Browsing by Author "Gwo, S"

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Characterization of prototype silicon pitch artifacts fabricated by scanning probe lithography and anisotropic wet etching
(2005-01-01)
Chien, FSS
;
Hsieh, WF
;
Gwo, S
;
Jun, J
;
Silver, RM
Scanning probe lithography (SPL) and anisotropic tetra-methyl ammonium hydroxide (TMAH) etching (SPL+TMAH) were used to fabricate a series of one-dimensional prototype pitch structures on (110)-oriented silicon substrates. Overall lateral dimensions of the test structure are 20 mum x 80 mum. Line scales, consisting of 10-mum-long, 100-nm-tall, and 40-nm-wide lines, are observable by optical and scanning electron microscopy (SEM). Etched features were produced with pitches varying from 100 nm to 8 mum. Large-scale pattern placement errors of the SPL tool have been evaluated by analysis of optical image data obtained with a calibrated optical metrology instrument. Small-scale errors were analyzed in the range of 100 nm to 2 mum using SEM. Sources of placement error are discussed and possible methods for minimizing them are presented. The SPL+TMAH process in conjunction with a closed-loop scan control has the precision necessary for repeatable device prototyping in the nanoscale regime. (C) 2005 American Vacuum Society.
Improved electrical characteristics of CoSi2 using HF-vapor pretreatment
(1999-05-01)
Wu, YH
;
Chen, WJ
;
Chang, SL
;
Chin, A
;
Gwo, S
We have developed a simple process to form epitaxial CoSi2 for shallow junction. Prior to metal deposition, the patterned wafers were treated with HF-vapor passivation. As observed by scanning tunneling microscopy (STM), this HF, treatment drastically improves the native oxide-induced sur face roughness. The epitaxial behavior was confirmed by cross-sectional transmission electron microscopy (TEM), Decreased sheet resistance and leakage current, and improved thermal stability are displayed by the HF treated samples, which is consistent with STM and TEM results.
Improved electrical characteristics of CoSi2 using HF-vapor pretreatment
(1999-05-01)
Wu, YH
;
Chen, WJ
;
Chang, SL
;
Chin, A
;
Gwo, S
We have developed a simple process to form epitaxial CoSi2 for shallow junction. Prior to metal deposition, the patterned wafers were treated with HF-vapor passivation. As observed by scanning tunneling microscopy (STM), this HF, treatment drastically improves the native oxide-induced sur face roughness. The epitaxial behavior was confirmed by cross-sectional transmission electron microscopy (TEM), Decreased sheet resistance and leakage current, and improved thermal stability are displayed by the HF treated samples, which is consistent with STM and TEM results.
Improved electrical characteristics of CoSi2 using HF-vapor pretreatment
(1999-07-01)
Wu, YH
;
Chen, WJ
;
Chang, SL
;
Chin, A
;
Gwo, S
We have developed a simple process to form epitaxial CoSi2 for shallow junction. Prior to metal deposition, the patterned wafers were treated with HF-vapor passivation. As observed hy scanning tunneling microscopy (STM), this HF treatment drastically improves the native oxide-induced surface roughness. The epitaxial behavior was confirmed by cross-sectional transmission electron microscopy (TEM). Decreased sheet resistance and leakage current, and improved thermal stability are displayed by the HF treated samples, which is consistent with STM and TEM results.
