Semiconductor Materials Processing Research Articles

GaAs ablation with ultrashort laser pulses in ambient air and water environments

Water-assisted ultrashort laser pulse processing of semiconductor materials is a promising technique to diminish heat accumulation and improve process quality. In this study, we investigate femtosecond laser ablation of deep trenches in GaAs, an important optoelectronic material, using water and ambient air environments at different laser processing regimes. We perform a comprehensive analysis of ablated trenches, including surface morphological analysis, atomic-resolution transmission electron microscopy imaging, elemental mapping, photoluminescence, and Raman spectroscopy. The findings demonstrate that GaAs ablation efficiency is enhanced in a water environment while heat-accumulation-related damage is reduced. Raman spectroscopy reveals a decrease in the broad feature associated with amorphous GaAs surface layers during water-assisted laser processing, suggesting that a higher material quality in deep trenches can be achieved using a water environment.

Correlative microscopy and monitoring of segregation processes in optoelectronic semiconductor materials and devices

The present work comprises a practical tutorial on the topic of correlative microscopy and its application to optoelectronic semiconductor materials and devices. For the assessment of microscopic structure–property relationships, correlative electron microscopy, combined also with scanning-probe and light microscopy, exhibits a collection of indispensable tools to analyze various material and device properties. This Tutorial describes not only the various microscopy methods but also the specimen preparation in detail. Moreover, it is shown that electron microscopy can serve to monitor phase segregation processes on various length scales in semiconductor nanoparticles and thin films. Algorithms used to extract phase information from high-resolution transmission electron micrographs are explained.

ІНДУКОВАНА ПЕРЕБУДОВА КРИСТАЛІЧНОЇ СТРУКТУРИ ТА АКУСТИЧНИЙ ВІДГУК В НАПІВПРОВІДНИКАХ НА ОСНОВІ ТЕЛУРИДУ КАДМІЮ ДЛЯ ЗАСТОСУВАННЯ В ОПТОЕЛЕКТРОНІЦІ ТА АКТУАЛЬНИХ НАПРЯМАХ НАПІВПРОВІДНИКОВОЇ ТЕХНІКИ (ОГЛЯД)

The reliability and competitiveness of modern semiconductor electronic technology are determined by the level of existing technologies. These requirements set the task of increasing the efficiency of methods for obtaining and post-growth processing of semiconductor materials and structures, research and control of their properties at all stages of manufacturing and operation of products. The question of the quality and maximum reliability of a wide range of various structures and devices for multipurpose purposes, in particular, opto, photoelectronics, sensors, etc., and sometimes the need to use it at the most achievable physical and technical parameters, or in extreme conditions, is becoming increasingly important. The solution to these problems is based on a comprehensive study of the processes of defect formation, failure and destruction of semiconductor structures and devices based on them. In modern conditions, for this purpose, in particular, the method of acoustic emission (AE) is used, based on the registration, theoretical processing of acoustic pulses that arise as a result of the formation, local changes and destruction of the structure of the material under external load. The most widespread practical application in various branches of semiconductor electronics have found materials based on CdTe, given, in particular, basic data on methods and sources of acoustic response induced by external influences. This method makes it possible to obtain information about the state of a solid in the process of deformation, in particular, to detect in a non-destructive way the presence or appearance of dislocations and microcracks. The AE process allows you to determine the mechanical stresses and deformations at which there is a transition from elastic to plastic deformation (yield strength) of the crystal and subsequent destruction. AE, which occurs during the deformation of a solid in local areas, in particular, under mechanical loads, ultrasound, laser irradiation, radiation exposure and in other cases, may have a thermomechanical nature and occur as a result of heterogeneous heating, for example, during the flow of electric current through a heterogeneous medium. Mechanical, thermomechanical or thermobaric stresses appear in crystals under appropriate phase transformations, in particular, during melting during laser irradiation. Thus, AE is an effective non-destructive method for identifying the initial stages of degradation and subsequent destruction of semiconductor materials, structures and devices under various external influences. The main purpose of this review is to distribute AE from macro objects (in technical diagnostics and control of industrial and domestic structures) to micro-objects for materials and structures of low-dimensional electronics, to expand the scientifically conscious application of AE in experimental and practical work in various semiconductor materials and structures on the example of CdTe-based semiconductors (wide- and narrow-band).

