AVS 56th International Symposium & Exhibition
    Nanometer-scale Science and Technology Tuesday Sessions
       Session NS-TuP

Paper NS-TuP1
Capture and Characterization of Nanoparticles at Trace Levels in Semiconductor Process Gases

Tuesday, November 10, 2009, 6:00 pm, Room Hall 3

Session: Nanometer-scale Science and Technology Poster Session
Presenter: J. Feng, Matheson TriGas Inc.
Authors: J. Feng, Matheson TriGas Inc.
M. Raynor, Matheson TriGas Inc.
D. Davia, Matheson TriGas Inc.
A. Seymour, Matheson TriGas Inc.
R. Torres, Matheson TriGas Inc.
Correspondent: Click to Email
Particulate contamination in process gases used in semiconductor fabrication can have harmful effects on device morphology, performance, reliability and yield. There are significant challenges in the measurement of particles in process gases, especially trace level nanoparticles <50 nm in reactive and corrosive gases. Optical particle counters and condensation nucleus counters are frequently used in inert gases to provide real time data on particle levels and size distributions. However these devices may not provide accurate size measurement or be compatible with reactive gases. Further, they don’t give any information on the composition of the particles, which may be important for determining the contamination source. An alternative method is to capture the particulate contamination on sampling filters and perform post microscopic analysis. This approach has been previously used for environmental particulate sampling but has not been widely applied to reactive semiconductor gases. In this work, a sampling system with nanopore-sized (NPS) membrane filter for capturing particles from difficult-to-measure gases is described, initially tested with a nanoparticle source in nitrogen and then applied to reactive process gases such as HBr. Feasibility of capturing iron oxide nanoparticles (30-50 nm) introduced into purified nitrogen via a particle shaker inert gas was demonstrated on NPS alumina filter. Sampling with HBr required compatibility testing of the filter membrane. Results indicated that the NPS alumina filter is capable of withstanding the corrosive effects of HBr, provided the sampling system and gas are properly dried. Membranes were analyzed using various surface analysis techniques such as AFM and SEM. Before collecting samples, blanks were collected to ensure that the delivery system was clear of any contamination. Typical results of contaminant particles from reactive gases such as HBr are presented. These data provide information on the particle content and form in the source container and delivery lines and efficiency of filters in removing particles from the flowing gas. SEM images of particles captured from a filtered gas sources via a delivery system show the presence of clusters of small particles, indicating that the particles may have an affinity for one another in the gas phase. SEM-EDS provides compositional data of the particles detected. The data show that in the case of HBr, the particles are mainly mixed metal bromides. The elements detected compare well to those detected by hydrolysis metal sampling with ICP-MS. Such information can assist in locating the source of particles and eliminating such sources