摘要:

Thin diamond films have been grown by the microwave chemical vapor deposition method on polished silicon substrates using a methane concentration of 1.5% in hydrogen and deposition times between 7 and 60 min. The films were studied in air by scanning tunneling microscopy (STM). For short deposition times we have found small isolated diamond crystals (100 nm wide and 20 nm high), growing on the scratches produced by the initial polishing of the silicon surface, along with a smooth granular structure. As the deposition time increases to 15 min, the granular structure shows a slight faceting whereas the crystal size increases appreciably. This deposition period is characterized by a lower growth rate than that observed for longer times, which is explained as due to the presumably high nondiamond component of the granular structure. At 30 min a continuous film is formed with predominant {111} faces. The same trend is found for samples grown after 60 min. STM images show that {111} surfaces are rougher than {100} ones supporting the 2×1 reconstruction of the {100} surface during diamond growth.

ISSN:0734-211X    

DOI:10.1116/1.587182

出版商:American Vacuum Society    

年代:1994

数据来源: AIP

摘要:

The fabrication of a nanoscale gated quantum wire in a GaAs modulation doped field effect transistor substrate is described. Both the wire conduction channel, with a 110 nm physical width, and the gates were patterned into the two‐dimensional electron gas of the substrate. This scheme produced in‐plane gated devices with 110 nm gate lengths and 75 nm separations between the active areas. Electron‐beam lithography was used to define masks for a subsequent flood exposure step with low energy argon ions (150 eV). This ion exposure technique produced very high gate‐to‐wire isolation, typically greater than 1014Ω at 4.2 K. The in‐plane design employed here drastically reduces gate capacitance compared with metal top‐gate designs, and promises ultrafast switching times. These devices showed no short channel punch‐through effects, exhibited low gate leakage, and had sufficient gain to permit integration of several such devices into more complex circuits such as logic gates.

ISSN:0734-211X    

DOI:10.1116/1.587114

出版商:American Vacuum Society    

年代:1994

数据来源: AIP

摘要:

A method is presented to discretize almost arbitrary curves and areas on nonrectangular grids. This method can be applied in focused ion and electron beam systems. Distortion of the physical writing grid can be taken into account at the discretization, thus eliminating the need for a correction step afterwards.

ISSN:0734-211X    

DOI:10.1116/1.587173

出版商:American Vacuum Society    

年代:1994

数据来源: AIP

摘要:

Electron beam lithography and reactive ion etching have been used to fabricate four level aspheric reflecting focusing diffractive optical elements. A fast (f/2), 1 mm diam, four‐phase‐level, reflecting, off‐axis imaging diffractive optical element, without spherical aberration, coma, and astigmatism, has been fabricated on silicon. Alignment and stitching errors have been held to less than 40 nm and the smallest pattern feature is 0.6 μm. The silicon grating is coated with gold to enhance reflectivity with an efficiency of 73%. The quality of diffractive optical elements is limited by the fidelity of the fabrication steps, and methods are demonstrated for proximity effect correction, alignment, high selectivity mask creation, and reactive ion etching that can be used for high quality diffractive optic element fabrication of essentially arbitrary type.

ISSN:0734-211X    

DOI:10.1116/1.587185

出版商:American Vacuum Society    

年代:1994

数据来源: AIP

摘要:

Limited‐area cathodes based upon impregnated dispenser cathode material have been investigated in an electron optical column at accelerating voltages of up to 30 kV. A peak axial brightness of about 6×105A/cm2 sr was obtained at this voltage using a flat cathode. Brightness values greater by a factor of 10 were measured using a conical limited‐area cathode with a tip radius of curvature of 0.075 mm. The latter measurements were affected by space–charge spreading in the beam.

ISSN:0734-211X    

DOI:10.1116/1.587153

出版商:American Vacuum Society    

年代:1994

数据来源: AIP

摘要:

There is considerable interest in the use of phase shift masks as a route to extend the resolution, contrast, and depth‐of‐focus of lithographic tools beyond what is achievable with the normal chrome mask technology. In the attenuating phase shift mask, the chrome layer is replaced with a slightly transparent layer and the mask is etched so that light through the layer is 180° out of phase with light through clear regions. Thus, optical interference occurs which has the effect of increasing contrast at edges and of improving depth‐of‐focus. In this article, experiments of thin film materials designed to provide both the desired 180° phase shift and optical absorption in a single layer are described.

