Impact of Accelerator Decomposition Products to the Stability of TSV Filling Processes

Filling of though silicon vias (TSV) with ECD copper is an important process step to realize high performance 3D integrated microelectronic devices. Organic additives are used to deposit the copper defect free into the high aspect ratio vias. The decomposition of these organic additives can disturb the TSV filling process. The impact of Accelerator decomposition products to the process stability of a model TSV filling processes was investigated. Copper (I) thiolate was found to be the main contributor to the process fluctuations. Already at very low concentrations the fill performance of a model TSV filling process is disturbed. (Fig. 1) The chemistry of copper (I) thiolate formation and decomposition is discussed and a method for copper (I) thiolate determination in TSV electrolytes is introduced. The increase of process stability by counteracting copper (I) thiolate is discussed and illustrated on hand of examples. Figure 1