Semiconductor Substrate Materials Research Articles

Molybdenum-14Rhenium alloy—The most promising candidate for high-temperature semiconductor substrate materials

The development of emerging high-temperature-resistant semiconductor materials is of great significance for the stability of signals and the reliability of sensors during extreme probing processes such as deep earth and space. However, current reports only focused on the properties of the semiconductor materials, neglecting the high-temperature-resistant properties of subsidiary components, such as substrate. In this study, for the first time, the feasibility of the Molybdenum-14Rhenium (Mo-14Re) alloy as a high-temperature semiconductor substrate material was verified at five temperature points (25 ℃ (room temperature, Rt.), 100 ℃, 200 ℃, 300 ℃, and 400 ℃, respectively). The results showed that the hardness (2.8 GPa to 2.4 GPa) of the Mo-14Re alloy changed slightly during the temperature up to 400 ℃; the Mo-14Re alloy generated protective Mo6+ and Re3+ oxides at different temperatures, which enhanced its oxidation resistance; the thermal expansion coefficient of the Mo-14Re alloy was 5.04 × 10−6/℃ at 400 ℃, which can be perfectly adapted to semiconductor components, such as silicon, silicon nitride, and gallium nitride. Simultaneously, the Mo-14Re alloy combined appropriate thermal conductivity, making it the most promising candidate for a new generation of high-temperature semiconductor substrate materials. This study can promote the application of semiconductor materials in extreme environments, such as high temperatures. Concurrently, this study can promote the development of deep earth exploration and aerospace fields and guide the selection of emerging high-temperature resistant substrate materials.

Mechanochemical grinding diamond film using titanium-coated diamond active abrasives prepared by vacuum micro-evaporation coating

The outstanding hardness and wear resistance of diamond materials pose significant challenges in their grinding processes for semiconductor substrate materials. To overcome this, a mechanochemical effect-based approach is used, which employs a grinding wheel comprising titanium (Ti)-coated diamond abrasives. A uniform Ti coating is vacuum-evaporated onto micrometer-scale diamond abrasives. The coating layer forms a diamond-TiC-Ti structure extending from the diamond matrix to the Ti coating direction. The material removal rate (MRR) of the DF is significantly increased as a result of the protruding active Ti coating on the diamond abrasives reacting with the DF at the interface contact locations. Increasing the grinding speed from 300 rpm to 700 rpm under a fixed grinding pressure of 300 N results in an MRR increment from 32 nm/min to 913 nm/min. Similarly, maintaining a grinding speed of 600 rpm while increasing the grinding pressure from 300 N to 600 N leads to an MRR increase from 388 nm/min to 1662 nm/min. The primary mechanism behind material removal is the reaction between the Ti coating and the DF, as well as the graphitization of the DF.

Tribological Study on Photocatalysis-Assisted Chemical Mechanical Polishing of SiC

Silicon carbide (SiC) is widely used as a power semiconductor substrate material, even if it takes a large amount of processing time to secure an appropriate surface as a wafer for devices after chemical mechanical polishing (CMP). Therefore, studies on SiC CMP have focused on shortening the processing time by increasing material removal efficiency. Among the methods of SiC CMP that have been widely studied recently, the photocatalysis-assisted CMP (PCMP) method is known to efficiently increase the material removal rate (MRR) of SiC under UV light and photocatalysts. However, a limited number of comparative studies have been conducted on PCMP from a tribology perspective. In this article, a comparative study was conducted from a tribology perspective on CMP, mixed abrasive slurry CMP (MAS CMP), and PCMP. The experimental results demonstrated that SiC PCMP has higher friction and processing temperature than MAS CMP and general CMP, which may be caused by photocatalytic oxidation and the TiO2 particles used as photocatalysts.

