Science and technologies based on terahertz frequency electromagnetic radiation (100 GHz–30 THz) have developed rapidly over the last 30 years. For most of the 20th Century, terahertz radiation, then referred to as sub-millimeter wave or far-infrared radiation, was mainly utilized by astronomers and some spectroscopists. Following the development of laser based terahertz time-domain spectroscopy in the 1980s and 1990s the field of THz science and technology expanded rapidly, to the extent that it now touches many areas from fundamental science to 'real world' applications. For example THz radiation is being used to optimize materials for new solar cells, and may also be a key technology for the next generation of airport security scanners. While the field was emerging it was possible to keep track of all new developments, however now the field has grown so much that it is increasingly difficult to follow the diverse range of new discoveries and applications that are appearing. At this point in time, when the field of THz science and technology is moving from an emerging to a more established and interdisciplinary field, it is apt to present a roadmap to help identify the breadth and future directions of the field. The aim of this roadmap is to present a snapshot of the present state of THz science and technology in 2017, and provide an opinion on the challenges and opportunities that the future holds. To be able to achieve this aim, we have invited a group of international experts to write 18 sections that cover most of the key areas of THz science and technology. We hope that The 2017 Roadmap on THz science and technology will prove to be a useful resource by providing a wide ranging introduction to the capabilities of THz radiation for those outside or just entering the field as well as providing perspective and breadth for those who are well established. We also feel that this review should serve as a useful guide for government and funding agencies.

https://iopscience.iop.org/article/10.1088/1361-6463/50/4/043001/pdf

The 2017 terahertz science and technology roadmap

The 2016 terahertz science and technology roadmap

A method for growing films for use in integrated circuits using atomic layer deposition and a subsequent converting step is described. In an embodiment, the subsequent converting step includes oxidizing a metal atomic layer to form a metal oxide layer. The atomic layer deposition and oxidation step are then repeated to produce a metal oxide layer having sufficient thickness for use as a metal oxide layer in an integrated circuit. The subsequent converting step, in an embodiment, includes converting the atomic deposition layer by exposing it to one of nitrogen to form a nitride layer, carbon to form a carbide layer, boron to form a boride layer, and fluorine to form a fluoride layer. Systems and devices for performing the method, semiconductor devices so produced, and machine readable media containing the method are also described.

Atomic layer deposition and conversion

A method of enhanced atomic layer deposition is described. In an embodiment, the enhancement is the use of plasma. Plasma begins prior to flowing a second precursor into the chamber. The second precursor reacts with a prior precursor to deposit a layer on the substrate. In an embodiment, the layer includes at least one element from each of the first and second precursors. In an embodiment, the layer is TaN. In an embodiment, the precursors are TaF 5 and NH 3 . In an embodiment, the plasma begins during the purge gas flow between the pulse of first precursor and the pulse of second precursor. In an embodiment, the enhancement is thermal energy. In an embodiment, the thermal energy is greater than generally accepted for ALD (>300 degrees Celsius). The enhancement assists the reaction of the precursors to deposit a layer on a substrate.

Enhanced atomic layer deposition

Photoconductive antennas (PCAs) have been extensively utilized for the generation and detection of both pulsed broadband and single frequency continuous wave terahertz (THz) band radiation. These devices form the basis of many THz imaging and spectroscopy systems, which have demonstrated promising applications in various industries and research fields. The development of THz PCA technology through the last 30 years is reviewed. The key modalities of improving device performance are identified, and literature is reviewed to summarize the progress made in these areas. The goal of this review is to provide a collection of all relevant literature to bring researchers up to date on the current state and remaining challenges of THz PCA technology.

https://www.spiedigitallibrary.org/journals/optical-engineering/volume-56/issue-1/010901/Review-of-terahertz-photoconductive-antenna-technology/10.1117/1.OE.56.1.010901.pdf

Review of terahertz photoconductive antenna technology

In a system for evaluating a semiconductor device, a laser beam generating unit generates a laser beam, and an optical fiber receives the laser beam to heat an area of the semiconductor device. A current deviation detector or a voltage deviation detector is connected to a terminal of the semiconductor device. As a result, the current deviation detector or the voltage deviation detector detects a current deviation or a voltage deviation at the terminal of the semiconductor device.

