There is a lot of confusion about what is considered “Prime” in the wafer business and there are definitely many grades of prime wafers being offered for sale today. A true prime wafer as far as we are concerned is a device quality wafer that any major fab could use to build the latest technology semiconductor devices on.
These wafers can be hard to find in small quantities and if you do find them they are very expensive. For most projects of a very exacting nature this is the “Prime” that we recommend, i.e. wafers that are Non-EPI, No Backseal and Site inspected for flatness, meeting a spec of at least 0.3um on a 20mm x 20mm site (backside referenced).
Insist on the wafers being double bagged and that the outer bag is the original foil bag from the manufacturer. If you can, ask that the original factory labels be left on the cassette. One more spec that is important is resistivity, if you are paying for good prime wafers the resistivity grouping must be tight. An example would be 5-10 Ohm/cm or 10-20 Ohm/cm etc. This will insure you will get an excellent film process with a very tight uniformity spec. Our favorite manufacturers of Prime wafers are Wacker, SEH, and Mitsubishi Sumitomo.
Uses for Prime Wafers: The wafers described above may be used for many high end projects such as very uniform LPCVD Nitrides, Fine Line Photolithography, accurate CMP Qualification, and other high end uses such as particle monitors.
Normally the polish is of a very high quality so if you are concerned about surface roughness these wafers will work very well for you. These are the wafers we choose to build thin film standards on.
See inventory purchase list for availability.