Gallium Arsenide‐Based Active Antennas for Optical Communication Photodetection with Robustness to Voltage and Temperature

AbstractAlthough gallium arsenide (GaAs) is one of the most commonly used semiconductor substrate materials, its intrinsic bandgap of 1.42 eV hinders the use of GaAs photodetectors for optical communication. In this study, hot‐electron‐based GaAs active antenna devices are demonstrated, displaying photoresponses well below the bandgap at the telecommunication wavelengths. Using a deep‐trench/thin metal (DTTM) active antenna, a metallic plasmonic structure, high photoresponsivities are achieved under zero bias at wavelengths of 1310 and 1550 nm. Even though the resistance of the semi‐insulating GaAs substrate is approximately 106 times larger than that of the n‐type silicon (Si) substrate, the photoresponsivities are commensurate with most previously reported hot‐electron n‐Si‐based photodetectors operating at communication wavelengths. Furthermore, the devices can be operated under a reverse‐biased voltage with significant enhancements in the photoresponsivities; the highest photoresponsivity (19.96 mA W−1 at 1310 nm) is greater than those reported in all previous studies. Moreover, these GaAs‐based devices are sufficiently robust to be operated over a wide range of operating temperatures (from −193 to +200 °C) while displaying a relatively large bandgap, low dark leakage currents, and high electron mobilities at low temperature. Because these devices can operate at high and low temperatures and at large voltage biases, they are suitable for use under harsh environmental conditions.

Hybrid Effect Study of Pad-Conditioning/Slurry-Supply by High-Pressure-Micro-Jet (HPMJ) Method during CMP Process

Surface clogging of polishing pad is inevitable during CMP (Chemical Mechanical Polishing) process of semiconductor wafers. In this paper, a novel slurry-feeding system utilizing HPMJ (High Pressure Micro Jet) apparatus was presented as in situ conditioning for CMP process. Clogging of pad surface can be greatly removed; the surface damage of polishing pad can also be extremely reduced by this new method. The experimental results exhibited that the material remove rate (MRR) of HPMJ method was almost constant value 100 μm h−1. However, the MRR value of conventional slurry-dripping method was about 50 μm h−1. On the other hand, surface roughness Ra changed both in hybrid HPMJ method and conventional slurry-dripping method after long-time continuous CMP process, the average Ra of hybrid HPMJ method was about 30% smaller than that of conventional slurry-dripping method, indicating that better surface quality could be obtained by HPMJ method polishing. It was demonstrated that HPMJ method showed higher MRR and lower surface roughness Ra for polishing process. HPMJ hybrid system mentioned in this study can also be applied to the polishing process of hard-to-process wide bandgap semiconductor substrate materials, such as SiC or GaN.

Enhanced Raman scattering on lead iodide film.

Surface-enhanced Raman scattering (SERS) on organic-inorganic hybrid perovskites have been proved a promising SERS-active substrate. As its inorganic skeleton, lead iodide (PbI2) also represents a novel semiconductor substrate material that serves as either a complement or an alternative to conventional metal-based SERS. Here, for the first time, enhanced Raman scattering (ERS) of 1,2-bis(4-pyridyl)ethylene (BPE) adsorbed on PbI2 film is observed. To our surprise, we obtained the same ERS spectra on the PbI2 as SERS spectra obtained on the perovskites, which demonstrates the enhancement of substrate comes from inorganic skeleton rather than organic-inorganic hybrid perovskites. Compared with the normal Raman spectrum of BPE molecules, we find the Bu mode of the BPE molecule was selectively enhanced. We demonstrate that it involves a charge transfer (CT) resonance mechanism and takes place between the HOMO of BPE and the conduction band edge of PbI2. Moreover, the PbI2 substrate performs good reproducibility, uniformity and good Raman enhancement (EF ≥ 105). It is believed that this unusual discovery not only enables PbI2 to be an enhanced substrate, which also provides a new advance toward a better understanding of SERS chemical mechanism.

