Silicon deep etching technique is the key fabrication step in the development of MEMS. The mask selectivity and the lateral etching control are the two primary factors that decide the result of deep etching process. T...Silicon deep etching technique is the key fabrication step in the development of MEMS. The mask selectivity and the lateral etching control are the two primary factors that decide the result of deep etching process. These two factors are studied in this paper. The experimental results show that the higher selectivity can be gotten when F - gas is used as etching gas and Al is introduced as mask layer. The lateral etching problems can be solved by adjusting the etching condition, such as increasing the RF power, changing the gas composition and flow volume of etching machine.展开更多
Glass materials play an increasingly important role in advanced technologies due to their superior physical properties.However,precise machining of glass remains a major challenge because of its brittleness and sensit...Glass materials play an increasingly important role in advanced technologies due to their superior physical properties.However,precise machining of glass remains a major challenge because of its brittleness and sensitivity to thermal and mechanical stresses.We present an approach that combines sphericalaberration–assisted filamentation with laser-induced deep etching to achieve ultra-high-precision micro-hole machining in fused silica substrates.By deliberately introducing spherical aberration into an intense femtosecond laser beam,thin,uniformly elongated,and stable filaments are generated,which effectively suppress unwanted plasma formation and thermal deformation typical of standard filamentation.Using this method,we fabricated micro-holes with diameters as small as 10μm across various sizes,maintaining an almost zero taper even in 1-mm-thick samples.The sidewalls exhibited nanoscale smoothness(R_(a)=38.1 nm,root mean square(RMS)=53.9 nm),and the hole area demonstrated excellent repeatability with only~1.0%variation across multiple trials.This simple optical configuration drastically reduces cost compared with existing approaches that rely on specialized components while moderately satisfying critical requirements for geometrical versatility,minimal damage,precision,and repeatability.We represent a significant step forward in precision glass machining and lay a foundation for future microstructured electronic,optical,and microfluidic devices.展开更多
In order to protect the finished structures on the front side during deep silicon wet etching processes, the wax coating for double-sided etching process on the wafer is studied to separate the aforementioned structur...In order to protect the finished structures on the front side during deep silicon wet etching processes, the wax coating for double-sided etching process on the wafer is studied to separate the aforementioned structures from the strong aqueous bases. By way of heating and vacuumization, the air bubbles are expelled from the coating to extend the protection duration. The air pressure in the sealed chamber is 0.026 7 Pa, and the temperature of the heated wafer is 300℃. Two kinds of the wax are used, and the corresponding photos of the etched wafer and the protection times are given. In 75 ℃ 10 % KOH solution, the protection duration is more than 8 h.展开更多
A novel technique to fabricate ultra deep high aspect ratio electrical isolation trenches with DRIE and dielectric refill is presented.The relationship between trench profile and DRIE parameters is discussed.By optimi...A novel technique to fabricate ultra deep high aspect ratio electrical isolation trenches with DRIE and dielectric refill is presented.The relationship between trench profile and DRIE parameters is discussed.By optimizing DRIE parameters and RIE etching the trenches’ opening,the ideal trench profile is obtained to ensure that the trenches are fully refilled without voids.The electrical isolation trenches are 5μm wide and 92μm deep with 0.5μm thick oxide layers on the sidewall as isolation material.The measured I-V result shows that the trench structure has good electrical isolation performance:the average resistance in the range of 0～100V is more than 10 11Ω and no breakdown appears under 100V.This isolation trench structure has been used in fabrication of the bulk integrated micromachined gyroscope,which shows high performance.展开更多
This paper experimentally studies the effects of the conductivity of a silicon wafer and the gap height between silicon structures and glass substrate on the footing effect for silicon on glass （SOG） structures in t...This paper experimentally studies the effects of the conductivity of a silicon wafer and the gap height between silicon structures and glass substrate on the footing effect for silicon on glass （SOG） structures in the deep reactive ion etching （DRIE） process. Experiments with gap heights of 5,20, and 50μm were carried out for performance comparison of the footing effect. Also,two kinds of silicon wafers with resistivity of 2-4 and 0.01-0. 0312Ω· cm were used for the exploration. The results show that structures with resistivity of 0.01 - 0. 0312Ω· cm have better topography than those with resistivity of 2-4Ω· cm; and structures with 50μm-high gaps between silicon structures and glass substrate suffer some- what less of a footing effect than those with 20μm-high gaps,and much less than those with Stem-high gaps. Our theoretical analysis indicates that either the higher conductivity of the silicon wafer or a larger gap height between silicon structures and glass substrate can suppress footing effects. The results can contribute to the choice of silicon type and optimum design for many microsensors.展开更多
