摘要:

Fabrication technologies for advanced photomasks with a molybdenum silicide (MoSi) film have been developed by using a variable‐shaped electron‐beam (e‐beam) system. These technologies were applied to the fabrication of 5X reticles for 16M‐bit DRAMs. The variable‐shaped e‐beam system is very effective in increasing the throughput for writing reticles which have a great number of figures, such as 16M‐bit DRAMs. The average writing time was 100 min, which was ∼ (1)/(3) of the time when using a conventional raster‐scan e‐beam system. Photomasks with the MoSi film have advantages in comparison with those with conventional chromium (Cr) film. Pattern defects did not appear during the photomask cleaning because of strong adhesion of the MoSi film to the quartz substrate. Moreover, an accurate feature size on the photomasks was obtained, because the MoSi film was easily dry etched. The feature size accuracy obtained was 0.03 μm in 3σ all over the 5 in. blanks.

ISSN:0734-211X    

DOI:10.1116/1.584836

出版商:American Vacuum Society    

年代:1990

数据来源: AIP

摘要:

Sample geometry has been shown to be a significant factor in determining the actual temperature of samples annealed in thermocouple controlled rapid thermal processing systems. Temperature differences of nearly 25 °C have been observed between full 4 in. wafers and quarter wafers under identical annealing conditions. Some of the geometry effects observed can affect the validity of temperature measurements in pyrometer controlled systems as well. The changes in sample temperature can be measured directly via thermocouples, and indirectly via secondary ion mass spectrometry (SIMS) and resistivity mesurements of ion implanted samples. Smaller samples are observed to heat up faster, and obtain a slightly higher maximum temperature than larger samples. Based on computer modeling this effect is attributed to the absorption of reflected/scattered radiation in addition to that directly incident on the sample. Small samples placed on top of full wafers during annealing are observed to heat up more slowly than the underlying wafer. This effect is likely due to imperfect thermal contact between the samples during the anneal. Small boron implanted samples annealed on top of whole wafers such that the implanted side is in contact with the whole wafer appear to experience a slight reduction in boron outdiffusion, similar to the reduced As outdiffusion observed for comparable anneals of GaAs wafers. In order to correctly compare reported temperature data from the literature, these geometry effects must be taken into consideration.

ISSN:0734-211X    

DOI:10.1116/1.584837

出版商:American Vacuum Society    

年代:1990

数据来源: AIP

摘要:

Laser induced fluorescence is used to monitor CF radicals in both a 13.56 MHz CF4processing plasma and a pulsed dc discharge. The axial spatial variation of CF shows a drop near added silver and copper substrates, a local maximum at polymer surfaces, and a flat approach to aluminum, SiO2, and silicon. The same behavior was previously observed with CF2and it is argued that the CF profile reflects its formation by electron impact on CF2rather than its heterogeneous reactivity. As oxygen is added to a CF4discharge, [CF] drops off faster than [CF2]. The voltage dependence of the CF decay rate in a pulsed discharge suggests CF oxidation involves molecular rather than atomic oxygen.

ISSN:0734-211X    

DOI:10.1116/1.584838

出版商:American Vacuum Society    

年代:1990

数据来源: AIP

摘要:

In this work, a novel method for the growth of good quality GaAs at extremely low substrate temperatures (as low as 120 °C) is introduced. This novel method is based on three different methods: The migration‐enhanced epitaxy method, the indium doping method, and the low growth rate method. The good quality of the GaAs layers are confirmed by Raman spectroscopy, 4 K photoluminescence, and transmission electron microscopy. This novel growth method results in the best GaAs material ever grown at 120 °C by any growth method using a molecular beam epitaxy machine.

ISSN:0734-211X    

DOI:10.1116/1.584839

出版商:American Vacuum Society    

年代:1990

数据来源: AIP

ISSN:0734-211X    

DOI:10.1116/1.584840

出版商:American Vacuum Society    

年代:1990

数据来源: AIP

摘要:

Strained InGaAs/GaAs quantum wells were grown on nonplanar substrates by molecular beam epitaxy and studied by scanning electron microscopy and low temperature spatially and spectrally resolved cathodoluminescence spectroscopy. For (100) ridges and grooves formed with (311)Asidewalls, almost complete removal of In from the strained quantum wells on the (311)Afacet is observed. Corresponding increases of In content in the quantum wells grown on the (100) facets indicate that most if not all of the In is displaced from the (311)Afacet via interplanar adatom migration. Ga adatom migration is also observed under our growth conditions such that quantum wells grown nominally near the critical layer thickness on structures less than ≂2.5 μm wide are no longer pseudomorphically strained, as detected by luminescence linewidth analysis. We present the first results of strained InGaAs/GaAs index guided injection lasers grown by single‐step molecular beam epitaxy over nonplanar substrates and show that differences greater than 50 meV in the effective band gap of a 70 Å quantum well can be achieved between the gain region and the nonabsorbing waveguide without relaxing the strain. Room temperature threshold currents as low as 6 mA for 4 μm×750 μm uncoated devices lasing continuously at a wavelength of 1.01 μm have been achieved.

