非晶硅室温微测辐射热计的研制

将聚酰亚胺作为绝热材料,对传统室温微测辐射热计结构进行了改进,成功制备了非晶硅室温微测辐射热计并进行了测试。以聚合物材料作为绝热材料,避免了表面牺牲层工艺和体加工技术,降低了成本、提高了成品率。在传统探测器结构基础上,在底部制备一层金属用作红外反射层,利用吸收层可以对红外辐射进行二次吸收。金属层和有源层间的隔离层对红外也有很好的吸收效果,由隔离层、有源层和钝化层构成三明治结构,可以显著改善对红外辐射的吸收。对器件的制备工艺进行了说明并对器件特性进行了测试,结果表明,在773 K黑体源8～14 μm红外辐射下,探测器的响应度最大为26.4 kV/W,表明器件具有较高的性能。     

柔性ZnS∶Cu电致发光器件制备和性能研究

采用喷墨印制工艺在聚对苯二甲酸乙二醇酯(PET)膜表面制备纳米银线(AgNWs)柔性透明导电膜。以纳米银线柔性透明导电膜分别作为顶电极和底电极，ZnS∶Cu为发光层，聚二甲基硅氧烷(PDMS)为介质层和包装层，采用旋涂工艺制备AgNWs/ZnS∶Cu&PDMS/AgNWs结构的柔性电致发光器件，并研究了电极的光电性能、介质层性能以及施加电压对器件性能的影响。研究表明，良好光电性的电极和高介电常数的介质层有利于提升器件发光强度。当以方阻20Ω/和透光度(550 nm)63.9%的薄膜作为电极，BaTiO₃和PDMS混合作为介质层时，施加200 V电压时器件的发光强度可达2.61 cd·m^-2,施加300 V电压时器件的发光强度可达6.41 cd·m^-2。器件弯曲180°后仍具有良好的电致发光特性。采用喷墨印制工艺制备4 cm×4 cm花朵图案的纳米银线柔性透明导电膜分别作为顶电极和底电极，ZnS∶Cu为发光层，BaTiO₃和PDMS作为介质层和包装层，制备电致发光器件，在200 V(50 Hz...     

InGaAs/InP光伏探测器阵列钝化工艺及均匀性研究

通过对气态源分子束外延结合常规器件工艺研制的晶格匹配InGaAs/InP光伏型探测器阵列光响应和暗电流特性的表征和比较,研究了聚酰亚胺和氮化硅两种钝化工艺对阵列器件性能和均匀性的影响,并对两种不同钝化膜阵列器件后续封装的可靠性进行了比较和分析.实验结果表明,气态源分子束外延材料具有良好的均匀性;氮化硅钝化器件总体性能上优于聚酰亚胺钝化器件.引线封装实验显示,SiN钝化膜有较好的抗冲击和热稳定性,具有更好的工艺相容性.     

电化学沉积Cu牺牲层工艺用于制备面外运动电热微驱动器

用电化学沉积Cu作为牺牲层制备面外运动电热微驱动器的悬空结构,并建立了一种简单、可靠的牺牲层工艺技术.该工艺具有工艺流程简单、牺牲层易获取、释放简单、腐蚀选择性好、结构保存完整等优点.通过退火去除残余应力、使用丙酮和F113进行悬空结构释放等方法改进工艺,可以得到理想的器件.证明电化学沉积Cu是比较好的制备悬空结构的牺牲层工艺.     