Out-of-plane microneedle structures are widely used in various applications such as transcutaneous drug delivery and neural signal recording for brain machine interface.This work presents a novel but simple method to ...Out-of-plane microneedle structures are widely used in various applications such as transcutaneous drug delivery and neural signal recording for brain machine interface.This work presents a novel but simple method to fabricate high-density silicon(Si)microneedle arrays with various heights and diverse cross-sectional shapes depending on photomask pattern designs.The proposed fabrication method is composed of a single photolithography and two subsequent deep reactive ion etching(DRIE)steps.First,a photoresist layer was patterned on a Si substrate to define areas to be etched,which will eventually determine the final location and shape of each individual microneedle.Then,the 1st DRIE step created deep trenches with a highly anisotropic etching of the Si substrate.Subsequently,the photoresist was removed for more isotropic etching;the 2nd DRIE isolated and sharpened microneedles from the predefined trench structures.Depending on diverse photomask designs,the 2nd DRIE formed arrays of microneedles that have various height distributions,as well as diverse cross-sectional shapes across the substrate.With these simple steps,high-aspect ratio microneedles were created in the high density of up to 625 microneedles mm^(-2)on a Si wafer.Insertion tests showed a small force as low as~172μN/microneedle is required for microneedle arrays to penetrate the dura mater of a mouse brain.To demonstrate a feasibility of drug delivery application,we also implemented silk microneedle arrays using molding processes.The fabrication method of the present study is expected to be broadly applicable to create microneedle structures for drug delivery,neuroprosthetic devices,and so on.展开更多
This paper reports a controllable multi-functional black silicon surface with nanocone-forest structures fabricated by an optimized deep reactive ion etching(DRIE)technique using SF6/C4F8 in cyclic etching-passivation...This paper reports a controllable multi-functional black silicon surface with nanocone-forest structures fabricated by an optimized deep reactive ion etching(DRIE)technique using SF6/C4F8 in cyclic etching-passivation process,which is maskless,effective and controllable.The process conditions are investigated by systematically comparative experiments and core parameters have been figured out,including etching process parameters,pre-treatment,patterned silicon etching and inclined surface etching.Based on the experimental data,the formation mechanism of nanocone shape is developed,which provides a novel view for in-depth understanding of abnormal phenomena observed in the experiments under different process situations.After the optimization of the process parameters,the black silicon surfaces exhibit superhydrophobicity with tunable reflectance.Additionally,the quantitative relationship between nanocones aspect ratio and surface reflectance and static contact angle is obtained,which demonstrates that black silicon surfaces with unique functional properties(i.e.,cross-combination of reflectance and wettability)can be achieved by controlling the morphology of nanostructures.展开更多
Silicon superjunction power MOSFETs were fabricated with deep trench etching and epitaxial growth,based on the process platform of the Shanghai Hua Hong NEC Electronics Company Limited.The breakdown voltages of the fa...Silicon superjunction power MOSFETs were fabricated with deep trench etching and epitaxial growth,based on the process platform of the Shanghai Hua Hong NEC Electronics Company Limited.The breakdown voltages of the fabricated superjunction MOSFETs are above 700 V and agree with the simulation.The dynamic characteristics, especially reverse diode characteristics,are equivalent or even superior to foreign counterparts.展开更多
One of the major challenges faced by the biomedical industry is the development of robust synthetic surfaces that can resist bacterial colonization.Much inspiration has been drawn recently from naturally occurring mec...One of the major challenges faced by the biomedical industry is the development of robust synthetic surfaces that can resist bacterial colonization.Much inspiration has been drawn recently from naturally occurring mechano-bactericidal surfaces such as the wings of cicada(Psaltoda claripennis)and dragonfly(Diplacodes bipunctata)species in fabricating their synthetic analogs.However,the bactericidal activity of nanostructured surfaces is observed in a particular range of parameters reflecting the geometry of nanostructures and surface wettability.Here,several of the nanometer-scale characteristics of black silicon(bSi)surfaces including the density and height of the nanopillars that have the potential to influence the bactericidal efficiency of these nanostructured surfaces have been investigated.The results provide important evidence that minor variations in the nanoarchitecture of substrata can substantially alter their performance as bactericidal surfaces.展开更多
