Depth resolution improvements using specimen rotation during depth profiling

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Abstract
It has been well documented that depth resolution (interface width) degrades with depth when crystalline materials are sputtered by ion beams, whereas amorphous materials are less susceptible to this phenomenon.1 Several techniques have been employed to reduce this interface broadening problem. Amongst them have been reactive ion beam sputtering,2 ion sputtering with two ion beams at opposing angles,3,4 and finally, ion sputtering while the specimen is being mechanically rotated3,5,6. We elaborate upon this last technique, using a more stable sample rotation device, supporting Zalar's results that the depth resolution of a polycrystalline thin film material is nearly independent of depth. Further results indicate that the measured interface widths were independent of ion beam accelerating voltage between 1.0 and 3.0 keV only when sample rotation was applied; and that the loss of depth resolution near the specimen surface and within bulk occurs as a result of mono‐directional ion beam sputtering. We have also demonstrated that surface roughness can actually be reduced by rotation during sputtering, thereby restoring the interface depth resolution.