A new application for ultra-fast and repeatable in-die determination of CD structures at the ~1 &mgr;m length scale using
BPR®/BPE® (Beam Profile Reflectometry/Ellipsometry) technologies on an Opti-Probe OP9000 series system, is presented and summarized. Two structures were measured and analyzed, including a poly-silicon CD standard and an advanced poly-silicon recessed structure relevant to advanced memory devices. A focused beam spot (~1 &mgr;m) and "fast BPR" data acquisition capability (~17 ms) were utilized to perform high-resolution scans across wafer and within single die regions. Rotating Compensator Spectroscopic Ellipsometry (RCSE®) signals were also used to independently determine and compare to BPR results from data collected over larger areas (~15 &mgr;m). The BPR/BPE and SE results for line CD were found to have high correlation. Further, model regression for SE data coupled with an artificial neural
network model and fast BPR were utilized to measure and calculate 10,000 points across a 1 mm2 area in a matter of
minutes. Overall, the results were found to be repeatable and correlated well to CD-SEM analysis.
Frequency-domain IR photothermal radiometry is introduced as a dynamic dental diagnostic tool and its main features are compared with modulated laser luminescence for quantifying sound and carious enamel or dentin. Dental caries found in the fissures or grooves of teeth is very difficult to diagnose or quantify with the present clinical techniques. Visual examination and dental radiographs do not detect the presence of decay until there has been significant carious destruction of the tooth. A high-spatial-resolution dynamic experimental imaging set-up, which can provide simultaneous measurements of laser-induced frequency-domain IR photothermal radiometric and luminescence signals form defects in teeth, was developed. Following optical absorption of laser photons, the new set-up can monitor simultaneously and independently the non-radiative conversion, and the radiative de-excitation in turbid media such as hard dental tissue. This work is intended to show the complementarity between modulated luminescence and photothermal frequency scans in detecting carious lesions in teeth. A sound extracted molar with a dentin-enamel interface was introduced to examine the depth profilometric abilities of the method. Occlusal surfaces of teeth with potential areas of demineralization or carious destruction in the fissures were examined and compared to the signals produced by the sound enamel establishing the depth profilometric abilities of the method. The significance to clinical dentistry lies in the potential of this technique to detect and monitor early carious lesions in the pits and fissures of teeth.
Frequency-domain IR photothermal radiometry is introduced as a dynamic dental diagnostic tool and its main features are compared with conventional laser luminescence for quantifying sound and defective enamel. A high-spatial- resolution dynamic experimental imaging set-up, which can provide simultaneous measurements of laser-induced frequency-domain IR photothermal radiometric and luminescence signals form defects in teeth, has been developed. Following optical absorption of laser photons, the new set-up can monitor simultaneously and independently the non-radiative conversion via IR photothermal radiometry; and the radiative de-excitation via luminescence emission.
Among diffusion methods, photothermal radiometry (PTR) has the ability to penetrate and yield information about an opaque medium well beyond the range of conventional optical imaging. Owing to this ability, pulsed-laser PTR has been extensively used in turbid media such as biological tissue to study the sub-surface deposition of laser radiation, a task which may be difficult or impossible for conventional optical methods due to excessive scattering and absorption. In this work, the optical and thermal properties of tissue- like materials are observed using frequency-domain IR photothermal radiometry. An approximate 3D heat conduction formulation with the use of 1D optical diffusion is developed to derive a turbid frequency-domain PTR model. The agreement in the absorption and transparent scattering coefficients of model phantoms is investigated. The present opto-thermal model for frequency-domain PTR may prove useful for non-contact, non-invasive, in situ measurement of optical properties of tissues and other multiply-scattering media.
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