Physics, technology, and modeling of polysilicon emitter contacts for VLSI bipolar transistors

Patton, G.L.; Bravman, J. C.; Plummer, J.D.

doi:10.1109/t-ed.1986.22738

Cited by 148 publications

(32 citation statements)

References 33 publications

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“…In bipolar junction transistors (BJT), significant (3-60 times) improvements of the current gain were achieved when the traditional phosphorus diffusion was replaced with a doped polysilicon emitter [3][4][5]. Subsequent studies on polysilicon emitter BJTs have elucidated the critical role of the interfacial silicon oxide layer, without which a direct deposition of polysilicon onto the mono-silicon leads to epitaxial growth and high recombination [4,6,7].…”

Section: Introductionmentioning

confidence: 99%

“…Subsequent studies on polysilicon emitter BJTs have elucidated the critical role of the interfacial silicon oxide layer, without which a direct deposition of polysilicon onto the mono-silicon leads to epitaxial growth and high recombination [4,6,7]. The interfacial oxide layer itself can be a source of recombination, but it can be suppressed thanks to a positive response to hydrogenation [4,8].…”

Section: Introductionmentioning

confidence: 99%

“…A thermionic diffusion model has also been proposed for characterizing hole transport in a polysilicon emitter [10,11,12]. On the other hand, failure to achieve improved performance has been explained by the phenomenon of interfacial oxide layer break up, as observed by high resolution transmission electron microscopy [4,8,[13][14][15][16] and quantitatively confirmed by contact resistivity measurements. Recently an analytical model has been developed based on the possibility that dopants penetrate through pinholes in the oxide, creating localized highly doped regions in the crystalline silicon; current crowding associated to those local contact regions could then explain both a low minority carrier recombination and a low majority carrier resistivity [16].…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Phosphorus-diffused polysilicon contacts for solar cells

Yan

Cuevas

Bullock

et al. 2015

Solar Energy Materials and Solar Cells

154

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Phosphorus-diffused polysilicon contacts for solar cells

Yan

Cuevas

Bullock

et al. 2015

Solar Energy Materials and Solar Cells

154

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“…In polysilicon emitter contacts, an interfacial oxide layer is invariably present at the polysilicon/ silicon interface, which has the advantage of increasing the current gain [2], [3] but the disadvantage of increasing the emitter resistance of the transistor [4]- [7]. A considerable amount of work has been published in the literature on the effects of the interfacial oxide on the base current [8]- [11] and emitter resistance [4]- [7], [12], [13] of polysilicon emitter contacts. It has been found that the nature of the interfacial oxide is significantly influenced by a number of factors, including the type of ex-situ clean (typically an HF etch) used prior to polysilicon deposition [9], [14], the polysilicon deposition conditions [15], [16], and the subsequent annealing conditions [8].…”

Section: Introductionmentioning

confidence: 99%

“…A considerable amount of work has been published in the literature on the effects of the interfacial oxide on the base current [8]- [11] and emitter resistance [4]- [7], [12], [13] of polysilicon emitter contacts. It has been found that the nature of the interfacial oxide is significantly influenced by a number of factors, including the type of ex-situ clean (typically an HF etch) used prior to polysilicon deposition [9], [14], the polysilicon deposition conditions [15], [16], and the subsequent annealing conditions [8]. A common requirement in all the work mentioned above is the need to achieve a well controlled interfacial oxide that gives low values of emitter resistance.…”

Section: Introductionmentioning

confidence: 99%

Impact of ex-situ and in-situ cleans on the performance of bipolar transistors with low thermal budget in-situ phosphorus-doped polysilicon emitter contacts

Rahim

Marsh

Ashburn

et al. 2001

IEEE Trans. Electron Devices

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Abstract-This paper investigates the effects of an in-situ hydrogen bake and an ex-situ hydroflouric acid (HF) etch prior to polysilicon deposition on the electrical characteristics of bipolar transistors fabricated with low thermal budget in-situ phosphorusdoped polysilicon emitter contacts. Emitter contact deposition in a UHV-compatible low pressure chemical vapor deposition (LPCVD) cluster tool is also compared with deposition in a LPCVD furnace. Transmission electron microscopy (TEM) and secondary ion mass spectroscopy (SIMS) are used to characterize the emitter contact material and the interface structure and a comparison is made with Gummel plots and emitter resistances on bipolar transistors. The SIMS results show that an in-situ hydrogen bake in a cluster tool gives an extremely low oxygen dose at the interface of 6.3 10 13 cm 2 , compared with 7.7 10 14 and 2.9 10 15 cm 2 for an ex-situ HF etch and deposition in a cluster tool or a LPCVD furnace, respectively. TEM shows that the in-situ hydrogen bake results in single-crystal silicon with a high density of defects, including dislocations and twins. The ex-situ HF etch gives polycrystalline silicon for deposition in both a cluster tool and a LPCVD furnace. The single-crystal silicon emitter contact has an extremely low emitter resistance of 21 m 2 in spite of the high defect density and the light emitter anneal of 30 s at 900 C. This compares with emitter resistances of 151 and 260 m 2 for the polycrystalline silicon contacts produced using an ex-situ HF etch and deposition in a cluster tool or a LPCVD furnace, respectively. These values of emitter resistance correlate well with the interface oxygen doses and the structure of the interfacial oxide layer. The high defect density in the single-crystal silicon is considered to be due to the high concentration of phosphorus ( 5 10 19 cm 3 ) in the as-deposited layers.Index Terms-Bipolar transistor, cluster tool, in-situ doped polysilicon, polycrystalline silicon, polysilicon, polysilicon emitter.

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Silicon nitride/silicon oxide interlayers for solar cell passivating contacts based on PECVD amorphous silicon

Yan

Cuevas

Wan

et al. 2015

Physica Rapid Research Ltrs

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This Letter demonstrates improved passivating contacts for silicon solar cells consisting of doped silicon films together with tunnelling dielectric layers. An improvement is demonstrated by replacing the commonly used silicon oxide interfacial layer with a silicon nitride/silicon oxide double interfacial layer. The paper describes the optimization of such contacts, including doping of a PECVD intrinsic a‐Si:H film by means of a thermal POCl3 diffusion process and an exploration of the effect of the refractive index of the SiNx. The n+ silicon passivating contact with SiNx /SiOx double layer achieves a better result than a single SiNx or SiOx layer, giving a recombination current parameter of ∼7 fA/cm2 and a contact resistivity of ∼0.005 Ω cm2, respectively. These self‐passivating electron‐selective contacts open the way to high efficiency silicon solar cells. (© 2015 WILEY‐VCH Verlag GmbH &Co. KGaA, Weinheim)

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Physics, technology, and modeling of polysilicon emitter contacts for VLSI bipolar transistors

Cited by 148 publications

References 33 publications

Phosphorus-diffused polysilicon contacts for solar cells

Phosphorus-diffused polysilicon contacts for solar cells

Impact of ex-situ and in-situ cleans on the performance of bipolar transistors with low thermal budget in-situ phosphorus-doped polysilicon emitter contacts

Silicon nitride/silicon oxide interlayers for solar cell passivating contacts based on PECVD amorphous silicon

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