摘要:

The formation of TaSi2by121Sb+bombardment of Ta films on 〈100〉 Si was examined as a function of ion dose, temperature during implantation, and postimplantation rapid thermal annealing. The redistribution of Sb, C, and O was determined during the various treatments. In addition, the influence of this redistribution on silicide formation was evaluated. Ion induced TaSi2growth exhibited a linear dose dependence that was weakly influenced by substrate temperature (200–400 °C) during ion bombardment. Under these conditions, TaSi2growth was dominated by atomic mixing rather than radiation enhanced diffusion. Interfacial carbon layers were readily dispersed by ion bombardment, and did not greatly influence TaSi2growth. In contrast, O and Sb segregated to the surface and the TaSi2/Si interface during ion bombardment. These O‐ and Sb‐rich layers inhibited both Si diffusion and subsequent TaSi2growth. Postimplant annealing resulted in the buildup of both interfacial C and O. Complete silicide formation was only accomplished at temperatures (1000 °C) sufficient for Si diffusion through the interfacial barriers and Sb surface depletion. Film characterization was performed using Rutherford backscattering spectrometry, secondary ion mass spectrometry, scanning electron microscopy, and x‐ray diffraction.

ISSN:1071-1023    

DOI:10.1116/1.583863

出版商:American Vacuum Society    

年代:1987

数据来源: AIP

摘要:

The origin of crystal defect in epitaxial Si film grown by the molecular beam epitaxial (MBE) method has been studied. Examination went down to the detail of crystal defect density, unintentionally doped carrier concentration, and carbon contaminations of the epitaxial film with both substrate orientations of (100) and (111). The crystal defect originated from the epitaxial interface has been affected by the excessive carbon content formed at the interface during the substrate cleaning process, because both the defect and the amount of carbon with (100) are statistically much lower than those with (111). Both unintentionally doped hole concentration which has a run number dependence and the crystal defect formed during the epitaxial growth have been much smaller with (100) than with (111). A similar trend in the run number has also been observed in terms of the residual gases of CO and CO2in the vacuum chamber. From these facts, it has been concluded that characteristics of the MBE film grown on the (111) surface are much more sensitive to the carbon contamination than those on the (100).

ISSN:1071-1023    

DOI:10.1116/1.583606

出版商:American Vacuum Society    

年代:1987

数据来源: AIP

摘要:

We have investigated the effects of varying Si oxidation conditions on intrinsic film stress for SiO2films formed on Si. This study includes stress measurements on four Si orientations: (100), (110), (111), and (311); at oxidation temperatures ranging from 700 to 1100 °C; wet (H2O) versus dry (O2) oxidations for (100) and (111) surfaces; and the effects of postoxidation annealing on stress. We find the following orientation dependence for intrinsic stress measured as a function of oxidation temperature: (110)≥(311)≥(100)>(111); a reduction in stress for wet versus dry studies; and an even larger reduction for postoxidation anneals. A recently proposed step model accounts for the differences in stress between the (111) and the remaining Si orientations. A number of Si oxidation models based on intrinsic stress are compared in their ability to describe observed kinetic behavior, and we conclude that within the Deal–Grove oxidation model, the linear rate constant is strongly influenced by stress in the initial regime while stress is also likely to be important for thicker films.

ISSN:1071-1023    

DOI:10.1116/1.583853

出版商:American Vacuum Society    

年代:1987

数据来源: AIP

摘要:

Laser photodeposition of zinc from diethylzinc is experimentally studied. Parametric studies of laser power, intensity, gas pressure, and temperature are evaluated to characterize the deposition process. The results of these experiments verify the trends predicted by a simple theoretical treatment. The investigated deposition process shows contributions from both gas‐phase molecules and adsorbed molecular layers. The ability to control the relative contribution from these two media is demonstrated.

ISSN:1071-1023    

DOI:10.1116/1.583866

出版商:American Vacuum Society    

年代:1987

数据来源: AIP

摘要:

We discuss the conversion efficiency and spectral characteristics of x‐ray sources produced by focusing 0.26 μm radiation on targets. We optimize the x‐ray emission in given spectral ranges by choosing the appropriate target atomic number and irradiation conditions. We study the exposure of PBS photoresist with well characterized subkilovolt and kilovolt x‐rays and find the sensitivity as well as the contrast of the resist increase with subkiloelectron volt radiation. The results confirm that the value of x‐ray energy per unit volume absorbed at the resist surface is approximately independent of wavelength. A model for the development rate is also proposed to reproduce the experimental data.

ISSN:1071-1023    

DOI:10.1116/1.583883

出版商:American Vacuum Society    

年代:1987

数据来源: AIP

摘要:

A computer‐controlled electron‐beam writing system has been developed. The system has various functions for fabricating thin film micro‐optical devices. The ability of 0.1‐μm patterning, smooth circular and elliptic scanning of an electron beam, and excellent blazing characteristics have been demonstrated. The system has been confirmed to be an efficient means for fabricating micro‐optical devices.

