InP/GaAs低温键合的新方法

通过对 InP/GaAs 异质键合实验方法的研究,提出了包括表面活化处理、真空预键合和退火热处理的三步法,在350℃低温下实现了InP/GaAs异质材料的键合。界面电流 电压(I V)特性的研究表明,350℃样品的界面过渡层极薄,电子主要以隧穿方式通过界面,而450℃的扩散使得过渡层增厚,界面电流 电压特性可视为双肖特基二极管的反向串联。同时,对键合样品也进行了拉力测试,实验结果表明 450℃样品的键合强度优于350℃样品。最后,对InP/GaAs异质材料的键合机理进行了探讨。     

Vacuum sealing using surface activation bonding of Si wafer

Bonding technology of Si wafer for vacuum seal is important in MEMS. We have tried the vacuum seal using surface activation bonding without any binder. It is the ultimate bonding technique and gives the precise dimension due to the direct contact. The technique is, however, not easy. We have investigated the surface conditions in order to achieve the bonding. The surfaces cleaned by Ar ion beam bombardment were measured by XPS and AFM. The natural oxide on the Si surface was removed by Ar ion bombardment. The surface roughness depended on the condition and the irradiation time of the Ar ion beam. The surface bonding at room temperature was achieved for the clean surface of the surface roughness less than Ra = 1 nm, but it was not done with the rough surfaces more than Ra > 2 nm. The vacuum sealing was checked using the cavities made in the Si wafer. The cavity part sealed in vacuum was depressed in the atmosphere, which was measured using a needle-contact profiler and a 3D laser profiler. The gas in the cavity was measured with a mass spectrometer by clashing the seal in vacuum. Any other gas except Ar gas closed in the cavity was not detected. We concluded that the vacuum sealing using surface activation bonding of Si wafer was achieved. The sealing condition has not changed even after one year.     

基于低温直接键合的血细胞计数芯片结构制备

研究了一种新颖的微流管道血细胞计数器的结构及其工作原理,采用流体动力学对其液体分层流动特性进行了仿真分析,结合图形制备和低温直接键合工艺制作了硅基微流体管道血细胞计数器结构,并采用红外透射方法对微流体管道结构进行了检测.对封闭管道的流通性及结构的键合强度也进行了测量.研究分析表明,采用上述工艺制备的微流体芯片结构与电子器件兼容性好,具有良好的化学惰性和热稳定性,而且管道结构规则,精度高,键合界面层薄,具有较好的应用前景.     

The role of hydrogen in a-C:H films deposited from hexane or acetylene using direct ion beam deposition method

The present work provides results of amorphous hydrogenated carbon (a-C:H) films deposited by direct ion beam deposition method. Hexane (C₆H₁₄+H_delivery) or acetylene (C₂H₂) precursors and their mixture with hydrogen (H₂) were used. The films were characterized by Raman spectroscopy (RS), ellipsometry, and electrical resistance measurements. RS indicates increase in sp³/sp² bonding ratio and disorder in graphite clusters, upon increasing of hydrogen content (from 0% to 50% for acetylene precursor) in the deposition gas mixture. The opposite trend is observed when the hydrogen concentration exceeded 50% (for acetylene) or additional hydrogen was added (for hexane). The data of electrical resistance measurements support the correlations defined by RS.     

Production of a low-energy radioactive nuclear beam with high purity using JAERI-RMS

Low-energy (1–2 MeV/nucleon) radioactive nuclear beams (RNBs) of ⁸Li, ¹²B and ¹⁶N have been produced through nuclear transfer reactions using a recoil mass separator (RMS) at Japan Atomic Energy Research Institute (JAERI). The contamination of the primary beam to the RNB was investigated quantitatively and was well suppressed. The typical beam intensities of ⁸Li-, ¹²B- and ¹⁶N-RNB were 1.4×10⁴, 7.8×10³ and , respectively. Their purities were 99%, 98% and 98.5%, respectively.     

Effects of low-energy ion beam glancing angle nitridation on nGaAs surface and Co-nGaAs Schottky contact properties

In this research, effects of low-energy nitrogen and argon ion beam irradiation at a glancing angle on chemical composition and morphology of the GaAs surface as well as electrical properties of Co-nGaAs Schottky contact are studied. Substantial reduction of the effective barrier height was observed. This reduction was explained by formation of the irradiation-induced thin n⁺ layer. This revealed that low effective barrier height and low noise Co-nGaAs Schottky contacts can be fabricated on GaAs by low-energy nitrogen ion beam irradiation of surface. On the other hand, GaAs surface irradiation by low-energy noble gas (argon) ion beam resulted in substantial increase of the low-frequency noise at liquid nitrogen temperature. Formation of a thin GaN layer as a result of the GaAs surface irradiation by low-energy nitrogen ion beam was observed by XPS. Experimentally registered decrease of the low-frequency noise (in the case of nitrogen irradiation) was explained in terms of the screening of irradiation-induced defects, passivation of dangling bonds at the GaAs surface nGaAs and increased surface and Schottky contact homogeneity due to the ion beam nitridation.     

Hydrogen influence on the structure and properties of amorphous hydrogenated carbon films deposited by direct ion beam

The present work provides results for amorphous hydrogenated carbon (a-C:H) films grown by direct ion beam deposition method. Acetylene and its mixtures with hydrogen were used. The films were characterized by Rutherford backscattering spectrometry, elastic recoil detection, Raman spectroscopy, ellipsometry, infrared spectroscopy, and microhardness measurements. These techniques indicated that an admixture of hydrogen yields a lower deposition rate, a higher content of total and bounded hydrogen in the a-C:H films, and a lower film density. The optical and mechanical properties depend on both, hydrogen concentrations in the gas phase and in the films, and show a strong diamond-like component, which reaches maximum at 34 at.% of hydrogen. Further hydrogen dilution enhanced only sp² clustering and possible reduced a number of both sp³ and C-C sp³ bonds. We suppose that these effects (in the high hydrogen concentration range) are not only related to the ion irradiation difference between the light hydrogen and the much heavier carbon but also to the diffusion in the a-C:H films.