| Popis: |
More sophisticated corrections of overlay error are required because of the challenge caused by technology scaling faster than fundamental tool improvements. Starting at the 45 nm node, the gap between the matchedmachine- overlay error (MMO) and technology requirement has decreased to the point where additional overlay correction methods are needed. This paper focuses on the steps we have taken to enable GridMapperTM, which is offered by ASML, as a method to reduce overlay error. The paper reviews the basic challenges of overlay error and previous standard correction practices. It then describes implementation of GridMapper into IBM's 300 mm fabrication facility. This paper also describes the challenges we faced and the improvements in overlay control observed with the use of this technique. Specifically, this paper will illustrate several improvements: 1. Minimization of non-linear grid signature differences between tools 2. Optimization of overlay corrections across all fields 3. Decreased grid errors, even on levels not using GridMapper 4. Maintenance of the grid for the lifetime of a product 5. Effectiveness in manufacturing - cycle time, automated corrections for tool grid signature changes and overlay performance similar to dedicated chuck performance |
