Non-Visual Defect Monitoring with Surface Voltage Mapping: Application for Semiconductor IC and PV Technology

2015 ◽  
Vol 242 ◽  
pp. 472-477 ◽  
Author(s):  
Piotr Edelman ◽  
Dmitriy Marinskiy ◽  
Alexander Savtchouk ◽  
John D'Amico ◽  
Andrew Findlay ◽  
...  
Keyword(s):  
Deep Level ◽  
Mapping Technique ◽  
Voltage Gradient ◽  
Kelvin Probe ◽  
Wafer Inspection ◽  
Si Solar Cells ◽  
Voltage Mapping ◽  
Voltage Transient ◽  
Dielectric Charge ◽  
Charge Deposition

Non Visual Defects (NVD) is a category of defects that cause electrical failures but are not detected with visual wafer inspection tools. Our approach for NVD detection is based on the Kelvin probe surface voltage mapping technique. The detection of defects is enhanced using field-effect created in a non-contact manner by corona charge deposition on the surface of semiconductor. Precise defect location is accomplished with surface voltage gradient magnitude mapping that enhances delineation of defects. Detected defects are characterized locally using the corona-voltage technique or isothermal voltage transient decay analysis. Presented examples include: dielectric charge and interfacial defect mapping on 300mm Si wafers; deep level emission mapping on epitaxial SiC and mobile ion mapping in Si solar cells.

Surface Voltage and μPCD Mapping of Defect in Epitaxial SiC

2016 ◽  
Vol 858 ◽  
pp. 353-356 ◽  
Author(s):  
Marshall Wilson ◽  
Alexander Savtchouk ◽  
Andrew Findlay ◽  
Jacek Lagowski ◽  
Piotr Edelman ◽  
...  
Keyword(s):  
Spectral Analysis ◽  
High Resolution ◽  
Carrier Lifetime ◽  
Deep Level ◽  
Probable Mechanism ◽  
Kelvin Probe ◽  
Large Magnitude ◽  
Force Microscopy ◽  
Low Intensity ◽  
Voltage Mapping

Kelvin-probe surface voltage mapping, SVM, on epitaxial SiC, charged with corona into deep depletion, reveals SV defects manifested as spots with decreased surface voltage. For 150μm thick epi-layer, SV defects coincide with low carrier lifetime spots revealed by microwave detected photoconductance decay, μPCD. In the photoluminescence image, these defects are seen as triangular dark spots, described in literature as stacking-fault related triangular defects. For thin epi-layers (2.2μm), defects are visible only in SVM. In this case, high resolution SVM performed with Kelvin Force Microscopy identifies a triangular defect shape. Two mechanisms are proposed, accounting for SV defects. For high intensity defects exhibiting large magnitude fast decreasing voltage, the probable mechanism is defect related leakage; causing neutralization of corona surface ions. Low intensity defects can be explained considering deep level emission. The latter mechanism has been investigated using SV transient and spectral analysis analogous to isothermal DLTS and Laplace DLTS.

scholarly journals Designing a Robust Kelvin Probe Setup Optimized for Long-Term Surface Photovoltage Acquisition

Sensors ◽  
2018 ◽  
Vol 18 (11) ◽  
pp. 4068 ◽  
Author(s):  
Elke Beyreuther ◽  
Stefan Grafström ◽  
Lukas Eng
Keyword(s):  
Deep Level ◽  
Surface Photovoltage ◽  
Probe Design ◽  
Relaxation Processes ◽  
Kelvin Probe ◽  
Electrical Stability ◽  
Temperature Dependent ◽  
Transient Spectroscopy ◽  
Photoinduced Charge

We introduce a robust low-budget Kelvin probe design that is optimized for the long-term acquisition of surface photovoltage (SPV) data, especially developed for highly resistive systems, which exhibit—in contrast to conventional semiconductors—very slow photoinduced charge relaxation processes in the range of hours and days. The device provides convenient optical access to the sample, as well as high mechanical and electrical stability due to off-resonance operation, showing a noise band as narrow as 1 mV. Furthermore, the acquisition of temperature-dependent SPV transients necessary for SPV-based deep-level transient spectroscopy becomes easily possible. The performance of the instrument is demonstrated by recording long-term SPV transients of the ultra-slowly relaxing model oxide strontium titanate (SrTiO 3 ) over 20 h.

Relationship between Constant Voltage and Constant Capacitance DLTS

1983 ◽  
Vol 20 (2) ◽  
pp. 145-149
Author(s):  
W. S. Lau ◽  
Y. W. Lam ◽  
C. C. Chang
Keyword(s):  
Deep Level Transient Spectroscopy ◽  
Deep Level ◽  
Constant Voltage ◽  
Unified Approach ◽  
Deep Traps ◽  
Capacitance Voltage ◽  
Voltage Transient ◽  
Transient Spectroscopy ◽  
Capacitance Transient ◽  
The Relationship

A unified approach is presented in the derivation of equations for the constant-voltage capacitance transient and constant-capacitance voltage transient in deep-level transient spectroscopy (DLTS), and for the relationship between them. The validity of these equations is independent of the device and nature of deep traps.

