The effect of fluorine from BF<sub>2</sub> source/drain extension implants on performance of PMOS transistors with thin gate oxides

Bourdelle, K.K.; Gossmann, H.‐J.; Chaudhry, S.; Agarwal, Aditya

doi:10.1109/55.924843

Cited by 5 publications

(3 citation statements)

References 11 publications

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“…We found that the positive fixed charge and the interface state density had large values near the gate edge and the gate-S/D overlap regions, as has been observed previously. 4 The NBTIs we observed for the samples having B-and BF 2 -implanted S/D and poly-Si films ͑Fig. 8a and b͒ display opposing trends for their different channel lengths.…”

Section: Resultsmentioning

confidence: 80%

“…2,3 Bourdelle et al have demonstrated that the performance of p-type metal oxide semiconductor field effect transistors ͑pMOSFETs͒ is degraded by the enhanced boron penetration that arises from the presence of fluorine from the BF 2 extension implants. 4 However, incorporation of small amounts of fluorine into metal oxide semiconductor ͑MOS͒ devices is known to dramatically improve the Si/SiO 2 interface resistance to ionizing radiation or hot-electron damage. 5 It has been reported that the threshold voltage shift ͑⌬V th ͒ resulting from NBTI degradation of pMOSFETs limits the device lifetime when the gate oxide thickness is below 3 nm.…”

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confidence: 99%

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Channel Length Dependence of Negative Bias Temperature Instability on pMOSFETs with either B- or BF[sub 2]-Implanted Source/Drain

Pan

2006

J. Electrochem. Soc.

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We evaluated the channel length dependence of the negative bias temperature instability in deep-submicrometer p-type metal oxide semiconductor field effect transistors (pMOSFETs) having either a boron- or BnormalF2 -implanted source/drain (S/D) and a poly-Si film. We found that long-channel-length (10μm) pMOSFETs having a BnormalF2 -implanted S/D exhibit a larger negative threshold voltage shift (ΔVth) than do those having a B-implanted S/D. This phenomenon indicates that fluorine atoms enhance boron diffusion into the gate oxide region, resulting in the increase in fixed-positive oxide charges and the decreased density of interface states. In contrast, the shorter-channel-length device having a BnormalF2 -implanted S/D displays a smaller value of ΔVth than does that possessing a B-implanted S/D. These observations indicate that fluorine atoms not only induce negative interface states but also suppress the positive interface traps that occur during NBTI stressing.

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Section: Resultsmentioning

confidence: 80%

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confidence: 99%

Channel Length Dependence of Negative Bias Temperature Instability on pMOSFETs with either B- or BF[sub 2]-Implanted Source/Drain

Pan

2006

J. Electrochem. Soc.

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“…Fluorinated gate oxide dielectrics have attracted considerable attention over the past years. [1][2][3][4][5][6][7][8] The incorporation of approximate amounts of F into the oxide near the Si/SiO 2 interface was shown to improve the oxide breakdown distribution and the interface hardness against hot-electron and radiation damages of metal-oxidesemiconductor ͑MOS͒ devices. [9][10][11][12][13][14] The improved reliability is that fluorine can break strained Si-O-Si bonds to cause local strain relaxation, and fluorine in the oxide can replace weak Si-H bonds to form strong Si-F bonds.…”

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Electrical and Reliability Improvement in Polyoxide by Fluorine Implantation

Kao

Lai

Lee

2007

J. Electrochem. Soc.

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We show that the incorporation of fluorine into the oxide grown on polysilicon ͑polyoxide͒ not only improves the electrical characteristics ͑i.e., lower leakage current, higher electrical breakdown field͒, but also improves the reliability ͑lower electron trapping rate, larger Q bd ͒. This improvement is believed to be due to the stress relaxation of the polyoxide and smoother polysilicon/polyoxide interface by the fluorine incorporation. The optimum fluorine dose ͑2 ϫ 10 14 ͒ shows the best characteristics such as E bd over 12 MV/cm and Q bd ϳ 2 C/cm 2 . However, excessive fluorination ͑1 ϫ 10 15 ͒ seems to result in performance degradation due to the generation of nonbridging oxygen centers.Fluorinated gate oxide dielectrics have attracted considerable attention over the past years. 1-8 The incorporation of approximate amounts of F into the oxide near the Si/SiO 2 interface was shown to improve the oxide breakdown distribution and the interface hardness against hot-electron and radiation damages of metal-oxidesemiconductor ͑MOS͒ devices. 9-14 The improved reliability is that fluorine can break strained Si-O-Si bonds to cause local strain relaxation, and fluorine in the oxide can replace weak Si-H bonds to form strong Si-F bonds. 15 The oxides grown incorporated with fluorine had also been reported to cause local strain-stress relaxation and to exhibit less interface state density because of the passivation of interface defects such as dangling bonds and strain bonds. 16 Recently, the effects of fluorine on the defect passivation and the hot carrier endurance of polysilicon thin-film transistors ͑TFTs͒ due to the similarity between the poly-Si/SiO 2 interface and the polysilicon grain boundaries were investigated. 17-19 The fluorine implantation not only improved the electrical characteristics such as on current, subthreshold swings, and mobility, but also improved the hot carrier immunity of the device 20,21 due to the fluorine passivation more uniformly reducing the trap states in the band tail and those in the midgap.The quality of polysilicon oxide ͑polyoxide͒ plays an important role in the performance of polysilicon TFTs 22 and nonvolatile memories. 23 The electrical properties of the polyoxide are mainly determined by the polysilicon/polyoxide interface roughness. 24 It had been demonstrated that the rough and nonuniform surface at the polysilicon/polyoxide interface enhanced the local electric field and resulted in low breakdown strength as compared to single crystalline silicon oxide. 25 It had also been reported that a compressive stress two or more times larger than the stress in the thermal oxide of single crystal was formed on the thermally grown polyoxide. This increased stress in thermal polyoxide is due to the oxidized polysilicon at grain boundaries enhancing the interface roughness, and causing an additionally compressive stress. 26 In this work, we show that the fluorine ions are directly implanted into the bottom polysilicon and the fluorinated polyoxides are grown in dilute ͑N 2 + O 2 ͒ ambie...

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Boron penetration through gate oxide from decaborane gate electrode implantation

Bourdelle¹,

Agarwal

Perel

2003

Electron. Lett.

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The effect of fluorine from BF₂ source/drain extension implants on performance of PMOS transistors with thin gate oxides

Cited by 5 publications

References 11 publications

Channel Length Dependence of Negative Bias Temperature Instability on pMOSFETs with either B- or BF[sub 2]-Implanted Source/Drain

Channel Length Dependence of Negative Bias Temperature Instability on pMOSFETs with either B- or BF[sub 2]-Implanted Source/Drain

Electrical and Reliability Improvement in Polyoxide by Fluorine Implantation

Boron penetration through gate oxide from decaborane gate electrode implantation

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The effect of fluorine from BF2 source/drain extension implants on performance of PMOS transistors with thin gate oxides

Cited by 5 publications

References 11 publications

Channel Length Dependence of Negative Bias Temperature Instability on pMOSFETs with either B- or BF[sub 2]-Implanted Source/Drain

Channel Length Dependence of Negative Bias Temperature Instability on pMOSFETs with either B- or BF[sub 2]-Implanted Source/Drain

Electrical and Reliability Improvement in Polyoxide by Fluorine Implantation

Boron penetration through gate oxide from decaborane gate electrode implantation

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The effect of fluorine from BF₂ source/drain extension implants on performance of PMOS transistors with thin gate oxides