Jim: What is the major advantage of using STEM instead of SEM for <90nm node structures?
Matt: While SEM is very capable of working in the <90nm regime, STEM is becoming popular. STEM offers a different image quality and contrast than traditional SEM. With STEM, it is possible to differentiate layers that could not be seen with the SEM. Traditional STEM has been done with a Transmission Electron Microscope (TEM), which can actually have sub-atomic resolution. However, today, in addition to traditional TEM techniques, one can obtain STEM results using an SEM based tool. With a sample prepared for STEM imaging (thin sample on the order of 100nm thick), an operator can obtain STEM data at 30KV or less from a traditional SEM instrument. While the SEM based STEM cannot provide sub-atomic resolution (like the TEM can), the technique is very useful and provides approximately 0.8 nm resolution and excellent image quality and layer delineation. In addition, performing chemical analysis using energy dispersive spectral analysis (EDS) on a thin sample can improve the spatial resolution to 15-20 nm vs the 300- 500 nm achievable on bulk materials.
http://www.fei.com/products/families/helios-nanolab-family.aspx
Jim: Some labs are short on space, how small are the smallest SEMs – and will they have all the same functions?
Matt: Our SEM's have become very small and can fit in some tight spaces. In general, a traditional SEM might consist of a console (desk) that hold a monitor and keyboard and mouse. Next to that might be a vacuum console where the sample and column resides. There are typically some peripheral electronics that might be included in 1-2 racks. It doesn't have to take up much more room than the area of 2 desks. However, we are conscious that some facilities might have severe room limitations and to that end we've designed a TableTop SEM (called the FEI Phenom). This unit has been said to look like a cappuccino maker and can fit on a table. The only peripherals involved with that unit are a very small pump and power supply.
http://www.fei.com/products/families/phenom.aspx
Jim: What equipment would you advise using to determine the composition of post reflow flux residue?
Matt: There are some key elemental analysis techniques like EDS and EELS that would be very useful. EDS can be done on a SEM or a TEM, EELS is a TEM based technique. Each has it's own pros and cons. An interesting application on flux and pastes is to examine them in cross section (cross sectioned using an FEI Focused Ion Beam or DualBeam) and then interrogate the cross section with EDS analysis to obtain qualitative or quantitative compositional information, while of course along the way obtaining high res SEM images to show layer delineation and any grain contrast.
Jim: Are there laboratories where our customers can demo FEI equipment?
Matt: Absolutely. We've got a few different state of the art NanoPorts (or demo labs) that are ready to show off our equipment. The primary
Matt is an account manager for FEI, come see him at Semicon West! Matt will be at the Indium booth to join in “Meet The Bloggers” at 2pm on Tuesday, and you can see the equipment at the FEI booth (2141 South Hall). For further information he can be reached at matt.weschler@fei.com.