Solid-state Image Sensors Research Articles

Special Issue on Solid-State Image Sensors

This editorial summarizes the contents of this special issue of the IEEE Transactions on Electron Devices on solid state image sensors. Several researches on CCD and CMOS image sensors are included in this issue.

Planar metallic nanoscale slit lenses for angle compensation

We demonstrate numerically, using a modified total-field/scattered-field formalism, that metallic lenses, based on arrays of nanoscale slits with varying widths in a planar metallic film, can be used to focus light and compensate for various angles of incidence. These structures could be used as integrated microlenses to improve the efficiency of pixels in solid-state image sensors. Our design guidelines simultaneously accomplish a prism and focusing action. Our results also indicate the importance of the aperture effect for such far-field focusing devices.

Which Photodiode to Use: A Comparison of CMOS-Compatible Structures

While great advances have been made in optimizing fabrication process technologies for solid state image sensors, the need remains to be able to fabricate high quality photosensors in standard CMOS processes. The quality metrics depend on both the pixel architecture and the photosensitive structure. This paper presents a comparison of three photodiode structures in terms of spectral sensitivity, noise and dark current. The three structures are n(+)/p-sub, n-well/p-sub and p(+)/n-well/p-sub. All structures were fabricated in a 0.5 mum 3-metal, 2-poly, n-well process and shared the same pixel and readout architectures. Two pixel structures were fabricated-the standard three transistor active pixel sensor, where the output depends on the photodiode capacitance, and one incorporating an in-pixel capacitive transimpedance amplifier where the output is dependent only on a designed feedback capacitor. The n-well/p-sub diode performed best in terms of sensitivity (an improvement of 3.5 x and 1.6 x over the n(+)/p-sub and p(+)/n-well/p-sub diodes, respectively) and signal-to-noise ratio (1.5 x and 1.2 x improvement over the n(+)/p-sub and p(+)/n-well/p-sub diodes, respectively) while the p(+)/n-well/p-sub diode had the minimum (33% compared to other two structures) dark current for a given sensitivity.

1-2 ランダム性を持たせた画素配置による固体撮像素子のエリアシング防止(第1部門 センシング&コンシューマエレクトロニクス&ストレージ)

1-2 ランダム性を持たせた画素配置による固体撮像素子のエリアシング防止(第1部門 センシング&コンシューマエレクトロニクス&ストレージ)

Special issue of IEEE Transaction on Electron Devices on Solid State Image Sensors

Special issue of IEEE Transaction on Electron Devices on Solid State Image Sensors

Influence of Terrestrial Cosmic Rays on the Reliability of CCD Image Sensors—Part 2: Experiments at Elevated Temperature

An aging effect in solid-state image sensors is studied: the generation of hard errors resulting in hot spots, warm pixels, or white pixels. This effect even occurs in image sensors that are simply stored on the shelf. The first paper described experiments that were set up to prove that the main origin can be found with neutrons that create displacement damage in the silicon bulk. These neutrons are part of terrestrial cosmic rays. This second paper is based on measurements done on devices that were stored on the shelf, but at elevated temperatures. In addition, annealing experiments were performed on packaged devices. The creation of these hot spots is independent of technology, architecture, sensor type, or sensor vendor, and it is observed in CCDs as well as in CMOS image sensors. However, the generation, and particularly the stability, of the hot spots seems to depend strongly on the storage temperature or on the annealing temperature.

Special issue of IEEE Transactions on Electron Devices on Solid State Image Sensors

Special issue of IEEE Transactions on Electron Devices on Solid State Image Sensors

Special issue on solid-state image sensors

Special issue on solid-state image sensors

Special issue of IEEE Transaction on Electron Devices on Solid State Image Sensors

Special issue of IEEE Transaction on Electron Devices on Solid State Image Sensors

Special issue of IEEE Transactions on Electron Devices on Solid State Image Sensors

Special issue of IEEE Transactions on Electron Devices on Solid State Image Sensors

Error analysis about CCD sampling in Fourier transform profilometry

The influence of sampling caused by 2-D solid-state image sensors (CCD) in FTP is discussed in this paper. As we all know, discrete fringe patterns processed by computer are obtained through two samplings. The first one is accomplished in the CCD image plane, and the second is accomplished in A/D convertor of frame grabber. In the previous analysis, sampling is just regarded as a point-sampling process because of ignoring the actual sensor structure of a CCD in the sampling process. Here we discuss the influence of the sensor structure of CCD in FTP, especially the influence from the light-sensitive area size variation. Certain formulas about sampling influence are given, and some simulations and a primary experimental demonstration are carried out to verify our analysis.

Electrophoretic Materials in Wafer Level Packages for Solid State Imagers to Meet Automotive Reliability Standards

Solid state image sensors are increasingly being adopted for automotive applications. The harsh operating environment and requirement for long life means reliability standards for automotive components far exceed those of the normal sphere of use, namely mobile telephones. Electrophoretic paints are widely used in the automotive and construction industries to endow fabricated metal products with corrosion resistant, decorative, coatings. This paper describes the first known use of these materials for semiconductor packaging. The application is a wafer level packaging process to encapsulate image sensors, which will comfortably surpass the automotive standard for reliability.

