Accurate barrier modeling of metal and silicide contacts

Shenai, K.; Sangiorgi, Enrico; Saraswat, Krishna C.; Swanson, R.M.; Dutton, R.W.

doi:10.1109/edl.1984.25864

Cited by 14 publications

(5 citation statements)

References 10 publications

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“…Referring to the mechanism in Eq. If the proposed mechanism for hydrogen adsorption were H2 + *2 ~ H2"2 [5] H2"2 --* 2(H*) [6] the rate equation would be v = k(H2*2) [7] Assuming [5] is in equilibrium (H2"2) K'l ---(H2)(*~) or H2"2 = K'l(H2)(*2) substitution would give r = k K'I H2 (*2) [8] which is also first order in hydrogen. A mechanism is proposed and has been analyzed by assuming each step, in turn, to be rate limiting.…”

Section: Discussionmentioning

confidence: 99%

“…If the proposed mechanism for hydrogen adsorption were H2 + *2 ~ H2"2 [5] H2"2 --* 2(H*) [6] the rate equation would be v = k(H2*2) [7] Assuming [5] is in equilibrium…”

Section: Discussionmentioning

confidence: 99%

“…The selective deposition technology has been used to make reliable low resistance contacts to shallow (0.3 ~m)N+ j unctions and a 32 bit microprocessor has been fabricated (6). Schottky barrier diodes were fabricated on (100) n-type silicon doped to a concentration of 2 • 101'~ cm -3 (7). Using selective deposition technology Schottky source/ drain contact p-type metal oxide semiconductor (PMOS) transistors have been fabricated (8).…”

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confidence: 99%

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The Kinetics of LPCVD Tungsten Deposition in a Single Wafer Reactor

McConica

Krishnamani

1986

J. Electrochem. Soc.

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The rate equation for the low pressure chemical vapor deposition (LPCVD) of tungsten from tungsten hexafluoride on (100) silicon was experimentally determined in a laboratory scale single wafer vacuum reactor. The reactor was designed and built as a high vacuum stainless steel system with a minimum of heat and mass transfer limitations. The tungsten film deposition is initiated by the silicon reduction of tungsten hexafluoride. In the absence of hydrogen, the silicon reduction results in a 10-40 nm self-limiting tungsten deposit, with the thickness dependent upon the native oxide layer prior to deposition. The hydrogen reduction of tungsten hexafluoride is one-half order in hydrogen, zero order in tungsten hexa-1 fluoride, and has an activation energy of 73,000 J mol-at temperatures from 561 to 683 K, and pressures from 0.067-1.3 kPa 4 1 05 8 1 0 (0.5 to 10 torr). The pre-exponential factor was found to be 6.8 • 10 nms Pa " (4.7 • 10 A rain-torr-~). A mechanism is proposed and two possible rate limiting steps yield rate expressions consistent with the observed kinetics. The rate limiting step could be either the addition of adsorbed monatomic hydrogen to adsorbed partially fluorinated tungsten or hydrogen fluoride desorption. In the absence of hydrogen the deposition was perfectly selective over all ranges of temperature and pressure. During the hydrogen reduction selectivity was lost in less than 600s at temperatures above 653 K (380~ Due to the observation that loss of selectivity is an activated process, it is concluded that deposition of tungsten on oxide is initiated by a chemical reaction rather than by random surface defects. Due to the high vacuum procedures, films were made with tungsten resistivities of 6 ~/cm, approaching the ideal 5.5 ~/cm for bulk tungsten.For very large scale integration (VLSI), a low resistance metal film is needed due to performance limitations of aluminum and polysilicon (1). As a result of these limitations, tungsten has been st,adied and successfully used for multilevel metalization by several facilities (2,3,4)

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Section: Discussionmentioning

confidence: 99%

“…If the proposed mechanism for hydrogen adsorption were H2 + *2 ~ H2"2 [5] H2"2 --* 2(H*) [6] the rate equation would be v = k(H2*2) [7] Assuming [5] is in equilibrium…”

Section: Discussionmentioning

confidence: 99%

mentioning

confidence: 99%

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The Kinetics of LPCVD Tungsten Deposition in a Single Wafer Reactor

McConica

Krishnamani

1986

J. Electrochem. Soc.

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“…Crowell [28] assumed a two-band model for the semiconductor and verified theoretically that minimum and maximum penetration occur in states located at the midgap and near the valence band edge, respectively. Quasi-self-consistent calculations were also developed to determine the junction electrostatics in metal (silicide)silicon interfaces [29].…”

mentioning

confidence: 99%

“…The physical mechanisms determining the transport of carriers in such structures are also not fully understood. In W-Si contacts formed by low-pressure chemical vapor deposition (LPCVD) [29] and in atomically clean Al-GaAs interfaces fabricated by MBE [30], there is no provision for an interfacial material. Even in such nearly ideal junctions, Schottky-barrier lowering is significant.…”

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confidence: 99%

Current transport mechanisms in atomically abrupt metal-semiconductor interfaces

Shenai

Dutton

1988

IEEE Trans. Electron Devices

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A comprehensive model for electron transport mechanisms across a fully formed Schottky-barrier junction is proposed in which the metal-semiconductor interface is approximated as a n abrupt quantum mechanical transition. Improved formulations of the barrier lowering mechanisms and carrier tunneling effects are derived where the dipole barrier lowering is modeled as a single exponential decay of the total surface charge density. Quantum calculations follow a twoband model in which the imaginary component of the electron wave vector in the semiconductor energy gap is obtained by including the effect of both conduction and valence states. The energy band profile effects are included in the calculation of tunneling current, and it is shown that the finite negative charge residing a t the metal-semiconductor interface considerably modulates the tunneling transmission probability of carriers. , Experimental results obtained from atomically clean AI-n'GaAs-nGaAs interfaces fabricated by in situ molecular-beam epitaxy (MBE) are shown to be in excellent agreement with the new transport calculations. In these devices, field-enhanced emission of electrons is observed where the interface electric field is accurately controlled by depositing very thin heavily Si-doped GaAs interfacial layers in a n ultrahigh vacuum environment of the MBE system. Extensive characterization of a number of devices over the temperature range from 77 to 423 K is performed, and the results indicate near-ideal behavior of these interfaces for temperatures above 100 K. At lower temperatures, a degradation in the diode ideality factor results from excessive tunneling currents.

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Metal–Semiconductor Devices

1986

VLSI Electronics Microstructure Science

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Accurate barrier modeling of metal and silicide contacts

Cited by 14 publications

References 10 publications

The Kinetics of LPCVD Tungsten Deposition in a Single Wafer Reactor

The Kinetics of LPCVD Tungsten Deposition in a Single Wafer Reactor

Current transport mechanisms in atomically abrupt metal-semiconductor interfaces

Metal–Semiconductor Devices

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