The general concepts governing the electrochemical deposition of metal films onto semiconductors are discussed. Deposition onto semiconductor surfaces is complicated due to the band structure of the semiconductor, which affects both the thermodynamics and the kinetics of metal deposition processes. The influence of the potential distribution at the semiconductor/solution interface on the charge transfer mechanisms involved in deposition of metals is discussed. Models for electrochemical nucleation and growth are described and the influence of the unique physical properties of semiconductors is analysed. Finally, we present recent results for electrochemical deposition of gold, copper and platinum onto n-type silicon.
In semiconductor electrochemistry there is considerable confusion concerning the potential distribution at the semiconductor/solution interface under weak depletion and accumulation conditions. The applied potential is partitioned between the space charge layer in the semiconductor and the Helmholtz layer on the solution side of the interface. Under deep depletion conditions, a change in the applied potential usually appears across the space charge layer and the band bending can be determined using the Mott-Schottky relation. Under conditions of weak depletion or accumulation, however, the applied potential is partitioned between the two double layers and determination of band bending is not straightforward. In this paper, expressions for the dependence of the band bending on the applied potential are derived and the consequences for chargetransfer processes are discussed.
During a typical microelectromechanical systems device fabrication process, a polysilicon top layer has to be polished with a slurry that yields a high polysilicon removal rate (
0.5μm∕min
or more) and a high selectivity over the underlying silicon dioxide and silicon nitride layers
(50:1)
. In this work, polysilicon polish rates as high as
550nm∕min
and selectivity over silicon dioxide and nitride of
∼130
and
∼260
, respectively, have been achieved using colloidal silica and calcined ceria-based slurries containing arginine or lysine mono hydrochloride, at
4psi
down pressure. At
8psi
, polysilicon polish rates close to
900nm∕min
and selectivities over both oxide and nitride that are close to 300 have been achieved. ξ potential, infrared spectroscopy, and contact angle data are used to explain the role of the amino acid additives in achieving the desired removal rate selectivities of polysilicon over silicon dioxide and silicon nitride.
Determination of the band bending in a semiconductor in contact with a solution is not straightforward since the potential is partitioned between the space charge layer in the semiconductor and the Helmholtz layer on the solution side of the interface. In deep depletion, a change in the applied potential usually appears across the space charge layer, however, under conditions of weak depletion or accumulation, the applied potential is partitioned between the two double layers and the band bending is usually unknown. In this article we show how microwave reflectivity measurements can be used to determine the potential distribution at the semiconductor/solution interface.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.