Papers by Keyword: Etch

Abstract: Silicon Carbide is an exceptionally hard and challenging to process semiconductor material. Effective device singulation retaining 100% die yield is hard to achieve with conventional saw dicing. Chips, microcracks and machining abrasions lead to reduced die strength and increased scrap. With rapid advancements in SiC device processing, resolving many fabrication issues, dicing yield losses are becoming an area of industrial concern. Plasma dicing has a proven track record in silicon and presents a potential solution to low yields during SiC dicing. Smooth vertical sidewalls with no machining damage, with etch rates approaching 5 μm/min, position SiC plasma dicing as a viable alternative ready for industrial uptake. Plasma etch processes development using Ni and Cu etch masks, with full singulation have been demonstrated, resulting in improved die strength compared to saw diced samples.

Abstract: In an increasingly electrified technology driven world, power electronics is central to the entire clean energy manufacturing economy. Silicon (Si) power devices have dominated power electronics due to their low cost volume production, excellent starting material quality, ease of fabrication, and proven reliability. Although Si power devices continue to improve, they are approaching their operational limits primarily due to their relatively low bandgap, critical electric field, and thermal conductivity that result in high conduction and switching losses, and poor high temperature performance. Silicon Carbide’s (SiC) compelling efficiency and system benefits have led to significant development efforts over the last two decades and today planar and trench MOSFETs, and JFETs are commercially available from several vendors as discrete components or in high power modules in the of 650 V to 1700 V voltage range. High impact application opportunities, where SiC devices are displacing their incumbent Si counterparts, have emerged and include automotive and rail power electronics with reduced losses and reduced cooling requirements; novel data center topologies with reduced cooling loads and higher efficiencies; variable frequency drives for efficient high power electric motors at reduced overall system cost; more efficient, flexible, and reliable grid applications with reduced system footprint; and “more electric aerospace” with weight, volume, and cooling system reductions contributing to energy savings. In particular, SiC insertion in electric vehicles brings major competitive advantages and is a volume application opportunity that can spur manufacturing economies of scale and lower system costs. As SiC continues to grow, the industry is lifting the last barriers to mass commercialization that include higher than Si device cost, relative lack of wafer planarity, the presence of basal plane dislocations, reliability and ruggedness concerns, and the need for a workforce skilled in SiC power technology to keep up with the rising demand. It should be noted that in many applications, insertion of SiC reduces overall system cost compared to Si even though SiC devices can cost 2-3 more than their Si counterparts. This is due to the passive component and cooling system simplifications enabled by the efficient high frequency SiC operation. In this paper, we will review key aspects of SiC technology and discuss overcoming barriers to mass commercialization.

Abstract: The use of various H₂O₂ based chemistries for TiW etch was studied on single wafer and wet bench tools. The focus of the investigation was put on the different behaviors of these chemicals on blanket and patterned wafers. The results of the etch rate tests showed much higher values on the wafers where copper was exposed, leading to the hypothesis that the etch rate on TiW should be driven by the catalysis effect of the transition metal on the H₂O₂ decomposition reaction. Additional optical inspections, ToF SIMS, SEM and TEM analyses were carried out to confirm this hypothesis and find the best conditions in terms of morphology for RDL applications. Finally, the collected data were also used to evaluate the process cycle time and cost of ownership.

Abstract: Silicon carbide (SiC) static induction transistors (SITs) were fabricated using home-grown epi structures. The gate is a recessed gate - bottom contact (RG - B). The mesa space designed is 2.5 μm and the gate channel is 1.0 μm. The developed devices adopted a p-type Al ion implanted gate and power performance was improved by decreased leakage current and enhanced break-down voltage. The lift-off with assistant dielectric, dense gate recess etching, high temperature anneals and PECVD passivation process technologies are adopted. One cell has 200 source fingers and each source finger width is 50 μm. 0.5 mm SiC SIT yield a current density of 110 mA/mm at a drain voltage of 50 V. A maximum current density of 160 mA/mm was achieved with Vd = 80V, and the maximum transconductance is 40mS/mm. The device blocking voltage with a gate bias of-12 V was 400 V. Packaged 2 × 2-cm devices were evaluated using amplifier circuits designed for class AB operations. A total power output in excess of 70 W was obtained with a power density of 17.5 W/cm and gain of 5.5 dB at L band 1 GHz under pulse 100μs and cycle ratio 1% RF operation and 80V drain to source voltage.

