Application of high resolution-ICP-MS (sector field-ICP-MS) to the fast and sensitive quality control of process chemicals in semiconductor manufacturing

For fast routine analysis of process chemicals used in semiconductor technology such as tetramethylammonium hydroxide (TMAH), ammonium fluoride/hydrofluoric acid mixtures, phosphoric, sulphuric or peroxodisulphuric acid (PDSA) low blanks are the paramount requirement for reliable sector field ICP-MS ultratrace analysis. When solutions containing a high amount of dissolved solids e.g. seawater samples have been analysed before, a thorough cleaning procedure and an adapted element menu is essential to lower the instrument blanks where possible or to achieve sufficient limits of detection (LoD) even at high blank levels. Due to its improved transmission and its ability to resolve spectral interferences inductively coupled plasma-sector field mass spectrometry is capable of detecting 1 ng/g of all metal impurities even K, Ca, and Fe in every matrix used for semiconductor production. LoDs range from < 1 to 30 pg/mL in diluted chemicals corresponding to 5 to 800 pg/mL in the original. This work describes the experiences with instrument cleaning and maintenance, sample preparation and introduction. The interface region between torch and lenses was seen to be the main source of blanks for elements such as Na. All sample manipulation has to be carried out under clean room conditions. The use of an inert sample introduction system (ISIS), platinum cones and at least medium resolution for elements between 24 and 80 amu creates a very robust method. High efficiency sample introduction systems such as USN and MCN have been studied alternatively.     

Controlling the bugs

In late 1984, the Reagan administration proposed a Coordinated Framework for Regulation of Biotechnology. Its proposed regulatory approach appears less constraining than the deep concerns of the 1970s concerning the risk of biotechnology would have suggested. Several distinctive characteristics of the early period of biotechnology, particularly the role of the research community in developing the initial regulatory system and the extent of federal funding, explain this development. The administration’s proposal may attract substantial support. However, implementation may lead to conflicts and problems, especially concerning human germ-line gene therapy and environmental release of viable genetically engineered organisms.