Papers by Keyword: Metrology

Abstract: A new design approach on 4H-SiC material is ongoing to improve the electrical performance of devices. As seen in silicon devices, multi-epitaxial growth enhances performance by reducing on-resistance (R_on). However, devices built on SiC face several challenges due to the very low dopant diffusion (e.g. phosphorus and aluminum) and defect evolution during the epitaxial growth. Monitoring defects like prismatic faults, stacking faults, partial dislocations, and micropipes, especially after regrowth, is essential to assess their impact on device performance. Defects with high killer ratio must be closely tracked to understand evolution thereof. In this work, we will show a method for early-stage process characterization and defect root-cause identification through sensitive inspections, effective reviews, and accurate defect classification to detect critical defects in 4H-SiC material when more than one epitaxial step is considered.

Abstract: The article presents a novel design solution comprising a base, a model eye, and a compressor, intended for a standard device used to calibrate eye tonometers. This device reliably generates values of intraocular pressure and related ophthalmological parameters. It is founded on the principles of objectivity and independence in metrological control, with direct traceability to the basic units of the International System of Units. The proposed design represents the next stage in the development of standard devices, addressing various metrologically unverified parameters within medical metrology, particularly values of intraocular pressure. Intraocular pressure is closely associated with glaucoma, a condition where elevated intraocular pressure leads to irreversible physiological changes in the eye. The presented technical solution establishes the foundation for robust metrological assurance of devices with measuring functions in this domain.

Abstract: X-ray computed tomography (CT) is becoming more commonly used in industry, in addi-tion to material testing, it is also suitable for dimensional measurements for metrological purposes.A great advantage of CT is that it is appropriate for evaluating dimensional characteristics of outerand inner surfaces in a non-destructive manner. But due to the complexity of CT dimensional mea-surements, several influencing factors affect the accuracy of the method. It is also a complicatingaspect that the metrological traceability of CT measurements is not fully developed. The precisionand accuracy of dimensional measurements by CT are affected by several factors including the objectof investigation and the measurement parameters. These factors may contribute to the difference be-tween the true value and the measured value of the length of a certain workpiece when measured byCT. It is yet an unsolved issue to determine all the effects to reduce measurement error and uncertainty.One particularly significant factor related to the measured object is its surface quality, which plays acritical role in affecting the reliability of CT measurements. Since the dependence of such deviationsfrom surface morphology has not yet been thoroughly examined, our aim is to study the influence ofsurface roughness on CT dimensional measurements by looking for correlation between the precisionof the length of 3D-printed workpieces measured by CT and the surface roughness of the sides ofthe workpieces. A slight negative correlation (with correlation coefficients −0.35 < r < −0.4) hasbeen shown between measurement errors and the average values of Ra, Rz and Rp, contrary to theprevious literature, where linear relationships have been found instead and the relationship with Rahas not been examined. It highlights the fact that this topic is not yet worked out in detail due to thecomplexity and unstandardized processes of CT measurements.

Abstract: The main goal of production quality paradigm is a joint improvement of production rate and conformity, while minimizing the waste of resources. This paradigm is aligned with the Zero-Defect Manufacturing (ZDM) approach, which aim is the defect removal in manufactured products. Simulation tools offer a high flexibility to analyse complex systems such as multi-stage manufacturing systems, allowing to optimize the required production rates and the quality of the products. To this end it is necessary to develop simulation models that integrate the discrete behaviour of products flow, and the spread of quality characteristics during the process. This work is focused on the modelling of the geometrical quality characteristics that depend on the deviations induced when the part is held by a processing fixture. For the modelling of this behaviour, Modelica language is selected because of its ability to integrate the modelling of multi-physical systems, including the discreet behaviour necessary to simulate the materials flow. For that purpose, this paper presents a Modelica library for the definition of simulation models able to analyse geometrical and dimensional deviations produced in process assemblies composed of a piece and a fixture. The use of Modelica language, which modelling is based on equations, requires the definition of a mathematical structure, based in this case on the TTRS (Technologically and Topologically Related Surfaces) model.

