ZALAR rotation

Ge at 8.3 and 6.8 eV, respectively, the ion-bombarded area was quite uniform, but as Buo decreased, more surface topography developed. Their SEM images of Si, Ge, Sn, and A1 after sputtering with 20 keV 02+ are shown in Fig. 4.22. Rotation of the sample (sometimes called Zalar rotation) [79] is commonly used with off normal incidence sputtering to minimize the formation of sputter-induced topography. 

As covered in Section 5.3.2.4.5, sample rotation (also referred to as Zalar rotation) during image depth profiling can minimize the latter. Alternatively, surface topography measurements carried out before and after image depth profiling can account for the latter two. Indeed, the effectiveness of this approach has been demonstrated via ex-situ Atomic Force Microscope (AFM) measurements (van der Heide 1998 Robinson et al. 2012). Based off of the success of this approach, lon-Tof has designed a hybrid APM/TOF-SIMS instrument. 

Zalar rotation Trademarked name introduced by physical electronics to describe centro-symmetric rotation of the substrate... 

Figure 7. (a) Principle of Zalar rotation in AES (b) typical shape of the sput-... 

Auger electron spectroscopy (AES) profile of the oxide in Fig. 4.13, obtained by Physical Electronics, Inc. Sputtering was by 2 keV argon, with Zalar rotation. 

Zalar, A. (1985) Improved depth resolution by sample rotation during Auger electron spectroscopy depth profiling. Thin Solid Films, 124, 223-230. 

This form of surface roughening along with the corresponding loss of depth resolution and increased variations in ion yields can be controlled using sample rotation (Zalar 1985) as will be discussed in Section 5.3.2.4.5. 

Since the major limitation on depth resolution arises from the sputtering process itself and from the sputter-induced microtopography, many attempts have been made to minimize such effects. The main aim is to suppress both the crystal orientation effects and the increase in roughness by rotating the sample during sputtering, as suggested by Zalar. If that is done in the correct way, then the sputter crater can be produced with a flat bottom, in the center of which is the analyzed area (79, 80]. 

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