Introduction rates of dominant defects have been determined for electron-irradiated, p-type silicon as a function of oxygen and boron concentration. Samples included those with oxygen content ranging from 8 × 1015 to 7 × 1017 cm−3. Initial results are described for samples with measured carbon content varying from 2 × 1015 to 6 × 1016 cm−3. Competing defect reactions involving the interstitial defects, Bi and Ci, and oxygen, boron, and carbon are observed. The identities of an electron trap (Bi-Oi) and a hole trap (Bi-Bs) have been clarified.

Carbon has been implanted into Si to overlap implanted concentrations of oxygen and nitrogen. Impurity incorporation and interactions produced by implantation at 50°C, and upon subsequent annealing to 900°C, were monitored by infrared absorption. Implantation with 0 and C introduces absorption bands for C-0 centers in addition to those for substitutional C, interstitial 0, and 0-vacancy centers. These centers are removed by annealing. The major effect of C in N-implanted layers is a suppression of absorption bands associated previously with N aggregates. There is, apparently, a strong interaction between C and displacement defects which can alter defect reordering and control the loss of C from substitutional sites.

We have made MINDO/3 calculations on a 47 silicon atom molecular cluster to model the diffusion of oxygen in silicon crystal. For interstitial oxygen (O1), we compute an activation energy for diffusion of 2.49 ev. We compute a binding energy of 0.1 ev. when two isolated interstitial oxygen atoms bond to a common silicon atom of the lattice. This complex (O2) is computed to move through the lattice with an activation energy of 1.36 ev. The diffusion path is through a four-member ring intermediate structure. We conclude that the diffusion constant for (O2) is eight orders of magnitude greater than that of (O1).

Results of new electron nuclear double resonance (ENDOR) experiments on the thermal donors (NL8) in silicon are presented. Hyperfine interactions (hf) with 17O were observed. Two types of oxygen were found, of each type there are at least two oxygen atoms. The size and tensor orientations of their hf interactions are consistent with the presence of four oxygen atoms with approx. <111>-symmetry in the core of the thermal donors.

A new kinetic model is presented for the formation of thermal donors in silicon. This model is based on the aggregation of the self-interstitials generated by oxygen precipitation, on preexisting oxygen related nuclei.

Several series of optical absorption lines are found in the wavenumber range 190–270 1/cm in as-grown crytals of n-type Si involving oxygen and nitrogen simultaneously. They are related to the electronic transitions associated with five kinds of shallow donors each consisting of nitrogen and oxygen atoms (N-O complex). The analysis of the generation kinetics shows that the complex of the main type consists of one oxygen atom and two or three pairs of nitrogen atoms.

The precipitation of oxygen in silicon can be initiated by both homogeneous and heterogeneous nucleation mechanisms. Homogeneous nucleation has been studied in much greater detail; however, in some cases, superior contaminant gettering has been reported for precipitation processes believed to be based on heterogeneous nucleation. In this study, we use rapid thermal annealing (RTA) to demonstrate conclusively that the nucleation mechanism for one such process is, in fact, heterogeneous. We also investigate the sensitivity of precipitation to slight alterations in thermal process steps. We interpret our results in terms of point-defect-induced changes in the critical radius (Rc) for precipitate growth.

Effects of high carbon concentration upon oxygen precipitate formation in Cz silicon have been investigated by combining various furnace and rapid thermal annneals. Even though oxide precipitate density increases with increasing carbon levels, Cs, synchrotron radiation section topographs of processed high carbon content wafers (Cs ∼ 4ppma) exhibit Pendellosung fringes, indicating a strain free bulk state. Our optical microscopic data have also shown very few defect etch features inside the bulk. A model based upon a direct coupling of both SiO2 and Si-C complex formation reactions is used to explain rather unique oxygen precipitation characteristics in the high carbon content Cz Si materials.

We have used FTIR spectrum processing to analyze the behavior of interstitial and precipitated oxygen during the intrinsic gettering process. The kinetics of precipitation and the microscopic growth characteristics of precipitates were compared with a theoretical model based on diffusion controlled precipitation process. The annealing time dependence of precipitate size has been found to follow the relation of r = tn with n = 0.7.

Resistivity and photoluminescence measurements have been made on Al-doped CZ Si, with high and with low C concentrations, heat treated at 450°C. The results are compared with those obtained from nominally undoped CZ Si with a low residual B concentration. It is shown that Al acceptors are completely lost, presumably by the removal of Al from substitutional sites by exchange with Si self interstitials generated during oxygen aggregation. Luminescence features observed are tentatively identified with electronic transitions at neutral Al-C and Al-thermal donor complexes.

The precipitation behaviour of the transition metals Co, Ni, Cu and Pd has been studied by means of conventional and high - resolution electron microscopy. Special experimental conditions for specimen preparation were chosen, which lead to the formation of haze. These conditions were the same for all metals. Therefore, a direct comparison of the respective precipitation phenomena was possible. Co and Ni were found to precipitate as Si - rich silicide particles exhibiting various morphologies attributed to different stages of particle growth and ripening. It is shown that the generation of Si- self - interstitials (and vacancies) plays a minor role in the preci-pitate formation. On the other hand Cu and Pd precipitate as metal - rich silicide particles. They form star - like colonies consisting of small particles and extended extrinsic edge - type dislocation loops. The precipitation behaviour of these two met-als is governed by the generation of Si - self - interstitials due to the large misfit of the metal - rich silicide particles.

