Investigation of critical dimension (CD) variation control on unstable substrate
With the development of the semiconductor devices, advanced technology node requires both tight critical dimension (CD) control and enough photo process window. In many circumstances, the unstable substrate can have great influence on photo CD, causing large variation in the performance of device. Although there have been intensive studies on this topic, we attempt to discuss the physical mechanism underneath within this paper, and to illustrate the phenomenon observed in the function layers. This paper is to investigate the contributions of several different factors on photo CD variation and discuss the possible controlling methods. Different substrate deposition methods and various surface treatment methods are applied in our experiment and the corresponding influence on CD variations are investigated. Results indicate that the surface treatments play important roles in controlling CD variation. The underlying mechanism is discussed.