METHOD AND SYSTEM FOR VIA RETARGETING

摘要

Embodiments of the present invention provide a system and method for SAV (self-aligned via) retargeting. The SAV (Self Aligned Vias) process aids in the alignment of the vias with the metal above (Mx+1) during the dual damascene process. The retargeting enables an increase the area of the via during photolithography without affecting the final critical dimension. SAV retargeting is the via retargeting during the mask tape-out to reshape the via and protect it against possible via-to-Mx+1 overlay error. With embodiments of the present invention, the via edge movement is linked to the actual driver behind the SAV retargeting, which is maintaining a minimum area coverage with the metal above at extreme overlay error conditions. Accordingly, for a via edge to get SAV retargeted, a calculation is first made to determine how much its opposite via edge is subject to be cut during SAV due to overlay error.

主权项

1. A method of retargeting a self-aligned via having a plurality of edges, comprising:
a) selecting a first edge of the via; b) obtaining a maximum bias value for the via; c) obtaining a via width; d) using a computer to compute a distance from the first edge to an opposite parallel Mx+1 edge; e) expanding the first edge of the via outward by an amount of the maximum bias value plus the via width minus the distance from the first edge to an opposite parallel Mx+1 edge in response to determining that the distance from the first edge to an opposite parallel Mx+1 edge is greater than the via width plus the maximum bias value; and f) repeating steps d) and e) for each additional edge of the plurality of edges.