Method of Contacting Conductors Through Contact Holes
Original Publication Date: 1989-Mar-01
Included in the Prior Art Database: 2005-Jan-27
If a contact hole H to an underlying electrically conductive layer, a conductor L1, is etched in a semiconductor process, as shown in Fig. 1A, this conductor usually serves as an etch stop. This works only if contact hole H rests on conductor L1 without protruding from its edge. Otherwise, etching continues beyond that edge and neighboring structures are damaged. To avoid this, conductor L1 should overlap contact hole H such that if the contact hole and conductor are misaligned, the contact hole does not touch the conductor edge. The required overlap a (alignment tolerance) corresponds to the permissible misalignment (not considering dimensional tolerances of the contact hole and the conductor for simplicity). The structure of Fig. 1A has the disadvantage that conductor L1 is widened at the position of contact hole H.