Selective Area Deposition Research Articles

Formation of CdTe columnar structures prompted by In- and Ga-rich nanodots

The vapor-phase epitaxy (VPE) deposition of CdTe on III–V heterosubstrates was performed in order to investigate the formation of micro-pixels usable in X-ray and thermo-photovoltaic converters. InSb and (Ga)InSb layers grown by molecular beam epitaxy on semi-insulating GaAs (1 0 0) wafers were employed as substrates. In these layers, the presence of Ga- and In-rich dots (200–500 nm in diameter) was detected using AFM and SEM-EDAX techniques. We found that these dots, which are in liquid phase at the VPE growth temperature (450 °C), act as nucleation points during the VPE process and prompt the selective area deposition of CdTe leading to the formation of columnar structures. Two important trends related to the growth morphology were established. First, the group V element does not affect the growth of CdTe columnar structures, i.e. the formation of these structures is independent of As or Sb. Second, the In-rich dots prompt the formation of CdTe columnar structures than the Ga-rich dots better.

Spatially selective electrochemical deposition of composite films of metal and luminescent Si nanoparticles

We report on a procedure for selective deposition of Si nanoparticles using an electrochemical process. A conducting substrate is immersed in alcohol in which the particles are suspended. Biasing the substrate positively relative to a platinum electrode draws the Si particles to the substrate. Thin particle coatings on metal, foil, or silicon substrates are demonstrated. Fluorescent spectroscopy shows that the deposited particles retain the high luminescence efficiency and spectral distribution characteristic of the dispersed state. The process is used to deposit composite thin films of metal and Si nanoparticles. Dielectric masking allowed selective area deposition. These processes have implications for flat panel or flexible particle-based displays.

Light-induced chemical vapour deposition painting with titanium dioxide

Light-induced chemical vapour deposits of titanium dioxide are obtained from titanium tetra-isopropoxide (TTIP) in an oxygen and nitrogen atmosphere with a long pulse (250 ns) 308 nm XeCl excimer laser using a mask projection set-up. The demonstrated advantages of this technique are: (i) selective area deposition, (ii) precise control of the deposited thickness and (iii) low temperature deposition, enabling to use a wide range of substrates. A revolving mask system enables, in a single reactor load, to deposit shapes of controlled heights, which overlap to build up a complex pattern. Interferential multi-coloured deposits are achieved, and the process limitations (available colours and resolution) are discussed.

Chemical vapor deposition of Si on chlorosilane-treated SiO2 surfaces. II. Selective deposition in the regions defined by electron-beam irradiation

This article reports a selective-area deposition process using chlorosilane-treated ultrathin SiO2 masks on which the patterns are directly defined by irradiation of a focused electron beam (EB). Three different chlorosilane gases (SiH2Cl2, SiHCl3, and SiCl4) were first adsorbed on the SiO2 surfaces, and the regions with reactive sites were defined by taking advantage of electron-stimulated desorption (ESD) of the surface adsorbates. For the SiHCl3- and SiH2Cl2-treated surfaces, the nucleation density was remarkably high in the EB-irradiated regions. Such nucleation enhancement was less significant for the SiCl4-treated surface. For the purpose of direct patterning and selective growth, we conclude that SiHCl3 is the optimum treatment gas because it effectively suppresses Si nucleation outside of the EB-irradiated patterns. The overall ESD sensitivity of the SiHCl3-adsorbed mask was 50 mC/cm2, and a significant nucleation enhancement was observed by irradiation of 7 mC/cm2. We also report an extension of this selective-area processing to window opening through the ultrathin SiO2 mask layer. The factors limiting the minimum feature size of the grown Si structures and the opened windows are discussed.

Fabrication of in situ Patterned Iron Oxide Films using Micro Contact Printing and Selective Deposition

In situ patterning of iron oxide thin layers were fabricated via microcontact printing (μCP) and selective area deposition. μCP is used to pattern two different surface moieties of self-assembled organic monolayers (SAMs) on Au/Cr/Si substrates. An elastomeric stamp is used to transfer hydrophobic (hexadecanethiol (HDT)) SAMs that are to sustain deposition of iron oxide precipitates. Hydrophilic (dithiothreitol, DTT) SAMs were used to induce crystalline iron oxide films. 0.05 M of iron nitrate (Fe(NO3)3·9H2O) aqueous solutions containing urea under nitric acid (pH ≤ 2) were used. Selective depositions were realized through precipitation of crystalline iron oxides at ambient temperature (80°C) onto the mixed SAM surfaces.

