Defects hillocks

Integrated circuits have been studied fairly extensively by acoustic microscopy (Miller 1983, 1985) in addition to disbonding the defects that have been reported also include resist/metal overhang, subsurface blisters and resist inclusions, hillocks shorting between metallization layers, spikes in... 

In the case of GaAs photoetching in Cr03-HF solutions, etch hillocks are formed both on n- and p-type crystals [113-114]. Hillocks, however, are also observed in the dark, and their occurrence has been explained on the basis of the complex reaction scheme described by Eqs. (58)-(61). The Cr03-HF etch has been found to be very sensitive to defects at GaAs and even more so at InP crystals [115]. 

The surface of the silicon crystal, no matter how it is finished, will have a certain number of lattice defects, which tend to dissolve preferentially resulting in formation of etch pits and other features. Terraces and steps of various sizes are inevitable consequences of anisotropic dissolution of the surfaces misoriented from the (111) surface. Also, a silicon surface, whether initially smooth or not, in HF solutions, has an intrinsic tendency to roughen and form micropores governed by sensitivity of the electrochemical reactions on a semiconductor electrode to surface curvature. Furthermore, the two groups of factors shown in Fig. 7.57 may affect each other. For example, the initial lattice inhomogeneities may provide the sites for deposition whereas localized deposition may enhance the development of etch features such as pits or hillocks. 

Many different etchants have been developed for the evaluation of different types of crystal defects such as flow-pattern defects [115], stacking faults [74, 192, 193], dislocations [69, 72-74, 194], dislocation network [72, 193, 195], oxide precipitates [196], swirl patterns [74, 75, 148], striations [74, 197], hillock defects [198], epitaxial defects [192], epitaxial alignment [199], grain boundary [69, 72, 200], twin band [69], diamond saw damage [201], pn junction [202-204], metallic precipitates [205], and damaged layer of mechanically polished surface [206],... 

In region A, with 7 > 0.1 and [HFl < 10 M, crystal defects are revealed as defect-related hillocks. The surface between these hillocks remains smooth for solutions with > 0.14. For solutions of region B and... 

Localized regions of high intrinsic stress can be found in films due to growth discontinuities or defects such as nodules (Figure 10.9) or surface features such as hillocks. These stressed areas can lead to localized adhesion failure under applied stress, giving pinholes in the film and flakes that can become particulate contamination in the deposition chamber (pinhole flaking). 

Whisker A surface feature that grows from a defect on the surface when the surface material is under compressive stress. Examples A tin whisker from lead-tin solder a silver whisker from silver metallization. See also Hillock. 

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