Hydrogenated amorphous carbon (a-C:H) nanotips have been successfully grown on Cu/Ti/Sis(100) by microwave plasmaenhanced chemical vapor deposition. A Cu etching process occurs simultaneously during the growth of the a- C: H nanotips. Both the Cu etching and a- C: H nanotips growth rates continuously increase with time. In the beginning, the Cu etching rate is approximately 3 nm/min and the upward growth rate of the a-C:H nanotips is approximately 1.2 nm/min. At the end of the growth, the Cu etching rate reaches 9 nm/min and the upward growth rate of the a-C:H nanotips reaches 5 nm/min. An etching-growth mechanism has been proposed to explain the formation of a-C:H nanotips on Cu/Ti/Si(100). The structure of the a-C:H nanotips exhibits very good field-emission characteristics where a low turn-on field of 3.2 V/μ m at 10 μ A/cm(2) is achieved. © 2005 The Electrochemical Society. All rights reserved.