Acceptance of Sub Resolution Assist Feature (SRAF) has been widely recognized in lithography patterning. In general,
with the insertion of SRAF in optically adjacent space area of design main feature, the aerial image intensity profiles of
the corresponding main features are apparently being either constructively or destructively alternated at imaging plane
[Figure 1]. From lithography patterning perspective, the optimized or better pattern imaging process requires
constructive SRAF. Such SRAF is inserted into available space for main feature to obtain optimal or better image
contrast, better imaging resolution and depth of focus (DOF) which is similar or close to optimal focus latitude.
However, the complementary destructive SRAF insertion can adversely occur in certain circumstances. In this paper, we
study the theoretical understanding of the constructive and destructive effects against design main features imaging
associated with the efforts to include SRAF (it's either driven by rule, model or mishap). In addition, an evaluation
scheme is developed and being explored in many aspects in order to describe the constructive and destructive response of
inserted SRAF. Such evaluation scheme has derived an application to detect the degree of SRAF insertion coverage
accuracy, impact on manufacturing, and most usefully, to access potential layout required optimization in design space
based on these complementary effects mechanism throughout several off-axis illumination conditions.