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Titel:
Mechanical strength of silicon wafers and its modelling
 
Auteur(s):
 
Gepubliceerd door: Publicatie datum:
ECN Zonne-energie 1-8-2005
 
ECN publicatienummer: Publicatie type:
ECN-RX--05-133 Conferentiebijdrage
 
Aantal pagina's: Volledige tekst:
4 Download PDF  (321kB)

Gepresenteerd op: 15th Workshop on Crystalline Silicon Solar Cells & Modules: Materials and Processes, Vail CO, USA, 7-10 augustus 2005.

Samenvatting:
Mechanical strength measurements of multicrystalline Si wafers are carriedout with a ring-on-ring test geometry. This geometry is very sensitive to the surface of the wafers rather than the edge. The measurements reveal the great importance of the saw damage on the mechanical stability of as-cut as well as textured wafers. The initial surface defects make a big and unexpected difference in the strength after a standard industrial acid etch. The strength analysis of wafers from different manufacturers shows no influence of bulk defects on strength. This geometry therefore permits to focus on the modification of mechanical stability by adaptations of, e.g., wafering or chemical treatment. The stress at breakage is translated into an apparent critical crack length, which can be used as an intuitive parameter to quantify the surface damage. The relationship between breakage force and wafer thickness from linear plate theory is analysed and verified.


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