摘要:

Polysilicon layers have been doped with high uniform concentrations of arsenic in short processing times using gas‐phase doping. The polysilicon layers were doped at total system pressures from 1 to 760 Torr with arsine or tertiarybutylarsine (TBA) as gas‐phase dopant sources. An arsenic concentration as high as ≳4×1020atm/cm3in 100 nm polysilicon layers was measured after a 60 s diffusion in 2.4% arsine in He at 1000 °C at 760 Torr. Using tertiarybutylarsine (TBA) at 3 Torr, a sheet resistance of 2.5 kΩ/⧠ was measured in a 100 nm polysilicon layer after 12 min at 900 °C. Doping at temperatures as low as 770 °C also gave high arsenic concentrations. Finally, a 6 μm deep DRAM trench capacitor was uniformly doped with arsenic to a concentration of 8×1019atm/cm3using gas‐phase doping and a two‐step polysilicon deposition process.

ISSN:0734-211X    

DOI:10.1116/1.587304

出版商:American Vacuum Society    

年代:1994

数据来源: AIP

摘要:

Auger depth profiles are used to compare sputtered Ti, reactively sputtered TiN, and TiN/Ti bilayer films in submicron (0.8 and 0.4 μm) contact/via holes, deposited with and without a collimator. Samples were cleaved and mounted to minimize difficulties associated with the sputter profiling of and data acquisition from recessed features. The Ti and N concentrations were calculated with a subtract‐and‐weight routine which usesdN(E)/d(E) peak‐to‐peak intensities. Transmission electron microscopy film thicknesses measurements were used to confirm that the sputter rates were comparable for the various sample mounting geometries. The thickness of films deposited on the contact base, relative to those on the surrounding oxide was greater when the collimator was used. For 0.8 μm contacts, the film thickness ratio obtained using the collimator was nearly twice that obtained with the uncollimated deposition (0.5 versus 0.25 for TiN; 0.8 versus 0.6 for Ti). The benefits of the collimator, for obtaining good coverage of the base of the hole, are more pronounced in smaller geometries. For films deposited with the collimated on 0.4 μm contacts the film thickness ratio was ten times that for films deposited without the collimator (0.4 versus 0.05 for TiN, 0.35 versus 0.03 for Ti). There was no evidence of variations in the TiN stoichiometry for films deposited in confined geometries versus the surrounding oxide for either deposition configuration. There was an increase in the depth of surface oxidation for the Ti‐only film deposited on the sidewalls using the collimator. Shadowing effects cause an increase in film porosity when the direction of collimated metal flux is parallel to the sample surface. On exposure to atmosphere, this porosity allows oxidation below the surface of the film.

ISSN:0734-211X    

DOI:10.1116/1.587305

出版商:American Vacuum Society    

年代:1994

数据来源: AIP

摘要:

The surface germylation process is an improved method to realize the fine pattern of ultra large scale integration and overcome the problems in conventional surface imaging resist technologies such as removability of the patterned resist. The surface germylation process is evaluated with electron spectroscopy for chemical analysis. After the germylation, the germanium is observed at the resist surface. The germanium introduced into the resist film is oxidized by oxygen dry etching and condensed at the resist surface. The density of the germanium introduced correlated to the etching resistance of the resist. The diffusion of the germylation agent into the resist film, which depends on the deep ultraviolet (UV) dose, is necessary to give the germanium oxide layer at the resist surface. In the near surface at the germylation layer at the deep UV dosed resist film, the germylation occurs completely to every reaction site in the resist film.

ISSN:0734-211X    

DOI:10.1116/1.587306

出版商:American Vacuum Society    

年代:1994

数据来源: AIP

摘要:

ISSN:0734-211X    

DOI:10.1116/1.587307

出版商:American Vacuum Society    

年代:1994

数据来源: AIP

摘要:

A high resolution dry etch process for InP via holes is presented. Using Cl2:HBr:BCl3:Ar reactive ion etching, etch rates in excess of 1 μm/min have been obtained on InP substrates with feature sizes as small as 15×15 μm2. The etch rate selectivity between InP and the photoresist was found to improve with the addition of HBr. The tapered sidewall profiles, suitable for subsequent metallization steps, can easily be achieved with this process.  

