Silicon needles fabricated by highly selective anisotropic dry etching and their field emission current characteristics

A new process to fabricate a silicon needle, whose tip radius is about 5 nm and aspect ratio is about 7, was developed. The silicon needles were fabricated by highly selective anisotropic dry etching. The etching mask was oxygen precipitation, which was formed by nitrogen ion implantation and the subsequent oxidation. The process is simple enough to be integrated with complementary metal-oxide-semiconductor (CMOS) circuits. The density of the silicon needle can be controlled by adjusting the dose for nitrogen ion implantation. The position of the silicon needle can be controlled by adjusting the position for nitrogen ion implantation, because silicon needles are formed only in the nitrogen ion implantation area. Furthermore, using these silicon needles as micro emitters, a field emission diode was fabricated. The Fowler-Nordheim plot shows that the field around the tip of the silicon needles was highly enhanced.