Dry etching properties of boron carbon nitride (BCN) films using carbon fluoride gas

Boron carbon nitride (BCN) films are attractive as a low-K material for the next generation devices. Patterning of BCN Films is required for interconnection integration. This study examines dry etching of a BCN film as a method of developing interconnections for future devices. Dry etching performance of BCN films with various carbon composition ratios (13%-30%) is investigated and a mechanism for dry etching is suggested. A BCN film (20% carbon) is etched using CF4 gas with an estimated etching rate of 150 nm/min. This etching rate is sufficient for LS1 manufacturing. The etching rate of BCN films decreased with increasing carbon composition ratio. It is observed that B-N and B-C bonds decrease in number and the peak of XPS signals from the Bls and Nls core levels shift to high energy. This suggests that the etching of BCN films mainly involves boron desorption. The following reaction may occur: B+CF4 -> BF3 up arrow + CFx (polymer). The CFx polymer can be easily removed by water-based chemical cleaning. We have Succeeded in patterning BCN films by dry etching using CF4 gas. In addition, we suggest a mechanism for etching of BCN films. (C) 2008 Elsevier B.V. All rights reserved.