ANALYSIS OF COPPER PLATING BATHS - SUPPRESSORS AND LEVELERS

摘要

New copper plating bath products are being introduced to meet the emerging needs of electroplating copper into sub-micron features on semiconductor wafers. The new products are designed to provide a fast, efficient, fill for even the most challenging wafer terrain. In a previously presented paper, the authors outlined a methodology to analyze these new baths for brightener type additives and their electrolysis by-products. It has been found that maintaining the concentration of these additives and by-products in the plating bath at certain levels is critical to the performance of the bath. This, however, is not the end of the story. In addition to brighteners, many acid copper plating baths also contain additives called "suppressors" and "levelers". It is theorized that the "suppressor" bath components help moderate the deposition rate of the copper fill and the "levelers" improve the topology of the copper overfill. Too much or loo little of these components in the bath can be detrimental to the quality of the copper deposition and may result in "fill failure" leading to a higher than necessary scrap rate for the wafers. This paper will cover the development of an analytical method using metal free liquid chromatography to quantitate the additive components and related electrolysis by-products found in a working copper plating bath.