摘要:

Nonalloyed Ohmic contacts ton‐InP have been made by sputter deposition of metals onto sputter‐etched InP surfaces. Contacts were Ohmic as deposited without intentional heating. For a 500 Å sputter‐etch depth, the contact to 8×1018cm−3n‐InP was Ohmic up to 5×104A cm−2with a specific contact resistance of 4×10−7Ω cm2independent of sputter etch energy over the range 200 to 870 eV. To 6×1017cm−3n‐InP, the corresponding value was 1.8×10−6Ω cm2. The In rich, degeneraten‐type sputter etch damaged surface is responsible for the quality of the contact, which is independent of the particular contacting metal, thus permitting the use of a barrier metal/noble metal combination. Nonalloyed contacts fabricated with Ti/Pt have low stress and excellent adhesion to InP. Even for the lowest etch energy, they are thermally stable, with no change caused by short periods up to 430 °C, or extended periods (∼100 h) at 250 °C. This contacting procedure and the resultant contact has many advantages over the usual Au:Sn or Au:Ge alloyed contact.

ISSN:1071-1023    

DOI:10.1116/1.582847

出版商:American Vacuum Society    

年代:1984

数据来源: AIP

摘要:

It was demonstrated that very thin silicon oxynitride films with concentrations covering the whole range between SiO2and Si3N4can be obtained by simultaneous high dose implantation of low energy oxygen and nitrogen ions into silicon. For ion energies of 5 keV homogeneous films about 5 nm in thickness resulted. These room‐temperature‐formed silicon oxynitride films were characterized by a combination of Auger electron spectroscopy (AES) and argon ion sputtering. The electron irradiation hardness was studied as a function of film composition.

ISSN:1071-1023    

DOI:10.1116/1.582852

出版商:American Vacuum Society    

年代:1984

数据来源: AIP

摘要:

The influence of deviations from TaSi2stoichiometry in cosputtered, amorphous Ta–Si films on interface reactions in contacts to silicon at 900 °C was investigated by TEM of thin cross sections through the contact windows. For Si rich films, the excess Si precipitates epitaxially in the contacts, whereas pits are formed for Ta rich films. Since the lateral Si transport involved ranges over several tens of microns, even a very small deviation from TaSi2stoichiometry leads to strong degradation of the contacts. The interfacial oxide has no influence on the contact reactions. Since slight deviations from disilicide stoichiometry cannot be avoided with cosputtering, the realization of a low‐resistive, high‐temperature‐stable TaSi2interconnection system with good contacts to Si would additionally require a high‐temperature‐resistant barrier layer. Experiments with a crystalline TaSi2pad and a TaN0.8barrier layer show insufficient stability at 900 °C, but suggest that most of the large lateral Si transport happens during the initial stage of crystallization.

ISSN:1071-1023    

DOI:10.1116/1.582853

出版商:American Vacuum Society    

年代:1984

数据来源: AIP

摘要:

Several types of thin dielectric films which can be deposited on substrates held near room temperature have been tested for use as insulators in integrated circuit structures. The types of insulation studied include single and double layer SiO films, Parylene polymer films, and SiO/Parylene composites. Test structures, which were fabricated with processes used in Josephson integrated circuits, allowed measurement of the number of electrical defects per unit area in the insulation between two Pb–In–Au films as well as the number of defects along edges of the lower metal film. The SiO/Parylene composite films had the lowest defect densities, as low as 0.2 cm−2over planar metal layers and 0.001 cm−1at insulated metal edges. Defect densities below those for single SiO films were also obtained by depositing the SiO in two layers through separate but indentical lift‐off stencils. The defect densities measured for these insulating films both before and after repeated thermal cycling to 4.2 K are believed to be adequate for proposed Josephson integrated circuits.

ISSN:1071-1023    

DOI:10.1116/1.582854

出版商:American Vacuum Society    

年代:1984

数据来源: AIP

摘要:

A laser direct writing technique for forming insulating layers of silicon dioxide from an organosilicate film on various substrate materials is shown. The process resolution is a function of the thermal properties of the substrate and is shown to be 1 μm. The technique allows for a local variation in the oxide thickness by changing process parameters. The quality of the laser written layers is compared to similar films formed by conventional organosilicate processing.

