Product Briefing Outline: Lam Research has officially launched its new Coronus plasma-based bevel cleaning system. Designed to reduce yield loss caused by defects that originate near the wafer’s edge, the Coronus system combines the multiple material cleaning capability of plasma with a proprietary confinement technology that protects the die area. Several major semiconductor customers are now moving into production with the Coronus bevel clean system, the company said. 

Problem: The wafer edge, where deposited films terminate and overlap with underlying materials, has been identified as a primary source of defects. The problem is exacerbated as manufacturers seek to reduce edge exclusion in order to increase the die number on the wafer. Although the greatest impact of edge defects is on adjacent die, material from edge defects can damage die at any point on the wafer. Mechanical-, chemical-, and laser-based cleaning methods lack the precise control and universal applicability of plasma cleaning. Initial evaluations of the Coronus system have focused on edge defects in FEOL (front-end of line) processes for STI (shallow trench isolation) and contact formation. Immersion lithography, with its potential for transporting materials from the edge to the active area, and multiple strategies in dual damascene processes in BEOL (back-end of line), are also candidates for significant yield gains from reduced edge defectivity.

Solution: With introduction of the Coronus system, edge defects can now be managed throughout the wafer flow with a single system. The company claims that customers have attributed significant defect reductions to employing the Coronus system for wafer edge cleaning, and that controlling the wafer edge throughout processing will lead to lower defects and higher overall yield, according to the company.

Applications: Wafer edge cleaning in FEOL and BEOL.

Platform: Available in both 200mm and 300mm configurations, the system is built on the production-proven 2300 platform with Dynamic Alignment, which provides a repeatable target cleaning area – wafer-to-wafer and lot-to-lot.

Availability: November 2007 onwards.