Possible mechanism of gallium bioleaching from gallium nitride (GAN) by Arthrobacter creatinolyticus: Role of amino acids/peptides/proteins bindings with gallium

The objectives of this work were to screen and characterize heterotrophic bacteria for gallium nitride (GaN) leaching; and to study the involved mechanism of bacterial leaching of Ga from GaN. Ga in the form of GaN has been extensively used as a semiconductor substrate material. The advantage of bioleaching for gallium recovery is the fact that it is a safer, environmentally-friendly method and includes energy-saving processes, which can leach metals at relatively low concentrations. Three bacterial isolates were isolated from cadmium-, and arsenic-contaminated soil in the presence of GaN. NKS4 showed the highest efficiency in Ga leaching at approximately 18% after 15 days, and the system pH was 9. The analysis of 16S rDNA sequences indicated that strain NKS4 was characterized and identified as Arthrobacter creatinolyticus (A. creatinolyticus). Further investigation revealed that the ability of Ga leaching from GaN by this bacterium involved amino acids. Fourier transform infrared spectroscopy (FTIR) was used to investigate the interaction of Ga and amino acids/peptides/proteins which were secreted from this bacteria.

Bioleaching of gallium from gallium arsenide by Cellulosimicrobium funkei and its application to semiconductor/electronic wastes

The aim of this work was to screen and characterize heterotrophic bacteria for gallium arsenide (GaAs) leaching. Ga in the form of GaAs has been extensively used as a semiconductor substrate material. The advantage of using microbes for gallium recovery is the fact that this method is a safer, environment-friendly and includes energy-saving processes, which can leach metals at relatively low concentrations. Eight bacterial isolates were isolated from cadmium-, and arsenic-contaminated soil in the presence of GaAs. Pad I and NKS III showed the highest efficiency in Ga leaching at approximately 63–81% after 15 and 30 days, respectively. The analysis of 16S rDNA sequences indicated that strain Pad I was close to strain NKS III; it was characterized and identified as Cellulosimicrobium funkei (C. funkei). Further investigation revealed that the ability of Ga leaching from GaAs by this bacterium involved amino acids. This process occurred in a weak base pH range. The results show a potential application of C. funkei to leach Ga from semiconductors or electronic wastes. The in-depth mechanism of bacterial leaching of Ga from GaAs was also investigated.

Internal Photoemission at Interfaces of ALD TaSiOx Insulating Layers Deposited on Si, InP and In0.53Ga0.47As

Electrical analysis of interfaces of (100)Si, (100)InP, and (100)In0.53Ga0.47As with TaSiOx (Ta/Si≈1) films atomic-layer deposited using SiCl4, TaCl5, and H2O precursors suggests Ta silicate as a good insulating and surface passivating layer on all three semiconductors. However, when a positive voltage is applied to the top metal electrode in a metal/ TaSiOx /semiconductor configuration, considerable hysteresis of the capacitance-voltage curves, both at 300 and 77 K, is universally observed indicating electron injection and trapping in the insulator. To shed some light on the origin of this charge instability, we analyzed interface band alignment of the studied interfaces using the spectroscopies of internal photoemission and photoconductivity measurements. The latter reveals that independently of the semiconductor substrate material, TaSiOx layers exhibit a bandgap of only 4.5±0.1 eV, typical for a Ta2O5 network. The density of electron states associated with this narrow-gap network may account for the enhanced electron injection and trapping. Furthermore, while a sufficiently high energy barrier for electrons between Si and TaSiOx (3.1±0.1 eV) is found, much lower IPE thresholds are encountered at the (100)InP/TaSiOx and (100) In0.53Ga0.47As/TaSiOx interfaces, i.e., 2.4 and 2.0 eV, respectively. The lower barrier may be related by the formation of narrow-gap In-rich interlayers between AIIIBV semiconductors and TaSiOx.

