Aluminum gallium nitride (AlGaN) material is used in GaN-based electronic and optoelectonic devices. The Al and Ga ratio can be adjusted to produce material with different compositions and electronic properties. In this set of experiments epitaxial films of (AlxGa1−x)0.5N0.5 with x ranging from 0 to 1 were investigated. Primary composition was determined with Rutherford backscattering spectrometry (RBS). From secondary ion mass spectrometry (SIMS) profiles a correlation of secondary ion counts was made to RBS determinations of primary composition. The SIMS data was also used to determine sputter rate and the relative sensitivity factor (RSF) of O, Mg and Si in (AlxGa1−x)0.5N0.5 material. The correlation of SIMS data with RBS and knowledge of the sputter rate and RSF dependence on composition are essential for the characterization of (AlxGa1−x)0.5N0.5 films

In order to investigate the luminescence properties of Er3+in GaN and the effect of oxygen (O) on Er3+ -related emission in GaN:Er, erbium (Er) ions were implanted into single-crystal h-GaN grown on a c-axis sapphire substrate at an energy of 2MeV. Oxygen ions were subsequently coiniplanted into GaN with Er ions. The influence of oxygen on Er-related emission in GaN with a large yellow band was studied by comparing photoluminescence (PL) measurements of GaN:Er and GaN:ErO. It was found that the optimum annealing temperature to obtain maximum PL intensity was 1200°C and that the E3+a-related PL intensities from GaN:ErO samples were negligibly enhanced in comparison with the GaN:Er samples. The temperature dependence of PL intensity in GaN:ErO showed no appreciable difference from that of GaN:Er. But good correlation between Er-related and a large yellow band emission was observed in GaN. This indicates that codoped oxygen ions influence Er-related and yellow band emission in GaN

Deuterium diffusion has been investigated in boron doped diamond as a function of the diffusion temperature and the boron concentration. The results show that, up to 480°C, hydrogen diffusion is limited by the boron concentration with a diffusion activation energy of 0.35 eV for [B] = 5×1019 cm−3. This first experimental evidence of deuterium-boron interactions in diamond is interpreted as the result of hydrogen ionization and diffusion of fairly mobile protons which form pairs with negatively charged boron acceptors

Commercial n-type 4H-SiC wafers were implanted with doses of MeV alpha particles, high enough to cause majority carrier modification. Analysis of infrared reflectivity spectra shows that the implanted crystals can be divided into three layers: a surface layer of about 30 nm followed by a compensation layer where the energy transfer of the incident particles is low and an overdoping layer in the region of maximum defect production, i.e. near the theoretical mean range of ions Rp

We investigate theoretically the energetics of nitrogen impurities in β-SiC, their geometrical relaxation, and electronic properties. We find that density-functional theory is able to calculate donor-ionization energies accurately once large enough simulation cells are used. For neutral interstitial defects, we find that configurations where N is three-fold coordinated have very low formation energies and high binding energies with the involved native defects. At the same time, such configurations introduce deep levels into the gap which may result in a non-activation of the donor

Thermal admittance spectroscopy has been used to study the thermal activation energy of nitrogen at the hexagonal and cubic sites in 4H-SiC as function of net doping concentration. The net doping concentration- of te samples, which was determined from 1/C2 vs. V plots, ranges from 1.5 × 1014 cm−3 to 4 × 1018 cm−3. The thermal activation energy of nitrogen was determined to be Ee O.054 eV and Ee O.101 eV for nitrogen at hexagonal and cubic sites respectively for ND - NA ≤ 1016 cm−3. As the free carrier concentration increases from 1016 cm−3 to 1.0 × 1018 cm3, the thermal activation energy of nitrogen at the hexagonal site decreases from 54 meV to 24 meV. At ND - NA ≥1.0 × 10 cm−3 hopping conduction is the only conduction mechanism and has an activation energy of 3-9 meV.

P-type conductivity is normally produced in silicon carbide by doping with Al or B. The aluminum atom substitutes for silicon in the SiC lattice. Several studies have shown that nitrogen, which substitutes for carbon atoms and produces n-type conductivity in SiC, sits at the two inequivalent lattice sites in 4H-SiC, and two N activation energies of 53 meV (h) and 100 meV (k) have been reported.

Hall effect measurements and infrared absorption studies of SiC doped with Al showed only one Al activation energy, however, and the published Al activation energy in SiC (3C, 4H, and 6H) ranges from 191 meV to 280 meV. This has lead to the general conclusion that the activation energy of Al acceptors in SiC does not depend on the polytype or on the lattice site occupied.

Thermal Admittance Spectroscopy (TAS) has been used to determine the activation energy of Al in 4H-SiC specimens where NA-ND ranged from 7.2 × 1015 cm2to 5.6 × 1018 cm−2. By analogy to B in 6H-SiC, we propose two levels for Al in 4H-SiC at Ev + 0.212 eV and Ev + 0.266 eV.

