Arsenic Clustering in Silicon

Schwenker, R. O.; Pan, Er; Lever, R. F.

doi:10.1063/1.1660706

Cited by 106 publications

(28 citation statements)

References 4 publications

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“…It has been found that the location of As atoms in the Si lattice and the accompanying electrical behavior at high concentrations is a complicated function of diffusion (1)(2)(3) temperature. .em at room temperat-ure into three types of precisely to the projected range (Rp) of 100 keV As and the depth of the original amorphous/crystalline interface (Fig.…”

Section: + Now At Microelec~ronics Center Of North Carolinamentioning

confidence: 99%

Direct evidence of arsenic clustering in high dose arsenic-implanted silicon

Sadana

Washburn

1984

Applied Physics Letters

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High dose (5–7.5×1015 cm−2) arsenic implantation was conducted in the energy range 50–120 keV into three types of (100)Si substrates: (i) bare Si, (ii) with a thermally grown screen oxide (775 Å), and (iii) preamorphized surface layer produced by self-implantation. The substrates were subsequently furnace annealed at 600 °C in N2. Cross-section transmission electron microscopy (XTEM) revealed that in all cases discrete layers of As related clusters and small dislocation loops occurred at depths matching the projected ranges of As into the Si substrates and original amorphous/crystalline interfaces respectively. The atomic profiles of As obtained by secondary ion mass spectrometry (SIMS) from these samples did not show any redistribution of As. The carrier concentration profiles from the spreading resistance measurements indicate that only 30% of As was electrically active. Comparison of XTEM and SIMS suggests that nucleation of the clusters occurred in the regions where As was present above the solid solubility limit in Si. The presence of recoiled oxygen has been found to stabilize the clusters.

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Section: + Now At Microelec~ronics Center Of North Carolinamentioning

confidence: 99%

Direct evidence of arsenic clustering in high dose arsenic-implanted silicon

Sadana

Washburn

1984

Applied Physics Letters

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“…An alternative mechanism of vacancy generation is the growth of interstitial defects. These may be small interstitial dislocation loops as found earlier in transmission electron microscopy (1,2). Also a climbing dislocation is a source of vacancies by the growth of the extra half-plane.…”

Section: Discussionmentioning

confidence: 93%

“…In Eq. [2] Ae is the emitter area, nio is the intrinsic carrier concentration for low impurity concentrations, Veb is the applied emitterbase voltage, and GD is the Gummel number of the base. This is given by N~ nio ~2 Gb= f--~-( n~, ~x [3] where Dn is the diffusion coefficient for electrons in the base, ni is the dope-dependent intrinsic carrier concentration, and the integration is carried out over the base (8).…”

Section: Electrical Measurementsmentioning

confidence: 99%

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Enhanced Diffusion of Implanted Arsenic and Boron in Silicon by Low‐Temperature Heat‐Treatment

Gurp

Slotboom

Smolders

et al. 1980

J. Electrochem. Soc.

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The parameters of high frequency transistors with implanted arsenic emitter and boron base were found to change significantly on annealing at temperatures between 600 ~ and 900~ with a maximum change at about 700~ The change can be interpreted as a decrease of boron concentration in the base and of the donor concentration gradient at the emitter-base junction. Determination of the concentration profiles by secondary ion mass spectrometry and by Rutherford backscattering spectrometry (RBS) showed that these decreases were due to enhanced diffusion of both arsenic and boron. Electron microscopy showed precipitation which was probably preceded by arsenic clustering, in agreement with RBS channeling results. These showed that the substitutional fraction of arsenic, which was between 95% and 98%, decreased by a few percent on annealing at 700~ The enhanced diffusion is thought to be caused by vacancy generation by either one of two precipitation-induced processes: dissociation of As-vacancy complexes or growth of interstitial defects.Implanted arsenic is now widely used as a donortype impurity in silicon. For example, bipolar transistors are made with implanted boron base and arsenic emitter. After implantation the As and B are electrically activated by an appropriate heat-treatment around 1000~ In a process which involved a subsequent annealing at 650~ we found that the parameters of high frequency transistors with shallow As emitter (0.2 #m) and B base (0.35 #m) were drastically affected by this annealing. The current gain, for example, was greatly increased.The effects of low temperature heat-treatments on Si with As diffused into it have been studied earlier.Osvenskii et al. (1) found interstitial dislocation loops by transmission electron microscopy on As-doped Si crystals which had been annealed at 800~ in vacuum after quenching from 1250~The loops were attributed to As precipitation. Schwenker et al. (2) found for As diffused at 1050 ~ and ll00~ to a depth of 6-9 #m into Si that heat-treatment between 500 o and 970~ in argon caused the sheet resistance to increase. Around 750~ this increase was maximum, being a factor of 2 at a surface concentration of 1.2 • 1021 cm -3 and less at lower concentrations. Transmission electron microscopy showed dark spots and interstitial hexagonal Frank dislocation loops. The effects on sheet resistance were ascribed to As clustering or vacancy-complex formation. An increase in sheet resistance due to heat-treatment between 500 ~ and 800~in vacuum was also found by Miyamoto et al. (3) who observed an increase of the lattice constant, which was supposed to be due to SiAS formation. Haskell et aI.(4) studied Rutherford backscattering on As in Si and found from channeling that 90% to 95% of the As was on lattice sites. Heat-treatment between 650 ~ and 900~ in argon increased the aligned As yield, showing As to be displaced from substitutional lattice sites.Shibayama et al. (5) observed an enhancement of both B and As diffusion in Si for As surface concentrations above about 1020 cm ...

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“…In each case, the energy to "peel off" an As atom is -1.5 eV, which is the same as the value of the reactivation activation energy Schwenker et a1. [6] extracted from their experimental data. Since EXAFS data established that in deactivated samples virtually all As atoms are second neighbors to each other, [7] we conclude that the dominant complexes in deactivated samples are As2V and As3V.…”

Section: Comples Diffusive Phenomena In Heavily Arsenic Doped Siliconmentioning

confidence: 99%