This letter proposes a novel design of a Micro Electro Mechanical System （MEMS） device featuring a metal grating vibratory mierostructure driven by electrostatic force to sense the spatial electric field. Due to the...This letter proposes a novel design of a Micro Electro Mechanical System （MEMS） device featuring a metal grating vibratory mierostructure driven by electrostatic force to sense the spatial electric field. Due to the advantages in slide-film damping and large vibration amplitude, such a device makes atmospheric packaging a low-cost option for practical manufacture. In this letter, we present the operating principles and specifications, the design structure, as well as the finite element simulation. Computational analysis shows that our design obtains good results in device parameters setting, while its simplicity and low-cost features make it an attractive solution for applications.展开更多
This paper proposes to develop a data-driven via＇s depth estimator of the deep reactive ion etching process based on statistical identification of key variables.Several feature extraction algorithms are presented to ...This paper proposes to develop a data-driven via＇s depth estimator of the deep reactive ion etching process based on statistical identification of key variables.Several feature extraction algorithms are presented to reduce the high-dimensional data and effectively undertake the subsequent virtual metrology（VM） model building process.With the available on-line VM model,the model-based controller is hence readily applicable to improve the quality of a via＇s depth.Real operational data taken from a industrial manufacturing process are used to verify the effectiveness of the proposed method.The results demonstrate that the proposed method can decrease the MSE from 2.2×10^（-2） to 9×10^（-4） and has great potential in improving the existing DRIE process.展开更多
Dicing of fabricated MEMS （microelectromechanical system） devices is sometimes a source of challenge, especially when devices are overhanging structures. In this work, a modified cleaving technique is developed to p...Dicing of fabricated MEMS （microelectromechanical system） devices is sometimes a source of challenge, especially when devices are overhanging structures. In this work, a modified cleaving technique is developed to precisely separate fabricated devices from a silicon substrate without requiring a dicing machine. This technique is based on DRIE （deep reactive ion etching） which is regularly used to make cleaving trenches in the substrate during the releasing stage. Other similar techniques require some extra later steps or in some cases a long HF soak. To mask the etching process, a thick photoresist is used. It is shown that by applying different UV （ultraviolate） exposure and developing times for the photoresist, the DRIE process could be controlled to etch specific cleaving trenches with less depth than other patterns on the photoresist. Those cleaving trenches are used to cleave the wafer later, while the whole wafer remains as one piece until the end of the silicon etching despite some features being etched all the way through the wafer at the same time. The other steps of fabricating and releasing the devices are unaffected. The process flow is described in details and some results of applying this technique for cleaving fabricated cantilevers on a silicon substrate are presented.展开更多
In order to connect several independent LEDs in series, inductively coupled plasma （ICP） deep etching of GaN is required for isolation. The GaN-based high-voltage （HV） LEDs with a 5 μm deep isolation groove and a...In order to connect several independent LEDs in series, inductively coupled plasma （ICP） deep etching of GaN is required for isolation. The GaN-based high-voltage （HV） LEDs with a 5 μm deep isolation groove and an acceptable mesa sidewall angle of 79.2° are fabricated and presented. The surface morphology and construction profile of the etched groove are characterized by laser microscopy and scanning electron microscopy. After contact metal formation and annealing, the electrical properties are evaluated by I-V characteristics. The trend of the I-V curve has good accordance with conventional LEDs. The contact resistance of HV LEDs is also tested and was reduced by 4.6 Ω compared to conventional LEDs, while the output power increased by 5 W. The results show that this technique can be applied to practical fabrication.展开更多
By applying the specific properties and the fabricating technology of the deep etched elements presented by us, the even device of deep etched binary optics has been designed and fabricated which can be used in quasi-...By applying the specific properties and the fabricating technology of the deep etched elements presented by us, the even device of deep etched binary optics has been designed and fabricated which can be used in quasi-molecule laser exposure system. This even device is light in weight, easy to adjust and has a high utilization rate of energy and is able to project well-distributed light beams. So it is better than the conventional one which was an array made up of quartz sticks. The properties and designed parameters were studied and simulated. The fabricated even was precisely tested by high precision Alpha-Steper. The testing result of the surface relief structures of the even has been profoundly analyzed by introducing “boundary errors”. The theory agrees well with the results of the experiment. This is the first successful application of the deep etched theory and technology of binary optics to the exposure system of microfabrication.展开更多