Abstract: With carbon nanotube as cold cathode, the field emission display based on the improved film-electrode was fabricated. The indium tin oxide film covered on the glass surface was etched to form the film-electrode. For one film-electrode stripe, the left bar electrode and the right bar electrode were formed on the both side of the bottom electrode. The carbon nanotube would be prepared on the bottom electrode surface. The cathode covering layer fabricated with the sintered insulation slurry would cover the left and right bar electrodes. It was confirmed that the emission current could be controlled by the formed electric-field with the improved film-electrode.

Abstract: Hydroxyapatite (HAP) is known as a kind of bioactive and biocompatible material, HAP coatings are used to improve the biocompatibility of substrate by some researchers. In this paper, homogenous precipitation of hydroxyapatite was formed in the system of CaNa₂EDTA -(NH₄)₂HPO₄-NH₄OH-H₂O, and HAP powder was obtained after calcinations at 800 and grinding. Add HAP in UHMWPE o-xylene solution to get dipping solution and prepare HAP/UHMWPE-coated titanium by dipping coating process. Scratch test demonstrated that Ti-HAP/UHMWPE material started to shine metallic luster under 1.03 N, and adhesive strength is 32MPa. UHMWPE not only simplified the process of preparing HAP-coated material, but also enhanced the adhesive strength, which shows great potential in biomedical areas.

Abstract: An extrinsic Fabry-Perot (F-P) interferometric (EFPI) sensor by using simple etching and fusing method is proposed and demonstrated. The cavity is formed by wet chemical etching of multi-mode fiber (MMF) end face in hydrofluoric acid solutions, and then it is fused to the end of a single-mode fiber (SMF) to form an extrinsic F-P structure. The strain and temperature of EFPI sensor are studied experimentally. The experimental results show that the interference wavelength becomes 2.648nm longer while the strain increases from 0N to 637N, and the strain sensitivity is about 0.004nm/N, and linearity is 0.999. The interference wavelength becomes 0.032nm shorter while the temperature increases from 20°C to 100°C. This kind of sensor has the many advantages of easy fabrication, good reliability, high-repetition, small size, low cost and mass-production, which offers great prospect for sensing applications.

Abstract: This research addresses the fabrication of crack-free 40-nm thin film YBa2Cu3O7 (YBCO) pixel structures based on high temperature superconductor (HTSC) microbolometers for highly sensitive thermal detectors that can be miniaturized for affordable passive millimeter-wave (MMW) imaging. A completely dry etch process is described for suspended transition edge bolometers by removing (releasing) the silicon substrate underneath a 3 micrometer wide pixel using gaseous plasma sulfurhexafluoride (SF6) chemical reaction. This is an improvement over conventional selective wet chemical etching techniques that are both harsh on the YBCO and require additional complex alignment steps to the substrate material leading to very poor device yields and performance. Issues relating to material roughness, etch redeposition, and silicon undercutting will be analyzed and methodologies to overcome/minimize such problems will be explained in detail.

Abstract: A new method of etching micro-grating structures (MGSs) on the surface of glazed stainless-steel directly is reported, which makes good use of the interference of nanosecond laser pulses. Through changing the experimental parameters such as working current of the laser and source beam diameter, the influences of these parameters on the depth of grooves and duty cycle of MGSs are analyzed. The results measured with conventional optical microscopy and atomic force microscopy (AFM) show that the depth of grooves of MGSs varies from 0 nm to 350 nm, the duty cycle of MGSs changes between 0.4 and 0.9, This method can be used to make a stencil-plate for nano-imprinting. It extends the application of nanosecond laser in laser-induced microstructures, and provides a new method for micromachining micro-optical component.

Abstract: The etching properties of the ZnO thin films in the inductively coupled Cl2/Ar plasma (ICP) were studied in the terms of etch rate and selectivity as functions of gas mixing ratio, ICP coil power and dc bias voltage. The maximum etch rate of 129.3 nm/min was obtained for the mixture of 20% Ar/80% Cl2. The X-ray photoelectron spectroscopy (XPS) analyses of the ZnO surfaces etched at various Cl2/(Cl2+Ar) mixing ratios revealed the formation of the ZnClx and ClOx reaction by-products as a result of the increased etch rate with increasing Cl2 addition, compared with 100% Ar+ sputter etching. From the analysis of these data, it was proposed that the maximum on the etch rate may be explained by the concurrence of chemical and physical pathways in the ion assisted chemical reaction.