Nitrogen Enhanced Selectivity of Debris (Carbon-Rich Material) Versus Polyimide
Original Publication Date: 1987-Dec-01
Included in the Prior Art Database: 2005-Feb-02
The introduction of nitrogen to a plasma etching environment increases the selectivity of the etching process. The method is described in the following. An excimer laser is used to etch vias and lands on a metallized ceramic polyimide (MCP) surface. The laser beam is patterned through a mask and ablates the polyimide in the desired areas. The ablated material is removed to the polyimide surface, as shown in the drawing. The debris is a carbon-rich substance. A pure oxygen (O2) plasma removes the debris with high selectivity. Selectivity (S) is defined as S = etch rate of debris/etch rate of polyimide. This implies that the etching mechanism of the debris is more strongly oxygen dependent than the etching of the polyimide. Although the selectivity in a pure oxygen plasma is high, the actual etch rate of the debris is slow.