摘要:

In this letter, a method is outlined and results presented for an x‐ray lithography micromachining process that offers a greatly improved sensitivity over the LIGA process. This process is based on photosensitive polyimide (PPI), which is a commercial photoresist typically used as a passivation layer or dielectric material in the semiconductor industry. The main benefit of this process is its high sensitivity, which is approximately two orders of magnitude greater than that of the PMMA used in the LIGA process. Using a synchrotron radiation x‐ray source, we have achieved resist patterns over 1000 &mgr;m thick. The capability has also been demonstrated for aspect ratios over 10, as well as the ability to print linewidths down to 0.5 &mgr;m. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.113906

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

The stress in the thin films of pure Cu and Cu (Mg) alloy deposited on oxidized silicon substrates has been measured in the range of room temperature to 500 °C by the use of aninsitulaser based curvature measuring tool. Results indicate that small amounts of Mg (∼2–3 at. %) in copper changes the stress‐temperature behavior significantly when compared with that of pure copper. The alloy, after the first annealing cycle which apparently equilibrates the film, shows a predominantly elastic stress‐temperature behavior up to ∼400 °C compared to pure Cu, which shows a departure from linearity at ∼200 °C. Rutherford backscattering and x‐ray diffraction studies were also carried out to elucidate the role of Mg in strengthening the copper film. The results indicate that additions of Mg to Cu increase the mechanical strength of the film and that such behavior is retained in several (subsequent) thermal cycles to 400 °C. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.113907

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

It is shown that, by modifying the conventional light scattering geometry, it is possible to characterize the root‐mean‐square roughnesswin a scale‐invariant rough surface forwvalues more than one order of magnitude larger than those previously reported. Measurement ofwon the order of the wavelength of light has been demonstrated. A consequence of this development is that one can combine the diffraction theory and the measurement to determine the surface roughness exponent &agr;, which was not possible under conventional light scattering conditions. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.113908

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

Electron beam deposition (EBD) is a maskless technique suitable for the fabrication of nanometer scale structures. Metals can be deposited from an organometallic gas, but simultaneous carbon deposition typically yields grossly impure (∼25% metal) deposits. We have found that the metal content of the deposited solid is dramatically improved by performing the whole EBD process in a reactive gaseous environment containing a source of oxygen (O2or H2O) in addition to the organometallic gas. With simple procedures we prepared Au deposits showing significantly diminished C content (up to 50% metal) as the partial pressure ofO2(orH2O) is increased in the gas. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.113909

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

We have grown stepwise equilibrated graded GexSi1−x(x≤0.20) buffers with threading dislocation densities between 102and 103cm−2in their unstrained cap layers. The Ge content of the buffer was increased stepwise. The equilibrating treatment was performed as aninsituannealing in hydrogen at 1050 °C after each and every layer of the buffer. Subsequently, the buffer was grown relaxed layer by relaxed layer. The extreme low threading dislocation density was present on the whole area of 4 in. wafers. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.113910

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

Electron microscopy studies of annealed GaAs layers grown by molecular beam epitaxy at low temperature (200 °C) were used to monitor growth of As precipitates. Ostwald ripening kinetics was used to deduce a migration enthalpy of 1.4±0.3 eV for the diffusion mediating defect. A conclusive picture of the dominant diffusion mechanism can be given, attributing this value to the migration enthalpy of gallium vacancies (VGa), which is well established by other experiments. The present studies indicate that growth of As precipitates is driven by supersaturation ofVGa. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.113911

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

High‐resolution transmission electron microscopy and selected area electron diffraction have been used to study Hg0.8Cd0.2Te wafer. Two kinds of chemical composition modulated structures were found. One is a one‐dimensional modulation with modulated wave vectorq*=(a*−b*)/5.6 and the other two‐dimensional modulation with modulated wave vectorsq1*=(a*−b*)/5.6 andq2*=(a*−b*)/11.2−0.22c*. Both structures have a common modulated wavelength of 2.54 nm. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.113912

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

The recombination velocity at single crystalline/polycrystalline Be‐doped GaAs interfaces is measured using time‐resolved photoluminescence. Samples with AlGaAs/GaAs double heterostructures are grown by molecular beam epitaxy on GaAs substrates patterned with SiO2. For a Be doping level of 3×1016cm−3, the interface recombination velocity at 77 K is in the range of (2 to 10)×6cm/s, and it is independent of the polycrystal grain size. The latter is explained by assuming that the carrier capture cross section is constant on the polycrystal grain surface. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.113913

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

The luminescence of GaAs layers grown by molecular beam epitaxy at low substrate temperature (230 °C) in a GaAs/In0.2Ga0.8As multiple quantum well structure is presented. The near‐band‐gap emission and defect‐related emission are observed for samples annealed at high temperature (800–900 °C), but are not observed for samples annealed at lower temperature (600–700 °C). The luminescence shows a strong correlation with the spacing between As precipitates based on the transmission electron microscope observations. The evolution of luminescence of annealed low‐temperature (LT) GaAs can be reasonably explained by the buried Schottky model. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.113914

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

Time‐resolved photoluminescence measurements of electron transport are reported in InGaAsP/InP graded‐gap separate‐confinement quantum well laser structures with a steplike grading profile. It is found that electron transfer over the graded‐gap region occurs on a subpicosecond time scale. The upper time limit for the electrons to pass one step of 22 nm width is 250 fs. The fast transfer times imply that the electron transport across the graded region is not affected by the presence of the steps. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.113915

出版商:AIP    

年代:1995

数据来源: AIP