摘要:

In this paper we present and discuss the surface properties of GaSb substrates correlated to the cleaning procedure. Different etchants were tested and the resulting surfaces were studied by Auger spectroscopy, then by reflection high‐energy electron diffraction and finally annealed under an Sb4flux in order to get a suitable substrate for molecular‐beam epitaxy. From the comparison of the surface properties we show that one of the tested etchants, which associates HCl, HBr, CH3COOH, and HNO3gives the best results: the etch rate can easily be controlled, the cleaned surfaces are smooth (i.e., free of etch pits) and the surface stoichiometry is the least disturbed by the cleaning procedure.

ISSN:0734-211X    

DOI:10.1116/1.584831

出版商:American Vacuum Society    

年代:1990

数据来源: AIP

摘要:

Cross contamination problems can, in certain circumstances, impose a serious limitation for a molecular‐beam epitaxy (MBE) system that is utilized to perform the growth of different high‐purity semiconductors. Due to the very high capital cost associated with MBE technology it is essential that cross contamination be eliminated to allow continued use of the apparatus. In this paper we provide full details of a major vacuum‐system cleaning exercise performed on an MBE reactor, previously used for cadmium telluride growth, which has allowed it to be subsequently and successfully used for the growth of state of the art high‐purity InSb epilayers. Secondary ion mass spectroscopy (SIMS) and electrical measurements performed on InSb layers grown prior to the full cleaning process showed them to be heavily contaminated with tellurium. However, corresponding data obtained following the decontamination exercise indicated the successful removal of the previously observed impurities to below the SIMS detection limit. The cleaning process described should be suitable for any laboratory requiring to change the usage of an existing MBE reactor to the growth of alternative materials.

ISSN:0734-211X    

DOI:10.1116/1.584832

出版商:American Vacuum Society    

年代:1990

数据来源: AIP

摘要:

The minimum laser fluences required to planarize interlevel vias in a two‐metal‐level test structure have been measured as a function of via size and sample temperature. Generally, the minimum fluence required increases as the via size increases, resulting in larger operating process windows for smaller vias. Under some circumstances, however, the planarization dynamics may be dominated by features associated with groups of vias. While required fluences for planarization and sample damage both decrease as the sample temperature increases, the relative insensitivity of the damage threshold generally results in larger process windows at higher temperatures.

ISSN:0734-211X    

DOI:10.1116/1.584833

出版商:American Vacuum Society    

年代:1990

数据来源: AIP

摘要:

Chemical vapor deposition of WSi2was studied through thermodynamic equilibrium calculations for the W–F–Si–H and W–F–Si–H–Cl systems. The calculations were made with a computer program that minimizes the Gibbs free energy by Langrangian multiplier techniques. The parameter range for these system analyses were: temperature 473 to 1073 K, pressure from 50 to 500 mTorr, and Si/W ratios of 3 to 1000. 21 gas phase species and eight solid species were included in the calculations for the W–F–Si–H system and 39 gas phase species and 15 solid species were considered for the W–F–Si–H–Cl system. At the equilibrium condition, H2, SiF4, and SiF2H2are the most prominent gaseous species for the W–F–Si–H system while WSi2and Si are formed in the solid phase. For the W–F–Si–H–Cl system, WSi2and Si are formed in the solid phase, while H2, SiCl4, HCl, SiF4and SiHCl3are the most prominent gas phase species. The SiCl2intermediate plays a key role in the surface activated reaction for this system.

ISSN:0734-211X    

DOI:10.1116/1.584834

出版商:American Vacuum Society    

年代:1990

数据来源: AIP

摘要:

The size of an ion probe is determined by many different factors such as virtual source size, magnification, probe current, and aberrations of its optical column. While operating or designing an ion optical system, it is often desirable to choose these parameters such that the optimum probe is obtained for the anticipated application. In this paper, we propose a routine which could be used to find the optimum magnification and aberrations of a system for given ion source parameters and probe requirements.

ISSN:0734-211X    

DOI:10.1116/1.584835

出版商:American Vacuum Society    

年代:1990

数据来源: AIP

摘要:

A multilayer resist system is used to obtain high‐definition and high aspect ratio masks by use of electron lithography. This technique overcomes most of the problems of obtaining with a short exposure time a high‐definition mask: a lift‐off metal deposition is made over a tick bilayer of hard‐baked resist which is then patterned by reactive ion etching in pure low‐pressure oxygen plasma. This inverted multilayer system can be used for dry etching of many different material sublayers and can be easily stripped away in a dedicated solvent after the etching. An example of application in self‐aligned structures is given.

ISSN:0734-211X    

DOI:10.1116/1.584852

出版商:American Vacuum Society    

年代:1990

数据来源: AIP

摘要:

The pyrolysis of triisobutylaluminum occurs much more readily on the surface of Al than on the surface of an oxide. This propensity allows Al to be grown selectively on a wafer and may simplify certain metallization steps in integrated circuit manufacture. In this study,abinitiomolecular orbital techniques have been used to elucidate how the transition state energy for beta‐hydride elimination of the alkyl ligand varies for Al atoms in different chemical environments. Elementary considerations of the nature of the four‐center transition state suggest that the energetics of promoting an electron to the emptypπ‐orbital on Al determines the energy of the transition state. Molecular cluster calculations are then used to show that the energy of this electron promotion increases substantially when comparing an Al atom bonded to other Al atoms versus O atoms, explaining the observed surface selectivity.

ISSN:0734-211X    

DOI:10.1116/1.584853

出版商:American Vacuum Society    

年代:1990

数据来源: AIP

摘要:

The failure of microelectronics chips due to formation of stress−induced voids in Al/Si alloy interconnects is discussed. The propensity for thermal voiding in Al/Si is associated with a particular microstructural and compositional state derived from poor vacuum coditions during deposition.(AIP)

ISSN:0734-211X    

DOI:10.1116/1.584854

出版商:American Vacuum Society    

年代:1990

数据来源: AIP

摘要:

Bohm diffusion has been found to be approximately valid for many plasmas in strong magnetic fields. Assuming Bohm diffusion describes electron diffusion directly [H. R. Kaufman, AIAA J.23, 78 (1985)], with an equal ion loss possible from the ambipolar field that is generated [F. F. Chen,IntroductiontoPlasmaPhysics(Plenum, New York, 1974), p. 169], an order‐of‐magnitude analysis can show why such electron diffusion should be expected.

ISSN:0734-211X    

DOI:10.1116/1.584855

出版商:American Vacuum Society    

年代:1990

数据来源: AIP