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)

With frame

3.1.1 Silicon: General Properties and Technologies

3.2.1 Single Crystals and Wafers

More to Recombination