This paper presents subcutaneous and continuous blood pressure(BP)monitoring using aluminum nitride(AlN)piezoelectric micromachined ultrasonic transducers(PMUTs)in an ambulatory sheep.A 37´45 PMUTs array with a f...This paper presents subcutaneous and continuous blood pressure(BP)monitoring using aluminum nitride(AlN)piezoelectric micromachined ultrasonic transducers(PMUTs)in an ambulatory sheep.A 37´45 PMUTs array with a footprint of 5×5mm^(2)has been designed and fabricated as a prototype device.The deep reactive ion etching(DRIE)process to open the backside holes on the silicon substrate has been optimized to create active device diaphragms with a radius of 29μm.The resulting PMUT unit has a measured resonant frequency of 6.5 MHz in water,an output acoustic pressure of 28 kPa at a distance of 10 mm,and a 6-dB bandwidth of about 33%.The BP monitoring scheme is validated through both in vitro and in vivo experiments to illustrate the correlation between the diameter of the blood vessel and pressure.Simulations indicate that possible issues in misalignment between the device and the blood vessel can result in a 60%reduction in signal strength with only 1 mm in misalignment.This highlights the advantage of subcutaneous implantation in maintaining a stable interface and consistent alignment for reliable long-term BP monitoring,in contrast to similar approaches via wearable system setups.The in vivo testing result shows BP wave fine features such as dicrotic notches and the averaged systolic/diastolic pressure errors are-1.2±2.1 and-2.9±1.4 mmHg,respectively,which meets the clinical standard as calibrated by a gold-standard arterial line pressure sensor.As such,this system highlights the potential applications in silent,continuous,and highly accurate BP monitoring for hypertension patients using this implantable MEMS-based technology.展开更多
This paper presents the fabrication of squama-shape micro/nano multi-scale structures and the analysis of the interaction among different-scale structures during the fabrication processes. Well-designed microstructure...This paper presents the fabrication of squama-shape micro/nano multi-scale structures and the analysis of the interaction among different-scale structures during the fabrication processes. Well-designed microstructures made of inverted pyramids and V-shape grooves are fabricated by KOH wet etching. High-dense high-aspect-ratio (HAR) nanostructures are fabricated atop microstructures by an improved maskless deep reactive ion etching (DRIE) process, with an optimized recipe to form micro/nano dual-scale structures (MNDS). Due to the impact of the profile of microstructures on the shape of nanostructures, dissymmetrical (i.e., squama-shape) nanopillars have been formed on the inclined surfaces of microstructures, while the symmetrical nanopillars are formed on the horizontal surfaces with different formation velocities. Furthermore, the optical properties of MNDS are not sensitive to structural parameters of microstructures, making the sample overcome the lithography limitation of conventional processes for photo-devices. Eventually, three-level structures are fabricated by sputtering a gold thin film on the MNDS, and the profile of MNDS is selective in the deposition of gold particles, which is very useful for practical applications.展开更多
A silicon pressure sensor is one of the very first MEMS components appearing in the microsystem area.The market for the MEMS pressure sensor is rapidly growing due to consumer electronic applications in recent years. ...A silicon pressure sensor is one of the very first MEMS components appearing in the microsystem area.The market for the MEMS pressure sensor is rapidly growing due to consumer electronic applications in recent years. Requirements of the pressure sensors with low cost, low power consumption and high accuracy drive one to develop a novel technology. This paper first overviews the historical development of the absolute pressure sensor briefly. It then reviews the state of the art technology for fabricating crystalline silicon membranes over sealed cavities by using the silicon migration technology in detail. By using only one lithographic step, the membranes defined in lateral and vertical dimensions can be realized by the technology. Finally, applications of MEMS through using the silicon migration technology are summarized.展开更多
文摘Silicon deep etching technique is the key fabrication step in the development of MEMS. The mask selectivity and the lateral etching control are the two primary factors that decide the result of deep etching process. These two factors are studied in this paper. The experimental results show that the higher selectivity can be gotten when F - gas is used as etching gas and Al is introduced as mask layer. The lateral etching problems can be solved by adjusting the etching condition, such as increasing the RF power, changing the gas composition and flow volume of etching machine.
