All-Electrochemical Synthesis of Submicrometer Cu Structures on Electrochemically Machined p-Si Substrates

Abstract

A maskless all-electrochemical method for the deposition of micro-and nanoscale Cu structures on p-Si is reported. The first step involves the electrochemical machining of p-type Si in HF by applying nanosecond voltage pulses between a tool and a Si electrode. This process generates a localized defect structure, which is successively utilized to achieve selective metal electrodeposition. The resolution of the process is limited mainly by the tool dimensions and by the time constants involved in electrochemical machining, which lead to a limited spread of the defect region on the Si surface. Copper isolated islands with 500 nm diameter have been grown by electrodeposition, with high selectivity. This process has the potential to become a preferred technique for the placement and growth of submicrometer metal islands on semiconductor surfaces.

Electrochemical Microstructuring with Short Voltage Pulses

“…As a consequence for the machining of stainless steel, highly corrosive electrolytes like HCl/HF mixtures have to be applied, thus keeping the passivation layer presumably very thin due to chemical etching. [23,24] Similarly, the machining of highly doped silicon is possible in the presence of HF, which dissolves silicon oxides formed during the electrochemical reaction. [23,24] In cases of transpassive dissolution in the presence of a thick oxide layer, for example, upon machining stainless steel in H 2 SO 4 , the application of short pulses does not suffice to confine electrochemical reactions and additional means, such as partial insulation of the electrodes, have to be applied for local confinement of the electrode reactions.…”

“…[23,24] Similarly, the machining of highly doped silicon is possible in the presence of HF, which dissolves silicon oxides formed during the electrochemical reaction. [23,24] In cases of transpassive dissolution in the presence of a thick oxide layer, for example, upon machining stainless steel in H 2 SO 4 , the application of short pulses does not suffice to confine electrochemical reactions and additional means, such as partial insulation of the electrodes, have to be applied for local confinement of the electrode reactions. [25] Electrochemical microstructuring with short voltage pulses is not restricted to local metal dissolution.…”

A potential method for electrochemical micromachining of titanium alloy Ti6Al4V

“…Recently, two new approaches for bulk micromachining of metals were proposed. One was ultrashort voltage pulses electrochemical machining reported by Schuster et al [23][24][25][26]. The other was anisotropic reactive ion etching with oxidation (ARIO) reported by Aimi et al [27].…”

Inducing and Imaging Localized Passivity Breakdown in Aluminum Using an AFM Approach

“…This technique has been used to conduct localized dissolution of metals in aqueous electrolytes at submicron spatial resolution (2,3). The same approach can be used to conduct local deposition (4,5). Localization of the interfacial potential drop at the working electrode:electrolyte interface required for the reduction/oxidation reaction is produced by matching the time the potential is applied to the time required for development of the local potential.…”