Controlling corrosion, particles in metal etch-and-strip cluster tool systems

Shams Tabrez, Changhun Lee, David Yang, and Yun-Yen "Jack" Yang, Many benefits can be derived from integrating two metal etch and two strip process modules on a single platform. For example, an increase in throughput per square foot of floor space is an important advantage because of the spiraling costs of new fab construction. Clustering serial processes reduces cycle time and the number of stations that operators have to supply with wafers. Cluster tools also provide ways to reduce particulate and molecular contamination and lower defectivity at both the chamber and system levels. Finally, on metal etch systems, clusters lessen the risk of corrosion from residual chlorine, since wafers are moved between etch and strip processes under continuous vacuum without exposure to moisture in ambient air. To obtain all the benefits of integrated serial processing, additional burdens are placed on the strip module design. For the etch module to operate continuously, the combined strip cycle and wafer transport time must be shorter than the time it takes to etch a wafer. This means the stripper must be fast and efficient so the highest possible level of system throughput can be achieved. Figure 1: Serial metal etch-and-strip system on a cluster platform. This article examines design considerations that permit an integrated serial etch-and-strip system to maintain high throughput and productivity while still guaranteeing a particle- and corrosion-free product. Particle and corrosion control findings will be presented that apply to both the process chamber and the integrated system. For reference, a serial metal etch-and-strip system, the TCP 9600PTX 2 x 2 with two metal etch process modules and two strip modules on an Alliance cluster platform (all made by Lam Research, Fremont, CA), is shown in Figure 1. Cluster systems implement particle control at both the process module and system levels. Generally, clusters