Improvement of Contact Clean using Single-wafer Clean process for90nm and Beyond

摘要

The removal of sub-micron particles is critical and related to the yield and device performance in IC manufacturing.There are several cleaning mechanisms in wet and dry that are currently being practiced in the industry. Wet cleaningusing immersion batch system and multi-functional bath has been the principal form of cleaning in the industry.However, there are some concerns of damage, more etching to sensitive structures and the removal of sub micronparticles without material removal or increase in surface roughness. [1-3] The increasingly demanding requirements of surface preparation processes are driving the industry toward single-waferprocessing, which offers a high degree of process control [4-5]. The semiconductor industry is at the same timerecognizing additional advantages to single-wafer cleaning such as small equipment footprint, short cycle time,increased flexibility, cost-effective use of fresh chemicals, low consumption, good particle removal and precise silicondioxide etching capabilities [6-7]. In this study, we focus on improving the local interconnect contact cleaning process for 90nm device by replacing theprocess of record (POR), which uses hydroxylamine chemical in a batch cleaning tool. As shown in Figure 1, contacts are open to the tungsten gate and the silicon simultaneously. Both contacts need to becleaned to reduce contact resistance and increase yield.