High-Resolution Chemical Depth Profiling of Solid Material Using a Miniature Laser Ablation/Ionization Mass Spectrometer

作者：Grimaudo Valentine; Moreno Garcia Pavel; Riedo Andreas^*; Neuland Maike B; Tulej Marek; Broekmann Peter; Wurz Peter

来源：Analytical Chemistry, 2015, 87(4): 2037-2041.

DOI：10.1021/ac504403j

High-resolution chemical depth profiling measurements of copper films are presented. The 10 mu m thick copper test samples were electrodeposited on a Si-supported Cu seed under galvanostatic conditions in the presence of particular plating additives (SPS, Imep, PEI, and PAG) used in the semiconductor industry for the on-chip metallization of interconnects. To probe the trend of these plating additives toward inclusion into the deposit upon growth, quantitative elemental mass spectrometric measurements at trace level concentration were conducted by using a sensitive miniature laser ablation ionization mass spectrometer (LIMS), originally designed and developed for in situ space exploration. An ultrashort pulsed laser system (tau similar to 190 fs, lambda = 775 nm) was used for ablation and ionization of sample material. We show that with our LIMS system, quantitative chemical mass spectrometric analysis with an ablation rate at the subnanometer level per single laser shot can be conducted. The measurement capabilities of our instrument, including the high vertical depth resolution coupled with high detection sensitivity of similar to 10 ppb, high dynamic range =10(8), measurement accuracy and precision, is of considerable interest in various fields of application, where investigations with high lateral and vertical resolution of the chemical composition of solid materials are required, these include, e.g., wafers from semiconductor industry or studies on space weathered samples in space research.

• 出版日期2015-2-17