Historically, electronics was the first discipline that exploited the properties of porous silicon (PSi) in the 1970’s [1]. Two decades later, a huge development of the studies about PSi has been observed since an efficient photoluminescence of this material was discovered. During this fruitful period, microelectronic devices also benefited from the progresses made in the domain of semiconductor electrochemical etching and from the comprehension of the unique properties of PSi. In particular, it was found that radio-frequency (RF) devices can took advantages of the isolating properties of PSi [2]. Indeed, highly resistive substrates are generally required to reduce eddy currents and capacitive couplings and then, to get high performance passive devices. The insulating properties of PSi, combined with the ability to locate these areas in different resistivity wafers, make this material promising in terms of development of monolithic insulator/semiconductor substrates [3]. In this presentation, we will present the recent advances that have been performed in GREMAN in the field of RF devices that integrate PSi. A specific emphasis will be put on thin and free-standing PSi membranes and 3D structures for high current density applications. In addition, we will describe the way PSi could be used as insulating material in power AC Switch. Many architectures involving PSi peripheries can lead to subsequent performance and reliability improvements [4, 5, 6]. In particular, by forming a relatively thick PS layer in a TRIAC periphery, low leakage currents (<10 μA) have been demonstrated up to a few hundred volts for both bias signs.

We will demonstrate that, at present, there is no doubt about benefits PSi can bring to microelectronic devices. Many other applications that require a silicon substrate such as integrated sensors [7], solar cells [8], conductive via [9] or energy micro-sources [10, 11] can also be of great interest for the microelectronics industry. For instance, we will show in details that porous silicon could also be useful for acoustic transducers as an integrated backing material in order to enhance the imaging quality.

Nevertheless, until now, PSi is not widely introduced in electronic component manufacturing. This point will also be discussed. References

[1] Watanabe Y., Arita Y., Yokohama T., and Igarashi Y. (1975) Formation and properties of porous silicon and its application. J. Electrochem. Soc. 122, 1351-1355.

[2] Yu M., Chan Y., Laih L., and Hong J. (2000) Improved microwave performance of spiral inductors on Si Substrates by chemically anodizing a porous silicon layer. Microw. Opt. Techn. Lett. 26, 232-234.

[3] Capelle M., Billoué J., Concord J., Poveda P., and Gautier G. (2014) Monolithic integration of common noise filter with ESD protection on silicon/porous silicon hybrid substrate, Appl. Phys. Lett. 104, 072104-1-4.

[4] Menard S., Gautier G., High-voltage vertical power component, US Patent 20,130,320,395.

[5] Menard S., Hague Y., Gautier G., Vertical Power Component, US Patent 20,130, 228, 822.

[6] Lu B., Ménard S., Morillon B., Alquier D. and Gautier G. (2018) IEEE Trans. on Electron Devices 65, 655-659.

[7] Barillaro, G., Bruschi, P., Lazzerini, G. M., & Strambini, L. M. (2010). Validation of the compatibility between a porous silicon-based gas sensor technology and standard microelectronic process. IEEE Sens. J., 10(4), 893-899.

[8] Tobail, O., Reuter, M., Eisele, S., & Werner, J. H. (2009). Novel separation process for free-standing silicon thin-films. Sol. Energy Mater. Sol. Cells, 93(6), 710-712.

[9] Defforge T., Billoué J., Diatta M., Tran Van F., and Gautier G. (2012) Copper selective electrochemical filling of macroporous arrays for through silicon via applications, Nanoscale Res. Lett. 7, 735-742.

[10] Haddad R., Thery J., Gauthier-Manuel B., Elouarzaki K., Holzinger M., Le Goff A., Gautier G., El Mansouri J., Martinent A., and Cosnier S. (2105) High performance miniature glucose/O2 fuel cells based on porous silicon anion exchange membranes, Electrochem. Comm. 54, 10-13.

[11] Westover A. S., Freudiger D., Gani Z. S., Share K., Oakes L., Carter R. E., and Pint C. L. (2015) On-chip high power porous silicon lithium ion batteries with stable capacity over 10000 cycles, Nanoscale 7(1), 98-103.