非制冷焦平面探测器牺牲层制备工艺研究

研究了牺牲层制备的工艺过程。通过对牺牲层材料选择、牺牲层图形化及牺牲层固化等工艺技术的研究,获得了图形质量较好的牺牲层样品。建立了优化的牺牲层制备工艺制度,为探测器的后续研究奠定了基础。     

MEMS开关中聚合物牺牲层去除方法研究

制作了一种以聚酰亚胺作为牺牲层的低下拉电压开关,聚酰亚胺牺牲层采用反应离子刻蚀(RIE)工艺进行刻蚀。研究了刻蚀功率对刻蚀时间的影响,检验了不同刻蚀功率与刻蚀时间组合条件下开关梁的结构完整性,优化了该RIE工艺。实验结果表明,聚酰亚胺牺牲层的去除效果较好,其侧向刻蚀率为1.3 μm/min。最终获得了具有2 μm以下间隙、结构完整的MEMS开关梁。     

制备Cu互连悬空结构的新型工艺研究

为了降低集成电路中的互连延迟,采取了一种新型的集成电路Cu互连工艺,以掩膜电镀的方法制备Cu互连的叠层结构,借鉴MEMS工艺的牺牲层技术,用浓磷酸对Al2O3牺牲层进行湿法刻蚀,不仅在互连金属间介质层而且在层内介质层都形成了以空气为介质的Cu互连悬空结构.用一种叉指测试结构对以空气和聚酰亚胺为介质的互连性能进行了比较,结果表明,采用空气介质减小了互连线耦合电容,为进一步降低集成电路的互连延迟提供了途径.     

用于相变存储器的W亚微米管加热电极性能

为了降低C-RAM器件的操作电流,利用0.18μm标准CMOS工艺线制备出外径为260nm的W亚微米管加热电极,并对其进行了电学性能的表征.使用W亚微米管加热电极制备出C-RAM器件,并通过疲劳特性测试分析了器件失效的原因.结果表明,W亚微米管具有良好的电学稳定性和疲劳特性,为降低C-RAM器件的操作电流提供了一种非常有效的途径.     

用于相变存储器的W亚微米管加热电极性能

为了降低C-RAM器件的操作电流,利用0.18μm标准CMOS工艺线制备出外径为260nm的W亚微米管加热电极,并对其进行了电学性能的表征.使用W亚微米管加热电极制备出C-RAM器件,并通过疲劳特性测试分析了器件失效的原因.结果表明,W亚微米管具有良好的电学稳定性和疲劳特性,为降低C-RAM器件的操作电流提供了一种非常有效的途径.     

更正

《电子与封装》2021年3月刊(第21卷第3期,总第215期),《基于二维半导体材料光电器件的研究进展》文中“3.1电极制备方法”节图1下(P030401-3)“在这篇文章中,分别选择了Cu、Ti和Pd作为电极,其接触电阻分别是2110 W/mm、1890 W/mm、1533 W/mm”,应为“2110Ω/μm、1890Ω/μm、1533Ω/μm”。     

The inverse problem in electroretinography: a study based on skinpotentials and a realistic geometry model

The problem of obtaining the retinal source distribution that generates the electroretinogram (ERG) from measured skin potentials is addressed. A realistic three-dimensional (3-D) volume conductor model of the head is constructed from magnetic resonance image (MRI) data sets. The skin potential distribution generated in this model by a dipole layer source at the retina is computed by using the boundary element method (BEM). The influence of the various compartments of the complete model on the results was investigated, and a simplified model was defined. An inverse procedure for estimating the source distribution at the retina from ERG's obtained from skin electrodes was developed. The procedure was tested on simulated potentials. A fair correspondence between the original and estimated source distribution was found. Furthermore, the ERG's measured at seven skin electrodes were used to estimate the source distribution at the retina. The ERG potential waveform at an additional skin electrode was computed from this source distribution and compared to the measured potential at this electrode. Again a fair correspondence was obtained. It is concluded that the methods may become a useful tool for clinical applications, i.e., for the assessment of localized defects in retinal function     

Electrical performance of the embedded-type surface electrodes containing carbon and silver nanowires as fillers and one-step organosoluble polyimide as a matrix

