Small Spot ESCA : Q&A

The above webinar discusses analyzing surface chemistry on micro-devices and its methodologies. Here you can examine a Q & A from the webinar of FAQs about this type of analysis.

Q: Does surface roughness have an effect on depth profiles?

A: Surface roughness does indeed have an effect on depth profiling. But with our new instrumentation, our ability to rotate a sample at multiple points coupled with our better charge neutralization helps to mitigate the effects that you would see from surface roughness. It may cause your sample to sputter etch at a bit slower rate than expected, but rotating will help decrease the effects that we see from that. Charge neutralization also helps to mitigate the effects one sees. So yes it’s possible, but there are caveats.


Q: How deep can you profile? How long does it take to sputter?

A: That depends on the sputter rate of the material under analysis. Again, we do a quality check four times a year on our instrumentation. And we know that silicon dioxide sputters at a rate of 10 nanometers per minute in our instrumentation. We have parameters that can increase or decrease that sputter rate and make it much faster or much slower, but if that’s a benchmark, it’s limited. Thus, with the 10-nanometer sputter rate, it just limits how deep we can get into the sample.

And some materials may sputter faster or slower, so it all depends on how much time you want to spend to get, say, a micron into the surface.

Something to keep in mind as you’re sputtering past a micron is that interfaces may be intermingled as you’re getting deeper into the surface because of the crater that’s being created. It depends on the data that can be collected, as well as the electronics, and the set-up of the instrumentation. Those are all factors to keep in mind as you’re sputtering one to two to three microns into a sample. Time is a big factor– how long do you want to spend to sputter a micron or more into your sample.

It’s possible, and we can do it. But once you get into the two to three micron range, there are several things to keep in mind. You may see artifacts as we sputter that deep into the sample. As long as you remember that there may be artifacts and that that data may have to be taken with a grain of salt, you can sputter as deep as you want, as long as you have the time to do it.


Q: Can you give me an example of when weight percentage analysis would be needed?

A: Weight percentage analysis is often needed when a client comes in with an idea of a product that’s been on the surface. It’s not always possible, but sometimes they say, hey, we know the weight percent of this product. Can we see some of that as we analyze our sample? So let’s say we have a particular product of poly dimethyl silicone, and can we see that reflected on our sample. Sometimes that can be calculated to weight percent that can be found. Weight percentage can also be useful or beneficial if you’ve tried to create a product similar to a competitor’s and you want to see if that works out. Sometimes that can be back calculated. Sometimes that comes with a caveat.


Q: How can you produce maps and line scans similar to what you showed in your depth profiling system?

A: A map is actually made up of multiple points so we analyze each point and software will combine the data to give it to you. So you are losing some sensitivity to data because it is a multidimensional analysis. We recommend doing a point analysis to get your overall composition. We take multiple points, and just like a pixelated picture the software combines all those pixels.