Spreading resistance measurements, Rutherford backscattering spectroscopy, ion channeling, and deep level capacitance transient spectroscopy are used to study ion implanted arsenic in silicon and its tail region. The following comparisons of the furnace annealed samples are made: Electrically active profiles versus total concentration profiles, tail diffusion versus total implant diffusion, and substitutional fractions. These results are compared to currently accepted models for arsenic diffusion in silicon.

Two hole trap levels H(0.45) and H(0.29) with properties close to those of metal-related defect states were found in virgin or implanted CZ silicon substrates submitted to a short duration Rapid Thermal Annealing (RTA) around 1000 °C. These hole trap levels were assigned to the presence of Fe or Cr in interstitial solution after RTA. Control experiments using chromium-diffused samples allowed to verify the quenching mechanism of chromium atoms in electrically active site during the annealing treatment, with a cooling rate-dependent concentration. After a subsequent low temperature annealing, the supersaturated interstitial solution of chromium evolves toward more stable defect configurations.

We summarize the recent results in hydrogen passivation in silicon, including presenting comprehensive diffusion profiles, i.e., profiles in floating zone n-type and p-type silicon vs resistivity. Domination of hydrogen diffusion by impurity trapping is clearly indicated for part of the profile in low resistivity p-type Si. Also mentioned are the current models of hydrogen passivation of dangling bonds, shallow acceptors, shallow donors, and hyper-deep defects.

Chalcogen (S,Se,Te) -doped silicon samples were hydrogen neutralized by different passivation techniques. The electrically active double-donor densities were determined by DLTS measurements. DLTS spectra reveal that both donor levels recover simultaneously. The activation energy for re-activation of neutralized isolated and pure pair sulphur double-donors is Ea(So/+) = 2,13 ± 0,15 eV and Ea(S2o/+) = 2,1 ± 0,15 eV, respectively.

The extended defects induced by hydrogen diffusion in silicon during the process of (1) CF4/x% H2(0≤x≤100) reactive ion etching, or (2) hydrogenation in H2 plasma, or (3) passivation of boron acceptors in H2 plasma, are studied by high resolution electron microscopy and secondary ion mass spectrometry. In reactive ion etched Si, a higher density of {111} planar defects are produced as the concentration of H2 in the etching gas and/or the overetch time is increased. The Si surface appears rough after reactive ion etching. Similar {111} planar defects are also found in Si after a H2 plasma treatment at 200°C for 3 hours, while the Si surface remains smooth. Boron im-plantation (30keV, 1015 at/cm2) and furnace annealing (1000°C, 30 min) processes are found to introduce stacking faults and perfect dislocation loops into silicon wafers. After subsequent exposure of boron implanted Si to a H2 plasma (200°C, 3 hours), microprecipitates associated with dislocation loops are observed.

These results indicate that the apparent surface roughness (top 30 Å layer) in reac-tive ion etched Si is caused by energetic ion bombardment (∼500 eV). However, the {111} planar defects in CF4/x% H2(x>40%) reactive ion etched Si and the {111} planar defects and microprecipitates in H2 plasma treated Si are induced by the super-saturation of hydrogen diffused into Si during the plasma treatment process.

We report first-principles total-energy calculations for H atoms in a Si lattice. Our results for single H atoms are presented in the form of total-energy surfaces, providing immediate insight in stable positions and migration paths. We examine the stability of different charge states (H+, H0, H−) as a function of Fermi-level position, and its impli-cations for H diffusion in p-type vs. n-type material. The results are used to scrutinize and supplement existing understanding of experimental observations. We also study the co-operative interactions of several H atoms, and propose a novel mechanism for H-induced damage.

Channeling and lattice location has been used to investigate the structure of the boron-hydrogen complex in crystalline silicon. The positions of both the boron and hydrogen atoms have been determined. The results are compared with Monte-Carlo simulations. The boron atom in the B-H pair is found to be displaced from a substitutional site by 0.28±0.03Å, while the hydrogen atom is predominantly at a bond-center site, with a small proportion in a back-bonded position.

The lattice site of H/D atoms in silicon doped with B and 111In atoms is investigated using the ion channeling and perturbed γγ angular correlation (PAC) technique. The results indicate that at 295 K the antibonding site is occupied by H/D and that this site is easily transformed into a near tetrahedral site under the influence of an analyzing ion beam. Based on PAC results, the population of a second site, possibly a bond-center site, is expected at low temperatures.

We have studied the hydrogen passivation of boron acceptors in bulk crystalline silicon with Raman scattering. Upon hydro-genation, distinct changes in the optical phonon lineshape and the localized vibrational modes of boron are observed. The hy-drogen in the passivated region gives rise to a specific Raman-active mode, whose vibrational frequency depends strongly on temperature and uniaxial stress. Implications of these results on possible structural models are discussed.