摘要:

Excimer‐laser projection lithography now appears to be in a position to extend production optical techniques to dimensions approaching 0.25 μm. Such methods could well be the basis for the bulk of the advanced manufacturing capability in microelectronics over the next decade. This technology is reviewed with an eye to the state of the art and to the optical‐, resist‐, and materials‐engineering issues that it presents.

ISSN:0734-211X    

DOI:10.1116/1.584004

出版商:American Vacuum Society    

年代:1988

数据来源: AIP

摘要:

Scanning tunneling microscopy has been used to evaluate the overall morphology and growth conditions for Ag ordered overlayer and island films on Si(111), and to determine the nature of the √3×√3 Ag/Si(111) structure. Current image tunneling spectroscopy (CITS) is used to examine the energy‐dependent tunneling and evaluate possible model structures for the √3×√3 structure. Support is found for a √3×√3 structure composed of Ag trimers embedded below the top layer of threefold coordinated Si atoms. The surface electronic structure for these √3 structures shows a 1.2 eV gap, and exhibits very few intrinsic states nearEF. The few defects observed in the √3 areas of this surface introduce deep levels while the most dominant tunneling features nearEFappear to be associated with Ag islands that coexist with √3 areas. The implications of the surface perfection and local electronic structure to Schottky barrier formation are discussed.

ISSN:0734-211X    

DOI:10.1116/1.584042

出版商:American Vacuum Society    

年代:1988

数据来源: AIP

摘要:

The surfaces of a thermally etched GaAs substrate and a GaAs epitaxial layer grown on its substrate by molecular‐beam epitaxy have been observed for the first time using reflection high‐energy electron diffraction (RHEED) and a Nomarski contrast microscope. The surface morphology of the thermally etched GaAs substrate degraded, taking on an orange‐peel appearance, as the etching depth was increased. When a GaAs epitaxial layer with a thickness of 150 Å was grown on a thermally etched substrate, the RHEED pattern became streaked, indicating that the surface was smooth on an atomic scale. However, using a Nomarski contrast microscope, it was observed that the surface morphology of the epitaxial layer remained rough with wave longer than the optical wavelength, in the same way as the substrate. Moreover, an epitaxial layer grown on a conventionally cleaned GaAs substrate was thermally etched, and the surface was observed using RHEED, a Nomarski contrast microscope, and electron microscopy of platinum–carbon replica, in order to reveal the morphology. The morphology of the thermally etched epitaxial layer was smooth and quite different from that of the thermally etched substrate. As far as the origin of the surface degradation in the thermally etched substrate is concerned, it is believed that residual carbon contamination on the substrate surface acts as a mask, preventing the sublimation of GaAs.

ISSN:0734-211X    

DOI:10.1116/1.584021

出版商:American Vacuum Society    

年代:1988

数据来源: AIP

摘要:

The superstructure at the Al–GaAs(001) interface has been observed for the first time by grazing incidence x‐ray diffraction with the use of a synchrotron source. The Al overlayer of 150 Å in thickness was deposited on the (4×6)‐reconstructed (001) GaAs surface. The Bragg peaks were observed at the fractional‐order reciprocal lattice points of (n/4l) in the [11̄0] direction and (0m/6) in the [1̄1̄0] direction. The discussion is addressed to the correlation between interface reactions and the stability of the superstructure at the interface.

ISSN:0734-211X    

DOI:10.1116/1.583988

出版商:American Vacuum Society    

年代:1988

数据来源: AIP

摘要:

The lattice mismatch and the half‐width of the rocking curves in GaInAsP epitaxial layers grown on (001) InP substrates have been determined by means of x‐ray double‐crystal diffractometry. The state of strain of GaInAsP epitaxial layers has also been investigated. The relaxed lattice constant of the epilayers in stress‐free states has been found from observed lattice deformation using strain relations.

ISSN:0734-211X    

DOI:10.1116/1.583995

出版商:American Vacuum Society    

年代:1988

数据来源: AIP

摘要:

The processes governing direct‐write etching of semiconductors with halogen gases are studied by concentrating on a specific materials system: the etching of silicon using the output from an argon‐ion laser and chlorine gas to form high‐aspect ratio trenches. Specifically, the effects of laser power, laser polarization, laser scan velocity, Cl2‐gas pressure, and the addition of buffer gases on the trench formation process have been studied. A simple model has been developed which relates trench depth and these parameters. Model results are presented and compared with experimental data.

