Lithography PR profile improvement and defects reduction by film pre-treatment

Photoresist (PR) profile and defect are very important in semiconductor manufacturing, the abnormal PR profile and defect will cause the following process abnormal even affect the device performance. For example, under-cut PR profile is easy to pattern collapse, while footing will cause the pattern bottom bridge, both of these will cause device hard fail. PR profile is affected by lots of factors, such as bottom reflectivity, PR properties, focus, etc. But an important impacted factor is often ignored, that is the film property contacting PR. If the property of under film does not match with PR, it will affect PR profile seriously, even bring defect issue. So investigating the friendly interface is a meaningful topic. In this paper, we focus on the effect of film treatment on PR profile and defect. Through the experiments, the methods including O₂ treatment, heat treatment, and wet treatment, the friendly methods to lithography are chosen, and the possible mechanism is proposed. The film treatment method provides us a new way to improve defect or PR profile, and further improve the lithography process window.