Embedded-type surface electrodes with silver nanowire (AgNW) and carbon nanotube (CNT) as conductive fillers and organosoluble polyimide (PI) as a matrix were investigated for their electrical conductivity and electrical durability under cyclic bending. The chosen polyimide was constituted with 4,4′-oxydiphthalic dianhydride and 2,2-bis(3-amino-4-hydroxyphenyl)hexafluoropropane through a one-step process. Two types of surface electrodes of CNT/PI and AgNW/PI were prepared at 90 °C. The flexible CNT/PI and AgNW/PI surface electrodes not only had high electrical conductivities of 6.3 and 100 S/cm, respectively, after 30 spraying cycles but also kept electrical durability after 1200-time bending tests. The ITO-coated ITO/PI and ITO/AgNW/PI electrodes, for a comparative purpose, had severe electrical failure under cyclic bending.     

Increasing bondability and ball-shear force of gold balls thermosonic bonding to flex substrates by depositing a nickel layer

To improve the bondability and ball-shear force of gold balls that are thermosonically bonded to copper electrodes over flex substrates, a nickel layer was deposited on the surface of the copper electrodes to increase their rigidity. A silver layer was then deposited on the nickel layer to prevent oxidation of the copper electrodes during the thermosonic bonding process. This nickel layer was expected to enhance the rigidity of copper electrodes over the flex substrates, increasing the thermosonic bonding efficiency of gold balls to copper electrodes over the flex substrates.Deposition the nickel layer on the copper electrodes improved the elastic modulus of the flex substrates, indicating that the nickel layer is effective in enhancing the rigidity of copper electrodes over the flex substrates. The bondability and ball-shear force of gold balls that are thermosonically bonded to copper electrodes increases with the thickness of the nickel layer given fixed bonding parameters. One hundred percent bondability and high ball-shear force can be achieved when gold balls are thermosonically bonded to copper electrodes with the deposition of a 0.5 μm-thick nickel layer. Herein, the ball-shear force was higher than that specified in JEDEC standards. Furthermore, gold balls that were thermosonically bonded to copper electrodes with a nickel layer had a large bonded area with an extensive scrape, while gold balls that were thermosonically bonded to copper electrodes without a nickel layer had a blank surface morphology. This experimental result was similar to that of tests of the elastic modulus of flex substrates, similarity can be used to explain that the effectiveness of the nickel layer in increasing the rigidity of copper electrodes, increasing the bonding efficiency at the bonding interface between gold balls and copper electrodes during thermosonic bonding process. After ball-shear test, a layer that was stuck on the ball bond was observed at the location of fracture of the ball bonds for gold balls they were thermosonically boned on copper electrodes with 0.5 μm-thick nickel layer. This observation implies that the ball-shear force of the gold balls that were bonded on the copper electrodes exceeded even the adhesive force of the layers that were deposited on the copper electrodes.The deposition of a 0.5 μm-thick nickel layer on copper electrodes over flex substrates improved the rigidity of the copper electrodes; the ultrasonic power could be propagated to the bonding interface between the gold balls and the copper electrodes, increasing the bondability and ball-shear force.     

An in vitro model of a retinal prosthesis

Epiretinal prostheses are being developed to bypass a degenerated photoreceptor layer and excite surviving ganglion and inner retinal cells. We used custom microfabricated multielectrode arrays with 200-microm-diameter stimulating electrodes and 10-microm-diameter recording electrodes to stimulate and record neural responses in isolated tiger salamander retina. Pharmacological agents were used to isolate direct excitation of ganglion cells from excitation of other inner retinal cells. Strength-duration data suggest that, if amplitude will be used for the coding of brightness or gray level in retinal prostheses, shorter pulses (200 micros) will allow for a smaller region in the area of the electrode to be excited over a larger dynamic range compared with longer pulses (1 ms). Both electrophysiological results and electrostatic finite-element modeling show that electrode-electrode interactions can lead to increased thresholds for sites half way between simultaneously stimulated electrodes (29.4 +/- 6.6 nC) compared with monopolar stimulation (13.3 +/- 1.7 nC, p < 0.02). Presynaptic stimulation of the same ganglion cell with both 200- and 10-microm-diameter electrodes yielded threshold charge densities of 12 +/- 6 and 7.66 +/- 1.30 nC/cm2, respectively, while the required charge was 12.5 +/- 6.2 and 19 +/- 3.3 nC.     

