[go: up one dir, main page]

WO2017199110A1 - Capteur microélectrique pour authentification biométrique - Google Patents

Capteur microélectrique pour authentification biométrique Download PDF

Info

Publication number
WO2017199110A1
WO2017199110A1 PCT/IB2017/051884 IB2017051884W WO2017199110A1 WO 2017199110 A1 WO2017199110 A1 WO 2017199110A1 IB 2017051884 W IB2017051884 W IB 2017051884W WO 2017199110 A1 WO2017199110 A1 WO 2017199110A1
Authority
WO
WIPO (PCT)
Prior art keywords
sensor
barrier layer
transistor
layer
microelectronic sensor
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Ceased
Application number
PCT/IB2017/051884
Other languages
English (en)
Inventor
Ayal RAM
Amir Lichtenstein
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Rg Innovations Pte Ltd
Original Assignee
Rg Innovations Pte Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Rg Innovations Pte Ltd filed Critical Rg Innovations Pte Ltd
Priority to CN201780041773.6A priority Critical patent/CN109475297B/zh
Priority to EP17732999.2A priority patent/EP3457916A1/fr
Publication of WO2017199110A1 publication Critical patent/WO2017199110A1/fr
Anticipated expiration legal-status Critical
Ceased legal-status Critical Current

Links

Classifications

    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N27/00—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means
    • G01N27/26—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating electrochemical variables; by using electrolysis or electrophoresis
    • G01N27/403—Cells and electrode assemblies
    • G01N27/414—Ion-sensitive or chemical field-effect transistors, i.e. ISFETS or CHEMFETS
    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10D—INORGANIC ELECTRIC SEMICONDUCTOR DEVICES
    • H10D30/00—Field-effect transistors [FET]
    • H10D30/40—FETs having zero-dimensional [0D], one-dimensional [1D] or two-dimensional [2D] charge carrier gas channels
    • H10D30/47—FETs having zero-dimensional [0D], one-dimensional [1D] or two-dimensional [2D] charge carrier gas channels having 2D charge carrier gas channels, e.g. nanoribbon FETs or high electron mobility transistors [HEMT]
    • H10D30/471—High electron mobility transistors [HEMT] or high hole mobility transistors [HHMT]
    • H10D30/475—High electron mobility transistors [HEMT] or high hole mobility transistors [HHMT] having wider bandgap layer formed on top of lower bandgap active layer, e.g. undoped barrier HEMTs such as i-AlGaN/GaN HEMTs
    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10D—INORGANIC ELECTRIC SEMICONDUCTOR DEVICES
    • H10D62/00—Semiconductor bodies, or regions thereof, of devices having potential barriers
    • H10D62/10—Shapes, relative sizes or dispositions of the regions of the semiconductor bodies; Shapes of the semiconductor bodies
    • H10D62/117—Shapes of semiconductor bodies
    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10D—INORGANIC ELECTRIC SEMICONDUCTOR DEVICES
    • H10D62/00—Semiconductor bodies, or regions thereof, of devices having potential barriers
    • H10D62/10—Shapes, relative sizes or dispositions of the regions of the semiconductor bodies; Shapes of the semiconductor bodies
    • H10D62/13—Semiconductor regions connected to electrodes carrying current to be rectified, amplified or switched, e.g. source or drain regions
    • H10D62/149—Source or drain regions of field-effect devices
    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10D—INORGANIC ELECTRIC SEMICONDUCTOR DEVICES
    • H10D62/00—Semiconductor bodies, or regions thereof, of devices having potential barriers
    • H10D62/80—Semiconductor bodies, or regions thereof, of devices having potential barriers characterised by the materials
    • H10D62/85—Semiconductor bodies, or regions thereof, of devices having potential barriers characterised by the materials being Group III-V materials, e.g. GaAs
    • H10D62/8503—Nitride Group III-V materials, e.g. AlN or GaN
    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10D—INORGANIC ELECTRIC SEMICONDUCTOR DEVICES
    • H10D64/00—Electrodes of devices having potential barriers
    • H10D64/20—Electrodes characterised by their shapes, relative sizes or dispositions 
    • H10D64/23—Electrodes carrying the current to be rectified, amplified, oscillated or switched, e.g. sources, drains, anodes or cathodes
    • H10D64/251—Source or drain electrodes for field-effect devices
    • H10D64/256—Source or drain electrodes for field-effect devices for lateral devices wherein the source or drain electrodes are recessed in semiconductor bodies