基金supported by the Creation of the Quantum Information Science R&D Ecosystem(Grant No.RS-2023NR068116)through the National Research Foundation of Korea(NRF)funded by the Korean government(Ministry of Science and ICT)by the Institute of Information and Communications Technology Planning&Evaluation(IITP)grant funded by the Korean government(MSIT)(Grant Nos.RS-2022-II221026 and RS-2025-02215576)。
文摘Glass materials play an increasingly important role in advanced technologies due to their superior physical properties.However,precise machining of glass remains a major challenge because of its brittleness and sensitivity to thermal and mechanical stresses.We present an approach that combines sphericalaberration–assisted filamentation with laser-induced deep etching to achieve ultra-high-precision micro-hole machining in fused silica substrates.By deliberately introducing spherical aberration into an intense femtosecond laser beam,thin,uniformly elongated,and stable filaments are generated,which effectively suppress unwanted plasma formation and thermal deformation typical of standard filamentation.Using this method,we fabricated micro-holes with diameters as small as 10μm across various sizes,maintaining an almost zero taper even in 1-mm-thick samples.The sidewalls exhibited nanoscale smoothness(R_(a)=38.1 nm,root mean square(RMS)=53.9 nm),and the hole area demonstrated excellent repeatability with only~1.0%variation across multiple trials.This simple optical configuration drastically reduces cost compared with existing approaches that rely on specialized components while moderately satisfying critical requirements for geometrical versatility,minimal damage,precision,and repeatability.We represent a significant step forward in precision glass machining and lay a foundation for future microstructured electronic,optical,and microfluidic devices.
文摘In order to protect the finished structures on the front side during deep silicon wet etching processes, the wax coating for double-sided etching process on the wafer is studied to separate the aforementioned structures from the strong aqueous bases. By way of heating and vacuumization, the air bubbles are expelled from the coating to extend the protection duration. The air pressure in the sealed chamber is 0.026 7 Pa, and the temperature of the heated wafer is 300℃. Two kinds of the wax are used, and the corresponding photos of the etched wafer and the protection times are given. In 75 ℃ 10 % KOH solution, the protection duration is more than 8 h.
文摘A novel technique to fabricate ultra deep high aspect ratio electrical isolation trenches with DRIE and dielectric refill is presented.The relationship between trench profile and DRIE parameters is discussed.By optimizing DRIE parameters and RIE etching the trenches’ opening,the ideal trench profile is obtained to ensure that the trenches are fully refilled without voids.The electrical isolation trenches are 5μm wide and 92μm deep with 0.5μm thick oxide layers on the sidewall as isolation material.The measured I-V result shows that the trench structure has good electrical isolation performance:the average resistance in the range of 0～100V is more than 10 11Ω and no breakdown appears under 100V.This isolation trench structure has been used in fabrication of the bulk integrated micromachined gyroscope,which shows high performance.
文摘This paper experimentally studies the effects of the conductivity of a silicon wafer and the gap height between silicon structures and glass substrate on the footing effect for silicon on glass （SOG） structures in the deep reactive ion etching （DRIE） process. Experiments with gap heights of 5,20, and 50μm were carried out for performance comparison of the footing effect. Also,two kinds of silicon wafers with resistivity of 2-4 and 0.01-0. 0312Ω· cm were used for the exploration. The results show that structures with resistivity of 0.01 - 0. 0312Ω· cm have better topography than those with resistivity of 2-4Ω· cm; and structures with 50μm-high gaps between silicon structures and glass substrate suffer some- what less of a footing effect than those with 20μm-high gaps,and much less than those with Stem-high gaps. Our theoretical analysis indicates that either the higher conductivity of the silicon wafer or a larger gap height between silicon structures and glass substrate can suppress footing effects. The results can contribute to the choice of silicon type and optimum design for many microsensors.