Characterization of cyclic dust growth in a low-pressure, radio-frequency driven argon-hexamethyldisiloxane plasma

In a dusty plasma, nanometer-sized solid dust particles can be grown by the polymerization of plasma species from a reactive precursor gas. This type of plasma can be found in large-scale astrophysical objects, as well as in semiconductor manufacturing and material processing. In a laboratory environment, the plasma parameters can be carefully controlled and the dynamics of dust growth as well as the interaction between the plasma and the dust can be studied. In this work, we investigate the cyclic growth of dust particles in a low-pressure, radio-frequency driven argon-hexamethyldisiloxane plasma using a multitude of diagnostics in a time-synchronized fashion. The combination of microwave cavity resonance spectroscopy, plasma impedance measurements, laser light scattering, laser light extinction measurements and optical emission spectroscopy offers a broad view on the temporal behavior of the plasma in concert with the plasma-grown dust particles. We have studied the variation of several discharge parameters such as plasma power and hexamethyldisiloxane content. Therefore, this multi-diagnostic approach contributes to the fundamental understanding of the mechanisms behind dust growth in low-pressure plasmas.

Laser processed semiconductors for integrated photonic devices -INVITED

We report results of laser processing of amorphous silicon and silicon-germanium semiconductor materials for the production of integrated photonic platforms. As the materials are deposited and processed at low temperatures, they are flexible, low cost, and suitable for multi-layer integration with other photonic or electronic layers. We demonstrate the formation of waveguides via crystallization of pre-patterned silicon components and functional microstructures through crystallization and compositional tuning of silicon-germanium alloy films. These results open a route for the fabrication of high density, multi-functional integrated optoelectronic chips.

Masking coating formation by the focused ion beams method for plasma chemical treatment

The application of the focused ion beams method makes it possible to obtain modified surfaces serving as a masking layer for subsequent processing of semiconductor materials. The use of plasma chemical etching as a method for profiling modified surfaces makes it possible to obtain cleaner surfaces than for liquid etching. In this paper, experimental studies of a masking coating formation were carried out using a focused ion beams method on a scanning electron microscope, followed by a relief formation by the plasma chemical etching method. The effect of local surface treatment of silicon by the focused ion beams method on the etching rate of the treated regions by the method of plasma chemical etching was examined. Samples with the formed regions were obtained, which demonstrated masking and stimulating properties during plasma chemical etching. The structures height after plasma chemical etching varied from 10 to 266 nm.

Chemical compatibility of fused filament fabrication-based 3-D printed components with solutions commonly used in semiconductor wet processing

3-D printing shows great potential in laboratories for making customized labware and reaction vessels. In addition, affordable fused filament fabrication (FFF)-based 3-D printing has successfully produced high-quality and affordable scientific equipment, focusing on tools without strict chemical compatibility limitations. As the additives and colorants used in 3-D printing filaments are proprietary, their compatibility with common chemicals is unknown, which has prevented their widespread use in laboratory chemical processing. In this study, the compatibility of ten widely available FFF plastics with solvents, acids, bases and solutions used in the wet processing of semiconductor materials is explored. The results provide data on materials unavailable in the literature and the chemical properties of 3-D printable plastics that were, are in line with literature. Overall, many 3-D printable plastics are compatible with concentrated solutions. Polypropylene emerged as a promising 3-D printable material for semiconductor processing due to its tolerance of strongly oxidizing acids, such as nitric and sulfuric acids. In addition, 3-D printed custom tools were demonstrated for a range of wet processing applications. The results show that 3-D printed plastics are potential materials for bespoke chemically resistant labware at less than 10% of the cost of such purchased tools. However, further studies are required to ascertain if such materials are fully compatible with clean room processing.

Thermal decomposition of sol-gel derived Zn0.8Ga0.2O precursor-gel: A kinetic, thermodynamic, and DFT studies

Gallium-doped zinc oxide has been widely accepted as the potential alternative to expensive tin-doped indium oxide (ITO) for transparent conductive layer applications. An extensive study reports the processing of ZnO-based semiconductor materials by utilizing a sol-gel method, however, no study has been reported to investigate both the kinetic and thermodynamic aspects of the gel decomposition for these materials. Here, we studied the kinetic and thermodynamic parameters of the sol-gel derived Zn0.8Ga0.2O precursor gel decomposition utilizing the thermogravimetric (TG) and differential thermal analysis (DTA). A non-isothermal method was used to calculate the activation energy, pre-exponential factors, reaction mechanism function, and order of reaction. In addition, density functional theory (DFT) was used to calculate the optical band gap and density of states. The results suggested that the gel decomposition followed the Jander: 3D model. The study is important for understanding the components of synthesis ranging from the formation of an activated complex to gel decomposition, while this study can be extended to other semiconductor processing methods.