ISSN:0734-211X    

DOI:10.1116/1.587308

出版商:American Vacuum Society    

年代:1994

数据来源: AIP

摘要:

The growth evolution of gold films evaporated on highly oriented pyrolitic graphite has been investigated using scanning tunneling microscopy. This is achieved by monitoring the morphology of sample surfaces which have been covered with increasing amounts of deposit. The smallest clusters observed at an early stage of the growth are a few nanometers in size. A saturation density of these clusters of about 2×1011cm−2was statistically estimated. Both random and oriented grains were observed.  

ISSN:0734-211X    

DOI:10.1116/1.587309

出版商:American Vacuum Society    

年代:1994

数据来源: AIP

摘要:

Deep donor to acceptor transitions between interstitial and substitutional Zn in InP are investigated in this study via the photoluminescence technique. Interstitial Zn is to be fully activated when treated by rapid thermal annealing process at 600 °C. When treated at 400 °C, however, interstitial Zn is partially activated so that medium distance deep donor‐to‐acceptor transitions become less available. This medium distance transition is estimated to be in a range between 35 and 60 Å.

ISSN:0734-211X    

DOI:10.1116/1.587310

出版商:American Vacuum Society    

年代:1994

数据来源: AIP

摘要:

Ohmic contacts between Au and sulfur‐passivatedn‐GaAs have been formed without annealing after deposition of the metal. The GaAs samples doped with either 2×1016or 3×1018cm−3Si were passivated with (NH4)2S in an aqueous solution, then the passivating sulfur was thermally desorbed in a vacuum. Desorption was followed immediately byinsituthermal evaporation of Au with the substrate at room temperature. OhmicI‐Vbehavior was measuredexsitu.C‐Vmeasurements on a sample with a native oxide surface barrier layer showed the surface carrier concentration on the higher doped sample increased from 3×1018to 7×1018cm−3after S desorption. Secondary ion mass spectroscopy data showed that S had diffused into the GaAs surface region. Thus S passivation prevented interfacial oxide formation during the exposure to air after the sample was passivated and before the vacuum chamber was pumped to a low pressure. Sulfur apparently diffused into the surface region during flash desorption in vacuum and increased the surfacen‐doping concentration which led to ohmic contacts without post‐annealing of the Au films.

ISSN:0734-211X    

DOI:10.1116/1.587311

出版商:American Vacuum Society    

年代:1994

数据来源: AIP

摘要:

Porous silicon, produced by the anodic oxidation ofp‐type single crystal wafers of silicon in hydrofluoric acid/ethanol electrolytes has been subjected to rapid thermal oxidation. For comparison purposes, and also to generate porous oxide for subsequent nitriding, other samples of porous silicon were subjected to conventional furnace oxidation. By TEM, EDS, and ESCA it was shown that the structures and compositions of the oxides produced by the two routes were similar. It was further demonstrated that oxidized porous silicon could be nitrided by rapid thermal processing. The resulting structure, although still porous, showed a much diminished etching rate in hydrofluoric acid, compared to the original oxide.

ISSN:0734-211X    

DOI:10.1116/1.587312

出版商:American Vacuum Society    

年代:1994

数据来源: AIP

摘要:

The wealth of optical phenomena offers interesting opportunities in the world of nanometer dimensions. The field of radiation has to be confined and controlled for this purpose by material structures such as small apertures or slits. Many optical effects manifest themselves in a novel way if the relevant dimensions are small compared to the wavelength. Our theoretical understanding therefore lags somewhat behind the experimental results which have made rapid progress in the past two to three years. This paper concentrates for this reason on the description of a model scanning near‐field optical microscope which allows us to gain some insight into the complex problems of coupling light into a nanometer‐sized structure, the distribution and possible field enhancement inside such structures, and the radiation from the nanoscale structure into the macroscopic world, where it can be detected by conventional means.

ISSN:0734-211X    

DOI:10.1116/1.587313

出版商:American Vacuum Society    

年代:1994

数据来源: AIP