摘要:

Ion beam assisted etching (IBAE) is a dry etching technique in which the sputter etching component of an argon ion beam and the chemical etching component supplied by a Cl2gas flux are independently controlled. This technique has been used to obtain anisotropic etching of GaAs with minimal surface damage over areas of a few square millimeters. The results reported here are achieved with an improved IBAE system designed to etch considerably larger areas. The system accurately and uniformly delivers reactive gas flux to the sample giving uniform etching rates over the 2‐cm‐diam area exposed to the ion beam. When the sample is exposed to high reactive gas fluxes, equivalent to a pressure of 1×10−2Torr, and 1 to 2 keV Ar+ions at 1 mA cm−2, etching rates of 5 to 10 μm/min are obtained making etched through‐holes in GaAs wafers realizable. Control of the ion beam collimation and the reactive gas flux allow for accurate control of undercutting making submicrometer etched structures in GaAs with aspect ratios>35:1 easily obtainable. In addition, damage studies of the ion beam assisted etched GaAs surfaces shows a low trap density in the range of 1013cm−3as determined by deep level transient spectroscopy (DLTS). The improved system uses two gas jets to supply the chemically reactive flux and a liquid N2cooled shroud to trap the unused reactive gas. The absolute reactive flux impinging on the sample is determined with a capacitance monometer and the ion beam collimation is controlled by varying the ion gun to sample distance.

ISSN:1071-1023    

DOI:10.1116/1.582671

出版商:American Vacuum Society    

年代:1983

数据来源: AIP

摘要:

Etching characteristics of GaAs, InP, and other materials using a scanning microplasma have been investigated. This technique utilizes enhanced reaction between a reactive ambient gas and a target at an excited region like a microplasma which is produced by irradiating a scanning focused ion beam. It was observed that the present technique gives an enhanced etching rate over a physical sputter etching and a very smooth etched surface. Dependence of etching rate on bombarding angle and reactant gas flow rate is also measured.

ISSN:1071-1023    

DOI:10.1116/1.582672

出版商:American Vacuum Society    

年代:1983

数据来源: AIP

摘要:

GaAs etching rate performed by RIE in CCl2F2gas has been shown to depend on many parameters: pressure, rf power and flow rate. Moreover addition of Ar in CCl2F2has been found to increase the etch rate. This observation and the AES study of etched GaAs surfaces has led to the conclusion that volatile chloride species contribute to the etching mechanism, while fluoride species which are less volatile inhibit etching. Schottky diodes presenting an ideality factor of 1.02 have been fabricated on CCl2F2etched GaAs surface.

ISSN:1071-1023    

DOI:10.1116/1.582673

出版商:American Vacuum Society    

年代:1983

数据来源: AIP

摘要:

High resolution reactive ion etching of GaAs and InP is achieved using SiCl4as the etching gas. Etching rates and profiles are examined at pressures between 1 and 10 mTorr and power densities from 0.2 to 0.9 W/cm2. Under the proper conditions, it is possible to obtain extremely vertical etch profiles and etch ratios of GaAs relative to masking materials such as Si3N4and NiCr which exceed 10 to 1.

ISSN:1071-1023    

DOI:10.1116/1.582674

出版商:American Vacuum Society    

年代:1983

数据来源: AIP

摘要:

We have found that silicon, when implanted with doses of gallium in excess of 1013ions/cm2, experiences little or no etching in aqueous caustic solutions. By exploiting a finely focused 40–50 keV gallium ion beam (0.05–0.1 μm diameter) in our scanning ion microscope, we have shown that it is possible to fabricate structures with submicrometer (0.1 μm) features. The silicon behaves as a negative resist with a sensitivity of about 1 μC/cm2. This etch‐stop process is largely insensitive to crystallographic orientation, except for the highly insoluble (111) plane in which damage‐promoted etching occurs.

ISSN:1071-1023    

DOI:10.1116/1.582675

出版商:American Vacuum Society    

年代:1983

数据来源: AIP

摘要:

High resolution patterns have been fabricated in 〈100〉 silicon by doping selected areas with gallium utilizing an ion microprobe. These doped regions are used as an etch mask for subsequent anisotropic etching of silicon. The etching was performed in a KOH:IPA solution at 80–90 °C. The resulting etch rate of the doped silicon is approximately inversely proportional to the gallium impurity concentration. At high doping concentrations an etch rate difference of greater than 1000:1 has been measured between the virgin silicon and the doped regions. Using this technique features as small as 30 nm have been produced.

