Diameter Si Substrates Research Articles

GaN epilayers grown on 100 mm diameter Si(111) substrates

We have grown GaN epilayers, with a thickness of 1.3–1.5 μm, on 100 mm diameter Si(111) substrates. The GaN films were grown by using buffer layers consisting of 3C–SiC and 2H–AlN. The buffer layers had flat surfaces without showing any grain microstructure. The GaN films were also flat and smooth without noticeable micro-cracks but had slip lines. X-ray diffraction and electron diffraction analyses showed that each of the buffer layers and the GaN film were single-crystals. The room temperature PL showed that the FWHM was as low as 35.5 meV, the narrowest for all reported GaN/Si films grown by blanket MOCVD. Voids on the top of a Si substrate were generated during the conversion of the Si surface to 3C–SiC. The voids may facilitate the Si top surface to act as a compliant layer to alleviate the film stresses resulting from mismatches in lattice parameters and thermal expansion coefficients between the films and substrate. This may be the mechanism that prevented films from cracking.

Comparison of 3C-SiC Films Grown By CVD on Si(111) and Si(211) Substrates

ABSTRACTIn this study, the near-surface region of air-exposed thin 3C-SiC films grown on 50-mm (2-in.) diameter Si(111) and Si(211) substrates have been investigated. Carbonization to create the film in a radio-frequency (RF) induction-heated horizontal atmospheric-pressure chemicalvapor- deposition reactor utilized a propane-hydrogen mix (3% C3H8 in ultra-high purity hydrogen) with a hydrogen carrier. Elemental and chemical-state identification of the thin-films are presented. Several structure sensitive techniques including X-ray diffractaion (XRD) in ω-2θ as well as scanning electron microscopy (SEM) to examine crystal structure, surface morphology and film thickness are included.

An experimental study of high pressure synthesis of diamond films using a microwave cavity plasma reactor

Diamond film deposition on Si “benchmark” substrates is experimentally investigated at high pressures using a microwave plasma disk reactor and CH4/H2 gas mixtures. In this microwave plasma reactor the plasma is formed inside a 12.7 cm diameter disk-like discharge region located at one end of an internally tuned cylindrical cavity applicator. A water cooling stage is employed to control substrate temperature. The input variables of the experimental evaluation are (1) methane concentration, expressed as c = %CH4H2 from 1∼8%, (2) total flow rate, ft, 200∼1400 sccm, (3) substrate temperature TS which varies from 700∼1125°C, (4) deposition time, t, 5 ∼ 100 h, (5) pressure, p, 80 ∼ 140 Torr, (6) incident power, Pinc, 2 ∼ 4.5 kW. The output films deposited on 2 in. diameter substrates were characterized by (1) growth rate in μm/h and mg/h, (2) film morphology, and (3) Raman spectra. In particular film growth rate versus CH4H2, flow rate, TS and t were performed on films deposited uniformly (<15%) over 2 in. diameter Si substrates. 5 h experiments indicated that the average film growth rate (over 2 in. diameter) varied from a few μm/h with c = 1% to 4.3 μm/h at c = 3% and then decreased for high c ratios. Average growth rate also varied with flow rate with a maximum of over 5 μm/h (∼ 35 mg/h). Growth rate increases as deposition time increases and reaches a maximum growth rate of 6.3 μm/h (∼44 mg/h) at t = 100 h. The film growth reaches a maximum around TS = 1100°C for both 2 and 3% chemistries.

Large Area Supersonic Jet Epitaxy of AlN, GaN, and SiC on Silicon

ABSTRACTAlN, GaN, and SiC thin films were grown on 100 mm diameter Si(111) and Si(100) substrates using Supersonic Jet Epitaxy (SJE). Precursor gases were seeded in lighter mass carrier gases and free jets were formed using novel slit-jet apertures. The jet design, combined with substrate rotation, allowed for a uniform flux distribution over a large area of a 100 mm wafer at growth pressures of 1–20 mTorr. Triethylaluminum, triethylgailium, and ammonia were used for nitride growth, while disilane, acetylene, and methylsilane were used for SiC growth. The films were characterized by in situ optical reflectivity, x-ray diffraction (XRD), atomic force microscopy (AFM), and spectroscopic ellipsometry (SE).

Various Properties of Sputtered TaxAl1-x Films

AbstractFilms of TaxxAl1-x have been prepared by diode sputtering from a target consisting of an Al mask placed on the face of a Ta target. The Ta target was 8″ in diameter while the Al mask was 0.125″ thick and machined with a grid-like shape. Films were deposited for a range of pressure, at a power of 300 watts, onto oxidized 100 mm diameter Si substrates that were placed on a planetary table beneath the target. The Al/Ta area ratio of the composite target was determined on the basis of the relative sputtering rates for these metals with the intent of producing a film composition with x = 0.5. The film composition was found to vary with argon pressure, going from 24 at.% Al at 4 mtorr to 72 at.% Al at 30 mtorr. This finding was quite unexpected. This result made it possible to deposit a wide range of film compositions from one composite target. The electrical resistivity has a broad maximum of,≈ 240 micro-ohm/cm between x=0.3 and 0.6. These results compliment and extend the earlier observations by Steidel \1] The as-deposited stress of the films varied from -400 to +150 MPa as x was decreased from 0.76 to 0.28. The temperature dependence of the film stress is hysteretic on the first cycle to 475 C. After the first cycle the films are driven more into tension by as much as 500 Mpa. The oxidation characteristics of one composition Ta0.66Al0.34 were characterized in some detail using a combination of electrical resistance, AES and XPS measurements. The results show that such films oxidize at temperatures in the 300 to 600C range via a diffusion-controlled process with an activation energy of 0.98 eV. Such films are substantially more oxidation-resistant than either ccα-or β-tantalum.

Ferroelectric PbZrxTi1-xO3 Thin Films Grown by Organometallic Chemical Vapor Deposition

AbstractFor the successful integration of ferroelectric thin films in IC technology, there is a need for a deposition technique capable of growing homogeneous layers at high growth rates over large-area structured substrates. Organometallic chemical vapor deposition (OMCVD) is a promising technique for meeting these demands.Ferroelectric layers of PbZrxTi1-xO3 (PZT) were grown by OMCVD on Pt-coated 10 cm diameter Si-substrates using the precursors tetra-ethyl-lead, tetra-iso-propoxy-titanium and tetra-tertiary-butoxy-zirconium at 700 °C without any post anneal. At this temperature the layers are single phase and highly (h00) and/or (00l) oriented. The layers show good ferroelectric switching properties with high remanent polarizations, but also with high coercive field strengths. Fatigue measurements are presented for these OMCVD grown PZT layers. The layers have a switching lifetime exceeding 1011 cycles at a switching amplitude of 5 V.

Epitaxial Growth of GaAs on 4-Inch Diameter Silicon Substrates by OMCVD.

ABSTRACTGaAs epitaxial layers grown on Si substrates up to 4 inches in diameter by OMCVD are characterized with respect to the materials parameters important for their application for device and circuit manufacturing. The layers are characterized using commercial flatness and surface quality measurement instrumentation, x-ray diffraction, Schottky diode characteristics, and photoluminescence. The 4-inch diameter GaAs epilayers are a singleoriented phase and are of comparable quality to GaAs epilayers grown on smaller diameter Si substrates.