摘要:

This paper reports a detailed thermodynamic analysis of the GaAs/Cl and InP/Cl chemical systems, which are of interest in the technological processing of these III–V materials. The thermodynamically predicted dependence of the steady state chemical etching on both Cl2pressure and temperature is derived assuming Langmuir free evaporation from the surface. The chemical potential data base used in this thermodynamic analysis has been checked for accuracy against all available vapor pressure measurements in the literature. The thermodynamically predicted chemical etching is compared to the etching observed in a Cl2plasma. This approach shows promise in semiquantitative modeling of the dependence of these reactions on both the temperature and Cl2pressure. In addition, changes in the surface morphologies resulting from plasma etching appear to be correlated with the thermodynamically predicted transitions of various compounds on the surface.

ISSN:1071-1023    

DOI:10.1116/1.583485

出版商:American Vacuum Society    

年代:1986

数据来源: AIP

摘要:

An etch process for SiO2in a C6F14+N2plasma at 1 Torr pressure and with a power of 10 W/cm3was examined for its etch rate dependence on gas composition, pressure, and electrode separation. Rates larger than 1 μm/min were obtained. The selectivity with respect to silicon could be made infinitely high by choosing various gas mixtures. An axial magnetic field increased the etch rate by 20%. The process was highly anisotropic. Ion and neutral mass spectroscopy was applied to illuminate the differences between this process and the conventional cathode coupled process (RIE) at pressures of 0.05 Torr.

ISSN:1071-1023    

DOI:10.1116/1.583486

出版商:American Vacuum Society    

年代:1986

数据来源: AIP

摘要:

The reactive ion etching (RIE) of GaAs/AlxGa1−xAs heterolayers has been examined as a function of alloy composition (x=0.00–0.31) and the etching parameters of pressure, rf applied power, gas flow rate, and time using CCl2F2as the etching gas. The information derived from this study was used to determine the GaAs to AlxGa1−xAs etch selectivities. The use of CCl2F2promotes the formation of nonvolatile reaction products on the surface of AlxGa1−xAs, so that even for small amounts of aluminum the etch rate of AlxGa1−xAs is significantly reduced compared to GaAs. This compositional factor favors the highly selective etching of GaAs over AlxGa1−xAs. High gas pressure and flow rate and a low rf applied power also contribute to high selectivities in this system. A selectivity (GaAs to AlxGa1−xAs etch ratio) of 300 was attained for a pressure of 20 mTorr and an rf power of 500 W.

ISSN:1071-1023    

DOI:10.1116/1.583487

出版商:American Vacuum Society    

年代:1986

数据来源: AIP

摘要:

The following electrostatic e‐beam deflectors are simulated numerically and compared: (1) Box deflector; (2) modified box deflector; (3) dokekapole deflector; (4) simplified octupole deflector; (5) 20‐pole deflector; (6) conventional octupole deflector. Two types of aberrations arise in the deflection of an electron‐image of negligible size: raster distortion and spot blurring. For each deflector, these aberrations are computed and plotted as functions of deflection amplitude. The present computations make no use of perturbational aberration theory but rely on the method of ray tracing in 3D fields. The full effect of fringe fields due to finite gap widths and finite lengths of electrodes is accounted for. The surface‐charge density method has been utilized for the accurate numerical calculation of the fields.

ISSN:1071-1023    

DOI:10.1116/1.583488

出版商:American Vacuum Society    

年代:1986

数据来源: AIP

摘要:

Experimental data from the IBM direct‐write electron beam lithography machine EL‐3 are used to evaluate a lower bound on the estimation error resulting from the application of optimal signal processing in determining the mark edge position for registration. The e‐beam is swept using a 20 kV accelerating voltage in a raster fashion across a bare rectangular groove of dimensions 5 μm wide×100 μm long×0.5 μm deep. Waveforms for backscattered electrons detected by diodes are processed statistically. The mathematical and numerical techniques are developed to handle a large but sparse noise correlation matrix. The bound obtained decreases exponentially with the sampling rate (at least throughout the range of measurement explored), and it represents the ultimate accuracy achievable with any signal processing technique. The implications of having multiple records of a waveform are included. Comparisons with other approaches are discussed.

ISSN:1071-1023    

DOI:10.1116/1.583489

出版商:American Vacuum Society    

年代:1986

数据来源: AIP

摘要:

A design method for a low aberration matrix lens is developed. The matrix lens consists of an electrostatic lens array and beam limiting aperture array located outside of the lens array. It is shown that off‐axial aberrations, which are dominant in the outer lenses, can be reduced by shifting the aperture from the optical axis of each lens to its optimum position. Using this aperture shift effect, a low aberration matrix lens consisting of einzel lenses is designed for submicron electron beam exposure systems. An aberration of 0.1 μm is predicted for a 40 mm2matrix lens with a beam half‐angle of 5 mrad.

ISSN:1071-1023    

DOI:10.1116/1.583490

出版商:American Vacuum Society    

年代:1986

数据来源: AIP

摘要:

A novel scheme is introduced which allows spatially resolved x‐ray photoelectron spectroscopy (XPS) studies to be performed in device applications by taking advantage of the ability to bias the various components of the device. The application of a bias voltage produces a shift in the Fermi level of the biased component and there is a corresponding shift in the binding energy of electrons emitted from this component. In this manner it is possible to discriminate between the XPS signals that are due to a given element but which originate from different regions of the sample. By analogy with the corresponding biasing scheme employed in SEM studies, this technique has been called voltage contrast XPS.

ISSN:1071-1023    

DOI:10.1116/1.583491

出版商:American Vacuum Society    

年代:1986

数据来源: AIP

ISSN:1071-1023    

DOI:10.1116/1.583492

出版商:American Vacuum Society    

年代:1986

数据来源: AIP