UPC researchers have discovered a technique to produce cheaper and more flexible multiple thin crystalline silicon wafers

A silicon sample after being removed from the cylinder.

Reduced costs for industry

A team of researchers from the Nanoengineering Research Centre (CRNE) and the Department of Electronic Engineering at the Universitat Politècnica de Catalunya · Barcelona Tech (UPCn has found a way to make the manufacture of crystalline silicon materials faster and more affordable. The results of their research have recently been published in the online version of the landmark journal Applied Physics Letters.

Thin crystalline silicon wafers measuring around 10 µm (micres) are costly but also very sought after in the field of microelectronics, especially in view of the growing demand for 3D circuit integration with microchips. Silicon wafers also have potential photovoltaic applications in the medium term in the conversion of sunlight to electricity and the production of more affordable, more flexible and lighter solar cells.

In recent years, techniques have been developed to obtain increasingly thinner crystalline silicon wafers from monocrystalline cylindrical ingots. Layers cut from the ingots using a multithreaded saw impregnated with abrasive material have a minimum thickness of around 150 µm. Obtaining wafers that are any thinner is more complicated, as existing methods only allow such wafers to be obtained one at a time. Furthermore, 50% of the silicon is lost in the process.

The technology developed by the research team – David Hernández, Trifon Trifonov and Moisés Garín, led by Professor Ramon Alcubilla – enables a large number of crystalline layers, controlled for thickness, to be produced from a single crystalline silicon wafer in just a single step. The outcome is a kind of crystalline silicon “millefeuille” produced more efficiently, more rapidly and more affordably than by existing methods.

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