A Review: Inductively Coupled Plasma Reactive Ion Etching of Silicon Carbide

The inductively coupled plasma reactive ion etching (ICP-RIE) is a selective dry etching method used in fabrication technology of various semiconductor devices. The etching is used to form non-planar microstructures—trenches or mesa structures, and tilted sidewalls with a controlled angle. The ICP-RIE method combining a high finishing accuracy and reproducibility is excellent for etching hard materials, such as SiC, GaN or diamond. The paper presents a review of silicon carbide etching—principles of the ICP-RIE method, the results of SiC etching and undesired phenomena of the ICP-RIE process are presented. The article includes SEM photos and experimental results obtained from different ICP-RIE processes. The influence of O2 addition to the SF6 plasma as well as the change of both RIE and ICP power on the etching rate of the Cr mask used in processes and on the selectivity of SiC/Cr etching are reported for the first time. SiC is an attractive semiconductor with many excellent properties, that can bring huge potential benefits thorough advances in submicron semiconductor processing technology. Recently, there has been an interest in SiC due to its potential wide application in power electronics, in particular in automotive, renewable energy and rail transport.

Effect of Reactive Ion Etching on the Luminescence of GeV Color Centers in CVD Diamond Nanocrystals

The negatively charged germanium-vacancy GeV− color centers in diamond nanocrystals are solid-state photon emitters suited for quantum information technologies, bio-sensing, and labeling applications. Due to the small Huang–Rhys factor, the GeV−-center zero-phonon line emission is expected to be very intensive and spectrally narrow. However, structural defects and the inhomogeneous distribution of local strains in the nanodiamonds result in the essential broadening of the ZPL. Therefore, clarification and elimination of the reasons for the broadening of the GeV− center ZPL is an important problem. We report on the effect of reactive ion etching in oxygen plasma on the structure and luminescence properties of nanodiamonds grown by hot filament chemical vapor deposition. Emission of GeV− color centers ensembles at about 602 nm in as-grown and etched nanodiamonds is probed using micro-photoluminescence and micro-Raman spectroscopy at room and liquid nitrogen temperature. We show that the etching removes the nanodiamond surface sp2-induced defects resulting in a reduction in the broad luminescence background and a narrowing of the diamond Raman band. The zero-phonon luminescence band of the ensemble of the GeV− centers is a superposition of narrow lines originated most likely from the GeV− center sub-ensembles under different uniaxial local strain conditions.

Versatilely tuned vertical silicon nanowire arrays by cryogenic reactive ion etching as a lithium-ion battery anode

Production of high-aspect-ratio silicon (Si) nanowire-based anode for lithium ion batteries is challenging particularly in terms of controlling wire property and geometry to improve the battery performance. This report demonstrates tunable optimization of inductively coupled plasma reactive ion etching (ICP-RIE) at cryogenic temperature to fabricate vertically-aligned silicon nanowire array anodes with high verticality, controllable morphology, and good homogeneity. Three different materials [i.e., photoresist, chromium (Cr), and silicon dioxide (SiO2)] were employed as masks during the subsequent photolithography and cryogenic ICP-RIE processes to investigate their effects on the resulting nanowire structures. Silicon nanowire arrays with a high aspect ratio of up to 22 can be achieved by tuning several etching parameters [i.e., temperature, oxygen/sulfur hexafluoride (O2/SF6) gas mixture ratio, chamber pressure, plasma density, and ion energy]. Higher compressive stress was revealed for longer Si wires by means of Raman spectroscopy. Moreover, an anisotropy of lattice stress was found at the top and sidewall of Si nanowire, indicating compressive and tensile stresses, respectively. From electrochemical characterization, half-cell battery integrating ICP-RIE-based silicon nanowire anode exhibits a capacity of 0.25 mAh cm−2 with 16.67% capacity fading until 20 cycles, which has to be improved for application in future energy storage devices.

Recent Advances in Reactive Ion Etching and Applications of High-Aspect-Ratio Microfabrication

This paper reviews the recent advances in reaction-ion etching (RIE) for application in high-aspect-ratio microfabrication. High-aspect-ratio etching of materials used in micro- and nanofabrication has become a very important enabling technology particularly for bulk micromachining applications, but increasingly also for mainstream integrated circuit technology such as three-dimensional multi-functional systems integration. The characteristics of traditional RIE allow for high levels of anisotropy compared to competing technologies, which is important in microsystems device fabrication for a number of reasons, primarily because it allows the resultant device dimensions to be more accurately and precisely controlled. This directly leads to a reduction in development costs as well as improved production yields. Nevertheless, traditional RIE was limited to moderate etch depths (e.g., a few microns). More recent developments in newer RIE methods and equipment have enabled considerably deeper etches and higher aspect ratios compared to traditional RIE methods and have revolutionized bulk micromachining technologies. The most widely known of these technologies is called the inductively-coupled plasma (ICP) deep reactive ion etching (DRIE) and this has become a mainstay for development and production of silicon-based micro- and nano-machined devices. This paper will review deep high-aspect-ratio reactive ion etching technologies for silicon, fused silica (quartz), glass, silicon carbide, compound semiconductors and piezoelectric materials.