APPLICATION OF HIGH RESOLUTION ICP-MS (SECTOR FIELD ICP-MS) TO THE FAST AND SENSITIVE QUALITY-CONTROL OF PROCESS CHEMICALS IN SEMICONDUCTORMANUFACTURING

For fast routine analysis of process chemicals used in semiconductor t echnology such as tetramethylammonium hydroxide (TMAH), ammonium fluor ide/hydrofluoric acid mixtures, phosphoric, sulphuric or peroxodisulph uric 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 analys ed before, a thorough cleaning procedure and an adapted element menu i s essential to lower the instrument blanks where possible or to achiev e sufficient limits of detection (LoD) even at high blank levels. Due to its improved transmission and its ability to resolve spectral inter ferences 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 clea ning and maintenance, sample preparation and introduction. The interfa ce region between torch and lenses was seen to be the main source of b lanks for elements such as Na. All sample manipulation has to be carri ed out under clean room conditions. The use of an inert sample introdu ction system (ISIS), platinum cones and at least medium resolution for elements between 24 and 80 amu creates a very robust method. High eff iciency sample introduction systems such as USN and MCN have been stud ied alternatively.