Fabrication of Via Holes With Adjustable Sidewall Slopes in Thick Insulating Layers
Original Publication Date: 1984-Jun-01
Included in the Prior Art Database: 2005-Feb-04
The present system deals with the problem of fabricating the tapered via holes in the insulating layer which may be glass, polyimide or some other material. Wet chemical approaches have been tried to generate these holes but have largely been unsuccessful due to the isotropic nature of the wet chemical etching and the difficulty in etching some of the constituent materials in the materials as in, for example, glass. The basic apparatus for laser-activated chemical etching is shown in the figure. Provision is made to maintain and control the mask-to- substrate distance accurately over the entire area of the substrate. This distance is in the range of 30 to 300 mm for a 45Œ wall angle slope for a via hole with a nominal 100 mm diameter.