Definitions

  • the present application relates to the field of microelectronic sensors based on high-electron-mobility transistors and their use in detection and continuous monitoring of electrical signals generated by a human body.
  • the present application relates to the open-gate pseudo-conductive high-electron-mobility transistors and their use in a biometric authentication.
  • a new type of the biometric authentication device by Bionym based on the electrocardiogram (ECG)
  • ECG electrocardiogram
  • This device called “Nymi”
  • Nymi is capable of capturing a unique electrocardiographic waveform of a person, and further maps it to ECG patterns.
  • Nymi is continuously worn as a bracelet or wristband on the user's wrist and uses learning algorithms to memorise the user's ECG patterns in order to increase the quality and authentication level of the user.
  • WO 2012151680 by Bionym discloses a biometric sensor based on the analysis of the ECG signals used to authenticate one or more individuals. This sensor relies on authenticating identity by matching the overall shape of the user's ECG waveform (captured via an electrocardiogram sensor).
  • a transistor comprises a substrate, on which a multilayer he tero-j unction structure is deposited.
  • This hetero-j unction structure may comprise at least two layers, a buffer layer and a barrier layer, which are grown from III-V single-crystalline or polycrystalline semiconductor materials.
  • a conducting channel comprising a two-dimensional electron gas (2DEG), in case of two-layers configuration, or a two-dimensional hole gas (2DHG), in case of three- layers configuration, is formed at the interface between the buffer and barrier layers and provides electron or hole current in the system between source and drain electrodes.
  • the source and drain, either ohmic or capacitively-coupled (non-ohmic) contacts are connected to the formed 2DEG/2DHG channel and to electrical metallizations, the latter are placed on top of the transistor and connect it to the sensor system.
  • An optional dielectric layer is deposited on top of the hetero-junction structure.
  • the open gate area of the transistor is formed between the source and drain areas as a result of recessing or growing of the top layer to a specific thickness.
  • the source and drain contacts are non-ohmic (capacitively-coupled), in order to electrically contact the 2DEG/2DHG channel underneath, which is about 5-20 nm bellow metallizations, the AC-frequency regime is used.
  • the capacitive coupling of the non-ohmic metal contacts with the 2DEG/2DHG channel is normally induced at the frequency higher than 30 kHz.
  • the DC readout cannot be carried out. Instead, the AC readout or impedance measurements of the electric current flowing through the 2DEG/2DHG-channel are performed.
  • the thickness of the top layer in the open gate area between the source and drain contacts is 5-9 nm, preferably 6-7 nm, more preferably 6.3 nm, and that corresponds to the pseudo-conducting current range between normally-on and normally-off operation mode of the transistor,
  • the surface of the top layer within the open gate area between the source and drain contacts has a roughness of about 0.2 nm or less, preferably 0.1 nm or less, more preferably 0.05 nm, and (iii) the non-ohmic source and drain contacts for the capacitive coupling with the conductive 2DEG/2DHG channel optionally replace the ohmic contacts.
  • the PC-HEMT multilayer hetero-junction structure of the present application is grown from any available III-V single-crystalline or polycrystalline semiconductor materials, such as GaN/AlGaN, GaN/AIN, GaN/InN,
  • the hetero-junction structure may be a three-layer structure consisting of two buffer layers and one barrier layer squeezed between said buffer layers like in a sandwich. This may lead to formation of the two-dimensional hole gas (2DHG) in the top buffer layer above the barrier layer which results in reversing polarity of the transistor.
  • 2DHG two-dimensional hole gas
  • the present application provides the PC-HEMT-based microelectronic senor for biometric authentication and method for using thereof.
  • Fig. la schematically shows a cross-sectional view of the PC-HEMT of an embodiment without a dielectric layer and with an RF generator.
  • Fig. lb schematically shows a cross-sectional view of the PC-HEMT of an embodiment with a dielectric layer and with an RF generator.
  • Fig. 2 schematically shows the dependence of the source-drain current (a charge carrier density) induced inside the 2DEG channel of a GaN/AlGaN HEMT on the thickness of the AlGaN barrier layer recessed in the open gate area.
  • Fig. 3 illustrates a theory behind the 2DEG formation (charge neutrality combined with the lowest energy level) at the conduction band discontinuity.
  • Fig. 4a shows sensitivity of the PC-HEMT for the 22-nm AlGaN barrier layer which is normally grown and then recessed to 6-7 nm.
  • Fig. 4b shows sensitivity of the PC-HEMT for the ultrathin AlGaN barrier layer which is grown to 6-7 nm and then recessed down to 5-6 nm and etched with plasma.
  • Fig. 5a schematically shows the formation of the 2DEG and 2DHG conducting channels in the Ga-face three-layer AlGaN/GaN PC-HEMT structure.
  • Fig. 5b schematically shows the formation of the 2DEG and 2DHG conducting channels in the N-face three-layer AlGaN/GaN PC-HEMT structure.
  • Fig. 5c schematically shows the formation of the 2DEG conducting channel in the N-face three-layer AlGaN/GaN PC-HEMT structure with an ultrathin Al(GaN)N layer for improved confinement.
  • Fig. 6a shows a cross-sectional view of the PC-HEMT of an embodiment with a non- recessed AlGaN barrier layer and with an RF generator.
  • Fig. 7a schematically shows a cross-sectional view of the PC-HEMT of an embodiment with capacitively-coupled non-ohmic source and drain contacts, without a dielectric layer and with an RF generator.
  • Fig. 7b schematically shows a cross-sectional view of the PC-HEMT of an embodiment with highly-doped source and drain areas and with an RF generator.
  • Fig. 8a schematically shows a PC-HEMT-based microelectronic sensor of an embodiment with a common suspended metal gate electrode and with an RF generator.
  • Fig. 8b schematically shows a PC-HEMT-based microelectronic sensor of an embodiment with a common mechanically suspended metal gate electrode, which has no physical contact with the PC-HEMT or array thereof.
  • Fig. 9 schematically shows a PC-HEMT-based microelectronic sensor of an embodiment with a common metal gate electrode placed in contact with the PC-HEMT or array thereof and discharged via the connection to a source electrode.
  • Fig. 10 schematically shows an optoelectronic sensor of an embodiment.
  • Fig. 11a shows the cardio-pulmonary hemodynamic data recorded with the sensor of an embodiment for User 1 with the 20 Hz low-pass filter.
  • Fig. lib shows the cardio-pulmonary hemodynamic data recorded with the sensor of an embodiment for User 1 with the 1-20 Hz band-pass filter.
  • Fig. 11c shows the cardio-pulmonary hemodynamic data recorded with the sensor of an embodiment for User 2 with the 20 Hz low-pass filter.
  • Fig. lid shows the cardio-pulmonary hemodynamic data recorded with the sensor of an embodiment for User 2 with the 1-20 Hz band-pass filter.
  • Figs, lle-llf show the ID FFT spectra calculated for User 1 and User 2.
  • Fig. llg shows the cardio-pulmonary hemodynamic data recorded with the sensor of an embodiment for User 3 with the 20 Hz low-pass filter.
  • Fig. llh shows the cardio-pulmonary hemodynamic data recorded with the sensor of an embodiment for User 3 with the 1-20 Hz band-pass filter.