ISSN:0734-211X    

DOI:10.1116/1.587163

出版商:American Vacuum Society    

年代:1994

数据来源: AIP

摘要:

A novel chemically amplified positive resist with high sensitivity for electron beam (EB) direct‐writing lithography has been developed for deep submicron pattern fabrication. This positive EB resist consists of a tert‐butoxycarbonyl group‐protected poly (p‐vinylphenol) type matrix polymer installing cyano group and a metal‐free photoacid generator (PAG). The matrix polymer is insoluble in aqueous alkaline solutions. The acid‐catalyzed deprotection of matrix polymer results in poly (p‐vinylphenol), which can be easily dissolved in an aqueous alkaline solution. Three types of monomers, which can generate an acid by EB irradiation, are investigated as PAG in this resist system. Resist pattern profile is dependent on PAG characteristics, and the profile could be tapered in spite of the high contrast. It is found that ketosulfone‐type PAG is one of the most effective catalysts for this resist system. High resist sensitivity below 1.5 μC/cm2at 20 keV is obtained after postexposure bake at 90 °C. Reverse tapered profile in a 0.5 μm thick resist can be achieved in a 0.2 μm line and space resist pattern by using a conventional alkaline developer. This new positive EB resist can be used to delineate 0.35 μm device patterns in a trilayer resist process. Furthermore, 0.2 and 0.3 μm line and space patterns in 0.5 and 1.0 μm film thickness, respectively, can also be fabricated below 2.0 μC/cm2at 50 keV.

ISSN:0734-211X    

DOI:10.1116/1.587130

出版商:American Vacuum Society    

年代:1994

数据来源: AIP

摘要:

The sensitivity of the Ag2Te/As2S3system has been measured as a top‐surface imaging, negative‐tone resist between 632.8 and 193 nm. The sensitivity atg‐line (435.8 nm) andi‐line (365 nm) is of the order of 5 and 0.5 J/cm2, respectively, and is much too low to take advantage of the significant advantages of this resist. These advantages are high contrast (∼10), an edge effect which compensates for the reduction of optical intensity at line edges and latent image formation in a layer whose thickness is significantly less than the depth‐of‐focus of high resolution stepper optical systems. Measurements at 248 and 193 nm show significantly higher sensitivity of 350 and 80 mJ/cm2, respectively, suggesting that this system may possess practical potential at these wavelengths. Exposures on a GCA XLS‐7500 stepper with 0.42 NA at 365 nm have yielded 0.35 μm linewidths.  

ISSN:0734-211X    

DOI:10.1116/1.587099

出版商:American Vacuum Society    

年代:1994

数据来源: AIP

摘要:

Polycrystalline silicon (poly‐Si) ‘‘slit nanowire’’ was fabricated in a slit formed with 100 nm lithography, microwave dry etching of silicon substrate, conformable filling of the trench by chemical vapor deposition (CVD) SiO2, slit etching of the CVD SiO2, conformable deposition of doped amorphous silicon, followed by etchback and annealing. Observation with transmission electron microscope confirmed that a poly‐Si slit nanowire, with a cross section of ∼5–8 nm×20 nm is fabricated. Appropriate annealing of thea‐Si layer makes the poly‐Si grains grow to more than 2 μm in length. This technique would make it possible to realize silicon quantum devices, and to fabricate conventional integrated circuit devices and light emitting slit nanowire devices on a same silicon chip, which would allow the fabrication of integrated optoelectronic circuits.  

ISSN:0734-211X    

DOI:10.1116/1.587104

出版商:American Vacuum Society    

年代:1994

数据来源: AIP

摘要:

A new process to form shallow trench isolation for ultra‐large‐scale integrated devices is presented. This technique utilizes chemical mechanical polish steps to provide a virtual planar surface at the end of processing for isolations of various size, ranging from 0.5 μm to several hundred μm. Superior uniformity has been obtained on wafers of 8 in. diam processed in a productionlike environment. Good device isolation also has been found.

ISSN:0734-211X    

DOI:10.1116/1.587107

出版商:American Vacuum Society    

年代:1994

数据来源: AIP