Selective Area Chemical Vapor Deposition of Si1 − xGex Thin Film Alloys by the Alternating Cyclic Method: A Thermodynamic Analysis. I. The System Si‐Ge‐Cl‐H

To investigate selective area chemical vapor deposition of thin films by the alternating cyclic (A.C.) process, a thermodynamic analysis has been performed over extensive temperature, pressure, input gas ratio, and deposited solid composition ranges. In the A.C. approach thin film deposition via the hydrogen reduction of and is followed cyclically by etching of spurious nuclei from mask regions via an embedded disproportionation reaction. The embedded disproportionation reaction between , , and the nuclei is made dominant when the hydrogen flow is interrupted cyclically. The thermodynamic calculations have been carried out via the computer program, SOLGASMIX, which is based on the minimization of the system's Gibbs free energy, and also using a first principles approach as an integrity check. These calculations have indicated that selective area deposition of thin films by the A.C. method is feasible. The analysis has also defined the parameter space in which to conduct the selective area deposition using the A.C. process. © 2000 The Electrochemical Society. All rights reserved.

Selective Area Chemical Vapor Deposition of Si1 − xGex Thin Film Alloys by the Alternating Cyclic Method: A Thermodynamic Analysis. II. The System Si‐Ge‐Cl‐H‐Ar

Results of the thermodynamic analyses of the system Si‐Ge‐Cl‐H‐Ar useful for depositing thin film alloys are presented. It is demonstrated that the use of argon as an inert carrier gas should lower the temperature of deposition of the alloy, increase the efficiency of deposition at a given temperature, and lower the temperature for onset of deposition composition plateaus. In addition, the use of an inert carrier gas such as argon should minimize back diffusion and flow rate perturbations during alternating cyclic (A.C.) selective area deposition of alloys. © 2000 The Electrochemical Society. All rights reserved.

Resistless pattern definition and Si selective-area deposition using an ultrathin SiO2 mask layer treated by SiHCl3

We report a selective-area deposition process using an ultrathin SiO2 mask on which SiHCl3 is chemisorbed. The key step of this process is resistless pattern definition utilizing electron-stimulated desorption (ESD) of Cl and Cl-containing groups from the mask surface. Compared to the previous report utilizing ESD of O from SiO2, sensitivity to the incident electron beam has been improved by a factor exceeding 104. Selective-area deposition of Si on the Cl-desorbed regions is demonstrated using an Si2H6 source gas.

Selective Area Chemical Vapor Deposition of Si1 − xGex Thin Film Alloys by the Alternating Cyclic Method: Experimental Data: I. Deposition Parameters

Alternating cyclic (AC), selective area deposition of thin and thick films, 0.1 to 3.5 μm, via the reaction of , , and using Ar as a carrier gas, was carried out in a hot‐wall, low pressure epitaxial reactor, using oxide masked silicon wafers. The AC process is based on the existence of an embedded disproportionation reaction within the overall deposition chemistry, which provides an effective mechanism for preventing the formation of nuclei in the areas where deposition is not desired. This disproportionation reaction is made dominant cyclically, by pulsing the hydrogen on and off periodically, in order to eliminate incipient nucleation. Experiments were carried out over a large portion of the available parameter space, as determined by extensive thermodynamic analyses, using a reference non‐AC process as a control, and comparing the results with different AC frequencies. The mole fractions used were 0.0012, 0.0025. 0.005, 0.01, 0.02, 0.03, and 0.05, the temperature was varied from 700 to 950°C, and the ratio varied from 1 to 9. The range of alloy composition deposited was from 0 to 30 mol %, Ge. Total gas flow rate was varied from 2 standard liters per min (slpm) to 20 slpm to modulate gas hydrodynamics. To varying degrees, various experimental conditions influenced the tendency for formation of spurious nuclei on the oxide surface. However, under all conditions, the AC technique was capable of preventing the formation of spurious nuclei on the oxide, guaranteeing essentially 100% selectivity control, for both nonimplanted wafers and ion‐implanted wafers. © 2000 The Electrochemical Society. All rights reserved.