Abstract: A method for continuous measurement of particle and particle precursor material in high purity liquids using aerosolization and condensation particle courting (A+CPC) is presented. A process for correlating wafter defects with the concentration values measured using A+CPC using Sequential Spin Coating + Surface Enhanced Particle Sizing (SSC + SEPS) is described. The method was applied to monitor the rinsate of an ion exchange resin following the SEMI C93 guide. The results showed correlation between the methods and the concentration values were used to calculate a deposition factor (liquid concentration/surface concentration) on the order of 1E5 (#/ml)/(#/cm²).

Abstract: Industrial X-ray computed tomography (XCT) is a tool for non-destructive testing and a volumetric analysis method with the ability to measure dimensions and geometry inside a component without destroying it. However, XCT is a relatively young technology in the field of dimensional metrology and thus faces several challenges. The achievement of a high measurement resolution, which is re-quired to detect small geometrical features, depends on a variety of influencing factors. In this arti-cle, the interface structural resolution (ISR) as one of the key challenges will be investigated. The two-sphere standard called the hourglass standard allows the determination of the structural resolu-tion by evaluation of the surrounding area of an ideal point contact of two spheres after the CT re-construction in form of a neck-shaped transition. Close to the contact point of the two spheres two opposing surfaces exist. Their distances from each other increase as the distance from the contact point of the two spheres increase. The determination of the distances between the spheres’ surface allows a statement about the ISR. A new developed specimen or standard with a variable gap size consisting of calibrated parallel gauge blocks allows statements about the ISR, too. Because of the higher number of probing points of the gauge block standard the results of the determined ISR are more stable compared to the hourglass standard. This paper compares the results of the computed tomography measurements for the designed interface structural resolution standard with those of the hourglass standard.

Abstract: Lattice structures can be highly complex imitating natural cellular materials. By the wide adoption of additive manufacturing technologies, lattice structures are a popular design element with many advantages for lightweight and highly functional parts. A detailed examination and an intense inspection of this type of new design element and this new production method is necessary to enable a broad industrialization. In this study we demonstrate how to use x-ray based industrial CT to measure lattice structures in additive manufacturing. This paper shows certain challenges and approaches for metrology on lattice structures. The results show significant deviations between designed and built parts, highlighting the need for quantification and non-destructive inspection.

Abstract: Numerical models based on cohesive zones are usually used to model and simulate the mechanical behavior of laminated carbon fiber reinforced polymers (CFRP) in automotive and aerospace applications and require different interlaminar properties. The current work focuses on determining the interlaminar fracture toughness (G_IC) under Mode I loading of a double cantilever beam (DCB) specimen of unidirectional CFRP, serving as prototypical material. The novelty of this investigation is the improvement of the testing methodology by introducing digital image correlation (DIC) as an extensometer and this tool allows for crack growth measurement, phenomenological visualization and quantification of various material responses to Mode I loading. Multiple methodologies from different international standards and other common techniques are compared for the determination of the evolution of G_IC as crack resistance curves (R-curves). The primarily metrological sources of uncertainty, in contrast to material specific related uncertainties, are discussed through a simple sensitivity analysis. Additionally, the current work offers a detailed insight into the constraints and assumptions to allow exploration of different methods for the determination of material properties using the DIC measured data. The main aim is an improvement of the measurement technique and an increase in the reliability of measured data during static testing, in advance of future rate dependent testing for crashworthiness simulations.

Abstract: A non-destructive metrology technique for critical dimension of Fin structure is important for better device characterization and development for improving yield. Due to extremely small dimension with high complexity in FinFET a new metrology solution needs to be evaluated. In-line atomic resolution profiler was performed to provide a suitable metrology for oxide recess metrology in Fin process. The technique could measure accurately the height and CD of Fin structures, which has the space with of 25 nm and the height of 60 nm. The uniformity of recess height could be measured, which could be interpreted by loading effect of etch process. High long term repeatability of the technique was achieved for process monitoring purpose.

Abstract: This paper demonstrates a variety of metrology methods for high selective silicon nitride etch in different process baths. Capability of measuring full matrix components is also presented. For the measurement of H₃PO₄ and H₂O, both NIR spectroscopy and conductivity methods work well. Si measurement in the etchant that contains an organo-silicon compound requires a new reagent development in comparison with the original reagent method developed for regular process contains inorganic Si only.