# 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

© H. Föll (Semiconductors - Script)