| 摘要 |
<p>A double metal contact structure comprising two layers of metal interconnects (14, 20) is formed by planarizing the first metal layer, using a planarizing dielectric material (26) between the contacts. A first dielectric layer (28), which serves as an etch stop, is formed over the planarized surface. A second dielectric layer (30) is formed over the etch stop layer. The second metal layer is formed by first etching contact holes (10) down through the two dielectric layers, employing a two-step etch process that is first selective to the second dielectric layer and then is selective to the first dielectric layer, thereby stopping at the top surface of the first metal layer. The process of the invention avoids gouging problems experienced with prior art approaches, with consequent shorting of upper metal layers to buried structures (18) and permits closer placement of contact structures (20a) than permitted by prior art processes.</p> |
