摘要:

We have used CHF3/O2reactive ion etching to reliably change the superconducting transition temperature (Tc) of aluminum thin films by 10–50 mK. Microanalyses using scanning Auger and scanning electron microscopy (SEM) indicate that the etching process results in a surface layer of high fluorine and low oxygen contents. The analyses show that photolithography and etching can produce very sharp interfaces between etched (loweredTc) and unetched (higherTc) regions. This technique is applied to study two specific configurations. First, long strips of aluminum thin films are patterned with a periodic structure of alternating regions of high and lowTc. The resistive transition of these films shows a surprisingly long proximity effect with a length scale of more than 50 μm, nearly two orders of magnitude greater than expected from established theory. Second, an aluminum strip with a singleS–N–S(high–low–highTc) structure possesses a resistive anomaly just above the lowerTc. This anomaly depends on the position of the measurement voltage probes relative to the interfaces and appears to have a length scale of several μm.

ISSN:0734-211X    

DOI:10.1116/1.585834

出版商:American Vacuum Society    

年代:1991

数据来源: AIP

摘要:

Dry etching‐induced damage is investigated using radical‐beam ion‐beam etching. This technique allows the systematic study of process‐induced damage over a wide range of etching rates and with varying components of physical and chemical etching. Induced damage is characterized byI‐Vmeasurements from Schottky diodes on etched surfaces and from luminescence from quantum wells situated in close proximity to etched surfaces. We have designed a novel multiple‐quantum‐well probe structure that also includes a 4000 Å‐thick quarter‐wavelength mirror stack layer to allowinsitumonitoring of etch rate and etched depth. Our work examines damage as a function of ion beam voltage and beam current density, microwave power, and with and without a reactive gas. We have found that damage increases with increased ion energy and decreases with etch yield.

ISSN:0734-211X    

DOI:10.1116/1.585835

出版商:American Vacuum Society    

年代:1991

数据来源: AIP

摘要:

The performance of a large diameter, 2.45 GHz multicusp electron‐cyclotron‐resonance (ECR) plasma etching system with regard to etch rate uniformity and submicron pattern definition in silicon is described. Results are compared to earlier work on a similar system operated at 915 MHz. The plasma source utilizes a 23 cm diam discharge and a 12‐pole static magnetic field geometry to create multicusp ECR zones in the plasma excitation region. Microwave excitation at 2.45 GHz with power levels up to 600 W is used to excite discharges for etching of single 125 mm diam wafers and multiple 75 mm diam wafers. For single 125 mm wafers with oxide masks the 3σ variation of silicon etch rate uniformity was 2.3% and for multiple 75 mm wafers with aluminum masks the 3σ variation was 8.1% over a 150 mm diam. Vertical anisotropic etching was obtained both at the center of the wafers and the peripheries. Etch profiles were evaluated as a function of position on the substrate and no substantial positional or orientation effects were observed. Microloading effects appear small for both oxide and aluminum masks. Submicron (0.6 μm) trenches and holes were anisotropically etched in silicon and show approximately a 5% lower etch rate than large (>5 μm) features. For the relatively low microwave input power densities used, etch rates ranged from 40 to 140 nm/min as the SF6ratio ranged from 5% to 15%.

ISSN:0734-211X    

DOI:10.1116/1.585836

出版商:American Vacuum Society    

年代:1991

数据来源: AIP

摘要:

We report on investigations of dry etching in GaInP/AlGaInP. As a method of dry etching we used CCl2F2/Ar reactive ion etching (RIE) and Ar ion beam etching (IBE). The suitability of these two methods for microstructure technology with respect to etch rates in investigated. First data on damage resulting from application of these two dry etching techniques in GaInP/AlGaInP are presented. The degree of damage was detected by performing photoluminescence measurement.

