Semiconductive device having a self-aligned contact and landing pad structure and method of making same

摘要

An integrated circuit and a method of forming the same comprises a semiconductor substrate with a field oxide region 90 and a spaced active region. A self-aligned window and contact is associated with each of the said regions. A first "dummy" polysilicon landing pad 130 is formed over the field oxide region 90 and below the self-aligned window 131 and a second "operative" polysilicon landing pad 132 is located above the first polysilicon pad 130. A silicon nitride barrier layer 105b may be formed during the process. Self-aligned windows 131, 140 may be defined and formed simultaneously to provide contacts to the second polysilicon landing pad 132 of a floating gate arrangement and the silicon substrate using a single resist and etch process. The etch process may comprise a number of steps involving a first etch step with low oxide/nitride selectivity, a second etch step with high oxide/nitride selectivity and a third etch step with high nitride/oxide selectivity.