ISSN:1071-1023    

DOI:10.1116/1.582676

出版商:American Vacuum Society    

年代:1983

数据来源: AIP

摘要:

Copolymer (methacrylonitrile–methacrylic acid), which has no significant deep UV absorption prior to prebake, starts to have a broad UV absorption with the maximum at 246 nm after prebake at 130 °C in air. Cyclized structures responsible for this absorption undergo photochemical reactions: (1) main chain scissions at deep‐UV exposure, initiated by removal of isocyanic acid, providing positive tone images; (2) hydrogen transfer reactions at mid‐UV exposures to result in conjugated structures or cross linkages, providing negative tone images. With relatively high sensitivity, 50 mJ/cm2for positive and 100 mJ/cm2for negative tone images, polymer patterns with vertical wall profiles are obtained. Postbake of these resist patterns increases dry etch resistance significantly.

ISSN:1071-1023    

DOI:10.1116/1.582677

出版商:American Vacuum Society    

年代:1983

数据来源: AIP

摘要:

X‐ray lithographic performance of poly(chloromethylstyrene) (PCMS), a high performance negative e‐beam resist, was investigated. Superior resolution, i.e., resist profile and linewidth control, was obtained by x‐ray exposure due to the essentially square x‐ray exposure profile and the significantly reduced amount of backscattered electrons from the substrate. Sensitivity and resolution were evaluated as a function of polymer molecular parameters. Dry etching characteristics were evaluated under polysilicon, SiO2and Al etching conditions. Excellent resolution, sensitivity and dry process compatibility were obtained and attributed to the high absorption of chlorine to PdLαradiation, the high chemical reactivity of the benzyl chloride moiety and the high plasma stability of the aromatic styrene moiety. Sensitivity of 300 000 molecular weight PCMS is 25–30 mJ/cm2(D0.5g) to PdLαradiation; resolution is 1 μm in 1 μm final thickness resist with vertical walls atD0.9g(70 mJ/cm2), and submicron in thinner layers. Dry etch resistance is comparable to that of AZ‐type photoresist. Postexposure deep UV hardening minimizes thermally induced flow and profile distortion even at temperatures greater than 300 °C. Lithographic performance of PCMS compares very favorably with other leading x‐ray resists including the mixture of poly(2,3‐dichloropropyl acrylate) and poly(glycidyl methacrylate‐co‐ethyl acrylate) (DCOPA), poly(allyl methacrylate‐co‐hydroxyethyl methacrylate) (EK88) and chloromethylated polystyrene (CMS).

ISSN:1071-1023    

DOI:10.1116/1.582678

出版商:American Vacuum Society    

年代:1983

数据来源: AIP

摘要:

This paper describes the lithographic processing of several positive novolak‐based resists exposed on the IBM x‐ray lithography system at the Brookhaven National Laboratory 750 MeV storage ring. One of the advantages of the storage ring exposure system has been the ability to use resist development processes which are the same as the corresponding optical or e‐beam processes. The exposure system and the x‐ray mask used for resist evaluation are described elsewhere in this symposium. Determining the best process conditions requires consideration of mask contrast as well as the desired linewidth and profile control, particularly in the presence of topography. Data will be presented and compared with results obtained using other lithographic systems (i.e., e‐beam and conventional source x‐ray). In particular, the relationship of mask absorber thickness to process window will be presented using a simple model of the development process. Using the process window defined by this model, we have exposed test patterns and typical device patterns in 1 to 2 μm thick conventional positive novolak resists. Linewidth control data as a function of dose and development time were determined for one resist at doses in the 100–200 mJ/cm2range and compared with corresponding results using electron beam exposure. The x‐ray exposures compared favorably with the electron beam exposures in the dosage ranges considered.

ISSN:1071-1023    

DOI:10.1116/1.582679

出版商:American Vacuum Society    

年代:1983

数据来源: AIP

摘要:

Direct engraving of mask patterns in a resist film was tried by exposing with synchrotron radiation. Using a stencil mask made of a Si3N4substrate, submicron structures could be successfully replicated. Fundamental aspects of resist decomposition by synchrotron radiation were also investigated by mass and electron spectroscopy.

ISSN:1071-1023    

DOI:10.1116/1.582636

出版商:American Vacuum Society    

年代:1983

数据来源: AIP