Defect-induced Stress Imaging in Single and Multi-crystalline Semiconductor Materials

Residual stress is a key feature which has to be taken into account in all steps of fabrication and processing of semiconductor materials and devices. The photo-elastic microscope SIREX (Scanning Infrared Stress Explorer) measures the depolarization of the light of an infrared laser probe caused by stress-induced birefringence in the sample. Subsequently, a map visualizes the in-plane optical anisotropy induced by stress. Hence, the system is applied as non-destructive tool to map stress distributions with high lateral resolution (3µm) and highest possible stress sensitivity (0.1 kPa). The so-called multi-polarization analysis results in maps of the in-plane maximum shear stress magnitude Δσ and the direction of the principal stress components. These maps can reveal the local stress fields of buried defects and their alignment in distinctive crystallographic directions. The fields are usually at least one order of magnitude larger in extension than the related defects themselves. Examples of extended defect structures in different crystalline semiconductor materials are presented in this paper. The emphasis has been put on line-shaped structures such as slip lines and twins which are partly accompanied by either tensile or compressive point-like stress sources. These structures are showing model characteristics for developing formal procedures of data and image processing under industrial conditions.

Laser processing of transparent semiconductor materials

A proposed method for laser processing of transparent semiconductor materials is based on thermal effect of increasing an absorption of light with a wavelength in the range of fundamental absorption-edge spectrum of the material. In this paper, we provide an analytical and experimental investigation of increase of absorption in semiconductor materials caused by laser radiation with wavelength in the range of absorption-edge of the material.

Special issue on electrochemical processing of semiconductor materials

Special issue on electrochemical processing of semiconductor materials

Compact electrically detected magnetic resonance setup

Electrically detected magnetic resonance (EDMR) is a commonly used technique for the study of spin-dependent transport processes in semiconductor materials and electro-optical devices. Here, we present the design and implementation of a compact setup to measure EDMR, which is based on a commercially available benchtop electron paramagnetic resonance (EPR) spectrometer. The electrical detection part uses mostly off-the-shelf electrical components and is thus highly customizable. We present a characterization and calibration procedure for the instrument that allowed us to quantitatively reproduce results obtained on a silicon-based reference sample with a “large-scale” state-of-the-art instrument. This shows that EDMR can be used in novel contexts relevant for semiconductor device fabrication like clean room environments and even glove boxes. As an application example, we present data on a class of environment-sensitive objects new to EDMR, semiconducting organic microcrystals, and discuss similarities and differences to data obtained for thin-film devices of the same molecule.

Introduction to the Special Issue on the APSPT 2013

The Asia–Pacific International Symposium on the Basics and Applications of Plasma Technology (APSPT) has been held in Taiwan or Japan every two to four years since 1997. It is an important annual event in the Asia–Pacific area and has been a great platform for scientists all around the world sharing novel and state-of-the-art research findings and exchanging innovative ideas in the field of plasma science and technology. The $11^{\mathrm{ th}}$ APSPT was held on December 11–14, 2019, at Kanazawa University, Kanazawa, Japan. The $11^{\mathrm{ th}}$ APSPT had a very strong program consisting of 13 sessions with 201 articles contributed by the 210 participants from nine countries. This Special Issue focuses on the following topics, which were also the focus topics in the $11^{\mathrm{ th}}$ APSPT. 1) Plasmas in semiconductor materials processing. 2) Plasmas in biomedical and agricultural applications. 3) Plasmas in nano-materials processing. 4) Plasma coating and surface modifications. 5) Plasmas in aerospace/space applications. 6) Plasmas in energy and environmental applications. 7) Plasmas-in-liquid. 8) Multiphase plasmas. 9) Thermal plasmas. 10) Cold plasmas. 11) Plasma diagnostics and modeling. 12) Advanced and novel plasma technologies and sources. As Guest Editors, we thank all the authors, the reviewers, the editors, and the IEEE staff to publish this Special Issue on time. Particularly, we would like to offer our special thanks to the Editor-in-Chief, Dr. S. Gitomer, and the Senior Editor, Prof. P. Chu, for their guidance and help throughout the review process. We hope this Special Issue will help to exchange our knowledge in plasma science and cultivate potential collaboration in the community. We look forward to see all participants again in the $12^{\mathrm{ th}}$ APSPT at Taiwan University of Science and Technology, Taipei, Taiwan, in December 2021.

Surface characteristics and damage of monocrystalline silicon induced by wire-EDM

Wire-EDM has recently shown itself as an alternative approach for slicing silicon and other semiconductor materials without the presence of significant chipping as normally found in the traditional machining processes. However, the intensive electrical spark between a wire electrode and silicon can cause damage to the cut surface and subsurface in micro and nano-scale aspects. This paper presents the influence of major process parameters on the cut surface characteristics and damage in the wire-EDMing of silicon. An n-type monocrystalline silicon wafer was cut under different spark energy densities, duty cycles and dielectric flushing rates. Poor cut surface quality and high amount of electrode material deposition were obtained when low spark energy density, small duty cycle and low dielectric flushing rate were applied. Moreover, the amorphous and defective crystal structures of silicon were apparent under the low spark energy condition. The interactions between the wire-EDMing parameters and cut surface characteristics drawn in this study could have significances for the further development of EDM technology towards the fine-scale and damage-free processing of semiconductor materials.

