摘要:

The absorption edges of elements can be investigated using an energy-modulated electron beam by plotting the derivative of the total x-ray yield against electron energy, called the appearance potential spectrum. A simple apparatus was built, consisting of a tungsten-electron source and a large-area windowless x-ray detector, located in an ultrahigh-vacuum system. The soft x-ray absorption edge structure of the light elements from beryllium to oxygen and a few heavier elements was obtained. Electron currents in the range of 1 mA were normally needed for most of the experiments, though successful recordings were made at 15 μA. All of these spectra show complex structure which is presumably related to the density distribution of the empty states in the valence band. The L-edge structure of iron and nickel is presented in pure and alloyed forms to demonstrate spectral shifts. Some anomalous structure was also obtained from certain specimens. Because of the low-energy of the probing electrons, the technique is basically a tool for surface analysis, sensitive to light elements. The simplicity of the apparatus makes it possible to adapt it to existing systems for surface studies.

ISSN:0022-5355    

DOI:10.1116/1.1318469

出版商:American Vacuum Society    

年代:1973

数据来源: AIP

摘要:

Causes of high-ohmic contact resistance were explored by analyzing several integrated circuit samples with an ion microprobe. Presence of oxide and dopant depletion at the interface were indicated. Mapping of oxygen vs depth through an oxide revealed that not only the elements present, but also the layered structure of the material could be observed. The possible production of artifacts due to electrostatic charges on the surfaces of a sample was noted.

ISSN:0022-5355    

DOI:10.1116/1.1318470

出版商:American Vacuum Society    

年代:1973

数据来源: AIP

摘要:

We study here the fabrication of p-channel MOS field effect transistors with 4 μ gate lengths, made with electron-beam lithography substituted for conventional photolithography. The remainder of the processing included tungsten metallization with self-aligned ion implanted source and drain regions as described by Moline et al., and by Boll and Lynch (IEDM, 1972). The resulting transistors were characterized by turn-on voltage,Vtof 1.3–1.6 V (〈0100〉 orientation) and 1.8–2.1 V 〈111〉. For the 〈100〉 devices, the distribution inVtacross each slice was very tight (2σ<0.1 V). The experimental values forVtcould be predicted from independently measured values of substrate doping and flatband voltage. Transconductance per square of gate was typically ∼ 14 ± 1.4 μʊ(i.e.,μΩ−1) (atVG–Vt=−3V) for devices with a gate oxide thickness of 1000 Å and a gate width of 200 μ. The value for mobility, μ, for the 〈100〉 devices was estimated to be160 cm2 V−1 sec−1. The punch-through voltage was 23 ± 1.5V. The bias-temperature stability of the resulting devices was found to be strongly dependent on the crystal orientation. Slices with 〈100〉 faces were highly stable (<0.08 V shift after five minutes of positive or negative application of106 V/cmat 300 °C); slices with 〈111〉 orientation were considerably less stable (up to 0.7V shift under the same conditions). The results are in general accord with previous results using conventional photolithography projected to account for narrower gate lengths. They indicate that no additional complications were introduced by the substitution of electron-beam lithography.

ISSN:0022-5355    

DOI:10.1116/1.1318471

出版商:American Vacuum Society    

年代:1973

数据来源: AIP

摘要:

In IGFET circuitry, it has been predicted that halving the lateral dimensions should bring about approximately a fourfold speed advantage; providing doping levels, vertical dimensions, and applied voltages are constant. We have used electron lithography to make p-channel IGFET inverter circuits with 9- and 4-μ gates and have demonstrated a sixfold improvement in the propagation delay for smaller circuits. The devices were made using a refractory metal and ion implantation as described by Moline et al., and by Boll and Lynch. (IEDM, Washington, 1972). The electron resist (used for all four lithographic stages) was much more sensitive than polymethylmethacrylate.

ISSN:0022-5355    

DOI:10.1116/1.1318472

出版商:American Vacuum Society    

年代:1973

数据来源: AIP

摘要:

This paper describes the design, fabrication and test results of a high-performance IGFET circuit made by combining electron-beam technology for all masking steps and ion implantation for the diffusion steps. The circuit consists of an eleven stage ring oscillator with two FET devices per stage. The enhancement mode device is the switching element and the depletion mode is used as load. The aluminum gate length of the devices is 1 μ and the width is 5 μ. The aluminum metallization, defined with electron-beam exposure of PMMA resist, also serves as a self-aligning mask for the ion implantation of source and drain in the gate region. The average delay per stage was determined by measuring the periodicity of the circuit oscillation and dividing by 22. Test results on several circuits indicate that the average delay per stage is approximately 295 psec.

