Mechanical characterization of low- k dielectric materials using nanoindentation

Abstract

Improvements in the dielectric constant of low- k materials play an important role in reducing gate delays in modern microelectronics. However, these improvements are often achieved through increases in porosity or usage of materials with low polarizability, which can reduce the overall mechanical strength of the material. This creates difficulties with further fabrication processes such as chemical–mechanical planarization. Therefore, the mechanical properties of low- k materials must be considered when evaluating the material's overall performance. Measuring the mechanical properties of these spin-on dielectrics and chemical vapor deposited films is made challenging by the fact that they have sub-micron thickness. The nanoindentation testing technique is uniquely suited for performing these measurements. Presented here is the mechanical analysis of three such low- k films using nanoindentation. All of these films are on a silicon substrate. Details of the testing methods and equipment are also discussed.