Study on Mechanism of Polishing Sapphire Crystal by Laser

Single sapphire crystal is an important optical element and semiconductor substrate material, widely used in industry, national defense and scientific research, etc. But, high hardness and good chemical stability of the sapphire make it hard to be polished by applying mechanical chemical polishing and other contact methods. Therefore, laser polishing will be one of polishing methods which are supposed to replace contact method polishing sapphire. This essay, based on the summary of the study on laser polishing mechanism and technique of processing sapphire by laser, from the perspective of the interaction mechanism of the laser and the substance, analyzes in theory the interaction of laser and sapphire during the sapphire is polished by the short-wavelength laser. Experiments proved that under the cases of 20mJ and 40mJ laser energy when green laser polishes sapphire, the main material removal mechanism is fracture, at the same time, light melt mechanism exists.

Effects of the Semiconductor Substrate Material on the Post-breakdown Current of MgO Dielectric Layers

The post-breakdown (BD) current-voltage (I-V) characteristics in MgO/Si and MgO/InP stacks with metal gate were investigated. We show that both stacks exhibit the soft and hard BD conduction modes and that the magnitude of the post-BD currents depends statistically on the substrate material, being larger in the case of the InP samples. This is contrary to what happens with the current in the fresh devices, which irrespective of the InP surface treatment, is larger for the Si samples. A comparative analysis of the post-BD conduction characteristics and direct evidences of the localized thermal effects on the metal gate electrode of both structures are presented.

Effect of the Semiconductor Substrate Material on the Post-breakdown Current of MgO Dielectric Layers

not Available.

HYBRID NANOMATERIALS FOR MULTI-SPECTRAL INFRARED PHOTODETECTION

Quantum dot infrared photodetectors (QDIPs) using quantum dots (QDs) grown by strained-layer epitaxy have demonstrated low dark current, multi-spectral response, high operating temperature, and infrared (IR) imaging. However, achieving near room-temperature, multi-spectral operation is a challenge due to randomness in QD properties. The ability to control dopant incorporation is important since charge carrier occupation influences dark current and IR spectral response. In this work, dopant incorporation is investigated in two classes of QDs; epitaxial InAs/GaAs QDs and CdSe colloidal QDs (CQDs) embedded in MEH-PPV conducting polymers. The long-term goal of this work is to combine these hybrid nanomaterials in a single device heterostructure to enable multi-spectral IR photodetection. Two important results towards this goal are discussed. First, by temperature-dependent dark current-voltage and polarization-dependent Fourier transform IR spectroscopy measurements in InAs/GaAs QDIPs featuring different doping schemes, we have provided experimental evidence for the important contribution of thermally-activated, defect-assisted, sequential resonant tunneling. Second, the enhanced quantum confinement and electron localization in the conduction band of CdSe / MEH-PPV nanocomposites enable intraband transitions in the mid-IR at room temperature. Further, by controlling the semiconductor substrate material, doping type, and doping level on which these nanocomposites are deposited, the intraband IR response can be tuned.

Near field properties in the vicinity of gold nanoparticles placed on various substrates for precise nanostructuring

We present theoretical results on the near field distribution in the vicinity of gold particles excited by laser radiation and placed on various substrate materials. The study is directed towards the precise nanostructuring of different material surfaces. The calculations are performed on the basis of the FDTD simulation technique. Metal (Au), semiconductor (Si) and dielectric (SiO2) substrate materials are investigated. Experimental results are shown to confirm the validity of the obtained FDTD simulation results. The results show that the field in the vicinity of the point of contact is enhanced, and the enhancement factor depends on the substrate material, particle size and the wavelength of the incident optical radiation. The characteristic size of the field enhanced area is found to be several times smaller than the gold particle size: for the case of the smallest particle diameter of 40 nm it is about 10 nm. The enhancement factor of the electric field on the substrate surface is highest when the substrate is gold metal and it decreases about two orders of magnitude when dielectric SiO2 substrate is used. The characteristic penetration depth of the enhanced field is within several tens of nanometres and the depth weakly depends on the substrate material and the laser excitation wavelength. The dependence of the gold particle size on the field enhancement factor is investigated as well. The present results can be used to predict and design precise nanostructuring on different materials with gold nanoparticles excited by a femtosecond laser pulse.

