The formation, imaging, and application of thin silicon-dioxide membrane

We have successfully formed and separated a very thin silicon-dioxide (SiO2) film with a thickness of approx. 1 nm. The thin SiO2 film was chemically grown on Si using a wet chemical treatment which is commonly used in semiconductor manufacturing. Highly selective etching of the underlying Si, through the native oxide, can be achieved using chlorine (Cl2) gas. Such a unique phenomenon allows the formation and separation of native oxide from the Si surface. The native oxide film, which is suspended at its edges by thick-SiO2, remains at the original level of the Si surface even after etching. The suspended Si-native oxide membrane is imaged using scanning electron microscopy (SEM). It is presumably the thinnest separated film ever recorded. The ∼1-nm-thickness SiO2 membrane suspended by thick-SiO2 can support subsequent film deposition. The sequential processes of native oxide formation on patterned Si, etching the Si by Cl2 through the native oxide, and film deposition onto the native oxide membrane, can make a cavity in the solid-state substrate. This novel technique of creating a cavity by using a membrane of Si-native oxide can be applied to fabricate 3D micro-systems like pipes, diaphragms, tubes, and wave-guides on the solid-state circuits.