Method of Producing "Fir-Tree Masks"
Original Publication Date: 1989-May-01
Included in the Prior Art Database: 2005-Jan-28
The described profile etch method, consisting of a combination of wet and dry etch steps, permits producing masks of almost any profile, such as fir-tree profile masks, with accurately controlled dimensions. As a result of the lift-off profile produced by the described method, such a mask can be readily removed after the pad has been vapor deposited. Initially, wet chemical etching, which is carried out from one side only, proceeds uncoupled and in several steps. For this purpose, a thin layer 2, such as a gold foil, is applied as a top layer to the mask material 1. The top layer itself is provided with a photoresist mask 3, the openings of which are selectively etched into the top layer (Fig. 1A). After the first wet chemical etch step (Fig.