Selective Area Chemical Vapor Deposition of Si1 − xGex Thin Film Alloys by the Alternating Cyclic Method: Experimental Data: II. Morphology and Composition as a Function of Deposition Parameters

Selective area deposition of thin films, with x as large as 0.63, on oxide masked silicon wafers, was carried out in a hotwall, low pressure chemical vapor deposition system, using an alternating cyclic method described in the companion paper. Part I. In order to remove any previously deposited on the walls of the system, an HCl clean of the system was performed prior to every deposition, thereby enabling good control over the composition of the deposited films. The effect of various processing conditions, such as deposition temperature, input gas phase composition, and deposition time on the resulting film composition, morphology, and crystalline perfection were studied. For a particular film composition, there exists a morphological thickness, , at a particular deposition temperature, at which the films make a transition from smooth to rough morphology. The rough films are in a relaxed state and exhibit three‐dimensional growth. Below , the films exhibit a smooth morphology. With lowering of deposition temperature while keeping all other conditions constant, the films become richer in Ge. Thermodynamic calculations were found to be in agreement with this observation. Energy dispersive X‐ray spectroscopy using an environmemal scanning electron microscope technique was used for composition determination purpose, and transmission electron microscopy was performed to study the crystalline quality of the selectively deposited films. © 2000 The Electrochemical Society. All rights reserved.

Controlled bond formation between chemical vapor deposition Si and ultrathin SiO2 layers

This article reports that chemically active sites on SiO2 surfaces can be either passivated or introduced intentionally by treating them in a proper chlorosilane gas, SiHnCl4−n (n=0,1,2). Our experiments of Si chemical vapor deposition on SiO2-covered Si have shown that Si deposition is suppressed on SiCl4- and SiHCl3-treated samples, while an SiH2Cl2 treatment drastically enhances Si nucleation. Thus, the chlorosilane treatment is a unique way for us to control the interface bonds between the SiO2 surface and the Si deposits on it. We also demonstrate resistless selective-area deposition using a SiHCl3-treated ultrathin SiO2 mask layer. Patterns are defined on the mask surface by direct electron-beam irradiation which induces Cl desorption thereby forming chemically reactive surface defects.

Synchrotron-radiation-induced, selective-area deposition of gold on polyimide from solution

Room-temperature photoinduced, selective-area deposition of gold films on polyimide from gold salt solution using synchrotron radiation x rays is described. A film growth rate as high as 40 nm/min is obtained. For thickness <50 nm, the films consist of nanograins with a grain size of about 200 nm. For thicker films, gold deposit forms a ramified morphology on top of the nanograin film. The change in morphology is discussed in terms of the change in the yield of the photoelectrons generated by x rays as a function of growth.

The Selective Area Deposition of Diamond Films

By selectively seeding, polycrystalline diamond films have been patterned on mirror-polished Si substrate using hot-filament chemical vapor deposition. Results show high selectivity and high quality in patterned diamond films deposited at 0.05% CH4/H2 concentration and at the growth rate of 2.6 µm/h. The selective area deposition (SAD) method is easy to be applied to a large and a different substrate.

MOMBE: superior epitaxial growth for InP-based monolithically integrated photonic circuits

Basic developmental steps are outlined for the application of metal organic molecular beam epitaxy as an epitaxial fabrication process for InP-based integrated photonic circuits. Besides high-quality performance of the individual devices, implementation of Fe-doped semi-insulating layers and selective area deposition of GaInAsP for the whole composition range are of concern. Low-loss semi-insulating waveguides were fabricated for optically interconnecting and electrically isolating different devices at deposition conditions that have proven adequate for selective area growth and, simultaneously, for effective suppression of Fe-movement. Fabricated laser/waveguide butt-joints, a basic building block for any integrated photonic circuit, demonstrate the potential of metal organic molecular beam epitaxy to form practically ideal lateral growth interfaces without compromising on device performance.