  • Fig. Hi shows the cardio-pulmonary hemodynamic data recorded with the sensor of an embodiment for User 4 with the 20 Hz low-pass filter.
  • Fig. llj shows the cardio-pulmonary hemodynamic data recorded with the sensor of an embodiment for User 4 with the 1-20 Hz band-pass filter.
  • Figs, llk-111 show the ID FFT spectra calculated for User 3 and User 4.
  • Figs, llm-lln show the cardio-pulmonary hemodynamic data recorded with the sensor of an embodiment for User 5 with the 20 Hz low-pass filter and 1-20 Hz band -pass filter.
  • Fig. Ho shows the ID FFT spectra calculated for User 5.
  • Fig. 12a shows the single heart cycles extracted from the above data for the five users.
  • Fig. 12b shows the heart cycles of the five different users normalised on a time and amplitude scale.
  • Fig. 13 shows a prototype of the biometric authentication device based on the sensor of an embodiment.
  • the senor of embodiments uses relatively complex waveforms recorded from the user's heart rhythmic cycles, hemodynamics of the right atrium and left atrium, pulmonary cycles, intestine, electromyography (EMG) of the nervous system, circulatory system and biomechanical waveforms generated by the user's internal organs. In addition, it is about lxlO 9 times mores sensitive than the Nymi device or any similar commercially available ECG-based sensor.
  • the major problem with the Nymi-type devices or any ECG-based sensors is their pronounced sensitivity to physiological conditions of a user. Many medications and various psychological conditions can directly affect, change and alter the heart rhythmic cycles, which are recorded by the sensor, so that the general authentication system may fail at times.
  • the ECG-based sensor or similar sensor sensing the hemodynamic electrical signals of the heart and lungs requires a full heart cycle or even two in order to authenticate the user. In a real- world application, this is a huge drawback in comparison to the existing capacitive fingerprint sensors, since it would take too long to authenticate the user or, for example to unlock a phone, compared to existing single-second authentication time.
  • the sensor of an embodiment of the present application is able to record a total one-time mapping of electrical fields produced by the user's internal body organs, for a digital snapshot of the user, which is completely unique as the user's genetic code.
  • the biometric authentication sensor of embodiments integrated into a monolithic printed- circuit board (PCB) chip performs the authentication completely on the hardware layer. It is essentially a closed end-to-end system requiring only a single point of contact to the user's body point at the time of authentication and having the highest level of security.
  • the biometric authentication sensor of embodiments is capable of detecting with its proximity sensor a user's distance and to prepare for instant and real-time authentication.
  • the instant biometric sensor does not need to be continuously worn on the user to learn the user's ECG data, but takes a one-time single snapshot during the setup to authenticate the user at any time.
  • the biometric sensor of embodiments can be integrated into any type of electronic system for a system switch, for the authentication of the user, or for locking devices on their hardware layer, where software does not play a role, and the highest level of security therefore can be achieved.
  • the biometric sensor of embodiments may be integrated into a mobile phone holder casing or as a sticker on the phone.
  • the sensor can be used to block and lockout memory cells on sensitive data devices and credit cards as a built-in integrated circuit (on a PCB) or as a standalone device. The latter is connected via Bluetooth to lock any device, by fixing this device to any Bluetooth connected device.
  • the biometric system can also be integrated directly as a component into a smartphone to provide a hardware layer lock to the phone or device, which creates a secure layer to the device's hardware with no authentication.
  • the biometric authentication sensor of embodiments is based on the open-gate pseudo-conductive high-electron mobility transistor (PC-HEMT) described, for example in the co-pending patent application U.S. 15/157,285, from which the present application claims priority.
  • PC-HEMT pseudo-conductive high-electron mobility transistor
  • the phenomenon of the pseudo-conductive current described in that application makes the biometric sensor of embodiments of the present application extremely sensitive.
  • working principle of the PC-HEMT sensor is based on ultra-high charge sensitivity at the sensor/body tissue surface interface.
  • a human heart physically represents a volume source of an electric dipole field acting within a volume electrolytic conductor represented by human body.
  • GUI graphical user interface
  • Fig. la shows a cross-sectional view of the PC-HEMT of an embodiment of the present application with a radio-frequency generator (20) connected to the PC-HEMT, said PC-HEMT comprising:
  • a multilayer hetero-j unction structure made of III-V single-crystalline or polycrystalline semiconductor materials, said structure comprising at least one buffer layer (11) and at least one barrier layer (12), said layers being stacked alternately, and said structure being deposited on a substrate layer (10);
  • a conducting channel (13) comprising a two-dimensional electron gas (2DEG) or a two-dimensional hole gas (2DHG), formed at the interface between said buffer layer (11) and said barrier layer (12) and providing electron or hole current in said transistor between source and drain contacts (15);
  • the thickness (d) of said barrier layer (12) beneath said metal gate electrode (17), between said source and drain contacts (15), is about 5-9 nm which corresponds to the pseudo-conducting current range between normally-on and normally-off operation mode of the transistor, and
  • the surface of said barrier layer (12) has a roughness of about 0.2 nm or less.
  • the PC-HEMT which is shown on Fig. la, may further comprise a dielectric layer (16) of 1-10 nm thickness.
  • This dielectric layer (16) is deposited on top of the barrier layer (12), as schematically shown in Fig. lb.
  • Metal gate electrode (17) is then placed directly on the dielectric layer (16) and is electrically connected to a wire contact with any single body point. This configuration prevents strong electrical leakage at the metal/barrier layer interface.
  • the dielectric layer (16) used for device passivation is made, for example, of SiO-SiN-SiO ("ONO") stack of 100-100-100 nm thickness or SiN-SiO-SiN (“NON”) stack having the same thicknesses.
  • This dielectric layer (16) is deposited on top of the barrier layer by a method of plasma-enhanced chemical vapour deposition (PECVD), which is a stress-free deposition technique.
  • PECVD plasma-enhanced chemical vapour deposition
  • the III-V semiconductor materials are selected from the pairs of GaN/AlGaN, GaN/AIN, GaN/InN, GaN/InAIN, InN/InAIN, GaN/InAlGaN, GaAs/AlGaAs and LaA10 3 /SrTi0 3 .
  • the electrical metallizations (14) connect the transistor to the electric circuit and allow the electric current to flow between ohmic contacts (15) via the two- dimensional electron gas (2DEG) channel (13).
  • the metallizations (14) are made of metal stacks, such as Cr/Au, Ti/Au, Ti/W, Cr/Al and Ti/Al.
  • the Cr or Ti layers of the metal stack is, for example, of 5-10 nm thickness, while the second metal layer, such as Au, W and Al, is of 100-400 nm thickness.
  • the metallizations (14) are chosen according to the established technology and assembly line at a particular clean room fabrication facility.