Influence of Terrestrial Cosmic Rays on the Reliability of CCD Image Sensors—Part 1: Experiments at Room Temperature

An aging effect in solid-state image sensors is studied: the generation of hard errors resulting in hot spots, warm pixels, or white pixels. These effects even occur in image sensors that are simply stored on the shelf. This paper describes experiments that are set up to prove that the main origin can be found with neutrons that create displacement damage in the silicon bulk. These neutrons are part of terrestrial cosmic rays. This statement is based on measurements done on devices that we stored on the shelf, that were flown around the world in airplanes, that were stored at high altitude, and that were stored in an underground laboratory. The creation of the hot spots is independent of technology, architecture, sensor type, or sensor vendor, and it is observed in charge-coupled devices as well as in complementary metal-oxide-semiconductor image sensors. In other words, it is a typical issue of the semiconductor base material: silicon! The paper is split up into two parts: this paper (part 1) describes the experiments done at room temperature, part 2 will concentrate on experiments done at higher temperatures.

The Hole Role in Solid-State Imagers

The importance of holes present in the pixels of solid-state image sensors is described by Theuwissen et al. (IEDM Tech. Dig. 2005, p. 817). Today's success of digital imaging is based on the positive effect of an accumulation layer that reduces the interface-related dark current and dark current fixed-pattern noise. This superb imaging feature is applied in charge-coupled devices as well as in complementary metal-oxide-semiconductor devices, in consumer as well as in professional equipment. Holes are not only used to improve the dark performance of imagers; other examples of efficient use of holes are fixing electrostatic potentials, creating gate structures, draining photon-generated charges, and constructing antiblooming means

Automated 3D Particle Field Extraction and Tracking System Using Digital in-line Holography

Digital holography for 3D particle field extraction and tracking is an active research topic. It has a great application in realizing characterization of micro-scale structures in microelectromechanical systems (MEMS) with high resolution and accuracy. In-line configuration is studied in this study as the fundamental structure of a digital holography system. Digital holographic approach, not only eliminates wet chemical processing and mechanical scanning, but also enables the use of complex amplitude information inaccessible by optical reconstruction, thereby allowing flexible reconstruction algorithms to achieve optimization of specific information. However, owing to the inherently low pixel resolution of solid-state imaging sensors, digital holography gives poor depth resolution for images. This problem severely impairs the usefulness of digital holography especially in densely populated particle fields. This study describes a system that significantly improves particle axial-location accuracy by exploring the reconstructed complex amplitude information, compared with other numerical reconstruction schemes that are merely traditional optical reconstruction. Theoretical analysis and experimental results demonstrate that in-line configuration presents advantageous in enhancing the system performance. Greater flexibility of the system, higher lateral resolution and lower speckle noise can be achieved.

Sampling of two-dimensional images: prevention from spectrum overlap and ghost detection

The aim of this work is to recall the key role of sampling theory in image sampling with 2-D solid-state image sensors. Sampling restrictions due to the actual sensor structure—especially in the case of noncontiguous sensitive pixels—are often neglected, although sampling principles are well known from a theoretical point of view. Our purpose is to present experimental results that demonstrate clearly what kind of ghost detection and spectrum overlapping may result if the spectral bandwidth of the incident image is not suited to the image sensor capa- bilities. These experimental results and image distortions are shown to be the direct consequences of the sampling principles that are recalled in the first part. Finally, a sequential acquisition procedure, based on image sensor scanning, is shown to fulfill sampling theory requirements and thus enlarges the bandwidth capabilities of any image sensor. © 2004

Spectral Responses of Te-Doped a-Se High-Gain Avalanche Rushing Amorphous Photoconductor (HARP) Films for a Solid State Image Sensor

In this paper, spectral responses of Te-doped a-Se HARP (High-gain Avalanche Rushing amorphous Photoconductor) thin films for a solid state image sensor have been reported. Te concentrations of Te-doped layer in a-Se HARP thin film were 15 wt.% and 26 wt.%, and thicknesses of Te-doped layer were 60 nm, 90 nm, and 120 nm. Spectral responses of Te-doped a-Se HARP films were investigated at bias voltages of 40 V and 60 V. Relative sensitivity and quantum efficiency of a-Se HARP films at 60 V were found to be improved by the increase of Te-doped layer thickness. This improvement is explained by the increased photogeneration efficiency at long wavelength region by the increase of Te-doped layer thickness and avalanche multiplication of the photogenerated carriers at a high electric field.

Digital holography of particle fields: reconstruction by use of complex amplitude.

Digital holography appears to be a strong contender as the next-generation technology for holographic diagnostics of particle fields and holographic particle image velocimetry for flow field measurement. With the digital holographic approach, holograms are directly recorded by a digital camera and reconstructed numerically. This not only eliminates wet chemical processing and mechanical scanning, but also enables the use of complex amplitude information inaccessible by optical reconstruction, thereby allowing flexible reconstruction algorithms to achieve optimization of specific information. However, owing to the inherently low pixel resolution of solid-state imaging sensors, digital holography gives poor depth resolution for images, a problem that severely impairs the usefulness of digital holography especially in densely populated particle fields. This paper describes a technique that significantly improves particle axial-location accuracy by exploring the reconstructed complex amplitude information, compared with other numerical reconstruction schemes that merely mimic traditional optical reconstruction. This novel method allows accurate extraction of particle locations from forward-scattering particle holograms even at high particle loadings.

Foreword special issue on solid-state image sensors

Foreword special issue on solid-state image sensors

Ultra-High-Resolution Method for Solid-State Image Sensors Using Multiple-Step Swing and Wobbling Operation.

An ultra-high-resolution method using a multiple-step swing and wobbling operation is described for improving the resolution of solid-state image sensors. The method is based on the periodical shifting of the device to form multiple pixels. By analyzing the operation of this method, the optimum operation conditions were derived for achieving high resolution with low aliasing and low field flicker phenomena. Also described is a multiple-step wobbling operation with triangular waves that achieves high resolution with even lower aliasing and a wider operation range. Suitable display conditions of the multiple-step swing imaging signals were derived for achieving high resolution display images.