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Back plate electroplating for high aspect ratio processes

Simone Luigi Marasso (Dipartimento di Scienza Applicata e Tecnologia, Politecnico di Torino , Torino, Italy, and CNR-IMEM, Parma, Italy)
Simone Benetto (Dipartimento di Scienza Applicata e Tecnologia, Politecnico di Torino , Torino, Italy)
Isabella Para (Dipartimento di Scienza Applicata e Tecnologia, Politecnico di Torino , Torino, Italy)
Chiara Ottone (Dipartimento di Scienza Applicata e Tecnologia, Politecnico di Torino , Torino, Italy)
Domenico Mombello (Dipartimento di Scienza Applicata e Tecnologia, Politecnico di Torino , Torino, Italy)
Denis Perrone ( Istituto Italiano di Tecnologia , Torino, Italy)
Sergio Ferrero (Dipartimento di Scienza Applicata e Tecnologia, Politecnico di Torino , Torino, Italy)
Luciano Scaltrito (Dipartimento di Scienza Applicata e Tecnologia, Politecnico di Torino , Torino, Italy)
Diego Pugliese (Dipartimento di Scienza Applicata e Tecnologia, Politecnico di Torino , Torino, Italy)
Matteo Cocuzza (Dipartimento di Scienza Applicata e Tecnologia, Politecnico di Torino , Torino, Italy and CNR-IMEM, Parma, Italy and Istituto Italiano di Tecnologia , Torino, Italy)
Fabrizio Candido Pirri (Dipartimento di Scienza Applicata e Tecnologia, Politecnico di Torino , Torino, Italy)

Microelectronics International

ISSN: 1356-5362

Article publication date: 2 May 2017

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Abstract

Purpose

In this process the electrical contact is brought to the backside of a standard silicon wafer. The details of the entire process are disclosed, from the photolithography processes to the electrodepositing step, and a model for electrical contact was designed.

Design/methodology/approach

The localized Cu growth of high aspect ratio (AR) microstructures was obtained through an SU-8 photolithography by exploiting the optimal adhesion on the silicon surface and the possibility of generating thick layers with a single spun process

Findings

The experimental results showed an unexpected behaviour that is theoretically explained in detail considering the energy band theory. The obtained geometries showed a remarkable 6:1 AR without any adhesion problem. The non-invasive front-side manipulation represents a noteworthy improvement and simplification for the design of a multi-step production process.

Originality/value

An alternative technological approach, called back plate electroplating, has been carried out to obtain Cu growth on the front side of a standard n-type Si wafer through a back side electrical contact. This technique was then applied to fabricate a master for hot-embossing in a LIGA (Lithographie, Galvanoformung, Abformung)-like process flow. For this purpose, an SU-8 thick mask on a standard n-doped wafer was used. Finally, by using this process, it was possible to obtain high AR Cu geometries, avoiding any complex designing and patterning of the contacts on the front side and thus ensuring good adhesion of the SU-8.

Keywords

Citation

Marasso, S.L., Benetto, S., Para, I., Ottone, C., Mombello, D., Perrone, D., Ferrero, S., Scaltrito, L., Pugliese, D., Cocuzza, M. and Pirri, F.C. (2017), "Back plate electroplating for high aspect ratio processes", Microelectronics International, Vol. 34 No. 2, pp. 69-74. https://doi.org/10.1108/MI-03-2016-0024

Publisher

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Emerald Publishing Limited

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