Depth profiles of the nickel donor center in p-type silicon diffused with dilute nickel measured by deep-level transient spectroscopy

Abstract

The depth profiles of the nickel donor center located at E v + 0.17 eV (E v : the top energy of the valence band) in p-type silicon diffused with dilute nickel at 525-900 °C and slowly cooled to room temperature were measured. Owing to the domination of the fast outdiffusion of nickel, the nickel center concentration at the sample surface was highest for the sample diffused at 525 °C, which abruptly decreased with increasing diffusion temperature. The concentrations of the center in the samples diffused at intermediate temperatures sharply increased with increasing depth and converged to an asymptotic value in the deep region. The concentration fractions of the center of the dissolved nickel in the deep region were 4 to 12% for the samples diffused below 900 °C, which were unexpectedly high compared with previous data. A possible formation mechanism of the center through a nitrogen-related defect was discussed.

Transformation of the nickel donor center by annealing in silicon measured by deep-level transient spectroscopy

“…Since sound diodes were always formed without etching the surfaces of the samples, no nickel precipitate was considered to form on the surfaces of the samples; all the contaminating nickel was dissolved in the bulk and no outdiffusion of the element occurred during the cooling of the samples. As reported in a previous paper, 24) the depth distribution of the nickel center was almost homogeneous throughout the depth (from 2.0 × 10 13 near the surface to 1.5 × 10 13 =cm 3 deep in the bulk). Since the bulk concentration of nickel is 3.8 × 10 14 =cm 3 when all the contaminating nickel homogeneously dissolves, the concentration fractions of the nickel center to the dissolved nickel are estimated to be from 4 to 5%.…”

“…Since DLTS is a sensitive and speciesdiscriminating probe, it is useful to assess the trace contamination of nickel in silicon, as demonstrated in a previous study. 24) It is also important to investigate the thermal behavior of the center and other nickel-related species after the diffusion of nickel for the actual assessment of nickel contamination. Several measurements reporting the annealing behavior of the center in heavily nickeldiffused samples 15,[17][18][19] and in a melt-doped sample 20) were reported.…”

Defect Formation of Nickel-Incorporated Large-Diameter Czochralski-Grown Silicon and Their Effect on Gate Oxide Reliability

“…That is, the nickel donor level was predominantly formed during crystal growth with a higher boron doping concentration. When boron doping concentration is increased, the Fermi level is lowered and becomes closer to the nickel donor level (E V + 0.17 eV at room temperature), 8,21,22 which is slightly shallower than the Fermi level at the given doping density (E F = E V + 0.2-0.3 eV). Therefore, it is obvious that the formation of electrically active interstitial nickel (Ni int ) in a higher doping concentration starts at a higher temperature than in a lower doping concentration under the same cooling process, thus the formation of Ni-B pair is enhanced and the bulk nickel concentration after crystallization is also increased.…”

“…17 However, most of these studies considered wafer samples that are contaminated from the surface and in-diffused at a certain temperature [10][11][12][13][14][15][16][17][18][19][20] or doped during float-zone (FZ) growth. 21,22 These experimental conditions are a good approximation for the surface contamination of nickel, but they cannot reflect the exact behavior of nickel that appears during the CZ-Si growth process, which is accompanied with other impurities such as dopants and the formation of secondary defects during the subsequent wafering process. Moreover, the extremely fast quenching rate of approximately 2000 K • s −1 for generating nickel precipitates in several studies [11][12][13][14] never arises in the actual large-diameter CZ-Si ingot growth process; therefore, this experimental condition cannot be used to determine the actual advantages and disadvantages of nickel silicide precipitated during singlecrystal production.…”

Origins of the nitrogen-related deep donor center and its preceding species in nitrogen-doped silicon determined by deep-level transient spectroscopy

“…At the diffusing temperature, most of the diffused nickel dissolves as interstitial Ni (Ni i ) and several to 10% of it forms Ni s 22) through a reaction with the N-V complex(B), and these nickel species are considered to be homogeneously distributed throughout the bulk of the sample. 22) During the cooling process, Ni i atoms rapidly out-diffuse and form precipitates at the sample surface. 27) While Ni i is known as the fastest diffuser, 28) Ni s is immobile.…”