An In Vitro Model of a Retinal Prosthesis

Epiretinal prostheses are being developed to bypass a degenerated photoreceptor layer and excite surviving ganglion and inner retinal cells. We used custom microfabricated multielectrode arrays with 200-mum-diameter stimulating electrodes and 10-mum-diameter recording electrodes to stimulate and record neural responses in isolated tiger salamander retina. Pharmacological agents were used to isolate direct excitation of ganglion cells from excitation of other inner retinal cells. Strength-duration data suggest that, if amplitude will be used for the coding of brightness or gray level in retinal prostheses, shorter pulses (200 mus) will allow for a smaller region in the area of the electrode to be excited over a larger dynamic range compared with longer pulses (1 ms). Both electrophysiological results and electrostatic finite-element modeling show that electrode-electrode interactions can lead to increased thresholds for sites half way between simultaneously stimulated electrodes (29.4 plusmn 6.6 nC) compared with monopolar stimulation (13.3 plusmn 1.7 nC, < 0.02). Presynaptic stimulation of the same ganglion cell with both 200- and 10- m-diameter electrodes yielded threshold charge densities of 12 plusmn 6 and 7.66 plusmn 1.30 nC/cm², respectively, while the required charge was 12.5 plusmn 6.2 and 19 plusmn 3.3 nC.     

Effects of different electroplated gate electrodes on electrical performances of flexible organic thin film transistor and flexibility improvement

Various electroplated metal gate electrodes (Ni, Cu, and Au) on flexible polyimide (PI) substrates were applied to the fabrication of inverted staggered pentacene organic thin film transistors (OTFTs). The metal gate electrodes additively electroplated onto the patterned negative photoresist mask on the Cu(seed)/Cr(adhesion) layers sputter-deposited on the O₂-plasma-treated PI substrates were effective in obtaining good adhesion between the metal gate electrode and organic substrate. It was found that the reduction in the surface roughnesses of the electroplated metal gate and of the subsequently deposited PVP (poly-4-vinyl phenol) gate dielectric layers was a critical factor in improving the device performance. The Ni-gated OTFT exhibited the best electrical characteristics, with a field-effect mobility of ≅0.2 cm²/V-s and a current on/off ratio of ≅10³, due to the better chemical stability of the Ni electrode and the smoother surface of the PVP layer on the Ni electrode, as compared to the OTFTs with PVP/Cu or PVP/Au gates. The results of the flexibility test showed that the field-effect mobility and current on/off ratio were not changed significantly when the OTFTs were subjected to 10,000 cyclic bendings with a bending radius of 6 mm in tension mode (outward bending).     

Cr/Cu/Al/Cr薄膜电极的防氧化性能

采用Al作为Cu导电层的主要防氧化保护层,在普通浮法玻璃上利用磁控溅射和湿法刻蚀技术制备Cr/Cu/Al/Cr复合薄膜及其电极,研究不同的热处理温度对复合薄膜及其电极的结构、表面形貌和导电性能的影响。由于有Al层作为保护层,在热处理过程中,Al先与穿过Cr保护层的氧进行反应,从而可以更有效地保护Cu膜层在较高的温度下不被氧化,所制备的薄膜在经过600℃的热处理之后仍然具有较好的导电性能。而对于Cr/Cu/Al/Cr电极,侧面裸露的金属层在热处理过程中的氧化是其导电性能逐渐下降的主要原因,退火温度超过500℃之后,电极侧面裸露部分的氧化范围不断往电极的中间扩散,导致了薄膜电极导电性能显著恶化。虽然如此,Cr/Cu/Al/Cr薄膜电极在430℃附近仍然具有较好的导电性能,电阻率为7.3×10-8Ω.m,符合FED薄膜电极的要求。以此薄膜电极构建FED显示屏,通过发光亮度均匀性的测试验证了Cr/Cu/Al/Cr电极的抗氧化性。     

