Methods of Forming Small Contact Holes
Original Publication Date: 1988-Jan-01
Included in the Prior Art Database: 2005-Feb-14
Processing to form via holes in an insulator having dimensions smaller than can be resolved with present lithography is described. A first process creates holes having 60-degree walls, and a second process results in steep-walled holes. Referring to Fig. 1, a hole of minimum size is formed in material 6 by a photo-etching process which does not attack insulating layer 2 on substrate 4. In process (a), for forming sloped walled holes in insulating layer 2, a layer 8 is conformally deposited on the material 6 sufficiently thick to nearly fill the hole in material 8, as shown in Fig. 2. For process (a), material 8 is ion etched by a process characterized by a high degree of sputter removal, i.e., the material is removed at a maximum rate when ions impinge at some angle other than normal to the material surface, e.g., 60 degrees.