ISSN:0734-211X    

DOI:10.1116/1.585837

出版商:American Vacuum Society    

年代:1991

数据来源: AIP

摘要:

A hybrid system consisting of a multipolar electron cyclotron resonance source driven by a microwave power supply at 2.45 GHz and a radio‐frequency (rf) powered electrode at 13.56 MHz is used for the etching of GaAs and InP. Both CCl2F2and Cl2are used as the gas sources, and the effect of rf and microwave power, pressure, as well as flow rate on etch rate and surface morphology are evaluated. Fast etch rate up to 3.4 μm/min is obtained for GaAs. Etch rate increases with rf power and decreases with microwave power when CCl2F2is used. Optical emission and x‐ray photoelectron measurements indicate that more C‐related compounds are generated when microwave power is on. With Cl2addition, etch rate increases with microwave power and smoother morphology is obtained. Etching for InP yields smooth morphology at a typical rate of 50 nm/min.

ISSN:0734-211X    

DOI:10.1116/1.585838

出版商:American Vacuum Society    

年代:1991

数据来源: AIP

摘要:

Reactive ion etching of InP in CH4/H2has been studied to assess anisotropy and surface morphology. Empirical models have been developed for etch and polymer deposition rates. Highly anisotropic features characterized by high ratios of etch to polymer formation rates are obtained at low methane concentration and relatively high power density. The inclusion of oxygen in the gas composition reduces polymer deposition but increases surface roughness.

ISSN:0734-211X    

DOI:10.1116/1.585839

出版商:American Vacuum Society    

年代:1991

数据来源: AIP

摘要:

The high selectivity between the etch rates of GaAs and AlxGa1−xAs or AlAs obtained in plasmas containing both chlorine and fluorine is widely used to obtain accurate and uniform etching of molecular beam epitaxy grown high electron mobility transistor and (less commonly) metal‐semiconductor field‐effect transistor (MESFET) layers. The influence of gas residence time on the selectivity of GaAs to Al0.3Ga0.7As in CCl2F2reactive ion etching (RIE) at 50 V dc bias is investigated, finding that maximum selectivity (>4000 to 1) and maximum GaAs etch rate (1.75 μm/min) are achieved with a residence time for CCl2F2of between two and four seconds. No evidence of any significant damage to MESFET layers when overetching a 50 Å Al0.3Ga0.7As etch stop was observed at these RIE conditions by either Hall measurements or byCVandIVcharacterization of Schottky diodes. MESFETs with 0.2 μm gates recessed in CCl2F2show good dc and microwave performance.

ISSN:0734-211X    

DOI:10.1116/1.585840

出版商:American Vacuum Society    

年代:1991

数据来源: AIP

摘要:

By monitoring device electrical parameters during remote plasma dry etching, we have demonstrated a novel method forinsituadjustment of saturation currents. Time‐elapsedI‐Vcurves and current‐versus‐time plots illustrate the low damage, controllable gate recess etching of a metal‐semiconductor field‐effect transistor device structure and two different high electron mobility transistors. Using a one‐dimensional Poisson solver, simulations of conduction versus depth are made and discussed in relation to experimental results.

ISSN:0734-211X    

DOI:10.1116/1.585841

出版商:American Vacuum Society    

年代:1991

数据来源: AIP

摘要:

Reactive‐ion etching (RIE) and chemically assisted ion‐beam etching are routinely used in the fabrication of submicrometer features. Both techniques are known to produce electrical damage. We have used a combination of Raman spectroscopy and photoreflectance to study the effects of dry etching on the depletion layer width and built‐in electric field of heavily doped GaAs. We find that RIE reduces the built‐in electric field and at the same time increases the depletion layer width. These results can be understood in terms of the formation of a more insulating layer near the surface. Our analysis shows that even though the Fermi‐level pinning position can change, the predominant effect of dry etching is to change the carrier density of the near‐surface region. We also observe that the use of chlorine‐based species in the etch reduces the electrical damage.

ISSN:0734-211X    

DOI:10.1116/1.585842

出版商:American Vacuum Society    

年代:1991

数据来源: AIP

摘要:

The reactive ion etching of the transparent conductor, indium tin oxide (ITO), in methane/hydrogen plasmas has been characterized. It is shown that ITO can be selectively etched on GaAs and AlGaAs. Anisotropic structures and gratings with submicrometer dimensions in ITO are presented. Application of the etching process to the fabrication of highly sensitive metal–semiconductor–metal (MSM) photodetectors with interdigitated ITO fingers is demonstrated.

ISSN:0734-211X    

DOI:10.1116/1.585843

出版商:American Vacuum Society    

年代:1991

数据来源: AIP