In this work, the adhesion of CVD dielectric caps to ULK MSQ spin-on
dielectric materials with k values of 2.2 and 2.0, and a ULK CVD material
with a k value of 2.7 is presented. A substantial improvement in cap
adhesion to both the k2.2 ULK MSQ and the k2.7 ULK CVD material is
demonstrated. The improvement is obtained using a low-k CVD glue material
between the ULK dielectric and the subsequent cap material and/or by
optimizing the CVD cap film deposition. Four-point bend measurement of
adhesion strength is used to quantify the improvement in interface adhesion.
The improvement in CVD cap adhesion is demonstrated to be strongly dependent
upon both the glue layer film and the cap deposition conditions. While
optimization of the CVD cap materials results in adequate adhesion for the
k2.2 ULK MSQ, these improvements are demonstrated not to extend to the k2.0
ULK MSQ film.