A new technique developed by MIT engineers may vastly
The new method, reported today in Nature, uses graphene—single-atom-thin sheets of graphite—as a sort of "copy machine" to transfer intricate crystalline patterns from an underlying semiconductor wafer to a top layer of identical material.
The engineers worked out carefully controlled procedures to place single sheets of graphene onto an expensive wafer. They then grew semiconducting material over the graphene layer. They found that graphene is thin enough to appear electrically invisible, allowing the top layer to see through the graphene to the underlying crystalline wafer, imprinting its patterns without being influenced by the graphene.
Graphene is also rather "slippery" and does not tend to stick to other materials easily, enabling the engineers to simply peel the top semiconducting layer from the wafer after its structures have been imprinted.
Jeehwan Kim, the Class of 1947 Career Development Assistant Professor in the departments of Mechanical Engineering and Materials Science and Engineering, says that in conventional semiconductor manufacturing, the wafer, once its crystalline pattern is transferred, is so strongly bonded to the semiconductor that it is almost impossible to separate without damaging both layers.
"You end up having to sacrifice the wafer—it becomes part of the device," Kim says.
With the group's new technique, Kim says manufacturers can now use graphene as an intermediate layer, allowing them to copy and paste the wafer, separate a copied film from the wafer, and reuse the wafer many times over. In addition to saving on the cost of wafers, Kim says this opens opportunities for exploring more exotic semiconductor materials.
Read more at: https://phys.org/news/2017-04-graphene-machine-cheap-semiconductor-wafers.html#jCp
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