Commercial Wafer Specifications

 
Here are the specification for Si wafers from one of the worlds top companies, Wacker Siltronic, as they appear in the Internet in Nov. 2000.
Notice: Concentrations here are in cm– 3. The conversion to part per milion (ppm) is simple:orrelation
The atomic density of Si is 4.96 · 1022 cm– 3 or about 5 · 1022 cm– 3. This gives us
1 ppm  =  5 · 1016 cm– 3
The lowest concentration given in the table (look for it) is 5 · 1010 cm– 3; it corresponds to 1 ppt or 10– 12.
Surface concentrations [S] (given in cm– 2) are converted to volume concentrations [V] by
[S] =  =  [V]
a
With a = lattice constant (= 0,5431 nm) or, more precise for single crystals, distance between the crystallographic planes. With a approximately 0,5 nm = 5· 10– 8 cm, we have
[V] = 5 · 1016 cm–3 = 1 ppm corresponds to S = 108 cm– 2
Many specifications relate to the "flatness" of the wafers and the perfection of the surface; the abbreviations used are
LLS (sometimes also abbreviated LPDs): Localized Light Scattering Defect; this relates to a detection method of sub-µm size surface imperfections (resulting from bulk microdefects)
SFQR: Site flatness quality requirements (??): Whatever it means in detail - definitely a measure of flatness in a region comparable to the size of a single chip.
(The rest: Who knows - to be included later)
 
Wafer specificatiOns

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© H. Föll (Semiconductor - Script)