ISSN:
1089-7623
Source:
AIP Digital Archive
Topics:
Physics
,
Electrical Engineering, Measurement and Control Technology
Notes:
Ion beam mass spectrometry (IBMS) has been developed for in situ, real-time monitoring of the ion composition of a plasma in the vicinity of the substrate surface up to a pressure of 50 mbar. Our system was designed for the specific case of diamond deposition in a microwave plasma enhanced chemical vapor deposition chamber, however, it can be adapted to other applications as well, without significant change in the process chamber. Ion beam mass spectrometer is a quadrupole mass spectrometer (QMS) based plasma sampling system installed into a separately pumped small analysis chamber. The interface between the two chambers is the top part of the IBMS, specially designed to serve as the sample holder of the reactor chamber (sample heating and biasing is possible). A technique containing wet etching and laser treatment has been developed to form a sufficiently small orifice in various substrates. This orifice samples the particles arriving onto the surface from the plasma but is small enough to maintain the flow effusive into, and an appropriate pressure in the analysis chamber. Directly behind the orifice specially designed ion-optics direct the ions coming from the process chamber into the QMS for mass and energy separation. Since the total flow from the reactor chamber is low, the mean free path in the analysis chamber is sufficiently longer than the distance from the orifice to the QMS, therefore, ions do not collide, thus they do not react after sampling. As a consequence, nonstable species are also detected. The carefully designed ion-optics ensure that a high ion current reaches the QMS. In this article, it is shown that the intensity ratios in the spectra correspond to the concentration ratios of the ions arriving to the substrate surface. The QMS is also equipped with a conventional cross electron beam ion source allowing measurements of neutral species by conventional ionization. © 1999 American Institute of Physics.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1063/1.1149912
