Chunmin Zhang
EPFL STI IMT ICLAB
MC A4 304 (Bâtiment MC)
Rue de la Maladière 71b, CP 526
CH-2002 Neuchâtel 2
Biography
Chunmin Zhang received her M.Sc. in Microelectronics and Solid-State Electronics delivered by Fudan University (China) in June 2014. Then she worked as a research assistant at Fudan University, studying semi-floating gate DRAM and normally-off GaN HEMTs.
In October 2015, she joined the Integrated Circuits Laboratory (ICLAB) at EPFL (Switzerland) and is currently pursuing a Ph.D. in Microsystems and Microelectronics under the supervision of Prof. Christian Enz. She focuses on semiconductor device modeling. Her main interest includes characterization and modeling of radiation effects on nanoscale MOS transistors for radiation-related applications.
Publications
Impact of GigaRad Ionizing Dose on 28nm Bulk MOSFE
Impact of GigaRad Ionizing Dose on 28nm Bulk MOSFETs for Future HL-LHC
The Large Hadron Collider (LHC) running at CERN will soon be upgraded to increase its luminosity giving rise to radiations reaching the level of GigaRad Total Ionizing Dose (TID). This paper investigates the impact of such high radiation on transistors fabricated in a commercial 28 nm bulk CMOS process with the perspective of using it for the future silicon based detectors. The DC electrical behavior of nMOSFETs is studied up to 1 Grad TID. All tested devices demonstrate to with stand that dose without any radiation-hard layout techniques. In spite of that, they experience a significant drain leakage current increase which may affect normal device operation. In addition, a moderate threshold voltage shift and subthreshold slope degradation is observed. These phenomena have been linked to radiation-induced effects like interface and switching oxide traps, together with parasitic side-wall transistors.
- Postprint: ESSDERC2016_28nm - PDF;
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GigaRad Total Ionizing Dose and Post-Irradiation E
GigaRad Total Ionizing Dose and Post-Irradiation Effects on 28 nm Bulk MOSFETs
The DC performance of both n- and pMOSFETs fabricated in a commercial-grade 28 nm bulk CMOS process has been studied up to 1 Grad of total ionizing dose and at post-irradiation annealing. The aim is to assess the potential use of such an advanced CMOS technology in the forthcoming upgrade of the Large Hadron Collider at CERN. The total ionizing dose effects show limited influence in the drive current of all the tested nMOSFETs. Nonetheless, the leakage current increases significantly, affecting the normal device operation of the nMOSFETs. These phenomena can be linked to the charge trapping in the oxides and at the Si/oxide interfaces, related to both the gate oxide and the shallow trench isolation oxide. In addition, it has been observed that the radiation-induced effects are partly recovered by the long-term post-irradiation annealing. To quantify the total ionizing dose effects on DC characteristics, the threshold voltage, subthreshold swing, and drain induced barrier lowering have also been extracted for nMOSFETs.
- Preprint: NSS2016_28nm - PDF;
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Characterization of GigaRad Total Ionizing Dose an
| Home > Characterization of GigaRad Total Ionizing Dose and Annealing Effects on 28 nm Bulk MOSFETs |
Characterization of GigaRad Total Ionizing Dose and Annealing Effects on 28 nm Bulk MOSFETs
This paper investigates the radiation tolerance of 28nm bulk n- and pMOSFETs up to 1 Grad of total ionizing dose (TID). The radiation effects on this commercial 28nm bulk CMOS process demonstrate a strong geometry dependence as a result of the complex interplay of oxide and interface charge trapping relevant to the gate-related dielectrics and the shallow trench isolation. The narrowest/longest-channel devices have the most serious performance degradation. In addition, nMOSFETs present a limited on-current variation and a significant off-current increase, while pMOSFETs show a negligible off-current change and a substantial on-current degradation. The postirradiation annealing annihilates or neutralizes oxide trapped positive charges and tends to partly recover the degraded device performance. To quantify the effects of TID and post-irradiation annealing, parameters including the threshold voltage, the free carrier mobility, the subthreshold swing, and the drain-induced barrier lowering are extracted.
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Total Ionizing Dose Effects on Analog Performance
Total Ionizing Dose Effects on Analog Performance of 28 nm Bulk MOSFETs
This paper uses the simplified charge-based EKV MOSFET model for studying the effects of total ionizing dose (TID) on analog parameters and figures-of-merit (FoMs) of 28nm bulk MOSFETs. These effects are demonstrated to be fully captured by the five key parameters of the simplified EKV model. The latter are extracted from the measured transfer characteristics at each TID. Despite the very few parameters, both the simplified large- and small-signal models present an excellent match with measurements at all levels of TID. The impacts of TID on essential parameters, including the drain leakage current, the threshold voltage, the slope factor, and the specific current, are then evaluated. Finally, TID effects on the transconductance Gm, the output conductance Gds, the intrinsic gain Gm/Gds and the transconductance efficiency Gm/ID are investigated.
- Preprint: ESSDERC2017_28nm - PDF;
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Characterization and Modeling of Gigarad-TID-Induc
| Accueil > Characterization and Modeling of Gigarad-TID-Induced Drain Leakage Current of 28-nm Bulk MOSFETs |
Characterization and Modeling of Gigarad-TID-Induced Drain Leakage Current of 28-nm Bulk MOSFETs
This paper characterizes and models the effects of total ionizing dose (TID) up to 1 Grad(SiO 2 ) on the drain leakage current of nMOSFETs fabricated with a commercial 28-nm bulk CMOS process. Experimental comparisons among individual nMOSFETs of various sizes provide insight into the TID-induced lateral parasitic devices, which contribute the most to the significant increase up to four orders of magnitude in the drain leakage current. We introduce a semiempirical physics-based approach using only three parameters to model the parallel parasitic and total drain leakage current as a function of TID. Taking into account the gate independence of the drain leakage current at high TID levels, we model the lateral parasitic device as a gateless charge-controlled device by using the simplified charge-based Enz-Krummenaker-Vittoz (EKV) MOSFET model. This approach enables us to extract the equivalent density of trapped charges related to the shallow trench isolation oxides. The adopted simplified EKV MOSFET model indicates the weak inversion operation of the lateral parasitic devices.
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Bias Dependence of Total Ionizing Dose Effects on
| Accueil > Bias Dependence of Total Ionizing Dose Effects on 28-nm Bulk MOSFETs |
Bias Dependence of Total Ionizing Dose Effects on 28-nm Bulk MOSFETs
This paper investigates the effects of total ionizing dose up to 1 Grad on 28-nm bulk MOSFETs under different bias conditions during irradiation. The aim is to assess the potential use of this commercial bulk CMOS technology in the future high-luminosity Large Hadron Collider at CERN that will require highly improved radiation-tolerant tracking systems.
- Fichiers: NSS2018_conference_record_v3 - PDF;
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Mobility Degradation of 28-nm Bulk MOSFETs Irradia
| Accueil > Mobility Degradation of 28-nm Bulk MOSFETs Irradiated to Ultrahigh Total Ionizing Doses |
Mobility Degradation of 28-nm Bulk MOSFETs Irradiated to Ultrahigh Total Ionizing Doses
Using the Y–function method, this paper experimentally investigates the effects of total ionizing dose up to 1 Grad on the channel mobility of a commercial 28-nm bulk CMOS process.
- PREPRINT: icta2018_v4_mobi_degra - PDF;
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