Unfilled Contact

Unfilled Contact

Material Name: No data
Record No.: 178
Primary Chemical Element in Material: No data
Sample Type: Wafer
Uses: No data
Etchant Name: None
Etching Method: No data
Etchant (Electrolyte) Composition: No data
Procedure (Condition): No data
Note: Figure 1 shows a SEM photograph of the defect found on the unit with successful FA. The defect was an unfilled contact, with an intact liner. This defect was not found by inline inspection because all contacts are unfilled at the time of the inspection, therefore at that inspection layer, the contact would not have looked defective. Defects such as this help to explain a low OHR, however, continued physical FA efforts are ongoing and will be needed to improve the OHR. Because the OHR is a direct measure of inline inspection capability and thus the short loop yield enhancement capability, it is perhaps the single most important result from the logic mapping process.
Reference: Brady R. Benware, Driving Baseline Yields on ASICs using Logic Mapping, ISTFA 2002, Proceedings of the 28th International Symposium for Testing and Failure Analysis, 3-7 November 2002, Phoenix Civic Center, Phoenix, Arizona, pp. 579-586.

Figure 1: SEM picture of an un-filled contact defect obtained through PFA.