Absolute lattice parameter measurement

Absolute lattice parameter methods are useful for determining alloy composition, understanding point defects and dopants in semiconductor substrate materials and for the evaluation of lattice relaxation in heteroepitaxial layers. This paper reviews the techniques available. The assumptions and uncertainties of each technique are discussed.

Modulation of submillimeter wave radiation by laser-produced free carriers in semiconductors

When a semiconductor substrate is illuminated by an optical beam whose photon energy exceeds its band-gap energy, free carriers are produced in the substrate, which provides a means of control for the substrate reflectance and transmittance of submillimeter electromagnetic waves. This paper is concerned with submillimeter wave modulation by an optically-excited semiconductor. High-resistivity silicon and GaAs are used as the substrate. Continuous radiation with a wavelength of 214 μm is used as the submillimeter wave. A Q-switched Nd:YAG laser is used to excite the free carriers. The experimental results are presented. Effects of semiconductor substrate material, wavelength of the excitation beam, and incident surfaces of the submillimeter wave and the substrate excitation beam, on the modulation waveforms are analyzed. As an application of the proposed modulation technique, submillimeter wave short pulses with variable duration are successfully generated. © 1998 Scripta Technica. Electron Comm Jpn Pt 2, 80(6): 1–9, 1997

Polishing of semiconductor materials

Different abrasive processes such as grinding and lapping are necessary to produce semiconductor wafers. However grinding and lapping leads to deterioration of the surface integrity of monocrystalline wafers. Therefore polishing and planarization is of utmost importance to produce microelectronic components. In this lecture the basics of polishing technology as well as different process models are presented. Additionally the properties of different semiconductor substrate materials Si, GaAs are discussed.

Absolute Lattice-Parameter Measurement

Absolute lattice parameter methods are useful for determining alloy composition, understanding point defects and dopants in semiconductor substrate materials and for the evaluation of lattice relaxation in heteroepitaxial layers. This paper reviews the techniques available. The assumptions and uncertainties of each technique are discussed.

Observations on Polishing and Ultraprecision Machining of Semiconductor Substrate Materials

Among the polishing techniques used for semi-conductor materials that are hard and brittle (Si), chemical-mechanical polishing (CMP) has many advantages and a few serious disadvantages too. For materials that are soft and brittle like GaAs, GaP, and InP, which have a very promising future, the CMP technique is now possible without the use of toxic agents. The elimination of the polishing process altogether, or a substantial reduction in polishing time is another strategy that has been successfully established by the use of electroyltic in-process dressing techniques (ELID). At the same time there are applications where profile requirements are not stringent like inexpensive night vision lenses, where partial ductile grinding and simple mechanical polishing are highly economical. Finally a simulated model for ultra precision grinding is presented here.

Microwave characterization of slot line and coplanar strip line on high‐resistivity silicon for a slot antenna feed network

AbstractThis article presents the effective dielectric constant (ϵeff) and attenuation constant (α) of an unshielded slot line and a coplanar strip line on a high‐resistivity (5000–10,000 ω‐cm) silicon wafer. The ϵeff (dc to 40 GHz) and α (dc to 26.5 GHz) in each case are determined from the measured resonant frequencies and insertion loss of a ring resonator. The measurements are carried out at room temperature. No dc bias is applied to the transmission lines. The attenuation for slot line and coplanar stripline on silicon are compared with microstrip line and coplanar waveguide on other semiconductor substrate materials. Lastly, a microstrip‐to‐slot‐line transition and its use in a feed network for linearly tapered slot antennas is demonstrated. © 1994 John Wiley & Sons, Inc.