An investigation of the synthesis and characterization of copper samples for use in interconnect applications

In this study nanostructured (grain size: 81 +/- 31 nm) micron-sized pure copper powder was compacted in a die using a uniaxial force at room temperature and at pressures ranging from 0.25 to 1.00 GPa. The pressure range selected was based on an ability of the silicon wafer to withstand the pressure without experiencing mechanical damage. The as-compacted copper compacts were sintered at 200 degrees C for 2 h in an atmosphere of argon. The purpose of this research study was to optimize the compaction pressure to get properties in the compacted copper sample that makes it suitable for use as an electronic packaging material. The characterization studies revealed that an increase in compaction pressure followed by sintering at a low temperature had a minimal to no influence on grain size but a noticeable influence on both porosity and hardness of the compacted sample. The microhardness of the as-compacted samples was found to be superior to the values obtained for the samples synthesized using the techniques of inert gas deposition and in situ compaction, solution phase synthesis, and plasma pressure compaction. The influence of compaction pressure on hardness of the sintered samples is rationalized in light of its intrinsic influence on microstructural development and processing-related artifacts. (c) 2006 Elsevier B.V. All rights reserved.