聚酰亚胺溶液黏度对液晶预倾角的影响

为了制备具有自取向功能的聚酰亚胺(PI)取向膜,避免摩擦工序在取向膜表面造成静电、灰尘、配向不良等不利影响,本实验通过一系列黏度不同且有水平及垂直取向功能的PI溶液,研究了PI液黏度和其取向膜表面粗糙度的关系,进而研究了PI膜表面粗糙度和液晶预倾角(θ_p)的关系。研究发现:取向膜表面粗糙度随着PI液黏度的增大而增大,θ_p随着粗糙度的增大而增大,但当粗糙度大于一定值(3.760nm)后,θ_p增长缓慢并趋于稳定。这主要是因为PI液黏度增大时,阻碍了相邻PI液滴通过分子链段协同运动向彼此扩散的几率,进而形成取向膜表面的"峰谷"形貌,这种"峰谷"形貌表面对液晶垂直取向起到了支撑作用,正是这种支撑作用使得液晶分子获得较大的θ_p。结合液晶面板响应时间对高预倾角的要求和Inkjet PI液滴喷嘴过小对PI液黏度的限制,得出PI液黏度大约为41CP时,此时取向膜表面粗糙度为4.830nm,液晶取向角为5.5°,能较好地满足液晶取向的要求。     

Tissue damage by pulsed electrical stimulation

Repeated pulsed electrical stimulation is used in a multitude of neural interfaces; damage resulting from such stimulation was studied as a function of pulse duration, electrode size, and number of pulses using a fluorescent assay on chick chorioallontoic membrane (CAM) in vivo and chick retina in vitro. Data from the chick model were verified by repeating some measurements on porcine retina in-vitro. The electrode size varied from 100 microm to 1 mm, pulse duration from 6 micros to 6 ms, and the number of pulses from 1 to 7500. The threshold current density for damage was independent of electrode size for diameters greater than 300 microm, and scaled as 1/r2 for electrodes smaller than 200 microm. Damage threshold decreased with the number of pulses, dropping by a factor of 14 on the CAM and 7 on the retina as the number of pulses increased from 1 to 50, and remained constant for a higher numbers of pulses. The damage threshold current density on large electrodes scaled with pulse duration as approximately 1/t0.5, characteristic of electroporation. The threshold current density for repeated exposure on the retina varied between 0.061 A/cm2 at 6 ms to 1.3 A/cm2 at 6 micros. The highest ratio of the damage threshold to the stimulation threshold in retinal ganglion cells occurred at pulse durations near chronaxie-around 1.3 ms.     

Enhancement of electrical properties in pentacene-based thin-film transistors using a lithium fluoride modification layer

We investigated the electrical performances of pentacene-based thin-film transistors with a thin LiF film as a modification layer between the source/drain electrodes and the active layer. Au, Pt, and Pd were employed as the source/drain (S/D) electrodes of the organic thin-film transistors (OTFTs). The thickness of the LiF layer was varied to optimize the electrical performances of the OTFTs. We found that the electrical performances of the devices with LiF layer are better than those without inserting the LiF layer, regardless of which one metal used for the S/D electrodes. The electrical performances of the devices in terms of drain current, on resistance, threshold voltage, on/off current ratio and mobility have been optimized when the thickness of the LiF buffer layer was at 1.0 nm. These improvements are attributed to work function of S/D contact materials were modified by the dipole of the inserted LiF layer and an ultrathin LiF layer provides the tunneling condition to enhance the carrier injection efficiently. Additionally, LiF layer with optimal thickness (1.0 nm) can modify surface roughness of pentacene film and partly enhance the carrier injection.