摘要:

For studying the technology of the critical dimension measurement using an electron beam (EB), a computer simulation based on the Monte Carlo and the surface charge methods is carried out, and a wave form of backscattered electrons (BE’s), which hardly suffer from the charging phenomenon, is precisely analyzed using this simulation. First, line widths obtained individually by threshold, maximum slope, and linear approximation methods are examined about various incident‐EB conditions such as an accelerating voltage and a beam diameter. The dependencies of pattern structures, such as dimension, side‐wall angle, and materials of the patterns, on measured line width are evaluated next. As a result of these calculations, it is found that the variation of the incident‐EB conditions doesn’t affect practically the results of the line‐width measurement in BE‐detection systems, while secondary‐electron signals are easily deformed by the charging phenomenon. Although the measured width much depends on the pattern structure, the linear approximation method is comparatively suitable for the purpose of obtaining the width of bottom edges in BE‐detection systems.

ISSN:1071-1023    

DOI:10.1116/1.584698

出版商:American Vacuum Society    

年代:1989

数据来源: AIP

摘要:

A low‐energy focused ion beam (FIB) would be a very useful tool for shallow doping with low damage density to the substrate. For a low‐energy FIB, an optical system using a retarding field is advantageous because of a low chromatic aberration coefficient which could not be reduced with a conventional column. Some evaluations were made for an optical column with a retarding electrode for practical use. The secondary electron trajectories within the equipotential space were calculated by the surface‐charge method, and some secondary‐electron images were observed with an experimental column having a retarding electrode.

ISSN:1071-1023    

DOI:10.1116/1.584699

出版商:American Vacuum Society    

年代:1989

数据来源: AIP

摘要:

Three achromatic deflectors intended for ion lithography are proposed, in which the beam is incident perpendicular to the target. One of these deflectors uses mixed electrostatic and magnetostatic fields, thereby exhibiting mass dependent deflection. Although this is not favorable for a deflector, this setup works well as an achromatic mass filter. Best performance is obtained using a pre‐lens deflector using one lens as a corrector. A two lens corrector has theoretically even better performance, but mechanical and electrical tolerances will probably inhibit good performance.

ISSN:1071-1023    

DOI:10.1116/1.584700

出版商:American Vacuum Society    

年代:1989

数据来源: AIP

摘要:

A new type of magnetic deflector [wire electron discharge machine (EDM) deflector] has been constructed for our gaussian round beam exposure system. To optimize the design of conventional saddle‐type deflection coils used for electron beam lithography systems (EBLS), one of the most important technical problems lies in the achievement of consistency between the computer aided design (CAD) calculated model and the actual structure of the windings. The present paper investigates the relation between the deflection aberration and winding width as well as winding distribution when the parameters of the deflector are optimized. The calculated results show that with 30° central angle of the winding and larger variance of the winding width the influence of third‐order aberration is negligible in micron‐EBLS and submicron‐EBLS. The design and experimental results are discussed for a new type of saddle coil used in EBLS and fabricated by the wire electron discharge machine (wire EDM) technology, this deflector indicates consistency between the CAD model and the actual structure of the winding. In our μm‐order EBLS using the wire EDM deflector, field stitching accuracy of<0.3 μm can be realized. The beam positioning accuracy is ∼0.2 μm.

ISSN:1071-1023    

DOI:10.1116/1.584701

出版商:American Vacuum Society    

年代:1989

数据来源: AIP

摘要:

Ion bombardment has been found to enhance the etch rate of amorphous rf‐sputtered Al2O3in hot H3PO4so that this material works as a dry‐etch‐durable ion beam resist. It is shown that the resist properties depend on the substrate temperature and the magnetic field strength near the target surface during the sputter deposition. The optimized Al2O3deposited at 380 °C and 9 mT is insoluble in 80 °C H3PO4when unbombarded, and has a sensitivity of 1×1014cm−2and a contrast (γ) of 1.5 for 50‐keV Ga+ions. Density measurement and x‐ray diffraction revealed that the optimized Al2O3has higher density and a more ordered structure. X‐ray masks were fabricated by defining 200‐nm‐wide grooves in 500‐nm‐thick WNxx‐ray absorber layers using the Al2O3patterned with focused 50‐keV Ga+beams, as a durable mask for electron cyclotron resonance type of plasma etching with SF6; the etch‐rate ratio of WNxto Al2O3was 30. Pattern transfer into poly(methylmethacrylate) from the fabricated mask was successfully carried out with synchrotron radiation.

