The silicon on glasses process is a common preparation method of micro-electro-mechanical system inertial devices,which can realize the processing of thick silicon structures.This paper proposes that indium tin oxides...The silicon on glasses process is a common preparation method of micro-electro-mechanical system inertial devices,which can realize the processing of thick silicon structures.This paper proposes that indium tin oxides(ITO)film can serve as a deep silicon etching cut-off layer because ITO is less damaged under the attack of fluoride ions.ITO has good electrical conductivity and can absorb fluoride ions for silicon etching and reduce the reflection of fluoride ions,thus reducing the foot effect.The removal and release of ITO use an acidic solution,which does not damage the silicon structure.Therefore,the selection of the sacrificial layer has an excellent effect in maintaining the shape of the MEMS structure.This method is used in the preparation of MEMS accelerometers with a structure thickness of 100μm and a feature size of 4μm.The over-etching of the bottom of the silicon structure caused by the foot effect is negligible.The difference between the simulated value and the designed value of the device characteristic frequency is less than 5%.This indicates that ITO is an excellent deep silicon etch stopper material.展开更多
Silicon-based neural microneedle arrays,such as the Utah Array,have demonstrated excellent performance in chronic recordings from the cerebral cortex.Unlike planar thin-film electrodes with recording sites arranged on...Silicon-based neural microneedle arrays,such as the Utah Array,have demonstrated excellent performance in chronic recordings from the cerebral cortex.Unlike planar thin-film electrodes with recording sites arranged on the surface of a silicon film,the recording sites of microneedle arrays are located at the tips of three-dimensional needles,which significantly complicates the fabrication process required for single-neuron recordings.To address this challenge,we develop a local de-insulation method for microneedle recording electrodes that eliminates the need for etching:the microneedle tips are encapsulated in a controllable-thickness protective layer,followed by deposition of a Parylene-C insulation layer.By optimizing the elasticity of the protection material,as well as its adhesion and shape on both the protective layer and the electrode shaft,we were able to precisely control the area of the removed insulated layers,resulting in consistent tip exposure.Experimental results show that the non-uniformity of the exposed microneedle recording sites in the silicon-based neural microelectrode arrays(each has 10×10 array)fabricated using this method is 3.32±1.02%.Furthermore,the arrays exhibited high stability and reliability in both mechanical performance and electrical characteristics.They achieved an average spike signal-to-noise ratio of 12.63±6.64 during in vivo testing.This fabrication technique provides a valuable method for the development of high-performance neural microelectrode array.展开更多
Output voltage drifting was observed in MEMS gyroscopes. Other than the quadrature error, frequency mismatch and quality factor, the dielectric parasitic charge was thought to be a major determinant. We studied the me...Output voltage drifting was observed in MEMS gyroscopes. Other than the quadrature error, frequency mismatch and quality factor, the dielectric parasitic charge was thought to be a major determinant. We studied the mechanism and variation of the parasitic charge in the MEMS gyroscopes, and analyzed the effect of the parasitic charge on the output stability. This phenomenon was extremely obvious in the Pyrex encapsulated MEMS gyroscopes. Due to the DC voltage required for the electrostatic actuation, the parasitic charge in the dielectric layer would accumulate and induce a residual voltage. This voltage had an impact on the resonant frequency of the gyroscopes, so as to affect the output stability. The theoretical studies were also confirmed by our experimental results. It was shown that the parasitic charge was harmful to the output stability of MEMS gyroscopes.展开更多
基金the Laboratory Open Fund of Beijing Smart-chip Microelectronics Technology Co.,Ltd and Chinese National Science Foundation(Contract No.52075519 and 61974136).
文摘The silicon on glasses process is a common preparation method of micro-electro-mechanical system inertial devices,which can realize the processing of thick silicon structures.This paper proposes that indium tin oxides(ITO)film can serve as a deep silicon etching cut-off layer because ITO is less damaged under the attack of fluoride ions.ITO has good electrical conductivity and can absorb fluoride ions for silicon etching and reduce the reflection of fluoride ions,thus reducing the foot effect.The removal and release of ITO use an acidic solution,which does not damage the silicon structure.Therefore,the selection of the sacrificial layer has an excellent effect in maintaining the shape of the MEMS structure.This method is used in the preparation of MEMS accelerometers with a structure thickness of 100μm and a feature size of 4μm.The over-etching of the bottom of the silicon structure caused by the foot effect is negligible.The difference between the simulated value and the designed value of the device characteristic frequency is less than 5%.This indicates that ITO is an excellent deep silicon etch stopper material.
基金supported by the National Natural Science Foundation of China under grant 62071447the National Key R&D Program of China under grant 2022YFF1202303.
文摘Silicon-based neural microneedle arrays,such as the Utah Array,have demonstrated excellent performance in chronic recordings from the cerebral cortex.Unlike planar thin-film electrodes with recording sites arranged on the surface of a silicon film,the recording sites of microneedle arrays are located at the tips of three-dimensional needles,which significantly complicates the fabrication process required for single-neuron recordings.To address this challenge,we develop a local de-insulation method for microneedle recording electrodes that eliminates the need for etching:the microneedle tips are encapsulated in a controllable-thickness protective layer,followed by deposition of a Parylene-C insulation layer.By optimizing the elasticity of the protection material,as well as its adhesion and shape on both the protective layer and the electrode shaft,we were able to precisely control the area of the removed insulated layers,resulting in consistent tip exposure.Experimental results show that the non-uniformity of the exposed microneedle recording sites in the silicon-based neural microelectrode arrays(each has 10×10 array)fabricated using this method is 3.32±1.02%.Furthermore,the arrays exhibited high stability and reliability in both mechanical performance and electrical characteristics.They achieved an average spike signal-to-noise ratio of 12.63±6.64 during in vivo testing.This fabrication technique provides a valuable method for the development of high-performance neural microelectrode array.
基金supported by the National Natural Science Foundation of China(No.61504130)
文摘Output voltage drifting was observed in MEMS gyroscopes. Other than the quadrature error, frequency mismatch and quality factor, the dielectric parasitic charge was thought to be a major determinant. We studied the mechanism and variation of the parasitic charge in the MEMS gyroscopes, and analyzed the effect of the parasitic charge on the output stability. This phenomenon was extremely obvious in the Pyrex encapsulated MEMS gyroscopes. Due to the DC voltage required for the electrostatic actuation, the parasitic charge in the dielectric layer would accumulate and induce a residual voltage. This voltage had an impact on the resonant frequency of the gyroscopes, so as to affect the output stability. The theoretical studies were also confirmed by our experimental results. It was shown that the parasitic charge was harmful to the output stability of MEMS gyroscopes.