ISSN:1071-1023    

DOI:10.1116/1.583898

出版商:American Vacuum Society    

年代:1987

数据来源: AIP

摘要:

EBES4 is an electron‐beam exposure machine designed for accurate submicron lithography with good throughput. It can write on optical and x‐ray mask substrates and directly on semiconductor substrates. Standard pattern data are preprocessed using a special purpose processor to remove overlap and to reverse the tone if required. The address size can be varied from 1/16 to 1/8 μm. Patterns are written by first breaking them into microfigures which can be rectangles, parallelograms, or 45° triangles with a maximum size of 16×16 addresses. Each microfigure is positioned on the continuously moving substrate using magnetic and electrostatic deflection systems. They are written by stepping in a raster with a 1/8 μm spot using an additional very high speed electrostatic deflection system. The coordinate system can be distorted by digital hardware to correct for mechanical errors or to register with another lithography level. The electron‐beam column with its thermal‐field‐emission gun, the hydraulic stage, the mask‐handling robot, the control system, and the pattern data flow are all described. The system is highly automated, and the pattern data flow, electron‐beam column setup, vacuum system switching, and cassette handling are all under the control of a VAXTM11/780. Distributed processors are used for lower level control tasks. Resists of up to 8 μC cm−2can be exposed at a rate of one 4 in. mask (containing 109microfigures) every 30 min at 1/8 μm address size, while resists requiring 20 μC cm−2can be exposed at a rate of one every 50 min. No damaging heating effects have been observed.

ISSN:1071-1023    

DOI:10.1116/1.583925

出版商:American Vacuum Society    

年代:1987

数据来源: AIP

摘要:

The electron‐beam column for AT&T Bell Laboratories’ EBES4 electron lithographic system forms a writing spot less than 125 nm in diameter (FWHM) with a current in excess of 250 nA at a fixed beam energy of 20 keV. A thermal‐field‐emission gun uses a long life zirconium–tungsten cathode operated at 1750–1800 K. The optical system contains three magnetic lenses and produces one intermediate crossover adjacent to a knife‐edge. The beam can be blanked in less than 500 ps by deflecting it so that it is interrupted by the knife‐edge. The beam current is changed by varying the strengths of the first and second lenses. Fast, accurate deflections are provided by three deflection systems: A telecentric magnetic deflection system covers a 0.28 mm square field and settles in 5 μs. Two electrostatic deflection systems cover 32 and 4 μm square fields with settling times of 100 and 1 ns respectively. The electron‐beam column has excellent mechanical stability and reliability, and requires very little maintenance.

ISSN:1071-1023    

DOI:10.1116/1.583926

出版商:American Vacuum Society    

年代:1987

数据来源: AIP

摘要:

A hydraulicX–Ystage system for application in electron beam lithography machines is described. TheX–Ytable is supported on hydrostatic bearings and is driven hydraulically. This system operates in a vacuum and is used in the AT&T Bell Laboratories’ EBES4 electron beam exposure system. TheX–Ystage system consists of a yoke assembly mounted on the end of a large hydraulic piston and cylinder assembly. TheX–Ytable is mounted on a movable carriage that rides on a smaller hydraulic piston fixed in the yoke assembly. Carriage motion in the yoke is orthogonal to the motion of the large hydraulic cylinder, providingXandYmotions, respectively. Both hydraulic axes use hydrostatic bearings to minimize sliding friction and to prevent undesired motion normal to the travel directions. The hydrostatic bearings, appropriately shaped, also prevent rotation. All sliding portions of theX–Ydrive are enclosed with flexible metal bellows. The entire hydraulic system, including the pump, is sealed and evacuated to about 50 mTorr. The hydraulic fluid is a narrow distillate fraction of a perfluorinated polyether vacuum pump oil. The position of theX–Ytable is measured to within (1)/(64) μm with a standard two‐axis laser interferometer system. Stage velocity can be as high as 10 cm/s but is typically less than 5 cm/s during pattern writing. Oil temperature is actively controlled to keep the stage head temperature constant within 0.1 °C under all operating conditions. The position of each axis is independently controlled by a 16‐bit microcomputer through an analog control board. The analog board drives a standard two‐stage electrohydraulic servovalve that controls oil flow to and from the hydraulic actuator. The analog gains and offsets are set digitally. Position feedback and positioning strategies, including acceleration and velocity limits, are implemented in the microcomputer.

ISSN:1071-1023    

DOI:10.1116/1.583927

出版商:American Vacuum Society    

年代:1987

数据来源: AIP

摘要:

A high‐throughput, high‐precision e‐beam direct writing system, the EB60, has been developed for both submicron VLSI memories and application specific integrated circuits (ASICs). The throughput is twenty and eighty 4‐in. wafers per hour for 0.5 μm VLSI memories and 0.8 μm ASICs, respectively, with ±0.1 μm overlay accuracy. To achieve this performance, a novel drawing method and the following key subsystems were developed: (1) Vector beam scanning during continuous stage movement with an advanced three dimensional registration method, which has reduced overhead time and results in a well balanced system design. (2) Variable shaped beam electron optical column with 0.2 μm beam edge resolution at 2.0×1.5 (1.5×2.0) μm maximum beam size and a current density of up to 70 A/cm2. (3) High‐speed beam deflection and dynamic focus system, including high‐speed analog circuits, all‐electrostatic deflectors, and an electrostatic dynamic focus lens. (4) Fast pattern controller, which executes 16 Mshot/s pattern data generation, and several data calculations for beam positioning error corrections and pattern writing during continuous stage movement. (5) High‐speed precision ceramicXYstage and high‐speed wafer handling mechanism which enables automatic exposure of 50 wafers. (6) Control software which is friendly to both operators and LSI designers. Through the coordination of the above subsystems, a lithography system with a high throughput and a wide range of applications has been developed.

ISSN:1071-1023    

DOI:10.1116/1.583928

出版商:American Vacuum Society    

年代:1987

数据来源: AIP