High-aspect-ratio deep Si etching of micro/nano scale features with SF6/H2/O2 plasma, in a low plasma density reactive ion etching system

Using three gasese of SF6, O-2 and H-2, deep vertical etching of silicon substrates in a low plasma density environment is reported. A reactive ion etching (RIE) unit with an operating frequency of 13.56 MHz has been used with plasma power densities below 1 W/cm(2). The vertical etching process is based on a sequential method with two sub-sequenes, etching and passivation. High etch rates of the order of 0.7 to 1.5 mu m/min for deep sub -micrometer features, and aspect ratios about 100 for nano-rods have been achieved.