摘要:

The charging effects of plasma immersion ion implantation (PIII) doping experiments have been investigated using a dynamic sheath model and PDP1 plasma simulation code. When the target has a dielectric film, charge accumulation during PIII can have a profound impact on doping results. Under certain process conditions, it can significantly reduce implant energy and dose and thereby alter the implant profile. In addition, it may degrade device reliability, especially for ultralarge‐scale integrated circuit devices. In order to minimize charging effects, shorter pulse widths along with moderate values of plasma density and pulse potential should be used.

ISSN:0734-211X    

DOI:10.1116/1.588121

出版商:American Vacuum Society    

年代:1995

数据来源: AIP

摘要:

Cathodic arc ion implantation was used to maken+–pjunction diodes andn‐channel metal–oxide–semiconductor (MOS) transistors. Antimony, with a dosage in the range of 6×1014to 4×1015ions/cm2, was implanted as then‐type dopant intop‐type 〈100〉 oriented silicon with a resistivity in the range of 2–5 Ω cm. The implantation voltage applied to the substrate was approximately −20 kV. Regular thermal oxidation and photolithography techniques were used in making the devices. TheI–Vcharacteristics of both diodes and transistors and the reverse breakdown of then+–pjunction were found to be comparable to the devices made by diffusion under similar conditions. The standard deviation of the sheet resistance of the implanted layer across a 3 in. wafer was found to be less than 4% of the average value. The implantation dosage and distribution characteristics were estimated by secondary ion mass spectrometry (SIMS) and Rutherford backscattering spectrometry (RBS) measurements. The experimental results were found to agree with numerically calculated values. The ion charge state of the arc plasma was extracted by comparing the experimental results and numerical results.

ISSN:0734-211X    

DOI:10.1116/1.588122

出版商:American Vacuum Society    

年代:1995

数据来源: AIP

摘要:

A technique to reduce charge buildup causing gate‐oxide deterioration during biased electron cyclotron resonance (ECR) plasma deposition has been developed. For SiO2planarization and filling techniques, it is necessary to resolve the charge build‐up phenomenon with the biased ECR plasma system. The deterioration is reduced by adjusting the magnet‐coil position in the ECR plasma system which means minimizing the magnetic‐flux density at the specimen surface.

ISSN:0734-211X    

DOI:10.1116/1.588123

出版商:American Vacuum Society    

年代:1995

数据来源: AIP

摘要:

In this article the effects of process parameters of CHF3+N2plasma etching chemistry (rf power 50–70 W, pressure 22.5–52.5 mTorr, and N2content 0%–95%) and mask materials (photoresist, aluminum, and silicon nitride) on the etching selectivity of silicon nitride over polysilicon are investigated. It was found that the selectivity increased with the N2content in the range of 0%–85% and then decreased, leading to the maximum selectivity (16) at 7.5 sccm CHF3+42.5 sccm N2(85% N2) at 60 W and 37.5 mTorr. The selectivity increased linearly with power and decreased with pressure. The higher the Si/N ratio of the nitride, the faster the nitride is etched. No influence of the residual stress level on the etch rate of the nitride was observed. The selectivity with resist masks was found to be higher than with either aluminum or nitride masks. Removal of N atoms is suggested to be one of the major rate‐limiting factors in the nitride etching. It is argued that the addition of N2in CHF3dilutes the polymer‐forming radicals and generates abundant N atoms, which diffuse to the substrate and combine with the N atoms adsorbed there due to etching. Both of these effects enhance nitride etch rate.

ISSN:0734-211X    

DOI:10.1116/1.588124

出版商:American Vacuum Society    

年代:1995

数据来源: AIP

摘要:

This paper describes the fabrication process and the reliable characteristics of a metal–insulator–metal capacitor using electron cyclotron resonance plasma‐SiO2as an insulator film. The metal–insulator–metal capacitors are additionally fabricated during the Al multilevel interconnection process since the deposition temperature of electron cyclotron resonance plasma‐SiO2is below 200 °C. Also, the leakage current characteristics of the film are excellent even without densification at high temperature. The experimental results confirm that a metal–insulator–metal capacitor fabrication process using electron cyclotron resonance plasma‐SiO2can be applied to analog large scale integration implementation.

