摘要:

To address the question whether it is possible to performinsituend point detection during etching using ellipsometry on patterned wafers, a number of experiments were performed on wafers that were covered with a photoresist line pattern on an oxide‐covered silicon substrate. Two situations were investigated, one in which the probe beam was directed parallel to the line pattern, and one in which the probe beam was perpendicular to the lines. For each situation, a separate ellipsometric model was developed. Employing photoresist and SiO2etch rates measured with blanket wafers, a good fit between the experimental curves and the simulations was obtained. Though the agreement between modeling and experiment is good, it is shown that the applicability of ellipsometry for end point detection on patterned wafers depends on the aspect ratio of etched holes, the selectivity of the etching process, and the pattern factor (the unmasked area fraction of the wafer). For comparison, experiments and simulations were also performed with a laser interferometer at normal incidence. In this case, only the selectivity and the pattern factor are important. It has been shown that the selectivity of the process becomes less important if the derivative of the reflectivity is used as an end point signal instead of the reflectivity itself. To optimize the end point signal for this method the wavelength can be used to maximize the change in the reflectivity slope at the end point of the process.

ISSN:1071-1023    

DOI:10.1116/1.586076

出版商:American Vacuum Society    

年代:1992

数据来源: AIP

摘要:

A spherelike granular structure has been observed to appear on the surface of single crystal silicon as a result of a two step reactive ion etching (RIE). Fluorocarbon plasma in RIE mode has been found to create a micromasking of bare silicon. Subsequent application of silicon etch recipe produces a texture with submicron spherical granules. Energy dispersion of x ray and Auger spectra analysis reveal that the suspected deposition or adsorption of etchant and effluent species onto the final surface is insignificant. The technique has a potential for controlling the reflectivity of silicon in specific regions of the spectrum and providing a large throughput.

ISSN:1071-1023    

DOI:10.1116/1.586033

出版商:American Vacuum Society    

年代:1992

数据来源: AIP

摘要:

Intrinsic silicon dioxide deposition rate dependences from tetraethoxysilane (TEOS) thermal pyrolysis were measured in an experimental cold wall low‐pressure chemical vapor deposition reactor designed to minimize reactant depletion and gas‐phase reactions. The apparent activation energy of 90 kJ mol−1±16 kJ mol−1over the range of temperatures from 873 to 1073 K is significantly lower than that typically measured in commercial or development‐scale hot wall reactors. The reaction rate exhibits a first order dependence on TEOS pressure. Film deposition proceeds without a nucleation‐induced incubation period. Interpretation of deposited film profiles in high aspect ratio trenches through rigorous ballistic transport‐reaction simulation reveals that deposition most likely occurs through a heterogeneous mechanism in which strong readsorption of the byproducts of TEOS decomposition inhibits silicon dioxide deposition.

ISSN:1071-1023    

DOI:10.1116/1.586034

出版商:American Vacuum Society    

年代:1992

数据来源: AIP

摘要:

A mathematical description of the method of testing by electron beam charging is used to clearly specify its measurement capabilities. The scanning electron microscopy parameters of beam current, frame scan time, and magnification, are used to derive the requirements necessary to distinguish between shorted and isolated structures.  

ISSN:1071-1023    

DOI:10.1116/1.586035

出版商:American Vacuum Society    

年代:1992

数据来源: AIP

摘要:

The scanning tunneling optical microscope (SNOM, STOM, PSTM, etc.) is the equivalent of the electron scanning tunneling microscope in the electromagnetic domain. Although it was born at the same time, its actual development is more recent. Here, some new results obtained with the version working in total reflection (STOM/PSTM) are reported. A grating of a periodicity of 417 nm and a thickness of 5 nm have been imaged both in TM and TE modes. It is first noted that the optical image is well resolved. Furthermore, the difference of behavior of the field versus the polarization of the incident light has been shown. More precisely, the TM mode seems to be highly sensitive to small index and topography variations due to surface contaminants. Such effects are generally not imaged by atomic force microscopy working in attractive mode, because they affect the surface topography slightly. The SNOM could be thus a very powerful tool for detecting pollutants over the surface of objects like glasses, lenses, gratings, etc., and in the biology domain.