ISSN:1071-1023    

DOI:10.1116/1.584702

出版商:American Vacuum Society    

年代:1989

数据来源: AIP

摘要:

The focused beam size and current for a JBX 5DII electron beam lithography system was measured for various shaped, (100) single‐crystal LaB6cathodes at 50‐kV beam voltage. The performance of a 90° full angle, conically shaped cathode with a 15‐μm spherical apex radius was compared with a similar cathode, but with a variable diameter flat at the cathode apex. As the flat size varied from 15 to 30 μm, the minimum beam size (for 50 pA of beam current) varied from 11 to 37 nm for a cathode temperature of 1830 K. The performance of the 15‐μm truncated compared favorably with the 15‐μm spherical shaped cathode. For larger beam diameters, the beam current for the truncated cathode exceeded that of the 15‐μm spherical shaped emitter. The truncated cathode was operated in excess of 3100 h with no performance degradation.

ISSN:1071-1023    

DOI:10.1116/1.584703

出版商:American Vacuum Society    

年代:1989

数据来源: AIP

摘要:

A simple model is presented which predicts the maximum attainable current density and associated optimum brightness and semi‐angle in a variable shaped spot (VSS) and a Gaussian spot (GS) electron beam lithography system for a given resolution (edge width). For a GS the optimum source demagnification factor is also predicted. The contribution of the forward scattering in the resist is taken into consideration. The model allows the assessment of the sensitivity of the attainable current density to various design and operation parameters. The model is based on the quadratic sum of uncorrelated and uncorrectable aberrations and solves the expression for the sum for the current density using the reduced brightness as variable. VSS systems are characterized by an optimum brightness and a high sensitivity to stochastic trajectory displacement due to electron–electron interaction. The acceleration potential has a paramount effect on the attainable current density, still enhanced when forward scattering due to the resist is included. In GS systems the chromatic and geometrical aberrations limit the attainable density. The brightness attainable with Lanthanum–hexaboride emitters is satisfactory for VSS systems but GS systems require very high brightness guns (e.g., TFE) to exploit the potential for achieving a high current density.

ISSN:1071-1023    

DOI:10.1116/1.584704

出版商:American Vacuum Society    

年代:1989

数据来源: AIP

摘要:

An attempt is made to derive model expressions of the gate capacitance of metal–oxide semiconductor structures inn‐channel inversion layers on ternary chalcopyrite semiconductors at low temperatures, takingn‐channel inversion layers on CdGeAs2as examples, under both the weak and strong electric field limits, respectively. It is found, on the basis of newly derived two‐dimensional electron energy spectra within the frame work ofk↘⋅p↘ formalism for both the limits by considering the anisotropies of the band parameters, that the gate capacitances increase with increasing surface electric field in an oscillatory manner and the crystal‐field splitting parameter enhances the numerical values of the gate capacitance for both the limits. In addition, the corresponding well‐known results forn‐channel inversion layers on parabolic energy bands are also obtained from the generalized expressions.

ISSN:1071-1023    

DOI:10.1116/1.584431

出版商:American Vacuum Society    

年代:1989

数据来源: AIP

摘要:

The influence of substrate temperature and InAs mole fraction on the incorporation of indium during molecular‐beam epitaxial growth of lattice mismatched InGaAs single quantum wells on GaAs have been investigated. For growth of In0.25Ga0.75As at temperatures570 °C), although it is less severe for these lower indium concentrations.

ISSN:1071-1023    

DOI:10.1116/1.584432

出版商:American Vacuum Society    

年代:1989

数据来源: AIP

摘要:

A GaAs on Si coplanar technology by molecular‐beam epitaxy, that is suitable to combine GaAs and Si circuits on chip is reported. Coplanarity is obtained after the GaAs is grown embedded in masked wells in the Si substrate, which were formed by wet chemical etching with a controlled solution of HF:HNO3. Scanning electron microscope and profiling studies show the extreme flatness and the intentional misorientation of several degrees of the recessed surfaces. A possible process is proposed to realize a coplanar surface by lifting off polycrystalline GaAs with the masking dielectric. The GaAs surface step height remaining after liftoff is<0.6 μm for a 2‐μm‐thick deposit. Metallization without loss of continuity is performed over the GaAs to Si border with evaporated metal lines, 150 nm thick and 1.25 μm wide, indicating the feasibility of interconnecting side by side integrated devices in both semiconductor materials.

ISSN:1071-1023    

DOI:10.1116/1.584433

出版商:American Vacuum Society    

年代:1989

数据来源: AIP