ISSN:0734-211X    

DOI:10.1116/1.588125

出版商:American Vacuum Society    

年代:1995

数据来源: AIP

摘要:

Electron cyclotron resonance etch rates of GaN, InN, and AlN are reported as a function of pressure, microwave power, and radio‐frequency (rf) power in a Cl2/H2/CH4/Ar plasma at 170 °C. The etch rates for GaN and InN increase as a function of rf power. At 275 W, the etch rates reach maximum values of 2850 and 3840 Å/min, respectively. These are the highest etch rates reported for these materials. As a function of pressure, the etch rates reach a maximum value at 2 mTorr and then decrease as the pressure is increased to 10 mTorr. The GaN and AlN etch rates increase less than a factor of 2 as the microwave power is increased from 125 to 850 W whereas the InN etch rate increases by more than a factor of 3.5. The maximum etch rate for AlN obtained in this study is 1245 Å/min at a microwave power of 850 W, 1 mTorr pressure, and 225 W rf power. Atomic force microscopy is used to determine root‐mean‐square roughness as a function of etch conditions for GaN and InN and, while very smooth pattern transfer can be obtained for a wide range of plasma conditions for GaN, the smoothness of the etched InN surface is more sensitive to rf power, microwave power, and process pressure. The surface composition of the GaN is characterized using Auger spectroscopy and has shown that the Ga:N ratio increases with increasing rf power or microwave power.

ISSN:0734-211X    

DOI:10.1116/1.588126

出版商:American Vacuum Society    

年代:1995

数据来源: AIP

摘要:

We have investigated the compatibility of Cl2/BCl3/IBr3etch gas mixtures with a cryo‐pumped ultrahigh vacuum chemically assisted ion‐beam etching system. The machine was designed for the fabrication of ultrahigh‐quality laser facets in monolithically integrated GaAs‐ and InP‐based optoelectronic integrated circuits. The chemical composition of etch byproducts deposited in the vacuum chambers and the pumping system has been examined in particular detail. After 70 h of process time, samples of such deposits were scraped from the chamber walls and the various stages of the cryo‐pump and roughing pump; these samples were analyzed using energy‐dispersive x‐ray measurements. Automated overnight regeneration of the cryopump, the use of integrated external bakeout heaters, and the implementation of a cryo‐pumped load‐lock chamber allow the deposition of reactive Cl‐containing residues to be confined to surfaces and components which can be cleaned or replaced during routinely scheduled yearly maintenance.

ISSN:0734-211X    

DOI:10.1116/1.588127

出版商:American Vacuum Society    

年代:1995

数据来源: AIP

摘要:

An anisotropic nonselective etch for GaAs/AlGaAs rib waveguides has been developed for use under electron cyclotron resonance conditions. The plasma chemistry features BCl3to minimize AlGaAs oxidation effects and small additions of N2to induce sidewall protection when using photoresist masks. The fundamental mode attenuation in GaAs/AlGaAs waveguides is sensitive to the choice of both plasma chemistry and masking material, but can be reduced to ≤1 dB cm−1for channel widths of 4–5 μm.

ISSN:0734-211X    

DOI:10.1116/1.588128

出版商:American Vacuum Society    

年代:1995

数据来源: AIP

摘要:

We have investigated the effects of ion mass (Ar+, Xe+), energy (0.3–5 keV), trajectory, and sample temperature on the ion sputtering processes for GaAs(110). Scanning tunneling microscopy images reveal that most ion bombardment events at 300 K create pits that are 1–5 unit cells in size, indicating that direct knock‐on collisions dominate. The average pit size increases moderately with ion energy but shows a significant variation with the incident angle. Vacancies are sufficiently mobile at 625–775 K that vacancy islands form and the yield can be determined directly. The sputtering yields for these nearly ideal surfaces exhibit structure that can be related to the nuclear stopping power and ion channeling, showing the influence of such geometric factors as surface path length, ion radius, and projected atom column density. Temperature dependent results for monolayer and multilayer sputtering show that adatoms ejected onto the surface refill vacancies but that the surface roughness, as measured by surface width, increases with ion fluence. While interlayer atomic transport is measurable at 625 K and increases with temperature, it is not sufficient to achieve layer‐by‐layer removal because Asxdesorption competes with interlayer transport above ∼800 K.

ISSN:0734-211X    

DOI:10.1116/1.588129

出版商:American Vacuum Society    

年代:1995

数据来源: AIP

摘要:

GaAs(001)c(4×4) surfaces were obtained in the 380–450 °C temperature range by thermal desorption of As cap layers from substrates prepared by molecular beam epitaxy. Although reflection high‐energy electron diffraction patterns showed little change in the temperature range explored,insituscanning tunneling microscopy and Auger spectroscopy, complemented byexsituatomic force microscopy, indicate that in the lower‐temperature range examined up to 11%–12% of the surface may still be occupied by adsorbed As in the form of wires and particles preferentially oriented along 〈100〉 directions.

ISSN:0734-211X    

DOI:10.1116/1.588130

出版商:American Vacuum Society    

年代:1995

数据来源: AIP