Radius of curvature considerations for direct wafer bonding

A study of the bondability of silicon samples that deviate from the ideal f latness (radius of curvature, R, greater 100 m) of industrial standard wafe rs is the major objective of this work. A theoretical model is developed to predict the force required to conform two silicon samples and the resultan t radius of curvature of the pair; this model is based on the elastic defor mation of thin plates. Experimental verification of this model is also exam ined. Silicon samples with a radius of curvatures as small as 15 m are used . These large deflections of the silicon samples are created by deposition of plasma enhanced chemical vapor deposition (PECVD) nitride film. Utilizin g a NH3 plasma surface treatment prelude to bonding and a 300 degrees C pre ssure anneal for 1h, conformal silicon samples wen formed.