Ultra thin crystalline silicon wafers created more cheaply
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A team of researchers from the Nanoengineering Research Centre (CRNE) and the Department of Electronic Engineering at the Universitat Politècnica de Catalunya • BarcelonaTech (UPCn) has found a way to make the manufacture of crystalline silicon materials faster and more affordable.
Crystalline silicon wafers with a thickness of around 10µm are costly, but in great demand because of growing interest in 3d integration and the development of more flexible and lighter solar cells.
The technology developed by the research team enables a large number of crystalline layers, controlled for thickness, to be produced from a single crystalline silicon wafer in one step. The outcome, says the team, is a kind of crystalline silicon 'millefeuille' produced more efficiently, more rapidly and more affordably than by existing methods.
The approach is based on making small pores in the material and applying high temperature during the manufacturing process. Multiple separate crystalline silicon wafers are obtained by carefully controlling the pore profiles. Precise control of pore diameter controls both the number of layers and their thickness. The 'millefeuille' silicon layers are then separated by exfoliation.
The number of silicon layers is determined by the thickness of the layers themselves and by the initial thickness of the wafer. According to CRnE, researchers have created 10 wafers with thickness ranging from 5 to 7µm from a 300µm thick wafer.