The present paper reviews current understanding on enhanced reactions of process-induced defects in GaAs under electronic excitation. Device processing to be employed for point defect generation is Be ion implantation and Ar plasma etching. It is shown that reduction of electronic active centers is clearly enhanced by annealing under forward bias application and by annealing under reverse bias application at temperature as low as 200°C. The enhancement mechanisms are discussed in terms of recombination-enhanced defect reaction and structural instability induced by charge state effect.

The effects of Inductively Coupled Plasma (ICP) and Electron Cyclotron Resonance (ECR) H2 plasmas on GaAs metal semiconductor field effect transistors (MESFETs), high electron mobility transistors (HEMTs) and heterojunction bipolar transistors (HBTs) have been measured as a function of ion flux, ion energy and process pressure. The chemical effects of hydrogenation have been compared to direct physical bombardment by Ar plasmas under the same conditions. Si dopant passivation in MESFETs and HEMTs and C base-dopant passivation in HBTs produces much larger changes in sheet resistance, breakdown voltage and device gain or transconductance than Ar ion bombardment and suggests that H2-containing plasma chemistries (CH4/H2 for semiconductor etching, SiH4 for dielectric deposition, CHF3 for dielectric etching) should be avoided, or at least the exposure of the surface minimized. In some cases the device degradation is less for higher source power conditions, due to the suppression of cathode dc self-bias and hence ion energy.

Zn diffusion into AlxGa1−xAs from polymer spin-on films has been investigated. An increase in Zn diffusivity has been observed with increase in the content of Al in A1GaAs compounds. The effect has been related to more coefficient of self-diffusion for Al than for Ga. The availability of the near-surface layer enriched with Al in epitaxial AlGaAs wafers has been found to result in poor reproducible diffusion characteristics.

Float zone silicon single crystalline wafers are submitted to He ion implantations at various energy levels and fluences in the ranges 40 to 120 keV and 1016 to 1017 cm−2, respectively. Cavities are formed after annealing at 900°C for 1 h in argon. Al-Si gettering results from the deposition of a backside 1 µm thick Al wafer and annealing at 900'C for 4 h in argon. The wafers are voluntarily contaminated by 1014 to 1017 cm−3nickel atoms and diffusion length of minority carriers is determined by SPV technique and measured before and after gettering.

It is found that gettering by cavities works fairly well provided the fluence is 1017 cm−2. The gettering efficiency decreases in heavily contaminated samples suggesting that the capture of impurities by the cavities is limited by the saturation of their internal surface. Al-Si alloying appears more efficient at higher contamination levels. This is most likely due to the high solubility of metal atoms in the liquid Al-Si alloy formed during the annealing.

The formation and dissolution of Ni and Cu silicides were investigated to determine effective intrinsic gettering (IG) for low temperature processes. Ni formed silicides easily at low contamination levels and these silicides formed the nuclei for OSF during subsequent annealing at temperatures above 1000°C. Ni silicides were dissolved and gettered during low temperature deposition of a poly-back seal (PBS) at 620°C, whereas Cu silicides, once formed, easily induced secondary defects on further annealing even at low temperatures and could not be dissolved or gettered by PBS. The sizes and densities of oxygen precipitates necessary to intrinsically getter Ni and Cu contamination levels of 1012atoms/cm2 were also investigated with respect to generation lifetime. Cu contamination at this level did not degrade generation lifetime or gate oxide integrity (GOI) yield. For Ni contaminated samples, a strong dependence of generation lifetime on both oxygen precipitate density and size was observed. Effective IG for Ni during a low temperature process was demonstrated using a 2-step low temperature process simulation.

The gettering of transition metals in silicon presents new challenges since older schemes such as internal gettering cease to be effective with newer technologies. The oxygen concentration in active regions is also a matter of concern when denuding cycles are not employed. Implantation of a deep layer of boron is a promising technique. The effects of boron implants at 1.7 MeV in the dose range 1014 – 1015 at./cm2 were studied with regard to the redistribution of both Fe and 0 after a thermal cycle. Fe was introduced onto the front surface of wafers by deposition after boron implantation. The redistribution of these species was monitored through SIMS depth profiles. In addition, diffusion length measurements from the back surface of the wafers were employed as a new means of assessing Fe gettering. In general there is a lowering of the surface oxygen concentration that increases with dose, or with temperature in the range 850-1000°C. The oxygen concentration can be lowered to a level comparable to denuded wafers at the upper end of this range. The amount of Fe gettering is higher after 850°C than after 1000°C at a given dose. Diffusion length measurements correlate well with SIMS data and provide a convenient method of investigating Fe gettering. This study has demonstrated the feasibility of optimizing a combination of dose and temperature for the gettering of Fe and the lowering of surface oxygen concentration to an acceptable level for device fabrication.

