摘要:

Basic properties of transition metal oxide films as a high‐resolution, negative working ion resist have been studied experimentally for focused ion beam (FIB) exposure. Thin amorphous films of WO3, MoO3, V2O5and a mixture thereof were formed on Si wafers and exposed to a 20–70 keV Ga+FIB. Development after writing was performed by chemical etching. The resist sensitivity and the contrast were measured as a function of the accelerating voltage of the FIB. The dry etching durability of the delineated resist patterns and their selectivity with respect to Si were also evaluated for SF6plasma etching. The details of the characteristics can be explained in terms of the physical and chemical properties of the resist material.

ISSN:1071-1023    

DOI:10.1116/1.584922

出版商:American Vacuum Society    

年代:1990

数据来源: AIP

摘要:

We report an initial attempt to explore the feasibility of using an excimer laser to planarize copper deposited over polyimide. Even though the polyimide is thermally sensitive, a 2.8 μm thick copper film, deposited over polyimide, was planarized with 248 nm, 25 ns, laser fluences from 1.7 to 2.6 J/cm2. Although planar surfaces were readily produced, a variety of defects were observed in the underlying structures.

ISSN:1071-1023    

DOI:10.1116/1.584923

出版商:American Vacuum Society    

年代:1990

数据来源: AIP

摘要:

The thermal desorption kinetics of Ga from initially As‐terminated Si(100) is investigated using laser‐induced fluorescence spectroscopy. During the Ga desorption process the surface does not remain fully As terminated because a significant fraction of the initial As coverage simultaneously desorbs with the Ga. For Ga coverages ≥ 0.55±0.1 ML (1 ML=6.8×1014atoms cm−2), Ga desorbs from As‐terminated Si initially by a fractional order kinetic mechanism. Lower Ga coverages desorb more slowly and by a first order mechanism. The results suggest that at high coverages Ga desorbs initially from islands, and then at lower coverages from a two‐dimensional (2D) layer. Based on the distinct differences between Ga desorption from bare Si(100) and the desorption of Ga from the 2D Ga/As interfacial layer, this layer is probably GaAs‐terminated Si(100). These results on the GaAs system are compared with those previously reported on the InAs system, which show that In interacts with As on Si(100) less strongly than does Ga.

ISSN:1071-1023    

DOI:10.1116/1.584924

出版商:American Vacuum Society    

年代:1990

数据来源: AIP

摘要:

We have characterized the removal of chlorine adsorbed on GaAs (100) surfaces by electron‐stimulated desorption (ESD). Such processes may form the basis for the use of electron beams as a focused energy source for high‐definition assisted etching. We find that chlorine adsorbed on a GaAs(100) surface is sensitive to ESD and that loss of chlorine proceeds via two processes on different time scales. Furthermore, chlorine adsorbed on areas of the surface that have not been under the influence of the electron beam does not diffuse at a detectable rate into areas stripped of chlorine by ESD. We have determined mass spectrometrically that, under low chlorine coverage conditions, ESD products consist solely of chlorine atoms, although it is possible that under a high chlorine flux etching may occur.

ISSN:1071-1023    

DOI:10.1116/1.584925

出版商:American Vacuum Society    

年代:1990

数据来源: AIP

摘要:

Minority carrier injection at forward‐biased WNx/n‐GaAs Schottky gates lead to diffusion capacitances in excess to the space charge capacitance and inductive reactances in certain frequency ranges.p‐buffer layers act as a minority carrier sink which enhances the minority carrier injection. This finally gives stronger excess capacitances and inductive reactances. Furthermore, excess diffusion capacitances can be observed at higher frequencies. The frequency dependent admittance behavior of forward biased WNx/n‐GaAs gates is studied in the temperature range between 77 K and room temperature.

ISSN:1071-1023    

DOI:10.1116/1.584926

出版商:American Vacuum Society    

年代:1990

数据来源: AIP

摘要:

A volumetric 10:1 ratio of citric acid (50% by weight) and hydrogen peroxide (30%) is shown to be a better selective etchant of GaAs/Al0.30Ga0.70As systems than the more commonly used ammonium‐hydroxide/hydrogen peroxide solutions in terms of the selectivity of the etching rate, the smoothness of the etched surface, and the abruptness of the etch‐defined edge. In addition, the citric acid/hydrogen peroxide solution does not attack Shipley 1400 series positive photoresists. This simple and reproducible selective etching process has been applied to prepare GaAs optical devices for transmission measurements (‘‘doughnut’’ samples).

