摘要:

The dynamic behavior of GaAs surfaces during and after growth by MBE has been probed by detailed measurements of the specular beam intensity in RHEED patterns from the surfaces. The damping of the intensity oscillations observed after growth has commenced is shown to be a strong function of arsenic pressure with high pressure causing strong damping and rough growth fronts. The specular beam intensity after steady‐state growth has been interrupted shows first an initial fast increase with the largest increase occurring at low arsenic pressure, and then a slow recovery to its equilibrium no‐growth intensity at a rate that increases with arsenic pressure. Measurements of the intensity recovery after short growths on an equilibrated no‐growth surface provide new information about the growth front behavior during the first few monolayers of growth. The surface recovers in the shortest time after deposition of either a small fraction of a monolayer or slightly more than an integer number of monolayers. Recovery is slow after deposition of half a monolayer due to the resulting high step density. Surprisingly, recovery is slowest after deposition of 1.0 monolayer, indicating that such surfaces are very different from the equilibrium no‐growth surface.

ISSN:0734-211X    

DOI:10.1116/1.582986

出版商:American Vacuum Society    

年代:1985

数据来源: AIP

摘要:

GaAs power field effect transistors (FET’s) with the highest power output per unit gate width (0.46 W/mm) reported to data at Ka‐band frequency were fabricated using molecular beam epitaxy material with active layer doping of 3.6×1017cm3. Power output of 110 mW and conversion efficiency of 11% were achieved with half‐micron gate GaAs FET’s in a 30 GHz amplifier with an associated gain of 3.4 dB. This report describes the molecular beam epitaxy (MBE) growth conditions and results of characterization of the power FET.

ISSN:0734-211X    

DOI:10.1116/1.582987

出版商:American Vacuum Society    

年代:1985

数据来源: AIP

摘要:

Vanadium silicide formation has been monitored by low energy noble gas ion scattering (IS), Auger electron spectroscopy (AES), and secondary ion mass spectrometry (SIMS). Vanadium deposited at 300 K shows no silicide formation. The topmost layer is composed of V atoms only. Annealing leads to a chemical reaction of vanadium and silicon to a vanadium silicide. Upon annealing atT=830 K the top layer consists of a Si layer. The silicide formation could be monitored by the VSi+2SIMS line. At 830 K a complete reaction of a 5000‐Å‐thick V film into a VSi2silicide occurs.

ISSN:0734-211X    

DOI:10.1116/1.582988

出版商:American Vacuum Society    

年代:1985

数据来源: AIP

摘要:

High‐current failure levels of TaSi2–polycide/Al‐alloy bilevel‐conductor composites were measured using 10 min increment step‐stress tests. Al‐alloy metallizations were Al and Al–1%Si; polycide and metal linewidths ranged from 2.5 to 3.0 μm; and interlevel‐contact sizes ranged from 1.5 to 2.0 μm2. In all cases, the weak links in the bilevel composite were the interlevel contacts. In units with contact resistances less than 1 Ω, failures occurred at the positive contact at polycide‐line current densities ≥1.4×107A/cm2, which resulted in Joule heating of the polycide line to ≥400 °C. Polycide line damage and Al, which had migrated in the direction of the electric field, often extended to distances>100 μm from the failed contact. Early failures, highly localized at the negative contact, were consistently experienced by units with initial contact resistances above approximately 1 Ω. The failure levels decreased (to current densities as low as 5×106A/cm2) with increasing initial contact resistance. Thirty cycles of thermal shock (−70 to +100 °C) resulted in no reduction in the current level at which high‐current failure occurred in units with good contacts.

ISSN:0734-211X    

DOI:10.1116/1.582989

出版商:American Vacuum Society    

年代:1985

数据来源: AIP

摘要:

A low‐reflectivity aluminum–silicon (LR Al–Si) film is prepared using a dc magnetron sputtering system under high Ar pressures. At a wavelength 4360 Å, the Al–2% Si film deposited at 3.99 Pa shows a specular reflectivity of 0.15 and a diffuse reflectivity of 0.10. The low‐reflectivity is ascribable to the formation of columnar structures of several hundred angstroms with open boundaries. The formation is caused by thermalization of sputtered Al(Si) atoms and the suppression of surface migration by Si atoms. Microvoids formed between columnar crystallites are thought to absorb incident light. This film is applied to multilevel metallization, and the results obtained include improvement of patternability in photolithography, reduction of hillock formation, and thermal stability of contact characteristics. This film is thus attractive because it is simply prepared and processing procedures for multilevel metallization do not require any major modification of conventional processes.