ISSN:0734-211X    

DOI:10.1116/1.583958

出版商:American Vacuum Society    

年代:1988

数据来源: AIP

摘要:

The breakdown andC–Vcharacteristics of SiO2films treated in either N2or NH3atmospheres at different temperatures have been investigated. The Auger electron spectroscopy profiles of the samples treated in a N2atmosphere at 1200 °C indicate that the nitrogen is preferentially incorporated into the Si/SiO2interface, thus increasing both the dielectric breakdown and the positive spatial charge associated with the interface. A similar increase of the dielectric breakdown is observed in the NH3treated samples, although in this case the nitrogen is found across the whole oxide thickness.

ISSN:0734-211X    

DOI:10.1116/1.583974

出版商:American Vacuum Society    

年代:1988

数据来源: AIP

摘要:

Gold–zinc and gold–cadmium alloy layers, suitable for Ohmic contact formation, have been deposited photoelectrochemically onp‐type III–V materials. It is shown that, while the nucleation of the plating process is greatly facilitated by illumination of the electrode, further growth of the alloy can proceed in the dark. Impedance measurements were used to investigate the influence of metal deposition on the potential distribution at the electrode interface. Contact properties of annealed gold–zinc layers on GaAs and InP are given. Auger electron spectroscopy measurements were used to study the surface chemistry during annealing. By choosing conditions to ensure maximum selectivity between illuminated and nonilluminated areas of the electrode, it is possible to write directly patterns of a desired composition and thickness using either a focused laser beam or mask projection.

ISSN:0734-211X    

DOI:10.1116/1.584048

出版商:American Vacuum Society    

年代:1988

数据来源: AIP

摘要:

TiN formation on TiSi2has been studied usinginsituRutherford backscattering spectroscopy and Auger electron spectroscopy. Two systems were investigated: (i) the reaction of Ti with nitrogen and (ii) the nitridation of TiSi2. When a Ti film on Si is annealed in N2or NH3, two reactions occur simultaneously: TiN forms at the surface and TiSi2at the interface. Oxygen, dissolved in the original Ti film, is expelled from the growing silicide and is piled up at the TiN/TiSi2interface. Around 600 °C, the complete conversion of the upper nitrogen‐containing layer into TiN is retarded by this oxygen and a TiNxO1−xlayer remains detectable between the TiN and TiSi2layers. At 750 °C, the TiN layer is formed very rapidly and further growth is blocked by the TiSi2layer that has developed underneath. Nitridation of TiSi2requires a temperature of at least 800 °C. Starting at the exposed surface, the silicide layer is gradually converted into TiN. Some of the Si released in this reaction segregates to the surface and forms islands. Most of the Si, however, segregates to the Si substrate where epitaxial regrowth occurs. Nitridation of TiSi2, therefore, results in rough layer structures, in contrast to nitridation of Ti on Si. The differences in layer morphology for these two processes are clearly evidenced by transmission electron microscopy cross sections.

ISSN:0734-211X    

DOI:10.1116/1.584052

出版商:American Vacuum Society    

年代:1988

数据来源: AIP

摘要:

Very thin silicon dioxide (<100 Å) has been widely used as a tunnel barrier for floating gate electrically erasable read only memory (EEPROM) devices. Small tunneling areas are required in the new EEPROM cell generations and the use of reactive ion etching (RIE) plasma is mandatory in order to define windows with a diameter<1.2 μm. The tunnel oxide has to be grown in these windows opened in the thicker (150–300 Å) gate oxide. The surface damage induced by plasma RIE requires postetch treatments. In this paper, we deal with the effects induced on the oxide characteristics by different postetch treatments. The analysis has been focused on both the recovery of the surface damage and the electrical characteristics of a 95‐Å‐thick tunnel oxide grown after different postetch processes. The oxide degradation under current stress has been evaluated using metal–oxide–semiconductor capacitors. The best preoxidation treatment that we found among our experiments has also been tested on an EEPROM cell. The tunnel oxide degradation, i.e., the cell threshold voltage shift, was found to be very negligible after 105write–erase cycles.

ISSN:0734-211X    

DOI:10.1116/1.584053

出版商:American Vacuum Society    

年代:1988

数据来源: AIP