摘要:

A masked ion beam/optical hybrid lithography process for fabricating GaAs MESFETs is described. Techniques for eliminating the damage caused by the ions penetrating through the resist into the GaAs substrate are discussed. Submicrometer gate GaAs FET fabricated using the hybrid lithography is shown and the electrical characteristics of the depletion‐mode device presented.

ISSN:1071-1023    

DOI:10.1116/1.582637

出版商:American Vacuum Society    

年代:1983

数据来源: AIP

摘要:

Floating‐gate transistors can be used as electron‐beam programmable nonvolatile switches. These switches can provide customization, temporary test access, or fault‐avoiding interconnections for large integrated circuits. To demonstrate the feasibility of using electron‐beam programming, a 128 K bit nMOS EPROM was fabricated. It contains over 200 000 electron‐beam programmable switches which are used for the data bits, for address definition in the row and column selectors, and for deselection of defective subsystems. Such large numbers of customizing links are feasible since the programming yield is very high and a programming rate of>1000 links/s is easily obtained. This paper discusses the design of the electron‐beam programmable ROM, design and process considerations for the individual floating‐gate devices, and results on yield, programming speed, reversibility, and nonvolatility.

ISSN:1071-1023    

DOI:10.1116/1.582638

出版商:American Vacuum Society    

年代:1983

数据来源: AIP

摘要:

A new concept for archival electron beam memory is being investigated. The storage medium consists of a two dimensional array of columns supported by a thin, electron transparent, membrane. Information is written by melting selected columns with an electron beam. The increase in cross‐sectional area of the resulting droplets provides contrast for electron transmission readout. In this paper, we describe a fabrication process for this storage medium. Gold columns are electroplated into a resist mold defined by electron beam lithography. Proximity effects are controlled by membrane and trilevel resist techniques. Two dimensional arrays of gold columns with 50 nm diameter, 100 nm period and 3:1 aspect ratios have been fabricated on 250 nm thick polyimide membranes.

ISSN:1071-1023    

DOI:10.1116/1.582639

出版商:American Vacuum Society    

年代:1983

数据来源: AIP

摘要:

Fabrication of apertures, slots, and grooves in silicon, gold–palladium, and lithium fluoride has been demonstrated using a 100 keV electron beam. For the LiF films we have been able to etch<2 nm wide by 50 nm deep grooves on 10 nm centers. Grooves in silicon 8 nm wide by 30 nm deep have been made by reactive ion etching in SF6. Apertures as small as 8 nm in diameter have been produced in AuPd films self‐supported over larger holes in 60 nm thick Si windows.

ISSN:1071-1023    

DOI:10.1116/1.582640

出版商:American Vacuum Society    

年代:1983

数据来源: AIP

摘要:

The fabrication of microstructures with minimum dimensions below 100 nm introduces several additional problems not normally associated with electron‐beam lithography at the 1/2 to 1 μm level. The quality of a 100 nm resist image, when defined by an electron beam pattern generator, depends strongly upon the exposure conditions such as beam energy and dose. Another important factor is the substrate, since it greatly influences the range and amount of backscattered electrons and, hence, the exposure contrast achievable in a given resist system. There is generally a big difference in energy deposited in the resist whether the exposure is performed on a thin membrane, on bulk silicon, or on a thick layer of a heavy metal, and also whether a single thin layer of resist or thick two or three‐layer systems are used. The characteristics of the resist and the development process itself are important aspects, too. In addition to controlling the resist image, one must also consider the properties and requirements of the subsequent transfer process to the working material such as lift‐off, plating, ion milling, and reactive ion etching. The specific process is often dictated by the materials and the geometry of the particular structure to be fabricated. So, as many of the conditions interact, it is impossible to define a single process that would be suitable for the wide range of applications that structures of this size are intended for. Using examples of x‐ray zone plates and FET gate definition, we discuss the merits of some of the processes used together with the techniques and problems associated with the evaluation of process performance at these dimensions.

