New classification method: Use optical inspection tool to establish haze library

As the medium of linking pattern design and wafer, reticle plays a crucial role in semiconductor manufacturing process. The pattern on the reticle will be transferred to wafer after scanner exposure, which makes the cleanness of reticle directly affect wafer yield. Defect appears when energy accumulates to a certain limit in the case of continuous exposure due to the environment, manufacturing process and material properties of the mask, which is collectively called Haze. Currently, how to identify and prevent haze is regarded as the most major difficulty in the industry.Corresponding actions are required regarding to different forms of haze for effective prevention. For example, MoO haze only occurs on MoSi reticle, where Mo ions migrate to the surface of the reticle under the effect of energy and combine with oxygen in the air to form the haze [1]. To this end, the prevention of the migration of Mo ions is required to reduce the occurrence of such haze. However, the premise of distinguishing the type of haze need to carry out many destructive experimental analysis, which not only brings extensive costs, but also elongates the prevention cycle. Herein, CXMT defines haze compounds and establishes the haze library based the cycle map of haze prevention. Specifically, we analyzed the haze in the aspects of haze distribution map, inspection image grey scale, size, compound composition. At the first, haze is preliminarily classified through the difference of the haze gray scale and the analysis of the haze size by the Reticle Analyzer system. Then we further probe its chemical elements to clarify the composition of different type haze and establish a complete haze library. This discovery allows us to classify the haze of different compounds with the reticle detection device TERON SL670^TM. When hazes with the same characteristics as the haze in the library appear, they can be classified without destructive experimental analysis and prevention actions to achieve the timely and effective control of the haze. In CXMT haze library, four types of haze are clearly defined, and the corresponding prevention has also achieved remarkable results, extending the lifetime of the reticle by two times