基金This work was supported by KIST(Korea Institute of Science and Technology)institutional grants(2E30965,and 2V07360)the National R&D Program through the National Research Foundation of Korea(NRF)funded by the Ministry of Science and ICT(Nos.2020R1C1C1006065,2021M3F3A2A01037366)+1 种基金This work was also supported by the Korea Medical Device Development Fund grant funded by the Korea government(the Ministry of Science and ICT,the Ministry of Trade,Industry and Energy,the Ministry of Health&Welfarethe Ministry of Food and Drug Safety)(Project Number:9991006818,KMDF_PR_20200901_0145-2021).
文摘Out-of-plane microneedle structures are widely used in various applications such as transcutaneous drug delivery and neural signal recording for brain machine interface.This work presents a novel but simple method to fabricate high-density silicon(Si)microneedle arrays with various heights and diverse cross-sectional shapes depending on photomask pattern designs.The proposed fabrication method is composed of a single photolithography and two subsequent deep reactive ion etching(DRIE)steps.First,a photoresist layer was patterned on a Si substrate to define areas to be etched,which will eventually determine the final location and shape of each individual microneedle.Then,the 1st DRIE step created deep trenches with a highly anisotropic etching of the Si substrate.Subsequently,the photoresist was removed for more isotropic etching;the 2nd DRIE isolated and sharpened microneedles from the predefined trench structures.Depending on diverse photomask designs,the 2nd DRIE formed arrays of microneedles that have various height distributions,as well as diverse cross-sectional shapes across the substrate.With these simple steps,high-aspect ratio microneedles were created in the high density of up to 625 microneedles mm^(-2)on a Si wafer.Insertion tests showed a small force as low as~172μN/microneedle is required for microneedle arrays to penetrate the dura mater of a mouse brain.To demonstrate a feasibility of drug delivery application,we also implemented silk microneedle arrays using molding processes.The fabrication method of the present study is expected to be broadly applicable to create microneedle structures for drug delivery,neuroprosthetic devices,and so on.
基金supported by the National Natural Science Foundation of China(Grant Nos.61176103,91023045 and 91323304)the National Hi-Tech Research and Development Program of China("863"Project)(Grant No.2013AA041102)+1 种基金the National Ph.D.Foundation Project(Grant No.20110001110103)the Beijing Natural Science Foundation of China(Grant No.4141002)
文摘This paper reports a controllable multi-functional black silicon surface with nanocone-forest structures fabricated by an optimized deep reactive ion etching(DRIE)technique using SF6/C4F8 in cyclic etching-passivation process,which is maskless,effective and controllable.The process conditions are investigated by systematically comparative experiments and core parameters have been figured out,including etching process parameters,pre-treatment,patterned silicon etching and inclined surface etching.Based on the experimental data,the formation mechanism of nanocone shape is developed,which provides a novel view for in-depth understanding of abnormal phenomena observed in the experiments under different process situations.After the optimization of the process parameters,the black silicon surfaces exhibit superhydrophobicity with tunable reflectance.Additionally,the quantitative relationship between nanocones aspect ratio and surface reflectance and static contact angle is obtained,which demonstrates that black silicon surfaces with unique functional properties(i.e.,cross-combination of reflectance and wettability)can be achieved by controlling the morphology of nanostructures.
文摘Silicon superjunction power MOSFETs were fabricated with deep trench etching and epitaxial growth,based on the process platform of the Shanghai Hua Hong NEC Electronics Company Limited.The breakdown voltages of the fabricated superjunction MOSFETs are above 700 V and agree with the simulation.The dynamic characteristics, especially reverse diode characteristics,are equivalent or even superior to foreign counterparts.