ISSN:1071-1023    

DOI:10.1116/1.582641

出版商:American Vacuum Society    

年代:1983

数据来源: AIP

摘要:

We have performed electron beam lithography studies on thick substrates using beam energies of 20–120 keV and a nominal beam diameter of 2 nm in a Philips 400 electron microscope with scanning capability. Metal lines as narrow as 10 nm were fabricated on Si and GaAs substrates using liftoff of a single thin layer of resist. High resolution (approximately 10 nm) patterns could be written at all beam energies with an exposure latitude that remained approximately constant up to energies for which the range of the backscattered electrons became significantly larger than the pattern area. For large area patterns written with the small beam, the proximity effect is greatly reduced, even at 20 keV, because of the sharp edge of the exposure profile. At high beam energies, the range of backscattered electrons is large enough that they contribute only a slowly varying background dose, leading to a relatively simple proximity correction even for complex patterns.

ISSN:1071-1023    

DOI:10.1116/1.582642

出版商:American Vacuum Society    

年代:1983

数据来源: AIP

摘要:

A sequence of edge defined techniques has been developed which allows the successive multiplication of the number of lines in a grating pattern. Holographic lithography at 351.4 nm wavelength in a liquid medium has been used as the primary pattern generation technique for producing gratings with periods of ≊160 nm. A shadowing technique is then used to produce x‐ray masks with precisely controlled linewidth‐to‐period ratios. Reactive‐ion etching in CHF3yields a square profile structure in SiO2with precise linewidth. The basic edge defined technique consisting of CVD deposition, reactive‐ion etching, and selective isotropic etching can then be repeatedly applied given a proper choice of materials and etches. Each cycle of the edge defined technique doubles the number of lines in the pattern. Careful linewidth control at each step can result in gratings with one‐half of the initial period with minimum fundamental components. Gratings with ∼40 nm period have been fabricated by doubling the number of lines in a 160 nm period grating twice.

ISSN:1071-1023    

DOI:10.1116/1.582643

出版商:American Vacuum Society    

年代:1983

数据来源: AIP

摘要:

Surface textures with carefully controlled size, order, and morphology can be prepared by using monolayers of colloidal particles to form a lithographic mask. Microstructures produced from the mask are identical and of predetermined size because monodisperse colloidal particles can be obtained in sizes ranging from ∼200 Å–30 μm. Ordering of particles, and hence, surface texture can be either random or periodic depending upon the method used to deposit the particles. Several applications of reproducible fine structure fabricated on the surface of large area substrates are discussed.

ISSN:1071-1023    

DOI:10.1116/1.582644

出版商:American Vacuum Society    

年代:1983

数据来源: AIP

摘要:

Various liquid metal alloy ion sources and a 100 keV mass separated focused ion beam system have been fabricated and their basic characteristics have been measured. These are mass spectra, energy spread and angular current intensity for ion sources, and focusing characteristics of the system. It was observed that Be–Si–Au ternary alloy ion sources produce doubly charged Be and Si ions and the importance of these ion sources is demonstrated by fabricating a GaAs JFET using a maskless ion implantation technique and by PMMA resist exposure.

ISSN:1071-1023    

DOI:10.1116/1.582646

出版商:American Vacuum Society    

年代:1983

数据来源: AIP

摘要:

An ion optical system for use with EHD ion sources was designed using a cad program and constructed based on the design. This system is composed of six‐cylinder electrodes of 10 mm diam where the two middle electrodes function as octopole deflectors. The design goal was to produce a submicron ion probe capable of scanning a 2×2 mm square field under the condition that ion beam energy, the energy spread and acceptance half‐angle are 30 keV, 20 eV and 2 mrad, respectively. Preliminary experiments using an electron gun showed that the optical characteristics such as focusing voltage, deflection efficiency and deflection distortion were in good agreement with the results of computer simulation. Deflection characteristics using an EHD Ga ion source showed that an undeflected probe size of 1.5 μm in diameter increased only by 0.4 μm for 0.87 mm deflection even if no dynamic correction is made.

ISSN:1071-1023    

DOI:10.1116/1.582647

出版商:American Vacuum Society    

年代:1983

数据来源: AIP