Zhenjiang Cui

Effects of UV cure on glass structure and fracture properties of nanoporous carbon-doped oxide thin films

The effects of UV radiation curing on the glass structure and fracture properties were examined for a class of nanoporous organosilicate low dielectric constant films. A detailed characterization by nuclear magnetic resonance spectroscopy and Fourier transform infrared spectroscopy showed significant changes in the glass structure with increasing curing time, marked by the removal of terminal organic groups and increased network-forming bonds following the initial removal of porogen material. The higher degree of film connectivity brought about by an increased cure duration is demonstrated to significantly enhance adhesive fracture properties and to moderately improve cohesive fracture resistance. Explanations for the enhanced fracture behavior are considered in terms of the glass structure. The important role of crack path selection during adhesive and cohesive fracture processes is used to rationalize the observed behavior.

A sample preparation method for four point bend adhesion studies

A method to prepare samples for four point bend testing is reported in this paper. The traditional method of sample preparation involves time-consuming steps of sawing with a diamond saw followed by polishing with fine grit to remove the roughness of the sidewall. The new method uses cleaving along the (100) crystallographic direction, which renders smooth surfaces and eliminates the polishing steps. Load-displacement curves comparing polished versus cleaved samples show that the new technique provides improved results. Elimination of fracture-inducing defects is the primary benefit of this method, which also leads to data with tighter distributions.

Benchmarking Four Point Bend Adhesion Testing: The Effect of Test Parameters On Adhesion Energy

The four‐point bend test method has been widely used to quantify the adhesion energy of interfaces in multilayer thin film stacks. However, the adhesion energy of an interface (Gc) may be effected by variances in the specimen preparation method and test procedure. In the present study, a less time consuming method of specimen preparation that involved cleaving (DPN‐free method) rather than dicing of specimen was found to offer a 90% test success rate with high accuracy and repeatability. The epoxy curing temperature and time were minor factors affecting Gc and their effect was within the test standard deviation of 0.3 J/m2. For a higher Gc interface, the epoxy thickness was found to result in a 20% increase in measured Gc as the bond layer was increased from 7 to 50 μm. The measured value of Gc also increased by 20% as the displacement rate was increased from 0.05 μm/s to 0.5 μm/s. The notch or scribe used to initiate the crack was found in one stack structure to have an effect on the interface that debonded. The delamination interface can be modulated through control of the notching step during sample preparation.

Novel Hardmask for Sub-20nm Copper/Low K Backend Dual Damascene Integration

As device nodes move below 20nm and increasing concerns for low k damage during plasma etch, alternative metal hardmask (HM) schemes have gained tractions for back-end-of-line (BEOL) integration. Conventional TiN hardmask has been in high volume manufacturing since the 90nm technology node, however, TiN faces many challenges, such as defectivity, line bending, and manufacturing robustness, which can only be overcome at the expense of shrinking the overall process window. A novel boron nitride (BN) based HM material was developed using a conventional CVD approach to address these issues.

Reliability of dielectric barriers in copper damascene applications

The film properties of two PECVD deposited dielectric copper barrier films have been optimized to improve BEOL device reliability in terms of electromigration. Two critical aspects that affect electromigration are the dielectric barrier film hermeticity and adhesion to copper. We use a method to quantify the barrier film hermeticity of the BLO/spl kappa/ I low-/spl kappa/ dielectric film to be similar to that of silicon nitride. In addition, the interfaces between damascene nitride with copper, as well as BLO/spl kappa/ I with copper have been engineered to improve the interfacial adhesion energy to >10 J/m/sup 2/ for both damascene nitride and BLO/spl kappa/ I.

Reliability of Dielectric Barrier Films in Copper Damascene Applications

The film properties of two PECVD deposited dielectric copper barrier films have been optimized to improve BEOL device reliability in terms of electromigration. Two critical aspects that affect electromigration are the dielectric barrier film hermeticity and adhesion to copper. We use a method to quantify the barrier film hermeticity and have optimized the hermeticity of the BLOκ™ low-κ dielectric barrier film to be similar to that of silicon nitride. By using FT-IR we find that the film porosity has a much stronger effect than the film stoichiometry on hermeticity. In addition, the interfaces between Damascene Nitride™ with copper, as well as BLOκ with copper have been engineered to improve the interfacial adhesion energy to >10 J/m2 for both Damascene Nitride and BLOκ.