  • the source and drain ohmic contacts (15) are made of metal stacks, such as Ti/Al/Mo/Au, Ti/Al/Ni/Au, Ti/Au and Ti/W having 15-50 nm thickness.
  • substrate layer (10) comprises a suitable material for forming the barrier layer and is composed, for example, of sapphire, silicon, silicon carbide, gallium nitride or aluminium nitride.
  • the he tero-j unction structure (11,12) is deposited on the substrate layer (10), for example, by a method of metalorganic chemical vapour deposition (MOCVD), and forms the 2DEG or 2DHG channel (13) in the close proximity to the interface between the buffer layer (11) and the barrier layer (12).
  • the barrier layer (12) then may be either recessed or grown as a thin layer between the source and drain contacts (15).
  • the 2DEG or 2DHG channel (13) formed near the interface between the buffer layer (11) and the barrier layer (12) serves as a main sensitive element of the transistor reacting to a surface charge and potential.
  • the 2DEG or 2DHG channel (13) is configured to interact with very small variations in surface or proximal charge or changes of electrical field on the barrier layer/metal gate interface interacting with the donor-like surface trap states of the barrier layer. This will be discussed below in detail.
  • the two-dimensional hole gas may also be a possible current carrier in a specific hetero-j unction structure.
  • 2DEG may be equally replaced with the term “2DHG” without reference to any specific PC-HEMT configuration.
  • the barrier layer (12) has a thickness of 5-9 nm in the gate area (d) between the source and drain contacts (15), preferably 6-7 nm, more preferably 6.3 nm, which corresponds to the pseudo-conducting current range between normally-on and normally-off operation mode of the transistor, and
  • the surface of this barrier layer (12) within the gate area has a roughness of 0.2 nm or less, preferably 0.1 nm or less, more preferably 0.05 nm.
  • the above specific thickness of the barrier layer (12) beneath the metal gate electrode (17), between the source and drain contacts is achieved by either dry etching the semiconductor material of this layer, i.e. recessing the barrier layer with the etching rate of 1 nm per 1-2 min in a controllable process, or coating the buffer layer (11) with an ultrathin layer of the III-V semiconductor material.
  • the surface of the recessed ultrathin barrier layer is post- treated with plasma (chloride) epi-etch process. Consequently, the natively passivated surface is activated by the plasma etch to create an uncompensated (ionised) surface energy bonds or states, which are neutralized after MOCVD growing.
  • Fig. 2 shows the dependence of the source-drain current (a charge carrier density) on the recessed barrier layer thickness.
  • the HEMTs that have a thickness of the barrier layer larger than about 9 nm are normally-on devices.
  • a thin sheet of charges is induced at the top and bottom of the interfaces of the barrier layer.
  • a high electric field is induced in the barrier layer, and surface donor states at the top interface start donating electrons to form the 2DEG channel at the proximity of the he tero-j unction interface without the application of a gate bias.
  • These HEMTs are therefore normally-on devices.
  • the HEMTs that have a thickness of the barrier layer in the open gate area lower than about 5 nm act as normally-off devices.
  • the barrier layer recessed or grown to 5-9 nm is optimised for significantly enhancing sensitivity of the PC-HEMT sensor.
  • This specific thickness of the barrier layer corresponds to the "pseudo-conducting" current range between normally-on and normally -off operation modes of the transistor.
  • "Pseudo-contacting" current range of the HEMT is defined as an operation range of the HEMT between its normally-on and normally-off operation modes.
  • Trap states are states in the band-gap of a semiconductor which trap a carrier until it recombines.
  • Surface states are states caused by surface reconstruction of the local crystal due to surface tension caused by some crystal defects, dislocations, or the presence of impurities.
  • Such surface reconstruction often creates "surface trap states” corresponding to a surface recombination velocity.
  • Classification of the surface trap states depends on the relative position of their energy level inside the band gap.
  • the surface trap states with energy above the Fermi level are acceptor-like, attaining negative charge when occupied.
  • the surface trap states with energy below the Fermi level are donor-like, positively charged when empty and neutral when occupied.
  • These donor-like surface trap states are considered to be the source of electrons in the formation of the 2DEG channel. They may possess a wide distribution of ionization energies within the band gap and are caused by redox reactions, dangling bonds and vacancies in the surface layer.
  • a balance always exists between the 2DEG channel density and the number of ionised surface donors which is governed by charge neutrality and continuity of the electric field at the interfaces.
  • the donor-like surface traps at the surface of the barrier layer of the transistor are one of the most important sources of the 2DEG in the channel.
  • the surface trap state is below the Fermi level.
  • the energy of the surface trap state approaches the Fermi energy until it coincides with it.
  • the thickness of the barrier layer corresponding to such situation is defined as "critical”. At this point, electrons filling the surface trap state are pulled to the channel by the extremely strong polarisation-induced electric field found in the barrier to form the 2DEG instantly.
  • Fig. 2 shows the dependence of the source-drain current (a charge carrier density) on the recessed AlGaN barrier layer thickness.
  • An energy equilibrium between the donor surface trap states and the AlGaN tunnel barrier leads to the 2DEG formation (charge neutrality combined with the lowest energy level) at the conduction band discontinuity.
  • decrease in the thickness of the barrier layer results in increase of the energy barrier.
  • the ionisable donor-like surface trap states responsible for electron tunnelling from the surface to the 2DEG drift bellow the Fermi level, thereby minimizing the electron supply to the 2DEG channel.
  • Fig. 3 Therefore, the recess of the AlGaN layer from 9 nm to 5 nm leads to extremely huge drop in the 2DEG conductivity for six orders of magnitude.
  • the mechanism of the 2DEG depletion based on recessing the barrier layer is strongly dependent on the donor-like surface trap states (or total surface charge).
  • the thickness of the barrier layer decreases, less additional external charge is needed to apply to the barrier layer surface in order to deplete the 2DEG channel.
  • There is a critical (smallest) barrier thickness when the 2DEG channel is mostly depleted but still highly conductive due to a combination of the energy barrier and the donor surface trap states energy.
  • the critical thickness even the smallest energy shift at the surface via any external influence, such as surface charging or reaction, leads immediately to the very strong 2DEG depletion.
  • the surface of the barrier layer at this critical thickness is extremely sensitive to any smallest change in the electrical current of the metal gate.