Numerical Analysis of Radiative Recombination in Narrow-Gap Semiconductors Using the Green’s Function Formalism

A numerical model based on the Green’s function formalism has been developed and used to investigate the radiative recombination processes in multiple narrow-gap semiconductor materials. Full band structures and adaptive band-dependent tetrahedral meshes were adopted to improve the accuracy of the calculation. As a validation, the spectrum of the absorption coefficient for germanium was examined, giving good agreement with the experimental data. The absorption coefficient and radiative recombination lifetime for HgCdTe were then investigated for different compositions, carrier concentrations, and operating temperatures. The results confirmed the accuracy of the widely used theoretical formula for the radiative recombination lifetime under the condition that the effective mass of holes in the formula must be carefully chosen. Based on all our comparisons and calculations, the Green’s function model is proved to be a reliable tool for predicting the radiative recombination properties of HgCdTe, which could further facilitate the investigation of more complicated processes such as photon-recycling issues.

Intense Pulsed Light Sintering of Electrodeposited CdS Thin Films

In order to manufacture market competitive solar cells, material processing methods with low capital and running costs are required. One method for achieving this goal would be to use atmospheric processing techniques with a high throughput. Here, we report the use of intense pulsed light (IPL) to process cadmium sulfide (CdS) thin films. IPL is an ultra‐fast and facile technique for the heat treatment of materials. Pulses of light from the UV to IR wavelengths are absorbed by the material, leading to localized heating and sintering. IPL has been used to successfully make Ag and Cu electrical contacts for use in electronic circuits, however little work exists on the use of IPL in the processing of semiconductor materials. CdS was selected due to its importance in solar cell manufacturing. This n‐type semiconductor has been used as a “window” material in high efficiency CdTe and Cu In(1−x)GaxSe2‐based solar cells. The effect of energy input and the energy density of the pulse on the films optical, compositional and morphological properties of the films was investigated using UV–Vis spectroscopy, XRD, and SEM. IPL sintering resulted in significant improvement to the CdS crystallinity with processing times <2 mins.

Self-Organizing Processes in Semiconductor Materials Science on the Example of Nanostructuring of por-Si

Self-organization processes in semiconductor materials on the example of nanostructuring of por-Si at long anodic etching of p-type Si in the electrolyte with internal source of the current are shown. In conditions of a “soft” etching of the Si point defects are formed and in the subsequently occurs their spatial-temporal ordering. This leads to the ordering pores and the nanostructuring of por-Si. Self-organization mechanism of Si nanocrystallites islets is described by the effects of the elastically-deformative, defectively-deformative and capillary-fluctuation forces.

Transferable pair potentials for CdS and ZnS crystals

A set of interatomic pair potentials is developed for CdS and ZnS crystals. We show that a simple energy function, which has been used to describe the properties of CdSe [E. Rabani, J. Chem. Phys. 116, 258 (2002)], can be parametrized to accurately describe the lattice and elastic constants, and phonon dispersion relations of bulk CdS and ZnS in the wurtzite and rocksalt crystal structures. The predicted coexistence pressure of the wurtzite and rocksalt structures as well as the equation of state are in good agreement with experimental observations. These new pair potentials enable the study of a wide range of processes in bulk and nanocrystalline II-VI semiconductor materials.

Status and Trends of Fixed Abrasive Polishing on Semiconductor

The necessity of fixed abrasive CMP in polishing semiconductor materials processing was analyzed. Compared the shortcomings of traditional free abrasive polishing with the advantages of fixed abrasive polishing, the applications of fixed abrasive polishing technology in semiconductor processing were described. A variety of fixed abrasive polishing pad production methods were introduced. The development trend of fixed abrasive polishing was prospected.

Investigation of Nanoscratch Processes in Semiconductor Materials for Application to Maskless Patterning

Features of nanoscratching processes with a diamond 90 degrees cube corner tip in semiconductor materials have been studied with different tip orientations and scratch procedures: constant and linearly increasing normal load during scratching, multi-scratching and the direct analysis of the generated scratch by re-scanning the scratch with a strongly reduced normal load. These scratch functions allowed a detailed investigation of the materials response due to the mechanical deformation process. Elastic material recovery, plastic deformation and material removal contribute to the generation of scratch groove profiles. For low applied normal loads mainly elastic deformation occurs whereas for larger normal loads stick-slip processes with periodic hillocks at the groove bottom and irregular pile-up along the scratch rim dominate the process. From the analysis of the scratch groove profile in Si(100), GaAs(100) and thin InSb films, quantitative values for the elastic deformation, the friction coefficient, stick-slip pattern, material removal and scratch depth as a function of the applied normal load are obtained. With multi-scratching a definite removal pattern with a reproducible scratch depth is obtained. These results can be used to optimise the scratch technique for application to maskless patterning.