ISSN:1071-1023    

DOI:10.1116/1.586036

出版商:American Vacuum Society    

年代:1992

数据来源: AIP

摘要:

The addition of hydrogen atoms to ethylene and benzene on a Cu(111) surface has been studied by temperature‐programmed desorption and integrated desorption mass spectrometry. The results show that adsorbed ethylene and benzene react with atomic hydrogen from the gas phase at temperatures as low as 110 K. The reaction intermediates, ethyl groups and partially hydrogenated benzene, can be isolated on the surface at this low temperature. When the surface is heated to above 150 K, hydrogen elimination reactions occur to produce ethylene, benzene, cyclohexadiene, and cyclohexene. Complete hydrogenation to alkanes also occurs for larger H‐atom exposures. The absence of these addition reactions when H atoms are adsorbed onto the surface before ethylene or benzene suggests Eley–Rideal mechanisms for these processes.

ISSN:1071-1023    

DOI:10.1116/1.586037

出版商:American Vacuum Society    

年代:1992

数据来源: AIP

ISSN:1071-1023    

DOI:10.1116/1.586038

出版商:American Vacuum Society    

年代:1992

数据来源: AIP

摘要:

A 100 kV optics with field emission source is designed for an electron‐beam nanolithography system. A new electrostatic gun lens permits high‐voltage operation with low aberrations. A demagnifying double‐lens column with fixed magnification and variable aperture is used. The optics are weighted towards 100 kV operation, but the beam voltage can be varied from 25 to 100 kV with resolution maintained below 20 nm. The gun uses a Zr/O/W<100≳ cathode operated near the extended‐Schottky emission regime to achieve 1%/h current stability at a fixed extraction voltage. With the source emitting a 0.5 mA/sr angular intensity, 1.5 nA can be focused to 6 and 10 nm with beam voltages of 100 and 50 kV, respectively. A target current density of 2000 A/cm2with an effective brightness of 1×108A/cm2 sr enables 2 MHz pixel rate exposures of PMMA at 100 kV with a vector‐scan deflection system.

ISSN:1071-1023    

DOI:10.1116/1.586039

出版商:American Vacuum Society    

年代:1992

数据来源: AIP

摘要:

The established methods after Parikh [M. Parikh, IBM J. Res. Dev.24, 438 (1980)] allow a dose correction using the ‘‘Two Gaussian Model’’ by considering the parameters α, β, and η. A guaranteed accuracy after development cannot be given for these methods because the development process, depending on resist type, thickness and contrast, is not taken into account. In order to calculate a final guaranteed accuracy considering α, β, η, and the full resist development process, we did a calculation in following steps. First, we calculated the proximity correction just for backscattered electrons by the method of ‘‘simple compensation’’ [V. V. Aristov, A. A. Svintsov, and S. I. Zaitsev, Microelectron. Eng.11, 641 (1989)]. In the second step, we simulated the proximity effect after development (modeling) with the before corrected dose distribution, but now considering all parameters: α, β, η, thicknessH, and contrast γ of positive resist. This leads to a guaranteed accuracy δ (maximum structure deviation) for a given design ruleLusing the correction method of simple compensation. This guaranteed accuracy can be expressed in dimensionless coordinates δ/α=f(L/α,H/α,η,γ). So the accuracy of the electron lithography in this approach is determined by the beam size, characterized by α. Simple compensation results in the accuracy equal to a fraction of α. A better proximity correction below the guaranteed accuracy is possible by using simple compensation in iteration and by correcting for α inside a small structure frame.

ISSN:1071-1023    

DOI:10.1116/1.586040

出版商:American Vacuum Society    

年代:1992

数据来源: AIP

摘要:

It is well‐known that many improvements concerning resolution and focus latitude can be obtained by the use of phase‐shifting masks. Different phase‐shifting mask designs are proposed already, and one of the most suitable designs for periodical structures is the alternated shifter design. If such phase‐shifting masks are investigated, it is assumed that all shifter parameters are ideal. A major problem, however, is the production of such an ideal phase‐shifting mask with perfect shifter parameters. In this work, the influence of shifter parameters such as transparency, thickness, and sidewall slope are studied for the alternated phase‐shifting design. The investigation is carried out by simulations and by experiments, and for various coherence factors. It is found that all shifter deviations cause linewidth differences between shifter and quartz lines, often resulting in a reduced depth‐of‐focus (DOF). Especially if various deviations occur simultaniously, the DOF reductions are important, putting stringent demands on mask processing in order to obtain tolerable shifter deviations. In order to print L/S down to 0.3 μm with reasonable DOF for production applications, the shifter transparency and thickness should not deviate more than 5% from their ideal values.  

ISSN:1071-1023    

DOI:10.1116/1.586041

出版商:American Vacuum Society    

年代:1992

数据来源: AIP