Selective area deposited blue GaN–InGaN multiple-quantum well light emitting diodes over silicon substrates

We report on fabrication and characterization of blue GaN–InGaN multi-quantum well (MQW) light-emitting diodes (LEDs) over (111) silicon substrates. Device epilayers were fabricated using unique combination of molecular beam epitaxy and low-pressure metalorganic chemical vapor deposition growth procedure in selective areas defined by openings in a SiO2 mask over the substrates. This selective area deposition procedure in principle can produce multicolor devices using a very simple fabrication procedure. The LEDs had a peak emission wavelength of 465 nm with a full width at half maximum of 40 nm. We also present the spectral emission data with the diodes operating up to 250 °C. The peak emission wavelengths are measured as a function of both dc and pulse bias current and plate temperature to estimate the thermal impedance.

Selective area metalorganic molecular-beam epitaxy of GaN and the growth of luminescent microcolumns on Si/SiO2

We demonstrate the selective area growth of gallium nitride on patterned Si(111)/GaN/SiO2 wafers by metalorganic molecular beam epitaxy using triethyl gallium as a Ga source. We show that such selective area deposition may be used to grow isolated microcolumns of GaN with lateral dimensions of tens of nanometers on Si/SiO2 wafers. Via high resolution cathodoluminescence imaging we show that such microcolumn structures are highly luminescent inspite of a large surface to volume ratio, indicating that nonradiative recombination at free surfaces is not a significant issue in this system.

Selective Area Laser Induced Deposition of Metal Boride Thin Films

ABSTRACTWe have developed a novel technique for the selective area deposition of rare earth hexaborides: laser-induced solution deposition (LISD). This technique is both simple and efficient and combines many advantages of both chemical vapor deposition and electrolytic deposition. The results of LISD deposition show that the polycrystalline thin films of rare earth hexaborides and sub-borides such as MB6, MB4, and MB2 (M = Gd, La) are formed through the light initiated chemical reaction of nido-decaborane (B10H14) and rare earth chloride in solution. These films grow with a strong texture growth axis and morphology that is dependent both on the selection of solvents and laser wavelengths and power used in LISD.

The adsorption of nickelocene: Part 2: decomposition and selective area deposition

We have studied the photofragmentation of nickelocene by photoemission and laser-induced photodesorption. The ultraviolet photolytic decomposition leads to relatively clean metal-to-ligand cleavage and photoinduced desorption of the cyclopentadienyl ligand fragments. This photolytic decomposition process is mechanistically different from the pyrolytic decomposition process, which results in the formation of C 3H 3 and C 2H 2 that desorbs both as free ligands and bound to nickel. The laser- and electron-induced fragmentation of nickelocene leads to the deposition of nickel containing features with considerable spatial resolution. Lines as fine as 10 nm across have been fabricated with electron beams. The photolytic decomposition of nickelocene can be used to fabricate micron-scale ferromagnetic nickel features in a wide variety of shapes and sizes.

Selective area laser-induced deposition of rare earth hexaborides from solution

We have developed a novel technique for the selective area deposition of rare earth hexaborides: laser-induced solution deposition (LISD). This technique is both simple and efficient and combines many advantages of both chemical vapor deposition and electrolyses deposition. We show that the deposition of polycrystalline thin films of rare earth hexaborides and sub-borides such as GdB 6, GdB 4, and GdB 2 is possible through the light initiated chemical reaction of nido-decaborane (B 10H 14) and gadolinium chloride in solution. These films grow with a strong texture axis and a morphology that is dependent both on the choice of solvents and wavelengths used in LISD.

MOMBE grown GaInAsP ( λg=1.05/1.15 μm) waveguide for laser integrated photonic ICs

The fabrication of advanced undoped and semi-insulating optical waveguides to be implemented in integrated photonic ICs on InP is demonstrated on the basis of the metal organic molecular beam epitaxy growth technique. The optimised deposition of waveguide layer structures of high crystalline and optical quality resulted in optical losses as low as 0.7/0.9 dB/cm (TE/TM polarisation) at λ=1.55 μm. Implementation of a thin InP marker between the slab and the rib served to control rib formation during dry etching. Doping with iron using an elemental source was applied for semi-insulating behaviour of the waveguide devices. Selective area deposition of the waveguide layer structure at a growth temperature of 485°C around a masked laser layer stack to enable laser/waveguide butt coupling has been developed to meet the requirements imposed by photonic ICs.