Semiconductor device evaluation system using optical fiber

A nondestructive inspection device (or method) is basically configured such that a laser beam (1300 nm) (3, 53) is irradiated on a surface (or back) of a semiconductor device chip (4) to scan. Due to irradiation of the laser beam, a defect position is heated to cause a thermoelectromotive current, which induces a magnetic field. A magnetic field detector (5) such as SQUID (55) detects a strength of the magnetic field, based on which a scan magnetic field image is produced. A display device (7) superimposes the scan magnetic field image on a scan laser microphotograph on a screen, so it is possible to perform defect inspection on the semiconductor device chip. Incidentally, a semiconductor device wafer (40) is constructed to include a thermoelectromotive force generator (21) and its wires (20a), which are electrically connected to first-layer wires (34a, 34b). By irradiation of the laser beam on the thermoelectromotive force generator, it is possible to detect a short-circuit defect (42), which lies between the first-layer wires. Further, it is possible to perform nondestructive inspection on a semiconductor integrated circuit, which is in an intermediate stage of manufacture before formation of bonding pads and which includes a closed circuit configured by a first-layer wire (34), including a thermoelectromotive force generating defect (41), a circuit via (35) and an inspection via (305) as well as a metal film (36), which is formed in a relatively broad range of a surface area and is used to form a second-layer wire (37).

Device and method for nondestructive inspection on semiconductor device

Laser beam 104 having an irradiation power not less than 1 mW is irradiated onto an observed region, and a variation in a power source current 112 is detected. When the laser beam 104 is irradiated onto a parasitic insulating film 107 which is a parasitic MIM structural spot, the current 112 increases due to a temperature characteristic of the current 112 flowing through the parasitic insulating film 107 , whereby the portion of the parasitic MIM structure can be detected. Moreover, laser beam 108 having a wavelength not less than 1.0 μm is irradiated onto an observed region from the back surface of the chip, and a variation in the power source current is detected. Light having a wavelength not less than 1.0 μm has the ability to travel through a Si substrate 110 so that the laser beam reaches a wiring portion. Irradiation of the laser beam onto the parasitic insulating film 107 having the parasitic MIM structure increases the current, so that the portion of the parasitic MIM structure can be detected.

Parasitic MIM structural spot analysis method for semiconductor device and parasitic MIM structure spot analysis method for silicon semiconductor device

Infrared laser beam (11) is irradiated onto an integrated circuit (12) as a sample mounted on a sample stage (21) from an infrared laser beam source (23) through a microscope section body (24) and an objective lens (25). A constant voltage source (15) is connected to a power source terminal of the integrated circuit (12). A variation in a current due to a variation in a resistance of a wiring portion due to the irradiation is produced at a ground terminal of the integrated circuit (12). A current variation inspection section (17) detects the current variation. A system control/signal processing section (27) processes the signal and allows an image/waveform display section (28) to display a current image, a defect image or a current waveform. A defect of a wiring may be detected using visible light beam after localization of a suspected failure portion using infrared beam.

Inspection method and wiring current observation method for semiconductor device and apparatus of the same

A method for estimating current or detecting defects in an interconnection by monitoring current change of the interconnection. A radiation beam such as a laser, electron or ion beam is irradiated to a subject region to be observed while scanning points of the subject region. Decrease of the supply current during the scanning is detected in the power supply line. The amount of decrease is approximately proportional to the current flowing originally. The value of the current in the interconnection or a defect existing in the interconnection can be estimated or found from the decreased amount. One of or the combination of selective scanning, threshold selection and thin film deposition makes it possible to apply this method to an actual device.

Kiyoshi Nikawa

Papers

Semiconductor device evaluation system using optical fiber

Device and method for nondestructive inspection on semiconductor device

Parasitic MIM structural spot analysis method for semiconductor device and parasitic MIM structure spot analysis method for silicon semiconductor device

Inspection method and wiring current observation method for semiconductor device and apparatus of the same

Method and system for testing an interconnection in a semiconductor integrated circuit