ISSN:0022-5355    

DOI:10.1116/1.1318473

出版商:American Vacuum Society    

年代:1973

数据来源: AIP

摘要:

Electron lithography and ion implantation have been used in the fabrication of integrated complementary P-channel and N-channel transistors. A digitally controlled single electron beam system, the Electron Micropattern Generator, aligned and exposed the eight mask levels required. The cumulative alignment tolerance was 3 μ. Fabricated devices had channel lengths of 1, 2, and 6 μ, and drain-source breakdown voltages of − 22 and+ 12 Vfor the P- and N-type, respectively. Ion implantation was used to produce self-aligned gate structures by extending the diffused source and drain contact regions to the gate edges. The implantation masks consisted of 3000 Å aluminum and 7700 Å PMM resist. Boron and phosphorus ions were implanted at 50 and 100 keV, respectively at dosages ranging from1×1014to1×1015 ions/cm2. Sintering and annealing operations were performed at 500 °C for 10 min inN2atmosphere. Sheet resistances ranged from 2700 to 1000 Ω/□ for implanted boron and 700−240 Ω/□ for the phosphorus. Evolving high-density circuits require shallow P-well junctions (≈ 2.7μ) and contact regions (≈ 0.7μ) in N-type 〈100〉 oriented silicon of 0.35 Ω-cm resistivity. Evaluation of the transistors showed enhancement mode operation withVTP=−4.8 VandVTN=+1.4 Vusing a gate dielectric structure consisting of CVD sandwich layers of 125 ÅSiO2plus 750 ÅSi3N4, yielding average surface state density of6×1011 charges/cm2. Evaluation of diffused and implanted transistors, as well as resistors, will be discussed.

ISSN:0022-5355    

DOI:10.1116/1.1318474

出版商:American Vacuum Society    

年代:1973

数据来源: AIP

摘要:

Bipolar microwave transistors have been fabricated using ion implantation and electron lithography, with a sputter-etched nickel-masked gold metallization process as originally developed by Herb and Labuda. The resulting devices showed the fine definition associated with the latter two technologies, together with the uniformity of electrical properties associated with ion implantation. The electrical properties of the transistors were found to be comparable to similar devices also made with ion implantation but employing conventional photolithography and electroplated gold metallization. It is suggested that the combination of technologies illustrated in the work will be generally applicable to bipolar integrated circuits.

ISSN:0022-5355    

DOI:10.1116/1.1318475

出版商:American Vacuum Society    

年代:1973

数据来源: AIP

摘要:

Direct metallic deposition exploits the advantages of electron-beam exposure for the production of fine structures and avoids the use of resists and chemical etching. The process involves the electron-induced decomposition of metallic compounds in areas precisely defined by an electron probe. In principle, the resistivity of the deposits formed by direct metallic deposition can be controlled by regulating the amount of molecular dissociation which takes place. To date, in experiments with silver chloride, deposits with submicron dimensions have been obtained. Typical sheet-resistance values of the deposits range from 10 to 1000 Ω/square for exposures varied from3×10−2to5×10−3 C/cm2. A Monte Carlo simulation of electron scattering in thin films on a supporting substrate has shown that the minimum deposit dimensions which can be expected from the process vary directly with film thickness and inversely with accelerating voltage. Experimental evidence is in agreement with the theoretical predictions.

ISSN:0022-5355    

DOI:10.1116/1.1318476

出版商:American Vacuum Society    

年代:1973

数据来源: AIP

摘要:

In order to analyze the imaging properties of an electron-optical system, it is necessary to know how various sources of aberration combine to increase the size of the final image or spot. Either linear mixing, or else quadratic mixing (based on the assumption that the aberration produces a Gaussian distribution), have been commonly used. In this paper a theory of aberration mixing is developed, starting from the assumption of a circularly symmetric current-density distribution, each point on which is subjected to a circularly symmetric aberration. If the effective radius of the spot (and of each contribution) is defined as the square root of the normalized second moment of the current-density distribution, then the following theorem is shown to hold: when a spot with a circularly symmetric current-density distribution suffers any circularly symmetric aberration, the effective radius of the resultant spot is the square root of the sum of the squares of the effective radii of the original spot and the aberration disk. If several sources of aberration are present, it follows that the effective radii all add quadratically. For a Gaussian distribution, it is shown that the effective radius is just the 1/epoint on the current-density distribution. For a rectangular distribution (e.g., defocusing or, to first approximation, astigmatism) and the distribution resulting from the spherical aberration of a lens, numerical constants are derived which relate the effective radius to the more usual and often more convenient outer diameter of the aberration disk.

ISSN:0022-5355    

DOI:10.1116/1.1318477

出版商:American Vacuum Society    

年代:1973

数据来源: AIP

摘要:

The solid-state light valve, consisting of an off-axis electron gun and an electro-optic target crystal, is used as a two-dimensional spatial light modulator for a collimated laser beam. With a 1 mil electron beam spot and 50 μA beam current, 1000 line resolution and real time operation at TV frame rates have been achieved. The electron optics and three error function figures of merit for a generalized off-axis electron beam system are presented. The component selection procedure and an analog correction preprocessor design on a precalculated basis are discussed.

ISSN:0022-5355    

DOI:10.1116/1.1318478

出版商:American Vacuum Society    

年代:1973

数据来源: AIP