The N 2 -SiH 4 rf glow-discharge plasma has been analyzed by line-of-sight mass spectrometry of species impinging on the deposition electrode (including N atoms), and properties ofSiNxHy films deposited from this plasma have been examined. At high rf power and low SiH 4 /N 2 gas ratio, most of the SiH 4 is consumed by reaction ofSiH m radicals with N atoms at the film surface and becomes incorporated into the film. No Si-N precursor species are seen in the plasma. This is in contrast to the NH r SiH 4 plasma, where the Si(NHzh radical is the key gas-phase precursor. If power is insufficient or SiH 4 flow is excessive, disilane is formed in the plasma. Under disilanefree plasma conditions, films slightly N rich with no Si-H bonding and only 11 at. % H (as N-H) can be deposited at high rate (21 nm/min). The film tensile stress characteristic of the NH3 process is absent in the N2 process due to the absence of precursor chemical condensation beneath the growing surface. However, step coverage is much worse in the N2 process due to the much higher sticking coefficients of the reactant radicals. The N2 plasma chemistry is the same using 400 kHz or 13 MHz rf power, but compressive stress and H content are both higher at the lower frequency due to H I implantation.551

The plasma-enhanced chemical vapor deposition process for SiN=H~ films has been in use for over two decades, but the chemistry of the process has yet to be explained. In the Present work, the composition of a 13 MHz NH~-SiH4 parallel plate glow discharge plasma was analyzed by line-of-sight sampling from the film deposition plane into a triple-quadrupole mass spectrometer, which can resolve compositional ambiguities at a given mass number by utilizing collision-assisted secondary cracking. At low RF power, disilane was the main plasma product even when NHjSiH4 was 25/1, whereas at higher power (0.1 W/cm ~ of cross section) disilane was eliminated and tetra-aminosilane, Si(NH~)4, and the triaminosilane radical, Si(NH2)3, became dominant. The concentration of these aminosilanes closely tracked deposition rate, and they are believed to be the principal SiN=Hy film precursors. Films deposited with Si(NH2)~ maximized and disilane suppressed in the plasma were excess in N and contained no Si--H bonding, consistent with the precursor composition. Silane utilization was near unity. The composition and properties of films deposited under these "amino-saturated" plasma conditions were examined vs. substrate temperaiure, Ts. With increasing Ts, there occurred a densification, a loss of H and excess N in a 3/1 ratio, and an increase in tensile stress, suggesting surface and subsurface chemical condensation of the adsorbed precursors via 3Si(NH2)4 -~ Si3N4 + 8NH3 ~. Postdeposition flash desorption showed NH3, not H2, to be the main volatile product of condensation. These results demonstrate that plasma chemistry can be manipulated to control film properties in a predictable manner.

No abstract

The chemistry of SiO~ deposition from undiluted and He-diluted N20-SiH4 mixtures was studied by line-of-sight mass spectrometry of plasma species coupled with analysis of film IR absorption and dielectric properties. It was found that if RF power is sufficient to generate an O atom supply well in excess of that needed to convert all of the Sill4 to SiO2, then clean IR spectra and high dielectric strength are obtained independent of dilution. Under these plasma conditions, many gas-phase products of the form Si~ H~ (OH).were detected. Their concentration increased steeply with the partial pressure of the reactants (Sill4 + N20), and they are the likely source of the downstream particles and deposition rate loss which were seen at 130 Pa of reactant pressure. Reduction of reactant partial pressure to 13 Pa either by He dilution or by undiluted total pressure reduction eliminated these problems. No other effects of He dilution could be detected either in the plasma chemistry or in the film properties. Both SiOH concentration and electron trapping rate in the films were much higher than in thermal oxide and were unaffected by He dilution. There is some evidence that He plasma treatment does improve Si interface quality. / .4 10 2 Pa 10 Pa plasma J r lllii::: i triple ~ "H quadrupole ~ Si, 4 smpaS~rometer ~L~._ LL 3 heater o~<:~ J ) unless CC License in place (see abstract). ecsdl.org/site/terms_use address. Redistribution subject to ECS terms of use (see 138.38.0.53 Downloaded on 2015-06-26 to IP ABSTRACTThe effects of the substrate temperature in the molecular beam epitaxy growth of In0 ~2A10.48As on (001)InP have been investigated. A strong dependence of the structural, electrical, and optical properties of InA1As films on the growth temperature has been found and optimized material can be grown at 530~ The low substrate temperatures deteriorate the material quality due to insufficient growth kinetics, while the higher temperatures allow the formation of composition inhomogeneities which also deteriorate the structural, optical, and electrical characteristics of In0~2A10.48As. Using In0 ~2A10.48As buffers grown at 530~ state-of-the-art InxGa~_~As/In0 ~2A1048As high electron mobility transistors were fabricated and showed reduced output conductance and no kink effect in the I(V) characteristics.) unless CC License in place (see abstract). ecsdl.org/site/terms_use address. Redistribution subject to ECS terms of use (see 138.38.0.53 Downloaded on 2015-06-26 to IP

We have used sputter-deposition and standard lithography to fabricate arrays of cantilevered metal mimsprings on 80 pm pitch, and we have obtained 100% electrical contact to 200-pad chips bonded facedown against them. Four-point resistance is 038 Q for Mo-Cr springs on A1 pads. Since the contacts themselves a~ not bonded and since the springs have high elastic compliance, this technology is very resistant to mechanical shock and stress, can accomodate large n o n p l d t y in mating surfaces, facilitates replacement of bad chips, and could be used for wafer-scale probing.