Investigation of intermittent haze in 300mm SiGe epitaxy process and its impact on PMOS device performance

One big challenge of epitaxy growth SiGe process is defect control. Many factors have impacts on SiGe film property, such as surface oxide remaining, surface damage of Si substrate post dry etch or wet etch, impurity of chamber ambient and etc. In this work, a special intermittent crater-like "haze" was discussed for surface characterization. It was found that haze happened intermittently and most likely tends to occur after tool idle over twenty hours. Furthermore the haze intensity trend down company with wafer seasoning. As a consequential result, the CMOS devices processed SiGe-epi under intermittent haze condition would result in performance degradation especially for junction leakage. Some countermeasures (or suggested solutions) to suppress this intermittent haze are proposed.