  • Vitushinsky et al (2013) has recently proved the above concept of pseudo- conducting by demonstrating that recessing AlGaN barrier layer of AlGaN/GaN hetero- structures in the open gate area can dramatically enhance the sensitivity of the transistor to surface interactions. They investigated the response to ppb levels of N0 2 in humid conditions, which finds application in air quality monitoring. They demonstrated that when the AlGaN barrier layer is relatively thick (22 nm), the surface charge sensitivity is around six orders of magnitude smaller compared to 6.3 nm AlGaN barrier. Recess of the gate area of the barrier layer down to 6.3 nm significantly reduced the 2DEG density, brought the PC-HEMT to the "near threshold" operation and resulted in highly increased sensitivity. Thus, the specific 5-9 nm thickness of the barrier layer responsible for the pseudo-conducting behaviour of the PC-HEMT gives the sensor an enormous sensitivity.
  • roughness of the barrier layer surface is another very important parameter that has not been previously disclosed. It has been surprisingly found that that the roughness of the barrier layer surface bellow 0.2 nm prevents scattering of the donor-like surface trap states.
  • Fig. 4a shows a decrease of electrical resistance for each treatment cycle with time for the 6-nm grown AlGaN barrier layer after short plasma activation (60 s).
  • the AlGaN barrier layer is not recessed, but instead the 2-3-nm SiN layer (so called "GaN cap layer”) is cracked and the surface states are ionised.
  • Fig. 4b shows the same plot, but for the HEMT having the barrier layer recessed to 5-6 nm and treated with plasma (etched) for 450 s. The difference in sensitivity was found to be almost one thousand times in the favour of the recessed structure.
  • roughness of the barrier layer surface is another very important parameter that has not been previously disclosed.
  • the hetero-junction structure may be a three-layer structure consisting of two buffer layers and one barrier layer squeezed between said buffer layers like in a sandwich, wherein the top layer is a buffer layer. This may lead to formation of the two-dimensional hole gas (2DHG) in the top buffer layer above the barrier layer which results in reversing polarity of the transistor compared to the two-layer structure discussed above.
  • III-V nitride semiconductor materials strongly affects the performance of the transistors based on these semiconductors.
  • the quality of the wurtzite GaN materials can be varied by their polarity, because both the incorporation of impurities and the formation of defects are related to the growth mechanism, which in turn depends on surface polarity.
  • the occurrence of the 2DEG/2DHG and the optical properties of the hetero-junction structures of nitride -based materials are influenced by the internal field effects caused by spontaneous and piezo-electric polarizations.
  • Devices in all of the III-V nitride materials are fabricated on polar ⁇ 0001 ⁇ surfaces.
  • any GaN layer has two surfaces with different polarities, a Ga-polar surface and an N-polar surface.
  • a Ga-polar surface is defined herein as a surface terminating on a layer of Ga atoms, each of which has one unoccupied bond normal to the surface.
  • Each surface Ga atom is bonded to three N atoms in the direction away from the surface.
  • an N-polar surface is defined as a surface terminating on a layer of N atoms, each of which has one unoccupied bond normal to the surface.
  • Each surface N atom is also bonded to three Ga atoms in the direction away from the surface.
  • the N-face polarity structures have the reverse polarity to the Ga-face polarity structures.
  • the barrier layer is always placed on top of the buffer layer.
  • the layer which is therefore recessed is the barrier layer, specifically the AlGaN layer.
  • the hetero-junction structure is grown along the ⁇ 0001 ⁇ -direction or, in other words, with the Ga-face polarity.
  • the physical mechanism that leads to the formation of the 2DEG is a polarisation discontinuity at the AlGaN/GaN interface, reflected by the formation of the polarisation- induced fixed interface charges that attract free carriers to form a two-dimensional carrier gas. It is a positive polarisation charge at the AlGaN/GaN interface that attracts electrons to form 2DEG in the GaN layer slightly below this interface.
  • polarity of the interface charges depends on the crystal lattice orientation of the hetero-junction structure, i.e. Ga-face versus N-face polarity, and the position of the respective AlGaN/GaN interface in the hetero-junction structure (above or below the interface). Therefore, different types of the accumulated carriers can be present in the hetero-junction structure of the embodiments.
  • the Ga-face polarity is characterised by the 2DEG formation in the GaN layer below the AlGaN barrier layer. This is actually the same two-layer configuration as described above, but with addition of the top GaN layer. In this configuration, the AlGaN barrier layer and two GaN buffer layers must be nominally undoped or n-type doped.
  • the AlGaN barrier layer in order to form the conducting channel comprising a two-dimensional hole gas (2DHG) in the top GaN layer above the AlGaN barrier layer in the configuration, should be p-type doped (for example, with Mg or Be as an acceptor) and the GaN buffer layer should be also p-type doped with Mg, Be or intrinsic.
  • the N-face polarity is characterised by the 2DEG formation in the top GaN layer above the AlGaN barrier layer, as shown in Fig. 5b.
  • the AlGaN barrier layer and two GaN buffer layers must be nominally undoped or n-type doped.
  • the last configuration assumes that the 2DHG conducting channel is formed in the buffer GaN layer below the AlGaN barrier layer.
  • the top GaN layer may be present (three-layer structure) or not (two-layer structure) in this case.
  • the AlGaN barrier layer must be p-type doped (for example with Mg or Be as an acceptor) and the bottom GaN layer should be also p-type doped with Mg, Be or intrinsic.
  • the top GaN layer may be omitted to obtain the two-layer structure.
  • the top GaN layer must be recessed to 1-9 nm thickness in the open gate area or grown with this low thickness, with the roughness below 0.2 nm, and the thickness of the AlGaN barrier can be adjusted properly during growth.
  • the top GaN layer must be recessed to 5-9 nm thickness in the open gate area with the roughness below 0.2 nm, and the thickness of the AlGaN barrier layer can be adjusted properly.
  • P-type doping concentrations of the GaN layer and AlGaN barrier have to be adjusted; the 2DHG has to be contacted (in the ideal case by ohmic contacts).
  • the top GaN layer must be recessed to 5-9 nm thickness in the open gate area with the roughness below 0.2 nm. Thickness of the AlGaN barrier can be adjusted during growth.
  • N-type doping levels of the GaN buffer layer and the AlGaN barrier layer must be adjusted; the 2DEG has to be contacted (in the ideal case by ohmic contacts).
  • the top GaN layer may be omitted to obtain the two-layer structure.
  • the top GaN layer must be recessed to 1-9 nm thickness in the open gate area with the roughness below 0.2 nm, and the thickness of the AlGaN barrier can be adjusted properly.
  • the deposition of a dielectric layer on top might be beneficial or even necessary to obtain a better confinement (as in case of the N-face structures).
  • the preferable structures of the embodiments are structures "B" and "C”. In the structure "B”, the 2DHG conducting channel formed in the top GaN layer, which has a higher chemical stability (particularly towards surface oxidation) than the AlGaN layer.
  • the 2DEG conducting channel might be closer to the surface. Therefore, the electron mobility might be lower than in the 2DEG structure with the Ga-face polarity.
  • the polarity of the heterostructure can be adjusted by the choice of the substrate (e.g. C-face SiC) or by the growth conditions.