基金funding from Marie Curie Actions under EU FP7 Initial Training Network SNAL 608184
文摘One of the major challenges faced by the biomedical industry is the development of robust synthetic surfaces that can resist bacterial colonization.Much inspiration has been drawn recently from naturally occurring mechano-bactericidal surfaces such as the wings of cicada(Psaltoda claripennis)and dragonfly(Diplacodes bipunctata)species in fabricating their synthetic analogs.However,the bactericidal activity of nanostructured surfaces is observed in a particular range of parameters reflecting the geometry of nanostructures and surface wettability.Here,several of the nanometer-scale characteristics of black silicon(bSi)surfaces including the density and height of the nanopillars that have the potential to influence the bactericidal efficiency of these nanostructured surfaces have been investigated.The results provide important evidence that minor variations in the nanoarchitecture of substrata can substantially alter their performance as bactericidal surfaces.
基金Supported by the National Natural Science Foundation of China (No.60172001).
文摘This letter proposes a novel design of a Micro Electro Mechanical System （MEMS） device featuring a metal grating vibratory mierostructure driven by electrostatic force to sense the spatial electric field. Due to the advantages in slide-film damping and large vibration amplitude, such a device makes atmospheric packaging a low-cost option for practical manufacture. In this letter, we present the operating principles and specifications, the design structure, as well as the finite element simulation. Computational analysis shows that our design obtains good results in device parameters setting, while its simplicity and low-cost features make it an attractive solution for applications.
基金supported by the National Natural Science Foundation of China(No.60904053)the Natural Science Foundation of Jiangsu(No. SBK201123307)the Priority Academic Program Development of Jiangsu Higher Education Institutions(PAPD)
文摘This paper proposes to develop a data-driven via＇s depth estimator of the deep reactive ion etching process based on statistical identification of key variables.Several feature extraction algorithms are presented to reduce the high-dimensional data and effectively undertake the subsequent virtual metrology（VM） model building process.With the available on-line VM model,the model-based controller is hence readily applicable to improve the quality of a via＇s depth.Real operational data taken from a industrial manufacturing process are used to verify the effectiveness of the proposed method.The results demonstrate that the proposed method can decrease the MSE from 2.2×10^（-2） to 9×10^（-4） and has great potential in improving the existing DRIE process.
文摘Dicing of fabricated MEMS （microelectromechanical system） devices is sometimes a source of challenge, especially when devices are overhanging structures. In this work, a modified cleaving technique is developed to precisely separate fabricated devices from a silicon substrate without requiring a dicing machine. This technique is based on DRIE （deep reactive ion etching） which is regularly used to make cleaving trenches in the substrate during the releasing stage. Other similar techniques require some extra later steps or in some cases a long HF soak. To mask the etching process, a thick photoresist is used. It is shown that by applying different UV （ultraviolate） exposure and developing times for the photoresist, the DRIE process could be controlled to etch specific cleaving trenches with less depth than other patterns on the photoresist. Those cleaving trenches are used to cleave the wafer later, while the whole wafer remains as one piece until the end of the silicon etching despite some features being etched all the way through the wafer at the same time. The other steps of fabricating and releasing the devices are unaffected. The process flow is described in details and some results of applying this technique for cleaving fabricated cantilevers on a silicon substrate are presented.
基金supposed by the National High Technology Research and Development Program of China(No.2009AA03A1A3)the National Key Technologies R&D Program of China(No.2011BAE01B14)
文摘In order to connect several independent LEDs in series, inductively coupled plasma （ICP） deep etching of GaN is required for isolation. The GaN-based high-voltage （HV） LEDs with a 5 μm deep isolation groove and an acceptable mesa sidewall angle of 79.2° are fabricated and presented. The surface morphology and construction profile of the etched groove are characterized by laser microscopy and scanning electron microscopy. After contact metal formation and annealing, the electrical properties are evaluated by I-V characteristics. The trend of the I-V curve has good accordance with conventional LEDs. The contact resistance of HV LEDs is also tested and was reduced by 4.6 Ω compared to conventional LEDs, while the output power increased by 5 W. The results show that this technique can be applied to practical fabrication.
基金This work was supported by the National Natural Science Founation of China the Science and Technology Fund of Shenzhen.