ISSN:0734-211X    

DOI:10.1116/1.582990

出版商:American Vacuum Society    

年代:1985

数据来源: AIP

摘要:

A bilayer resist system is demonstrated using chlorinated polymethylstyrene‐polydimethylsiloxane (CPMS/DMS) block copolymers. The copolymers are prepared using anionic polymerization techniques and are subsequently sensitized to electron beam, and 250–300 nm radiation by preferential chlorination of the polymethylstyrene block. The electron lithographic performance of a block copolymer containing 15.5 wt. % silicon, 0.58 chlorines per methylstyrene unit (totalM̄w=8.7×104) and polydispersity=1.3 was determined to exhibit a sensitivity (D0.5g)=0.9 μC/cm2, and contrast=1.3. The etch ratio compared to the HPR‐204 planarizing layer was 13.5 : 1 with an observed resolution range of 0.75 to 1.0 μm. These results derive from the intrinsic behavior of block copolymers, which provides for the synergistic combination of inherently distinct polymer species while avoiding macroscopic phase separation prevalent in homopolymer blends. The concept of utilizing block copolymers as resists is general and may be extended to positive tone resists as well.

ISSN:0734-211X    

DOI:10.1116/1.582991

出版商:American Vacuum Society    

年代:1985

数据来源: AIP

摘要:

So‐called ‘‘spin‐on‐Glass’’ materials (herein abbreviated as SOG) have generated a considerable amount of interest in the field of microelectronic materials and processing. The materials have been used for some time as doping sources, and have recently been investigated for use as dielectric layers, planarizing layers, RIE etch stops in multilevel lithography processes, and as final passivation layers. We report here the use of a commercially available SOG, Owens‐Illinois GR‐650 as a planarizing layer. Additionally we report a process by which this material can be converted from the as‐deposited organic polysiloxane material to an inorganic SiO2. This conversion is effected at low (≤100 °C) temperatures by an rf‐generated oxygen plasma. This process is particularly attractive for fabricating devices when the higher temperatures of plasma deposited SiO2(>250 °C) or thermally converted SOG (≊500 °C) cannot be tolerated.

ISSN:0734-211X    

DOI:10.1116/1.582992

出版商:American Vacuum Society    

年代:1985

数据来源: AIP

摘要:

A lithographic method using focused ion beam exposure and subsequent dry etching is examined. The lithographic mechanism is also investigated. Employing resist patterns formed by this method, an x‐ray mask is prepared. It is shown that Ga ion exposed regions of polymer resists act as aninsitumask during the O2reactive ion etching dry development of unexposed regions. Gallium distribution and its chemical shift in a resist after exposure or development are measured by XPS. The surface gallium atoms of resist exposed to oxygen plasma are changed to Ga2O3, which covers the resist surface and acts asinsitumasks against the oxygen plasma. The feasibility of the lithographic method is demonstrated by a preparation of submicron pattern x‐ray masks.

ISSN:0734-211X    

DOI:10.1116/1.582993

出版商:American Vacuum Society    

年代:1985

数据来源: AIP

摘要:

Polyimide layers approximately 10 μm thick on Si wafers were ion beam etched (IBE) by Ar. Ion energies up to 1000 eV and beam current densities as high as 0.3 mA/cm2were used to a total dose of 54 mC/cm2. After etching, the samples were exposed to iodine vapor for fixed periods of time. The diffusion of iodine into the samples was used to probe for ion induced changes in the polyimide structure. The concentration of the diffused iodine was measured as a function of depth by Rutherford backscattering spectrometry. For the IBE samples the surface concentration of iodine was markedly decreased. The iodine diffusivity in the near surface region of thickness 0.2 μm was reduced by two orders of magnitude. These results indicate that etching appears to cause modification of the polyimide film at depths far greater than the range of the incident ions or their secondary electrons in polyimide.

ISSN:0734-211X    

DOI:10.1116/1.582994

出版商:American Vacuum Society    

年代:1985

数据来源: AIP

ISSN:0734-211X    

DOI:10.1116/1.582995

出版商:American Vacuum Society    

年代:1985

数据来源: AIP