Paper AS-FrM8
An Investigation of Detection Limits and Common Interference Factors in Depth Profiling Hydrogen and Deuterium by Time-of-Flight Secondary Ion Mass Spectrometry

Friday, November 13, 2009, 10:40 am, Room C2

Hydrogen depth distribution is very important information in today’s novel material research. Time-of-flight secondary ion mass spectrometry (ToF-SIMS) has been used for this task for quite a while. Normally, dual beam strategy, in which a cesium ion beam is used for sputtering, and a primary ion beam (Ga⁺, In⁺, Au⁺, Bi⁺ …) is used for measurement, is applied in hydrogen depth profiling. Residual gas in vacuum chamber has been found to significantly interference SIMS hydrogen depth profiling, so that deuterium is introduced to substitute hydrogen for SIMS analysis if feasible. Apparently, the information of detection limits and common interference factors are very important for ToF-SIMS users, but such information was not easily available. In this work, we investigated detection limits of hydrogen and deuterium in four widely used materials, including silicon wafer, quartz, zinc oxide and titanium oxide. Deuterium ions were quantitatively implanted into these samples, and they were used as the standard to evaluate detection limits of both hydrogen and deuterium. It is found that hydrogen detection limit is about 100-400ppm, limited by residue gas interference. On the other hand, detection limit of deuterium can be as low as 1-10ppm due to no interference. These results will be discussed along with some common interference factors.