Behavior of surface ions on semiconductor devices

Schlegel, E. S.; Schnable, G. L.; Schwarz, R.; Spratt, J.P.

doi:10.1109/t-ed.1968.16548

Cited by 35 publications

(11 citation statements)

References 7 publications

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“…Even though bulk and surface leakage currents are negligibly small, they can have indirect effects related to surface charge inversion (16)(17)(18)(19)21). Using a specially fabricated MOS IC, an inversion-induced leakage after autoclave stress was observed (33).…”

Section: Discussionmentioning

confidence: 99%

Bulk and Surface Conduction in CVD SiO2 and PSG Passivation Layers

Comizzoli¹

1976

J. Electrochem. Soc.

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Measurements of electrical conduction in the bulk of chemical vapor deposited (CVD) SiO.2 and phosphosilicate glass (PSG) passivation layers typically used for over-me~al IC protection are reported. Moisture uptake increases the bulk conductivity, and the moisture effects depend on phosphorus content. The bulk current thermal activation energy of CVD SiO.~ (0.6 eV) is constant with varying moisture exposure. Before moisture exposure, phosphorus-containing glass has an activation energy of 0.8 eV, and it decreases with moisture exposure. Surface conductivity is also reported as a function of relative humidity. Conductivity values are related to IC leakage currents, and it is suggested that bulk currents in PSG should not contribute to aluminum corrosion in the absence of defects, such as cracks or pinholes.SiO~ and phosphosilicate glass (PSG) are important materials in silicon device passivation (1). Thin layers of PSG (hundreds of angstroms) have been described as useful for Na-gettering under gate metal of MOS devices (2-4). Thin layers must be used to avoid instabilities due to PSG polarization (3, 5-7). For overmetal passivation of IC's, thicker layers (about 104fl,) can be used (since polarization of the PSG is unimportant in this geometry). Generally, over-metal layers are deposited by chemical vapor deposition (CVD) (8-11 ). The phosphorus addition lowers intrinsic stress over aluminum metal and provides Na-gettering capability (12), which is particularly useful in plastic packaged devices. In addition, the passivating glass over metal provides important scratch protection during the device production process (13), and serves as insulating protection against loose conducting particles in hermetic packages (14).The bulk and surface electrical properties of CVD passivation over metal are important in understanding Na-gettering (4, 15) device leakage as affected by lateral charge spreading (16-21), metal corrosion (22-25), and moisture effects (24,25).In this report, measurements of bulk electrical conductivity as a function of water uptake and temperature, and surface conductivity as a function of relative humidity (RH) are reported for CVD SiO2 and CVD PSG. The data are used in estimating electrical and moisture effects typical for IC's. Sample PreparationThe glass layers were deposited on degenerate ntype (0.01 ohm-cm) silicon wafers at 450~ at a growth rate of about 1000 A/min to a total thickness of 1 ~m, using a reactor described by Kern (11,26). Phosphorus concentrations, determined by etch rate analysis, are 0, 4.8, and 8.5 weight per cent (w/o) P in the glass. No postdeposition heat-treatments were applied. * Electrochemical Society Active Member.

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Section: Discussionmentioning

confidence: 99%

Bulk and Surface Conduction in CVD SiO2 and PSG Passivation Layers

Comizzoli¹

1976

J. Electrochem. Soc.

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“…Measurements of effective surface recombination velocities on semiconductor surfaces have clearly demonstrated that recombination can be affected by both by the concentration of recombination centers as well as band bending at the interface. 50 Silicon surfaces which demonstrated long carrier lifetimes, and therefore low SRV, under band bending conditions were shown to have higher SRV measurements when redox couples in solution changed the band bending to be closer to flat band, as shown in Figure 1.14. The electric field in the space charge region prevents holes from getting to the surface and therefore slows the rate of recombination.…”

Section: Electrochemistry Band Bending and Surface Statesmentioning

confidence: 96%

“…This phenomenon holds true even though band bending of this nature requires positively charged surface states, indicating that these pre-existing surface states are not available for recombination with electrons at the surface. 50 …”

Section: Figure 114 Schematic Of Band Bending and Surface Recombinatmentioning

confidence: 99%

Measurement of the Band Bending and Surface Dipole at Chemically Functionalized Si(111)/Vacuum Interfaces

2013

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The core-level energy shifts observed using X-ray photoelectron spectroscopy (XPS) have been used to determine the band bending at Si(111) surfaces terminated with Si–Br, Si–H, and Si–CH3 groups, respectively. The surface termination influenced the band bending, with the Si 2p3/2 binding energy affected more by the surface chemistry than by the dopant type. The highest binding energies were measured on Si(111)–Br (whose Fermi level was positioned near the conduction band at the surface), followed by Si(111)–H, followed by Si(111)–CH3 (whose Fermi level was positioned near midgap at the surface). Si(111)–CH3 surfaces exposed to Br2(g) yielded the lowest binding energies, with the Fermi level positioned between midgap and the valence band. The Fermi level position of Br2(g)-exposed Si(111)–CH3 was consistent with the presence of negatively charged bromine-containing ions on such surfaces. The binding energies of all of the species detected on the surface (C, O, Br) shifted with the band bending, illustrating the importance of isolating the effects of band bending when measuring chemical shifts on semiconductor surfaces. The influence of band bending was confirmed by surface photovoltage (SPV) measurements, which showed that the core levels shifted toward their flat-band values upon illumination. Where applicable, the contribution from the X-ray source to the SPV was isolated and quantified. Work functions were measured by ultraviolet photoelectron spectroscopy (UPS), allowing for calculation of the sign and magnitude of the surface dipole in such systems. The values of the surface dipoles were in good agreement with previous measurements as well as with electronegativity considerations. The binding energies of the adventitious carbon signals were affected by band bending as well as by the surface dipole. A model of band bending in which charged surface states are located exterior to the surface dipole is consistent with the XPS and UPS behavior of the chemically functionalized Si(111) surfaces investigated herein.

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“…with o the surface conductivity of the oxide, Cox the capacitance per unit area of the oxide, and x and y the directions in which charge motion can take place. The solution of this equation depends on the boundary conditions and initial value of the potential V. In the case of a structure which can be considered to be one-dimensional the surface potential can be described by a so-called complementary error function [12]. In all other cases the solution should be approached by means of a numerical procedure.…”

Section: A Description Of the Oxide-surface Potentialmentioning

confidence: 99%

Investigations of the surface conductivity of silicon dioxide and methods to reduce it

1987

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In this paper we describe our investigations of the electrical conductivity of the silicon dioxide-air interface. It appears that this conductivity is caused by the adsorption of water vapour on the oxide surface and strongly depends on the relative humidity of the surrounding air. Considering this fact we have decided to investigate the possibility to reduce the surface conductivity by means of a chemical modification of the oxide surface, which reduces the adsorption of water vapour on it. To measure the conductivity we have used a so-called open-gate FET structure. The performance characteristics of this structure and the experimental results obtained with it are presented. We have found that by using silane agents like HMDS and DCDMS the surface conductivity of silicon dioxide can be reduced with at least a factor 1000 and 10000 respectively.

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Behavior of surface ions on semiconductor devices

Cited by 35 publications

References 7 publications

Bulk and Surface Conduction in CVD SiO2 and PSG Passivation Layers

Bulk and Surface Conduction in CVD SiO2 and PSG Passivation Layers

Measurement of the Band Bending and Surface Dipole at Chemically Functionalized Si(111)/Vacuum Interfaces

Investigations of the surface conductivity of silicon dioxide and methods to reduce it

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