Plasma ion implantation (PII) doping processes utilizing PH3/He and B2H6/He plasmas to fabricate CMOS devices are presented. The impact of plasma chemistry of PH on device structure and characteristics are studied. By using an optimized process condition, low contamination levels and good device characteristics have been achieved.

Many kinds of ULSI Circuit (DRAM, LOGIC, FRAM [1] etc.) are produced at the same production line to reduce the costs. So we have to control many kinds of metal contamination. We investigated the influence of metal contamination on minority carrier diffusion length and oxide charge. The metal impurities we studied are Fe, Cu, Ni, Cr, Al, Na, Ca, FRAM electrode metals (Pt, Ru), metals included in PZT ferro-electric capacitors (Pb, Zr, Ti) [2], metals added to PZT (La, Nb) [3], and metals used for SBT Ferro-electric capacitors (Sr, Bi, Ta) [4].

The distribution of hydrogen penetrated into n-type silicon crystals during chemical etching is described mathematically. The depth profiles of the defects passivated by hydrogen and of defect-hydrogen complexes are also calculated. Comparison with the experimental data obtained on the silicon crystals with radiation defects and doped with transition metals reveals that the model adequately describes the processes in the crystal. By comparing the parameters of the depth profiles, the passivation and appearance of different defects are shown to be caused by the same diffusing species. The number of hydrogen atoms contained in the defect-hydrogen complexes and the distance of the hydrogen-defect interaction are determined from the characteristic length of the defect distribution. The diffusion length (1 to 3 νm) and diffusivity (> 5-10−9 cm2s−1) of hydrogen at room temperature are found indirectly based on the other defect distribution.

Suppression of arcing between the target and plasma during PVD is a key issue for defect reduction, yield improvement and high quality metallization in microelectronics manufacturing. An integrated mini sparcle product has been designed for Endura HP PVD™ sputtering sources. Characteristics of arcing and mechanisms for suppression are discussed here. Process characterization with Ti, TiN and Al sputtering proves that the arc suppression unit has little adverse impact on film properties. The uniformity of reactive sputtered TiN is improved with arc suppression. Marathon evaluation indicates significant reduction in TiN defect and Interconnect metal stack defect. The study of the application for a wide variety of materials (Al, Ti, TiN, SiW, Si) establishes a correlation between deposition rate loss and sputtering power and this relation is found to be almost independent of the materials sputtered. The impact on throughput for typical metal stack is also presented in this paper.

In this paper the results of studies of the influence of radiation and thermal processing on activation of impurity centers (Au, Ag, Pt, Rh) in p-n-structures based on doped silicon are presented. It is shown that the thermal processing in the temperature range of 600-700°C leads to significant increasing of the concentration of electrically active impurities in the samples irradiated by, -rays as compared to the non-irradiated samples as well as to increasing of their decay temperature. These effects depend on the type and fluence of irradiation and can be explained by formation of additional electrically active states of impurities due to decay of complexes of radiation defects and electrically non-active impurities. A possible mechanism of activation process of impurity centers in silicon under radiation and thermal processing is discussed.

Extensive monitoring of device characteristics in the manufacturing of ULSI with advanced LOCOS isolation revealed the strong dependence of device leakage currents on the process of patterning of silicon nitride films applied as a hard mask for local oxidation of silicon wafers. At the same time, the level of the leakage currents strongly correlated to stress-induced dislocation density in the device structures. Formation of microtrenches on the wafer surface at the nitride film edges was identified to have a major impact on the leakage currents. Surprisingly, structures having nitride film edge profiles with feet were consistently dislocation-free after the local oxidation. This showed that nitride etching process created surface damage that provided effective sites for crystal defect nucleation in silicon at the film edges. Computer simulations demonstrated that the feet at nitride edges substantially suppress stress growth during local oxidation.

Thermal evolution of ion implantation-induced defects and the influence of concurrent titanium silicidation in pre-amorphized p-type Si (implanted with 25 KeV, 1016 cm2Si+) under rapid thermal processing (RTP) have been investigated. Presence of implantation-induced electrically active defects has been confirmed by current-voltage (IV) and deep level transient spectroscopy (DLTS) measurements. DLTS characterization results show that the evolution of electrically active defects in the Si implanted samples under RTP depend critically on the RTP temperature: Hole traps HI (0.33 eV) and H4 (0.47 eV) appear after the highest temperature (950 °C) anneal, while a single trap H3 (0.26 eV) shows up at lower anneal temperatures (≤ 900 °C). The thermal signature of H4 defect is very similar to that of the iron interstitial while those of HI and H3 levels appear to originate from some interstitial-related defects, possibly complexes. A most interesting finding is that the above interstitial related defects can be eliminated completely with Ti silicidation, apparently a result of vacancy injection. However the silicidation process itself introduces a new H2 (0.30 eV) level, albeit at much lower concentration. This same H2 level is also seen in unimplanted samples under RTP. The paper will present details of defect evolution under various conditions of RTP for samples with and without the self-implantation and silicidation.