  • an AC electrode (20) generating radio frequency (RF) square-sinus pulses is connected to the PC-HEMT as shown in Figs, la- lb. It is defined as an "RF generator", because it emits specific frequency pulses in the range between 100 MHz to 100 GHz domain on the signal line through the body of a user using a microcontroller to switch between the AC pulse and the PC-HEMT sensing. The grounds of the RF generator and PC-HEMT are connected.
  • the RF electromagnetic energy can be coupled into a human body.
  • the cardio-pulmonary signals from the body of the user are then combined with the RF signals from the generator.
  • These RF pulses sent to the body of a user may be internally "modified” by blood channels or other organs and tissues and reflected back to the PC-HEMT sensor.
  • the AC pulsed signal may be modulated by the body's electrical fields and by various organs and tissue that would create a very unique "fingerprint" of the user.
  • Fig. 6a shows a cross-sectional view of another configuration of the PC-HEMT of the present application with a radio- frequency generator (20) connected to the PC-HEMT, said PC-HEMT comprising:
  • a multilayer hetero-j unction structure made of III-V single-crystalline or polycrystalline semiconductor materials, said structure comprising at least one buffer layer (11) and at least one barrier layer (12), said layers being stacked alternately, and said structure being deposited on a substrate layer (10);
  • a conducting channel (13) comprising a two-dimensional electron gas (2DEG) or a two-dimensional hole gas (2DHG), formed at the interface between said buffer layer (11) and said barrier layer (12) and providing electron or hole current in said transistor between source and drain contacts (15);
  • the barrier layer (12), specifically AlGaN layer, is not recessed, and the dielectric layer (16) of 1-10 nm thickness is deposited on the non- recessed barrier layer, followed by placing the metal gate electrode (17) on top of it.
  • the metal gate electrode (17) thereby creates a hard mask for AlGaN recessing to the pseudo- conducting point and then exhibits a shadow gating effect to the open recessed areas.
  • the charge trapping at the AlGaN/dielectric/metal interface is no longer affecting the recessed sensitive AlGaN area, and hence, the electrical leakage from the metal gate to the 2DEG channel is significantly decreased.
  • Fig. 6b shows a cross-sectional view of still another configuration of the PC-HEMT of an embodiment of the present application comprising:
  • said metal electrode (17) has no physical contact with said barrier layer (12) beneath.
  • Capacitive coupling is defined as an energy transfer within the same electric circuit or between different electric circuits by means of displacement currents induced by existing electric fields between circuit/s nodes.
  • ohmic contacts are the contacts that follow Ohm's law, meaning that the current flowing through them is directly proportional to the voltage.
  • Non-ohmic contacts however do not follow the same linear relationship of the Ohm's law.
  • electric current passing through non-ohmic contacts is not linearly proportional to voltage. Instead, it gives a steep curve with an increasing gradient, since the resistance in that case increases as the electric current increases, resulting in increase of the voltage across non-ohmic contacts. This is because electrons carry more energy, and when they collide with atoms in the conductive channel, they transfer more energy creating new high-energy vibrational states, thereby increasing resistance and temperature.
  • connection module (107) for connecting the sensor to the user interface; and ⁇ a radio frequency generator (20) connected to said PC-HEMT or an array thereof (100) for emitting millisecond pulses to sample the body of a user.
  • the fabricated sensor is glued on the flexible fibro-plastic PCB (108), and its wire bond connectors are protected with epoxy-based glob-top (109).
  • the voltage source (104) can be any suitable and commercially available battery of the Li-ion type or any energy harvester with AC-DC or DC-DC converters.
  • the ADC card (106) is any suitable analogue-to-digital converter card that can be purchased, for example, from National Instruments ® or LabJack ® .
  • the current amplifier (105) can be any commercially available femtoampere amplifier, for example SRS ® SR570, DLPVA-100-F-S, FEMTO ® current amplifier DDPCA-300 or Texas Instruments ® INA826EVM.
  • the sensor shown in Fig. 8b contains a common suspended metal gate electrode (110), which has no physical contact with the PC-HEMT or array thereof (100).
  • the metal gate electrode (110) in this case is placed directly above the PC-HEMT or array thereof (100), at the height of 10-100 nm. This configuration prevents any electrical leakage normally occurring at the metal gate/barrier layer interface.
  • the third option would be the use of the photoeffect that may also induce an electric current in the 2DEG channel.
  • a photoeffect in a silicon layer should be created.
  • E the photon energy
  • h Planck's constant
  • v the frequency of the photon.
  • the bandgap of silicon at room temperature is 1.12.eV, which means that silicon becomes transparent for wavelength larger than 1240 nm, which is the near infrared range.
  • All the aforementioned PC-HEMT configurations may further comprise an electro-optical (EO) crystalline material, such as lithium niobate (LiNbO) or lithium tantalite (LiTa0 3 ), which is brought into a physical contact with a human skin at any single body point.
  • EO electro-optical
  • the sensor of an embodiment may be based on a piezoelectric electro-optical crystal transducer (EOC) combined with the pseudo- conducting 2DEG-based structure.
  • EOC piezoelectric electro-optical crystal transducer
  • Modulated light from the light source illuminates the EOC, and then falls on the 2DEG-based structure.
  • the 2DEG-based structure is ultrasensitive to an incident light, which creates j?-7?-pairs in the AlGaN barrier layer, and consequently, strongly affects the 2DEG-conductivity. Irradiation of the 2DEG-based structure with light switches the 2DEG-channel from normally-off to a pseudo-conducting or normally-on state.
  • a lock-in amplifier (119) connected to said voltage source (104) for amplification of a signal with a known carrier wave obtained from said SAW sensor chip and increasing the signal-to-noise ratio;
  • an analogue-to-digital converter (ADC) with in-built digital input/output card (106) connected to said lock- in amplifier (119) for outputting the converted signal to a user interface; and
  • a radio frequency generator (20) connected to said SAW sensor chip (100) for emitting millisecond pulses to sample the body of a user.
  • an analogue-to-digital converter with in-built digital input/output card connected to said current amplifier for wirelessly outputting the converted signal to a smartphone or to an authentication cloud;
  • a wireless connection module for wireless connection of said wearable device to a smartphone or to an authentication or medical-diagnostic telemedicine cloud; and ⁇ a radio frequency generator connected to said PC-HEMT of an embodiment, or an array thereof, for emitting a radio frequency signal in a form of millisecond pulses to sample the body of a user.
  • the wireless connection module can be a short- range Bluetooth or NFC providing wireless communication between the wearable device and a smartphone for up to 20 m. If this module is WiFi, the connection can be established for up to 200 nm, while GSM allows the worldwide communication to a medical-diagnostic telemedicine cloud.

