First-Principles Study of Boron Diffusion in Silicon

Windl, Wolfgang; Bunea, Marius M.; Stumpf, R.; Dunham, Scott T.; Masquelier, Michael P.

doi:10.1103/physrevlett.83.4345

Cited by 216 publications

(116 citation statements)

References 21 publications

Supporting

Mentioning

102

Contrasting

Order By: Relevance

“…Two interstitial-mediated diffusion mechanisms, the kick-out mechanism [Cowern, 1999] (Equation 3.1) and the interstitialcy mechanism [Sadigh, 1999;Windl, 1999] (Equation 3.2) have been proposed for B diffusion in Si:…”

Section: Experimental Approach and Resultsmentioning

confidence: 99%

Diffusion in silicon isotope heterostructures

Silvestri¹

2004

View full text Add to dashboard Cite

The simultaneous diffusion of Si and the dopants B, P, and As has been studied by the use of a multilayer structure of isotopically enriched Si. This structure, consisting of 5 pairs of 120 nm thick natural Si and 28 Si enriched layers, enables the observation of 30 Si self-diffusion from the natural layers into the 28 Si enriched layers, as well as dopant diffusion from an implanted source in an amorphous Si cap layer, via Secondary Ion Mass Spectrometry (SIMS). The dopant diffusion created regions of the multilayer structure that were extrinsic at the diffusion temperatures. In these regions, the Fermi level shift due to the extrinsic condition altered the concentration and charge state of the native defects involved in the diffusion process, which affected the dopant and selfdiffusion.The simultaneously recorded diffusion profiles enabled the modeling of the coupled dopant and self-diffusion. From the modeling of the simultaneous diffusion, the dopant diffusion mechanisms, the native defect charge states, and the self-and dopant diffusion coefficients can be determined. This information is necessary to enhance the physical modeling of dopant diffusion in Si. It is of particular interest to the modeling of pushing me to achieve. I am grateful to Ana for her unwavering love and support, for giving me the time during this busy year to write this thesis, but also for knowing when I need a break.

show abstract

Section: Experimental Approach and Resultsmentioning

confidence: 99%

Diffusion in silicon isotope heterostructures

Silvestri¹

2004

View full text Add to dashboard Cite

show abstract

“…1) and the interstitialcy mechanism [14,15] (Eq. 2) have been proposed for B diffusion in Si: where the subscripts s and i refer to substitutional and interstitial boron, respectively, and I refers to self-interstitial atoms.…”

Section: Resultsmentioning

confidence: 99%

“…To verify that TED was not present in these experiments, additional samples were implanted with Si at a dose of 7x10 15 cm -2 at 50 keV and 1x10 16 cm -2 at 65 keV. These samples were then prepared, annealed, and analyzed as described above.…”

Section: Methodsmentioning

confidence: 99%

Self- and Dopant Diffusion in Extrinsic Boron Doped Isotopically Controlled Silicon Multilayer Structures

et al. 2002

View full text Add to dashboard Cite

Isotopically controlled silicon multilayer structures were used to measure the enhancement of self-and dopant diffusion in extrinsic boron doped silicon. 30 Si was used as a tracer through a multilayer structure of alternating natural Si and enriched 28 Si layers. Low energy, high resolution secondary ion mass spectrometry (SIMS) allowed for simultaneous measurement of self-and dopant diffusion profiles of samples annealed at temperatures between 850 o C and 1100°C. A specially designed ion-implanted amorphous Si surface layer was used as a dopant source to suppress excess defects in the multilayer structure, thereby eliminating transient enhanced diffusion (TED) behavior. Self-and dopant diffusion coefficients, diffusion mechanisms, and native defect charge states were determined from computer-aided modeling, based on differential equations describing the diffusion processes. We present a quantitative description of B diffusion enhanced self-diffusion in silicon and conclude that the diffusion of both B and Si is mainly mediated by neutral and singly positively charged self-interstitials under p-type doping. No significant contribution of vacancies to either B or Si diffusion is observed.

show abstract

“…In fact, current first principles calculations on various charge-state systems are still quite uncertain. 7,8,14 This catalytic reaction may provide an explanation for the experimental observation that a large fraction of B atoms remains electrically active. ͑In these experiments, the Si implant doses were 1ϫ10 9 -5ϫ10 13 cm Ϫ2 and the doped B concentration was about 7ϫ10 15 cm Ϫ3 .…”

mentioning

confidence: 91%

Catalytic role of boron atoms in self-interstitial clustering in Si

Hwang

Goddard

2003

Applied Physics Letters

View full text Add to dashboard Cite

Using density functional theory ͑DFT͒ calculations and kinetic simulations, we have investigated the influence of boron atoms on self-interstitial clustering in Si. From DFT calculations of neutral interstitial clusters with a single B atom ͑B s I n , nр4͒, we find that the binding of B ͑B s I n →I nϪ1 ϩB s I) becomes substantially weaker than that of an interstitial ͑B s I n →B s I nϪ1 ϩI) when nу4. This implies boron can be liberated while leaving an interstitial cluster behind. Our kinetic simulations including the boron liberation explain well experimental observations reported by J. L. Continued scaling of Si devices below 0.1 m requires formation of ultrashallow junctions to avoid short-channel effects. 1 Ultralow-energy ion beams are currently most widely used to introduce dopants into the Si substrate. Generally this must be followed by high-temperature thermal annealing to eliminate substrate damage generated by energetic ion bombardment and to electrically activate the injected dopants. During the implantation and annealing, the dopant atoms exhibit transient enhanced diffusion ͑TED͒. This is a particularly serious problem for boron ͑a major p-type dopant͒, which exhibits large TED. The consequent doping profile spreading imposes a great difficulty in forming ultrashallow pn junctions in deep submicron device structures.It is now well understood that excess Si self-interstitials generated during implantation are mainly responsible for the B TED. Due to large mobility even at room temperature, 2 single interstitials can diffuse and annihilate at the surface. Therefore, at the onset of annealing most interstitials are likely to remain in the form of clusters. It is widely believed that, in ultrashallow junction formation by ultralow energy ion implantation, the main sources for free interstitials during postimplantation annealing are small interstitial clusters and boron-interstitial complexes 3-6 along with extended ͕311͖ defects. The formation of boron-interstitial complexes have been extensively studied using first principles calculations, 7,8 also supported by recent experiments. 9 However, little is known about the role of single B atoms in the growth of small interstitial clusters.Deep level transient spectroscopy recently provided direct evidence for the existence of small Si interstitial clusters. 10 These results showed that the small interstitial clusters did not contain large numbers of B atoms even in a B doped layer ͑where B concentration was not high enough to induce B clustering͒. This was surprising because recent ab initio calculations 7,8 suggested that Si interstitials interact very strongly with substitutional B to form stable B s I, B s I 2 , and B s I 3 complexes with large thermal stability comparable to that of small interstitial clusters. 7,8 In order to provide a basis for understanding the formation of interstitial clusters in the presence of B, we have carried out ͑i͒ first-principles quantum mechanics calculations on the structures and energetics of small interstitial cluster...

show abstract

First-Principles Study of Boron Diffusion in Silicon

Cited by 216 publications

References 21 publications

Diffusion in silicon isotope heterostructures

Diffusion in silicon isotope heterostructures

Self- and Dopant Diffusion in Extrinsic Boron Doped Isotopically Controlled Silicon Multilayer Structures

Catalytic role of boron atoms in self-interstitial clustering in Si

Contact Info

Product

Resources

About