High-Speed Deep-Level Luminescence Imaging in Multicrystalline Si Solar Cells

2012 ◽  
Vol 725 ◽  
pp. 149-152 ◽  
Author(s):  
Futoshi Okayama ◽  
Michio Tajima ◽  
Hiroyuki Toyota ◽  
Atsushi Ogura
Keyword(s):  
Solar Cells ◽  
Solar Cell ◽  
Exposure Time ◽  
High Speed ◽  
Deep Level ◽  
Selective Detection ◽  
High Speed Imaging ◽  
Si Solar Cell ◽  
Si Solar Cells ◽  
Band Pass

We demonstrated high-speed imaging of photoluminescence (PL) and electroluminescence (EL) for not only band-to-band but also multiple deep-level emissions in a multicrystalline Si solar cell. We used a cooled InGaAs camera with a photosensitive range of 900 - 1700 nm equipped with band-pass filters for the selective detection of various deep-level emissions. The exposure time for imaging was only 1 - 10 seconds. Comparisons of the present PL images with the microscopic PL mappings confirmed for us that essentially the same luminescence patterns were obtained.

scholarly journals Kelvin probe force microscopy in liquid using electrochemical force microscopy

2015 ◽  
Vol 6 ◽  
pp. 201-214 ◽  
Author(s):  
Liam Collins ◽  
Stephen Jesse ◽  
Jason I Kilpatrick ◽  
Alexander Tselev ◽  
M Baris Okatan ◽  
...  
Keyword(s):  
Contact Potential Difference ◽  
Liquid Interface ◽  
Kelvin Probe Force Microscopy ◽  
Physical Models ◽  
Mapping Technique ◽  
Kelvin Probe ◽  
Contact Potential ◽  
Force Microscopy ◽  
Solid Liquid Interface ◽  
Solid Liquid

Conventional closed loop-Kelvin probe force microscopy (KPFM) has emerged as a powerful technique for probing electric and transport phenomena at the solid–gas interface. The extension of KPFM capabilities to probe electrostatic and electrochemical phenomena at the solid–liquid interface is of interest for a broad range of applications from energy storage to biological systems. However, the operation of KPFM implicitly relies on the presence of a linear lossless dielectric in the probe–sample gap, a condition which is violated for ionically-active liquids (e.g., when diffuse charge dynamics are present). Here, electrostatic and electrochemical measurements are demonstrated in ionically-active (polar isopropanol, milli-Q water and aqueous NaCl) and ionically-inactive (non-polar decane) liquids by electrochemical force microscopy (EcFM), a multidimensional (i.e., bias- and time-resolved) spectroscopy method. In the absence of mobile charges (ambient and non-polar liquids), KPFM and EcFM are both feasible, yielding comparable contact potential difference (CPD) values. In ionically-active liquids, KPFM is not possible and EcFM can be used to measure the dynamic CPD and a rich spectrum of information pertaining to charge screening, ion diffusion, and electrochemical processes (e.g., Faradaic reactions). EcFM measurements conducted in isopropanol and milli-Q water over Au and highly ordered pyrolytic graphite electrodes demonstrate both sample- and solvent-dependent features. Finally, the feasibility of using EcFM as a local force-based mapping technique of material-dependent electrostatic and electrochemical response is investigated. The resultant high dimensional dataset is visualized using a purely statistical approach that does not require a priori physical models, allowing for qualitative mapping of electrostatic and electrochemical material properties at the solid–liquid interface.

Abstract 25: The Use of Voltage Mapping for Slow Pathway Visualization and Ablation of Atrioventricular Nodal Reentry Tachycardia in Pediatric and Young Adult Patients

2012 ◽  
Vol 111 (suppl_1) ◽  
Author(s):  
Lindsey Malloy ◽  
Ian Law ◽  
Nicholas Von Bergen
Keyword(s):  
Low Voltage ◽  
Pediatric Population ◽  
Adult Patients ◽  
Voltage Gradient ◽  
Slow Pathway ◽  
Anatomical Location ◽  
Voltage Mapping ◽  
Atrioventricular Nodal Reentry Tachycardia ◽  
Reentry Tachycardia ◽  
Lower Voltage

Atrioventricular nodal reentry tachycardia (AVNRT) is a common arrhythmia in both pediatric and adult patients. Ablation of the arrhythmia substrate has typically been guided by anatomical location and electrogram morphology within the triangle of Koch. Using an anatomic approach can be challenging because of unusual pathway locations and anatomic variance. The use of voltage gradient mapping has been proposed in adults to aid in identification of the “slow pathway”, guiding placement of the ablation applications. The purpose of this study was to evaluate this novel technique of voltage guided ablation of AVNRT in a pediatric patient population, with a smaller triangle of Koch. Patients with atrioventricular nodal reentry tachycardia at the University of Iowa Children’s Hospital who underwent voltage mapping within the slow pathway area were included. Using intracardiac electrical recordings, three-dimensional voltage maps of the right atrium were created. A voltage map identified a bridge of lower voltage signals surrounded by even lower voltage tissue. This bridge was used to guide cryoablation of the slow pathway. Patient demographics, appearance of the intracardiac voltage mapping, timing of procedure, lesions to success, and total number of lesions was obtained. In this study there were 29 patients with an average age of 14 years (range 7 to 20 years) who underwent AVNRT ablation with voltage mapping. Ten were male. In these patients there was procedural success (no inducible AVNRT, single AV node echo beat or less) in all patients. In 25 of 29 patients, there was an adequate lower voltage saddle to allow guided ablation. The successful ablation site was within the first three lesions in 15/25 patients. Total lesions ranged from 5-34. There has been recurrence in 1 patient over an average follow-up period of one year (range five months - twenty months). The use of voltage guided ablation of a low voltage saddle in atrioventricular nodal reentry tachycardia is a technique that appears to be effective and safe in the pediatric population and has the advantage of allowing an electrically guided ablation therapy. Voltage guided ablation of atrioventricular nodal reentry tachycardia is a safe and effective technique for ablating AVNRT.

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