Landscapes

  • Life Sciences & Earth Sciences (AREA)
  • Chemical & Material Sciences (AREA)
  • Health & Medical Sciences (AREA)
  • Physics & Mathematics (AREA)
  • Molecular Biology (AREA)
  • Microelectronics & Electronic Packaging (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Electrochemistry (AREA)
  • Engineering & Computer Science (AREA)
  • Analytical Chemistry (AREA)
  • Biochemistry (AREA)
  • General Health & Medical Sciences (AREA)
  • General Physics & Mathematics (AREA)
  • Immunology (AREA)
  • Pathology (AREA)
  • Junction Field-Effect Transistors (AREA)

Abstract

Dans certains modes de réalisation, un capteur microélectronique comprend un transistor à grande mobilité d'électrons pseudo-conducteur à grille ouverte et est utilisé pour l'authentification biométrique d'un utilisateur. Le transistor comprend un substrat, sur lequel une structure à hétérojonction à multiples couches est déposée. Cette structure à hétérojonction comprend une couche tampon et une couche barrière, toutes deux formées à partir de matériaux semi-conducteurs monocristallins ou polycristallins III-V. Un canal conducteur de gaz électronique bidimensionnel (2DEG) est formé à l'interface entre les couches tampon et barrière et fournit un courant électronique dans le système entre les électrodes de source et de drain. Les contacts de source et de drain, qui peuvent être soit ohmiques, soit non ohmiques (à couplage capacitif), sont connectés au canal 2DEG formé et aux métallisations électriques, ces dernières étant placées au-dessus du transistor et le connectent au système de capteur. L'électrode de grille métallique est placée entre les zones de source et de drain sur ou au-dessus de la couche barrière, qui peut être en creux ou formée pour avoir une épaisseur spécifique. Une couche diélectrique facultative est déposée sur la couche barrière.
PCT/IB2017/051884 2016-05-17 2017-04-03 Capteur microélectrique pour authentification biométrique Ceased WO2017199110A1 (fr)

Priority Applications (2)

