84
S. Leu and D. Sontag
Fig. 4.8 Illustration of a the slurry process; b the diamond wire process; c multi wire configuration;
d wire web. Courtesy of Meyer Burger Technology AG
illustrated in Fig. 4.8b, c, d. The kerf loss (Fig. 4.8a, b) depends on wire diameter
and the size of the SiC grains (Slurry) or the size of diamonds. The glycol/oil in
the slurry process and the coolant additives in the diamond cutting process are
recycled. The silicon from the kerf can only be recovered in contaminated form
and it is therefore not yet economically worthwhile to recycle it. The wire is fed
from a first roll (not shown in Fig. 4.8d) onto the so-called wire web consisting
of two rolls (Fig. 4.8d) and after the cutting process it is rewound onto a fourth
roll (not shown in Fig. 4.8d).
Only since 2015, did one learn how to cut multicrystalline material with the diamond wire process. However, unlike the slurry cut wafer surface, the wafer surface cut
by diamond wires in this way cannot be textured using traditional wet-chemical methods. New texturing processes such as plasma texturing or metal catalytic texturing
must be used.
4.1.6 Texturing of the Front Surface
If the surface of monocrystalline silicon wafers is treated in an alkaline etching bath,
one obtains an anisotropic etching effect (see also Chap. 7); this process depends
on the crystal orientation.
11 For {100} oriented monocrystalline silicon material,
11 Details on the crystal orientations can be found in Chap. 7.