On annealing a boron implanted Si sample at similar to800 degreesC, boron in the tail of the implanted profile diffuses very fast, faster than the normal thermal diffusion by a factor 100 or more. ...

Transient enhanced diffusion of Boron in Si

The paper presents the damage accumulation in silicon carbide (SiC) as a function of the ion mass, the ion energy and the implantation temperature. A defect-interaction and amorphization model is used to analyse the dose dependence of defect production, as obtained by the various methods. The temperature dependence of the amorphization dose can be represented assuming a thermally enhanced annealing within the primary collision cascades. On the basis of such a model, a critical implantation temperature is obtained, which was found to vary with the ion mass and the implantation energy. The concurrent influence of implantation temperature and ion fluence on the resulting damage distribution in SiC is demonstrated. The damage annealing of ion implanted SiC is investigated for low, medium and high damage concentrations. The effect of the implantation temperature and the concentration of implanted atoms, both influencing the kind of defects obtained after implantation, on the annealing behaviour is analysed.

Ion-beam induced damage and annealing behaviour in SiC

Reliable and accurate temperature measurement during microwave processing of ceramic bodies is controversial. Although thermocouples are routinely used in conventional thermal furnaces, their presence in microwave furnaces can locally distort the electromagnetic field, conduct heat away from the sample, induce thermal instabilities and microwave breakdown, and lead to serious measurement errors. These thermocouple effects have been studied and found to be more pronounced in low- and medium-loss ceramic materials. To decrease the thermocouple effects during the processing of advanced ceramic materials, an optical, noncontact temperature sensing system has been developed, calibrated, and incorporated into a computer-controlled microwave furnace.

Temperature Measurements during Microwave Processing: The Significance of Thermocouple Effects

Native point defects control many aspects of semiconductor behavior. Such defects can be electrically charged, both in the bulk and on the surface. This charging can affect numerous defect properties such as structure, thermal diffusion rates, trapping and recombination rates for electrons and holes, and luminescence quenching rates. Charging also introduces new phenomena such as nonthermally photostimulated diffusion, thereby offering distinctive mechanisms for defect engineering. The present work incorporates the first comprehensive account of semiconductor defect charging, identifying correspondences and contrasts between surfaces and the bulk as well as among semiconductor classes (group IV, groups III–V, and metal oxides). For example, small lattice parameters, close-packed unit cells, and basis atoms with large atomic radii all inhibit the formation of ionized interstitials and antisites. The charged defects that exist in III–V and oxide semiconductors can be predicted with surprising accuracy from the chemical potential and oxygen partial pressure of the ambient. The symmetry-lowering relaxations, formation energies, and diffusion mechanisms of bulk and surface defect structures often depend strongly on charge state with similar qualitative behavior, although for a given material surface defects do not typically take on the same configurations or range of stable charge states as their counterparts in the bulk.

Charged point defects in semiconductors

Advances in Induction and Microwave Heating of Mineral and Organic Materials

Control of dopant diffusion during high-temperature cycling is critical in forming shallow electrical junctions in silicon as needed in integrated-circuit manufacturing. However, junctions formed by implantation can be anomalously deep due to a transiency associated with ion-induced defects which greatly enhances dopant diffusion. The purpose of this work was to investigate methods of defect engineering the implantation process to control or eliminate transient-enhanced diffusion (TED). TED of boron has been attributed to excess interstitials introduced into the lattice during implantation, known as the plus-one model. Effects of pre-amorphization (i.e., amorphization prior to dopant implantation using isoelectric ions) on TED of boron, and particularly, the role of the end-of-range (EOR) defects at the amorphous-crystalline interface, are discussed. These EOR defects were varied by altering the implantation conditions during pre-amorphization. Also, other means of controlling the transiency are discussed, in particular, the use of high-energy ions to introduce excess vacancies into the lattice where dopant diffusion occurs. These vacancies are shown to interact with the excess interstitials introduced during dopant implantation to suppress TED.

Methods of defect-engineering shallow junctions formed by B+-implantation in Si

Rapid thermal processing utilizing microwave energy has been used to anneal N, P, and Al ion-implanted 6H-SiC. The microwaves raise the temperature of the sample at a rate of 200°C/min vs 10°C/min for conventional ceramic furnace annealing. Samples were annealed in the temperature range of 1400-1700°C for 2-10 min. The implanted/annealed samples were characterized using van der Pauw Hall, Rutherford backscattering, and secondary ion mass spectrometry. For a given annealing temperature, the characteristics of the microwave-annealed material are similar to those of conventional furnace anneals despite the difference in cycle time.

Rapid thermal annealing of ion implanted 6H-SiC by microwave processing

Abstract In this study we have performed N, P, Al, B, V, Si, and C implantations to obtain p-type, n-type, and semi-insulating regions in 6HSiC crystals. Post-implantation annealings were performed in either a conventional ceramic processing furnace or using microwaves in the temperature range of 1200–1700°C. The material was characterized by secondary ion mass spectrometry, Hall, Rutherford backscattering via channeling, and two-probe I–V measurements. N-type regions with a maximum room temperature electron concentration of 2 × 1019 cm−3 were obtained using N and P implantations. Though p-type regions were obtained by Al and B, the room temperature hole concentrations were low due to the deep acceptor levels associated with these impurities. The Si and C bombardment gave regions with resistivities as high as 109 Ω cm compared to 1 Ω cm in the starting material.

E. G. Roth

Papers

Methods of defect-engineering shallow junctions formed by B+-implantation in Si

Rapid thermal annealing of ion implanted 6H-SiC by microwave processing

Ion implantation in 6h-sic