Application Number Priority Date Filing Date Title
CN201780041773.6A CN109475297B (zh) 2016-05-17 2017-04-03 用于生物识别认证的微电子传感器
EP17732999.2A EP3457916A1 (fr) 2016-05-17 2017-04-03 Capteur microélectrique pour authentification biométrique

Applications Claiming Priority (4)

Application Number Priority Date Filing Date Title
US201615157285A 2016-05-17 2016-05-17
US15/157,285 2016-05-17
US201662362165P 2016-07-14 2016-07-14
US62/362,165 2016-07-14

Publications (1)

Publication Number Publication Date
WO2017199110A1 true WO2017199110A1 (fr) 2017-11-23

Family

ID=59215820

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/IB2017/051884 Ceased WO2017199110A1 (fr) 2016-05-17 2017-04-03 Capteur microélectrique pour authentification biométrique

Country Status (3)

Country Link
EP (1) EP3457916A1 (fr)
CN (1) CN109475297B (fr)
WO (1) WO2017199110A1 (fr)

Families Citing this family (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB201915873D0 (en) * 2019-10-31 2019-12-18 B Secur Ltd Device, system and method for acquiring and monitoring of biometric electrical signals
US11545485B2 (en) * 2021-03-09 2023-01-03 Infineon Technologies Austria Ag Type III-V semiconductor substrate with monolithically integrated capacitor
CN115411136B (zh) * 2022-09-20 2025-09-05 浙江大学杭州国际科创中心 光电神经突触器件、对应的制备方法和工作方法

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20080265258A1 (en) * 2005-03-15 2008-10-30 Sumitomo Electric Industries, Ltd. Group III Nitride Semiconductor Device and Epitaxial Substrate
WO2012151680A1 (fr) 2011-05-10 2012-11-15 Agrafioti Foteini Système et procédé permettant une reconnaissance d'identité en continu ou instantanée basée sur des signaux biométriques physiologiques
EP2799852A1 (fr) * 2013-04-29 2014-11-05 Stichting IMEC Nederland Capteur à base 2DE et dispositif pour détecter un signal ECG

Family Cites Families (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP5336075B2 (ja) * 2004-04-28 2013-11-06 バーティクル，インク 縦構造半導体装置
US9595479B2 (en) * 2008-07-08 2017-03-14 MCube Inc. Method and structure of three dimensional CMOS transistors with hybrid crystal orientations
KR101878746B1 (ko) * 2011-12-06 2018-07-17 삼성전자주식회사 육방정계 질화붕소 시트, 그의 제조방법 및 이를 구비하는 전기소자
US9143123B2 (en) * 2012-07-10 2015-09-22 Infineon Technologies Ag RF switch, mobile communication device and method for switching an RF signal
CN105353019B (zh) * 2015-11-13 2018-02-02 南京大学 无栅AlInN/GaN场效应晶体管传感器及其制备方法
WO2017153908A1 (fr) * 2016-03-10 2017-09-14 Rg Healthcare Pte Ltd Capteur microélectronique pour diagnostic intestinal et surveillance de la motilité intestinale

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20080265258A1 (en) * 2005-03-15 2008-10-30 Sumitomo Electric Industries, Ltd. Group III Nitride Semiconductor Device and Epitaxial Substrate
WO2012151680A1 (fr) 2011-05-10 2012-11-15 Agrafioti Foteini Système et procédé permettant une reconnaissance d'identité en continu ou instantanée basée sur des signaux biométriques physiologiques
EP2799852A1 (fr) * 2013-04-29 2014-11-05 Stichting IMEC Nederland Capteur à base 2DE et dispositif pour détecter un signal ECG

Non-Patent Citations (2)

* Cited by examiner, † Cited by third party
Title
RUSSELL D M ET AL: "A high bandwidth fully implantable mouse telemetry system for chronic ECG measurement", ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY,EMBC, 2011 ANNUAL INTERNATIONAL CONFERENCE OF THE IEEE, IEEE, 30 August 2011 (2011-08-30), pages 7666 - 7669, XP032320454, ISBN: 978-1-4244-4121-1, DOI: 10.1109/IEMBS.2011.6091889 *
See also references of EP3457916A1

Also Published As

Publication number Publication date
EP3457916A1 (fr) 2019-03-27
CN109475297B (zh) 2022-03-11
CN109475297A (zh) 2019-03-15

Similar Documents

Publication Publication Date Title
US10945643B2 (en) Microelectronic sensor for biometric authentication
ES2887734T3 (es) Sensor microelectrónico para autenticación biométrica
EP3426147B1 (fr) Capteur microélectronique pour diagnostic intestinal et surveillance de la motilité intestinale
US10918297B2 (en) Microelectronic sensors for non-invasive monitoring of physiological parameters
US20200221969A1 (en) Microelectronic sensors for sensing electrical signals from a human body in a sub-terahertz range
US10905346B2 (en) Pseudo-conductive high-electron mobility transistors and microelectronic sensors based on them
US10523181B2 (en) Surface acoustic wave RFID sensor for material and structure sensing
ES2897018T3 (es) Sensor microelectrónico para la monitorización no invasiva de los niveles de glucosa en la sangre
EP3482495B1 (fr) Capteur rfid à ondes acoustiques de surface pour accessoires vestimentaires hémodynamiques
WO2017199110A1 (fr) Capteur microélectrique pour authentification biométrique
WO2021105839A1 (fr) Capteurs microélectroniques pour réseaux inter-puces pouvant enregistrer et traiter des signaux neuronaux et des potentiels d'action

Legal Events

Date Code Title Description
NENP Non-entry into the national phase

Ref country code: DE

121 Ep: the epo has been informed by wipo that ep was designated in this application

Ref document number: 17732999

Country of ref document: EP

Kind code of ref document: A1

ENP Entry into the national phase

Ref document number: 2017732999

Country of ref document: EP

Effective date: 20181217