Diffusion and outdiffusion of aluminium implanted into silicon

Galvagno, G.; Via, F. La; Priolo, F.; Rimini, E.

doi:10.1088/0268-1242/8/4/002

Cited by 33 publications

(14 citation statements)

References 13 publications

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“…The diffusion coefficient of Al in Si is one order of magnitude higher than for B, so that doped layers in the 10-100 m depth range can be formed without huge thermal budgets. 1 This application is particularly useful in power devices with a high breakdown voltage (up to 1500 V), where a substantial reduction of the electrical field at the device edge can be reached by deep diffused low doped rings.…”

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Thermal Oxidation of High Dose Aluminum Implanted Silicon

Iacona

Raineri

Via

et al. 2000

J. Electrochem. Soc.

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Al implantation and diffusion is used during Si device fabrication when p-type low doped deep junctions are required. The diffusion coefficient of Al in Si is one order of magnitude higher than for B, so that doped layers in the 10-100 m depth range can be formed without huge thermal budgets. 1 This application is particularly useful in power devices with a high breakdown voltage (up to 1500 V), where a substantial reduction of the electrical field at the device edge can be reached by deep diffused low doped rings.Only a small fraction of the implanted Al atoms is electrically active after a thermal treatment. The reasons for this phenomenon have been already investigated. 2 Precipitation and Al outdiffusion are the two main involved mechanisms. 3 The Al solid solubility in Si is quite low (1 ϫ 10 19 cm Ϫ3 at 900ЊC 4 ); however, even at a concentration below solid solubility, Al x O y precipitates are formed due to the high reactivity of Al with the oxygen present in the Czochralski grown wafers (oxygen content 10 18 cm Ϫ3 ). 5 No precipitation occurs if implants are performed into epitaxially grown Si, where the oxygen content is less than 1 ϫ 10 16 cm Ϫ3 , and the Al concentration does not exceed the solid solubility limit. However, the oxygen concentration can be high also in epi layers after an oxidation process due to the oxygen drive-in and diffusion from the surface to the bulk. Nevertheless, during device fabrication, the oxidation of Al implanted Si layers is a necessary step. Furthermore, Al diffusion can be performed in an oxidizing environment to reduce the thermal budget, even if this determines a poor electrical activity.Even if many works have been carried out on the Al diffusion, some aspects are still unclear. In particular, the Al behavior during the thermal oxidation of Si is still not understood. The aim of this work is to carefully characterize the Al redistribution in the SiO 2 /Si system during thermal oxidation of high dose Al implanted Si. The Al redistribution has been quantitatively obtained by secondary ion mass spectrometry (SIMS), while the carrier profiles have been measured by spreading resistance profiling (SRP). The structure and the morphology of the SiO 2 /Si system have been determined by transmission electron microscopy (TEM) and by atomic force microscopy (AFM). ExperimentalAl ions were implanted at 35 keV into floating zone (FZ) grown Si(100) wafers to a dose of 3 ϫ 10 15 ions/cm 2 . The projected range was 57 nm and the straggling was 24 nm. The Al concentration has a peak value of about 5 ϫ 10 20 cm Ϫ3 , and it becomes lower than the solid solubility (about 1 ϫ 10 19 cm Ϫ3 at 920ЊC 4 ) only at depths higher than 100 nm. This means that Al precipitation is expected to occur around the projected range. The implant produced a 100 nm thick amorphous surface layer that regrew epitaxially during the temperature ramp-up of the oxidation process.The oxidation was performed in a horizontal furnace. Before the oxidation process, wafers were cleaned by a standard RCA procedure to el...

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Thermal Oxidation of High Dose Aluminum Implanted Silicon

Iacona

Raineri

Via

et al. 2000

J. Electrochem. Soc.

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“…Several micron penetration of Al into Si can be achieved for long annealing durations [36]. This Al diffusion induces a p-doping of the Si layer close to the surface and creates a p-n junction in the Si wafer [38], similar to the process used in Si solar cell manufacturing. The schematic of a tentative band profile illustrating this hypothesis is shown in Fig.…”

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Electron beam induced current microscopy investigation of GaN nanowire arrays grown on Si substrates

Neplokh¹,

Ali²,

Julien³

et al. 2016

Materials Science in Semiconductor Processing

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“…The measured The assessed diffusivity of Al in solid silicon was mainly based on the experimental data available in the literature [8,[97][98][99][100][101][102][103][104][105][106][107]. The measured The assessed diffusivity of Al in solid silicon was mainly based on the experimental data available in the literature [8,[97][98][99][100][101][102][103][104][105][106][107].…”

Section: Typical Examplesmentioning

confidence: 99%