the meter definition as redefined in 1983. It is proposed to define precision mechatronics as the science and engineering of high level precision systems and machines. The paper describes a precision mechatronic machine. This device represents a long range positioning machine having a resolution of 0.1 nm over the range of 25 mm x 25 mm x 5 mm. The integration of several optical and tactile nanoprobes makes the 3D-nanopositioning suitable for various tasks. New developed nanoprobes (optical focus probe, nanoindenter, metrological scanning force microscope) and results of measurement will be presented.

Abstract: This paper presents a scanning squareness measurement method for large ultra-precision components. A rectangular block as the squareness reference is used. The squareness error of the rectangular block is eliminated according to the geometric principle that the sum of four internal angles of a rectangle is 360°. And the straightness error of each line of the rectangular block is eliminated by means of scanning method with two 1D probes. The above two error separation technologies are combined effectively and the data processing method is developed. Additionally, the standard uncertainties including tilt and squareness errors of the rectangular block, temperature drift and random errors of the measured values of the probes are analyzed theoretically. It is confirmed that a combined standard uncertainty of less than 1 arcsec can be obtained for typical values of the parameters.

Abstract: Vertical metro-scopes using Abbe’s principle AVM are used for different dimensional measurements. The accuracy of their measurement is low compared to other available techniques used in the calibration of gauge blocks. This uncertainty can be improved through the use of laser interferometer system in combination with it. This paper describes the improvement, the results of the calibration of a set of gauge blocks and the uncertainty budget for such a calibration. The uncertainty of such calibration is estimated to be within ± (0.06+L/650) *m; L in mm; for gauge blocks less than 200 mm. An inter-comparison between the results of such improved AVM and the results obtained from one of the gauge block electronic comparators available on the market proved that the differences in the mean results are insignificant.

Abstract: Tooth flank form deviation of micrometers influences vibration and noise characteristics of gears and therefore strict quality control of tooth flank form is demanded. However, since gear checker is structurally-complex, it is difficult to analyze how error factors of gear checkers influence the measurement result. In this research, Virtual Gear Checker (VGC) is proposed, which is a simulation program of gear measurement considering the mechanisms and motions of gear checkers and possible error factors. The influence of the error factors on the measurement result can be clarified by VGC. VGC is also able to calculate the theoretical measurement result of non-involute helicoid artifact. It is easy for VGC to measure tooth flank form repeatedly in virtual space and therefore it can assess the uncertainty of measurement with gear checker. The uncertainty of gear measurement is calculated as an example.

Abstract: A technique to compensate the geometry errors of industrial robot using Laser Tracker System (LTS) has been presented in this paper. A Spherically Mounted Retro-reflector (SMR) is mounted on the end-effector of industrial robot. The positions of SMR are measured by LTS and compared with the nominal value of industrial robot to get geometry error database of robot. The updated error database, together with real-time measuring of the positions on the robot’s end-effector can be used to compensate the geometric errors of the robot. Using this technique to compensate the industrial robot, the geometry errors can be decreased from 0.1mm to 0.04mm.

Abstract: In current application of measurement uncertainty evaluation, dynamic uncertainty evaluation simply uses the static uncertainty methods. To change the situation, a new evaluation method of measurement uncertainty is investigated based on Bayesian principle in this paper. Bayesian evaluation method uses conjugate normal-inverted gamma distribution as the distribution function in uncertainty evaluation, which can be employed to evaluate both static and dynamic measurement uncertainty. The evaluation method put forward in this paper can achieve higher evaluation accuracy than the conventional methods, particularly in processing dynamic data with small samples. It has been proved in theory and by computer simulation.