ISSN:0734-211X    

DOI:10.1116/1.584841

出版商:American Vacuum Society    

年代:1990

数据来源: AIP

摘要:

The influence of finite substrate size on misfit dislocation densities in strained systems is examined through the growth of InxGa1−xAs on nonplanar patterned (100) GaAs substrates consisting of parallel mesas of widths between 6500 Å and 1.3 μm and of macroscopic length. Cross‐sectional transmission electron microscopy (XTEM) studies on In0.11Ga0.89As films reveal that while the mean misfit dislocation spacing for the growth in the nonpatterned region was ∼1500 Å, for the growth on the mesas no misfit dislocations running parallel to the mesa length were observed. This is likely due to strain relief at the mesa edges, possibly brought about by the ability to transfer strain energy from cluster coalescence boundaries to the mesa edges and/or reduced cluster coalescence boundaries when the mesa size becomes comparable to or less than the effective migration length.

ISSN:0734-211X    

DOI:10.1116/1.584842

出版商:American Vacuum Society    

年代:1990

数据来源: AIP

摘要:

We report for the first time on the suppression of Be diffusion in molecular‐beam epitaxy Al0.1Ga0.9As by incorporating In into the epilayer. The minimum diffusion coefficient of Be‐doped Iny(Al0.1Ga0.9)1−yAs layers with a carrier concentration of 7×1019cm−3and an InAs mole fraction of 0.07 grown at 600 °C was about 2×10−15cm2/s, which is five times smaller than that without In incorporation. The photoluminescence intensity of the layers drastically decreased above a value ofyof 0.05, probably due to crystal degradation resulting from misfit dislocations. A heterojunction bipolar transistor with a 100 nm‐thickp+In0.055(AlxGa1−x)0.945As base layer (Al graded compositionx: 0 to 0.1, emitter area: 4×5 μm2) yielded a dc current gain of 27 at a collector current of 8 mA.

ISSN:0734-211X    

DOI:10.1116/1.584843

出版商:American Vacuum Society    

年代:1990

数据来源: AIP

摘要:

We report on results that compare the planar confinement, diffusion, and surface segregation of Si δ‐doped in GaAs for growth by gas source molecular‐beam epitaxy and conventional molecular‐beam epitaxy. For gas source molecular‐beam epitaxy growth, Si diffusion versus inverse anneal temperature shows a unique two component Arrhenius form in which activation energies for diffusion differ by the fundamental GaAs band gap energy, 1.5 eV. Capacitance–voltage profiles of as‐grown δ‐doped Be and Si layers in GaAs produce record full width at half‐maximum, 1.9 and 2.4 nm, respectively, for the gas source molecular‐beam epitaxy case.

ISSN:0734-211X    

DOI:10.1116/1.584844

出版商:American Vacuum Society    

年代:1990

数据来源: AIP

摘要:

By evaporating gallium from apBN crucible which was previously used for evaporation of Al, ‘‘Ga‐spitting’’ and formation of Ga‐cell related oval defects have been eliminated in molecular‐beam epitaxy (MBE) of GaAs. MGE‐GaAs layers as thick as 20 μm were totally free from the Ga‐cell related oval defects. Remaining oval defects were those related to particulates and substrate contamination and their densities were 100 and 500 cm−2on 5 and 20‐μm thick layers of GaAs on GaAs substrates. However, these particulates related oval defects were hardly seen on up to 4‐μm thick GaAs layers grown on Si substrates. Aluminum wets and reacts with thepBN crucible when heated up to 1300 °C during evaporation of Al. Condensed gallium near the orifice wets the such aluminum treatedpBN surface and is not expected to spontaneously flow to the Ga charge in the form of droplets. As a result, Ga spitting does not occur and related oval defects do not form.

ISSN:0734-211X    

DOI:10.1116/1.584845

出版商:American Vacuum Society    

年代:1990

数据来源: AIP