Nano-oxidation of silicon nitride films with an atomic force microscope: Chemical mapping, kinetics, and applications
(2001-02-15)
Chien, FSS
;
Chou, YC
;
Chen, TT
;
Hsieh, WF
;
Chao, TS
We demonstrate that local oxidation of silicon nitride films deposited on conductive substrates with a conductive-probe atomic force microscope (AFM) is a very promising approach for nanofabrication. Scanning Auger microscopy and spectroscopy are employed to verify the chemical changes after AFM-induced oxidation. Furthermore, the growth kinetics are found to have a logarithmic relationship of oxide height versus pulse duration [h proportional to ln(t/t(0))]. In contrast to rather slow thermal oxidation process, AFM-induced oxidation on silicon nitride has an anomalously high initial oxidation rate (similar to 30 000 nm/s at 10 V) and a small onset time t(0) (similar to 10 mus). As for the applications in ultrahigh-density recording, an oxide dot array (similar to 100 Gbit/in.(2)) produced by this process is demonstrated. The nitride film patterned by AFM can be utilized as an etching mask to fabricate "subtractive" silicon nanostructures, due to the large etching selectivity of Si3N4:SiO2:Si in various etchants. With this method, which is entirely compatible with the existing microelectronic processes, synthesis of ultrahigh packing density and ordered nanostructures could become readily achievable. (C) 2001 American Institute of Physics.
Nanomachining of (110)-oriented silicon by scanning probe lithography and anisotropic wet etching
(1999-10-18)
Chien, FSS
;
Wu, CL
;
Chou, YC
;
Chen, TT
;
Gwo, S
We have demonstrated that silicon nanostructures with high aspect ratios, having similar to 400 nm structural height and similar to 55 nm lateral dimension, may be fabricated by scanning probe lithography and aqueous KOH orientation-dependent etching on the H-passivated (110) Si wafer. The high spatial resolution of fabricated features is achieved by using the atomic force microscope based nano-oxidation process in ambient. Due to the large (110)/(111) anisotropic ratio of etch rate and the large Si/SiO2 etch selectivity at a relatively low etching temperature and an optimal KOH concentration, high-aspect-ratio gratings with (111)-oriented structural sidewalls as well as hexagonal etch pit structures determined by the terminal etch geometry can be obtained. (C) 1999 American Institute of Physics. [S0003-6951(99)03242-8].
Nanometer-scale conversion of Si3N4 to SiOx
(2000-01-17)
Chien, FSS
;
Chang, JW
;
Lin, SW
;
Chou, YC
;
Chen, TT
It has been found that atomic force microscope (AFM) induced local oxidation is an effective way for converting thin (< 5 nm) Si3N4 films to SiOx. The threshold voltage for the 4.2 nm film is as low as 5 V and the initial growth rate is on the order of 10(3) nm/s at 10 V. Micro-Auger analysis of the selectively oxidized region revealed the formation of SiOx. Due to the large chemical selectivity in various etchants and great thermal oxidation rate difference between Si3N4, SiO2, and Si, AFM patterning of Si3N4 films can be a promising method for fabricating nanoscale structures. (C) 2000 American Institute of Physics. [S0003-6951(00)03003-5].
Silicon nanostructures fabricated by scanning probe oxidation and tetra-methyl ammonium hydroxide etching
(2002-06-15)
Chien, FSS
;
Hsieh, WF
;
Gwo, S
;
Vladar, AE
;
Dagata, JA
Fabrication of silicon nanostructures is a key technique for the development of monolithically integrated optoelectronic circuits. We demonstrated that the process of scanning probe microscope (SPM) oxidation and anisotropic tetra-methyl ammonium hydroxide (TMAH) etching is a low-cost and reliable method to produce smooth and uniform silicon nanostructures on a variety of silicon substrates. Etched structures with a pitch of 100 nm, positive- and negative-contrast structures, and features height greater than 100 nm have been produced on bare silicon, and Si3N4-coated and silicon-on-insulator wafers. Evolution of hexagonal pits on two-dimensional grid structures were shown to depend on the pattern spacing and orientation with respect to Si(110) crystal directions. We successfully combined SPM oxidation with traditional optical lithography in a mixed, multilevel patterning method for realizing micrometer-and nanometer-scale feature sizes, as required for photonic device designs. The combination of SPM oxidation and TMAH etching is a promising approach to rapid prototyping of functional nano-photonic devices. (C) 2002 American Institute of Physics.