ISSN:1071-1023    

DOI:10.1116/1.584928

出版商:American Vacuum Society    

年代:1990

数据来源: AIP

摘要:

The thermally stable Pt/Ti metallization scheme was applied to Zn doped InAs layers in order to evaluate the influence of the outstanding electrical properties of the latter, such as the narrow band gap and the fact that the surface Fermi level pins in the conduction band, on the ohmic contact performance. These contacts applied to 1×1018, 5×1018, and 1×1019cm−3Zn doped InAs layers, grown directly on InP(Fe) substrates, were already ohmic as‐deposited with a specific resistance values of 3.0×10−5, 9.8×10−6, and 7.5×10−6Ω cm−2, respectively. Rapid thermal processing for 30 s at elevated temperatures yielded even a further reduction of the specific contact resistances, with a minimum value of less than 6×10−7Ω cm2, for a 450 °C anneal. This heat treatment enhanced limited reactions in both the Pt/Ti and Ti/InAs interfaces, but, however, did not lead to the degradation of the stable microstructure.

ISSN:1071-1023    

DOI:10.1116/1.584929

出版商:American Vacuum Society    

年代:1990

数据来源: AIP

摘要:

This paper describes the work of fabricating optical logic devices and GaAs groove grating by the LKJ‐1B ion beam etching machine and the LDJ‐2A ion beam sputtering film system developed in our laboratory. The two‐dimension multiple optical beam splitter is a device that produces phase delay which is determined by groove depth [Δφ=(2π/λ)(n−1)d]. K9 optic glass was used as the substrate material. The wavelength of the incident light was 6328 Å (He–Ne laser). The etching depth and the accuracy weredπ=λ/2(n−1)=6128 and 100 Å, respectively. The difference in the splitting light intensity between theory and experiment was ±3.6%. The author has fabricated the groove grating with periods of 10, 4, and 2 μm and depths of 3000, 5000, and 7000 Å. The sidewall slope is about over 85°.

ISSN:1071-1023    

DOI:10.1116/1.584930

出版商:American Vacuum Society    

年代:1990

数据来源: AIP

摘要:

We report high quality GaAs/Ge/GaAs heterojunctions grown by molecular‐beam epitaxy. Antiphase domain (APD) free GaAs on Ge growth, as verified by high‐energy electron diffraction and transmission electron microscopy, has been achieved for epitaxial (100) Ge surfaces misoriented towards [011] while APDs are observed to annihilate after roughly 500 Å of GaAs growth on nominally (100) epitaxial Ge. The outdiffusion of Ga and As into epitaxial Ge and outdiffusion of Ge into epitaxial GaAs was investigated byinsitux‐ray photoemission spectroscopy and secondary ion mass spectroscopy. The electrical properties of the heterojunctions are studied and the transistor characteristics of a prototype N–Al0.22Ga0.78As/p+‐Ge/n‐GaAs heterojunction bipolar transistor is presented.

ISSN:1071-1023    

DOI:10.1116/1.584931

出版商:American Vacuum Society    

年代:1990

数据来源: AIP

摘要:

A step by step development of surface morphology as a function of deposition temperature (617–897 °C, by 40 °C steps) of Ge crystals grown by chemical vapor deposition using GeH4in an He atmosphere is experimentally demonstrated. Three temperature regions are observed. A net‐like rough surface morphology composed of many interconnected elongated crystals is observed in the low temperature range (617–697 °C). In the high temperature range (817–857 °C) isolated islands of three‐dimensional structures having a pyramid‐like geometry and their interactions are observed. The medium range (737–777 °C) is found to be a transition between the above ranges. As a whole, the degree of surface order obtained increases with the deposition temperature. The mechanisms influencing the morphology are explained by the temperature dependence of the GeH4decomposition rate, Ge atom, surface mobility and migration length, nucleation and re‐evaporation rates, activity of surface defects and nucleation sites, and finally, parasitic oxide formation.

ISSN:1071-1023    

DOI:10.1116/1.584932

出版商:American Vacuum Society    

年代:1990

数据来源: AIP