KLA-Tencor Instrument Minimizes Wafer Damage Through Patterned Process Tool Monitoring
Integrated circuit (IC) manufacturers may save millions of dollars by using a new instrument called the AIT II from KLA-Tencor Corp. (San Jose, CA). Introduced on Wednesday, November 11, the instrument will help minimize the number of wafers exposed to out-of-control process conditions by helping engineers immediately detect process tool excursions.
An extension of AIT technology from KLA-Tencor, the AIT II is an advanced system for patterned process tool monitoring for 0.18 µm and smaller geometries. The instrument can also bridge to 300-mm wafers. Because the AIT II delivers high throughput, superior sensitivity, and low cost of ownership, it can help support the increased process tool inspection needs of advanced device manufacturing, including demanding chemical mechanical planarization (CMP) and etch applications.
Patterned process tool monitoring, a highly efficient means of monitoring process tool performance, is rapidly being adopted as a complementary approach to line and yield monitoring. This shift in inspection strategies is being driven by the yield challenges resulting from sub-quarter micron device reductions.
Patterned process tool monitors inspect product wafers to determine the status and defect contribution of a particular process tool. These complement both line monitors that inspect product wafers to determine the overall defectivity of an entire process zone, and yield monitors that inspect product wafers from a particular lot throughout the manufacturing cycle and correlate data to yield.
The key capabilities required for patterned process tool monitoring are high throughput to prevent manufacturing bottlenecks, surface selectivity to minimize the detection of defects from previous layers, and a high defect capture rate. These capabilities allow a greater sampling rate, increasing the statistical validity of the defect data. This is critical to the immediate detection of process tool excursions.
The AIT II incorporates KLA-Tencor's production-proven, double-darkfield technology, which combines low-angle illumination with low-angle collection optics. This technology provides superior defect capture by suppressing color variation and grainy background noise, as well as increasing small particle sensitivity and providing surface selectivity to minimize the detection of previous layer defects. In the AIT II, this proven illumination system has been further enhanced with a collection area significantly greater than that of the AIT, resulting in increased defect capture.
The improved collection optics optimize the AIT II for CMP and etch process tool monitoring. At the same time, the system's programmable spatial filters (PSFs) improve defect collection on array structures, while selectable polarization of the illumination beam increase sensitivity by minimizing process noise. The AIT II's ability to vary the die-to-die signal processing threshold and contrast levels for different areas of the device further increases detection sensitivity to particles and pattern defects.
For more information, call 408-875-7039.