文摘By applying the specific properties and the fabricating technology of the deep etched elements presented by us, the even device of deep etched binary optics has been designed and fabricated which can be used in quasi-molecule laser exposure system. This even device is light in weight, easy to adjust and has a high utilization rate of energy and is able to project well-distributed light beams. So it is better than the conventional one which was an array made up of quartz sticks. The properties and designed parameters were studied and simulated. The fabricated even was precisely tested by high precision Alpha-Steper. The testing result of the surface relief structures of the even has been profoundly analyzed by introducing “boundary errors”. The theory agrees well with the results of the experiment. This is the first successful application of the deep etched theory and technology of binary optics to the exposure system of microfabrication.
基金supported in part by BSAC(Berkeley Sensor and Actuator Center)The PMUT devices were fabricated at the UC Berkeley Marvell Nanofabrication Lab。
文摘This paper presents subcutaneous and continuous blood pressure(BP)monitoring using aluminum nitride(AlN)piezoelectric micromachined ultrasonic transducers(PMUTs)in an ambulatory sheep.A 37´45 PMUTs array with a footprint of 5×5mm^(2)has been designed and fabricated as a prototype device.The deep reactive ion etching(DRIE)process to open the backside holes on the silicon substrate has been optimized to create active device diaphragms with a radius of 29μm.The resulting PMUT unit has a measured resonant frequency of 6.5 MHz in water,an output acoustic pressure of 28 kPa at a distance of 10 mm,and a 6-dB bandwidth of about 33%.The BP monitoring scheme is validated through both in vitro and in vivo experiments to illustrate the correlation between the diameter of the blood vessel and pressure.Simulations indicate that possible issues in misalignment between the device and the blood vessel can result in a 60%reduction in signal strength with only 1 mm in misalignment.This highlights the advantage of subcutaneous implantation in maintaining a stable interface and consistent alignment for reliable long-term BP monitoring,in contrast to similar approaches via wearable system setups.The in vivo testing result shows BP wave fine features such as dicrotic notches and the averaged systolic/diastolic pressure errors are-1.2±2.1 and-2.9±1.4 mmHg,respectively,which meets the clinical standard as calibrated by a gold-standard arterial line pressure sensor.As such,this system highlights the potential applications in silent,continuous,and highly accurate BP monitoring for hypertension patients using this implantable MEMS-based technology.
基金supported by the National Natural Science Foundation of China (Grand Nos. 91023045, 61176103)the Key Laboratory Fund(Grant No. 9140C790103110C7903)
文摘This paper presents the fabrication of squama-shape micro/nano multi-scale structures and the analysis of the interaction among different-scale structures during the fabrication processes. Well-designed microstructures made of inverted pyramids and V-shape grooves are fabricated by KOH wet etching. High-dense high-aspect-ratio (HAR) nanostructures are fabricated atop microstructures by an improved maskless deep reactive ion etching (DRIE) process, with an optimized recipe to form micro/nano dual-scale structures (MNDS). Due to the impact of the profile of microstructures on the shape of nanostructures, dissymmetrical (i.e., squama-shape) nanopillars have been formed on the inclined surfaces of microstructures, while the symmetrical nanopillars are formed on the horizontal surfaces with different formation velocities. Furthermore, the optical properties of MNDS are not sensitive to structural parameters of microstructures, making the sample overcome the lithography limitation of conventional processes for photo-devices. Eventually, three-level structures are fabricated by sputtering a gold thin film on the MNDS, and the profile of MNDS is selective in the deposition of gold particles, which is very useful for practical applications.
基金Project supported by the National Major Science&Technology Program of China(No.2011ZX02507-001)
文摘A silicon pressure sensor is one of the very first MEMS components appearing in the microsystem area.The market for the MEMS pressure sensor is rapidly growing due to consumer electronic applications in recent years. Requirements of the pressure sensors with low cost, low power consumption and high accuracy drive one to develop a novel technology. This paper first overviews the historical development of the absolute pressure sensor briefly. It then reviews the state of the art technology for fabricating crystalline silicon membranes over sealed cavities by using the silicon migration technology in detail. By using only one lithographic step, the membranes defined in lateral and vertical dimensions can be realized by the technology. Finally, applications of MEMS through using the silicon migration technology are summarized.