ISSN:1071-1023    

DOI:10.1116/1.582855

出版商:American Vacuum Society    

年代:1984

数据来源: AIP

摘要:

An experimental system for studying surface reactions in the process of microwave plasma etching has been developed. In the system, a surface etched in the microwave plasma can be analyzed with x‐ray photoemission spectroscopy (XPS) without exposure of the surface to room air. In addition, we have developed a procedure for calculating a thickness of a surface layer stoichiometrically different from the substrate material and densities of atoms in the layer. Chemical changes in etched Si and SiO2surfaces caused by exposing these surfaces to room air are investigated with XPS to show the utility of the system. When the surfaces etched in SF6microwave plasma are exposed to room air, the chemical states of the surfaces change rapidly. This is mainly due to surface oxidation and adsorption of hydrocarbon compounds to the surfaces. The rapid changes are more clearly shown from increases in surface layer thickness and the number of O and C atoms in the layer. It is clarified that exposure of etched surface to room air causes the serious disturbance, and that accurate information can not be obtained any longer. The present system which eliminates this disturbance allows accurate measurement of surfaces for detailed investigation of the surface reaction in microwave plasma etching.

ISSN:1071-1023    

DOI:10.1116/1.582856

出版商:American Vacuum Society    

年代:1984

数据来源: AIP

摘要:

The reactive ion etching of GaAs has been investigated in BCl3plasma discharges. Etching rates have been characterized as functions of pressure (10–25 mTorr), power density (∼0.05–0.5W/cm2), and Cl2/BCl3gas compositions. Rates of ∼12–20 nm/min have been obtained, and are significantly lower than for other chlorinated plasmas. Etching profiles exhibit a high degree of anisotropy and smooth surface morphologies.

ISSN:1071-1023    

DOI:10.1116/1.582857

出版商:American Vacuum Society    

年代:1984

数据来源: AIP

摘要:

One of the problems in defining LSI patterns by the lift‐off technique is burrs, which appear at film pattern edges. The cause of burrs formed at the SiO film pattern edges is discussed. Burrs result from indirectly deposited thin layer residues on the resist pattern side walls. This layer is called a ‘‘side wall layer.’’ A model experiment is carried out and it is shown that the reflection of evaporated SiO molecules is the cause of indirect deposition. SiO molecule reflection probability during deposition is measured. The side wall layer is simulated using the reflection probability. It is concluded that reflection at the substrate surface and reflection at the vacuum chamber wall contribute to an equal degree to the side wall layer formation. Several methods of suppressing the side wall layer, which are also applicable to materials like Pb with higher reflection probability, are discussed. Cooling the substrate or the vacuum chamber, or setting up a shielding board in the chamber are predicted to be effective.

ISSN:1071-1023    

DOI:10.1116/1.582858

出版商:American Vacuum Society    

年代:1984

数据来源: AIP

摘要:

For the purpose of reducing radiation damage and delineating fine patterns in electron beam direct writing lithography, fundamental characteristics of a three‐layer resist using heavy metal as an intermediate layer is investigated in detail. An exposure and development simulation program, ELSIS, is extensively used to estimate resolution and linewidth control. The exposure intensity distributions for a line source are calculated to evaluate pattern delineation characteristics and degree of proximity effect in this three‐layer resist. The developed pattern profiles of positive‐type resist and absorbed energy density profiles in negative‐type resist are calculated. Some relevant experimental data also are presented. These results indicate that several advantages can be expected from this three‐layer resist, such as an apparent increase in resist sensitivity and a reduction of the interproximity effect.

ISSN:1071-1023    

DOI:10.1116/1.582859

出版商:American Vacuum Society    

年代:1984

数据来源: AIP

摘要:

Measurements of minority‐carrier lifetimes (τ) in shallow‐junction GaAs LED’s under varying gas‐pressure conditions prior to and following γ irradiation indicate (1) τ is noticeably influenced by gaseous ambient and, (2) this influence is greaterfollowingirradiation than prior to irradiation. This dependence of τ upon surface phenomena indicates γ irradiation changes surface conditions considerably. Combination of both mechanisms on surface effects can be utilized to bring about noticeable improvement in diode speed of response using only modest dosages of nuclear irradiation (up to 60% improvement for only 13 Mrad). It is believed that γ irradiation affects trap density particularly, while changes in gas type and pressure change both trap density and electron capture cross sections at the surface through adsorption–desorption processes. This is believed to be the first time γ ray induced decrease of τ has been studied in different post‐irradiation gaseous environments.

ISSN:1071-1023    

DOI:10.1116/1.582860

出版商:American Vacuum Society    

年代:1984

数据来源: AIP