Background Statement for SEMI Draft Document 4643
Withdrawal (with no replacement) of
SEMI T1-0095-0303R
SPECIFICATION FOR BACK SURFACE BAR CODE MARKING OF SILICON WAFERS
Note: This background statement is not part of the balloted item. It is provided solely to assist the recipient in reaching an informed decision based on the rationale of the activity that preceded the creation of this document.
Note: Recipients of this document are invited to submit, with their comments, notification of any relevant patented technology or copyrighted items of which they are aware and to provide supporting documentation. In this context, “patented technology” is defined as technology for which a patent has issued or has been applied for. In the latter case, only publicly available information on the contents of the patent application is to be provided.
This standard is over ten years old. Because it has a reference to an unidentified patent, which may cover its use, it no longer meets the requirements of the Regulations for citing patented materials. Furthermore, it is not suitable for use on large diameter wafers and is probably no longer in common use, if in fact it is used at all. Therefore, it is proposed to withdraw this standard without replacement. In the event that any negatives are cast on this action, persons desiring to continue its use should be prepared to revise it to be in conformance with existing editorial and intellectual property requirements.
This letter ballot will be reviewed and adjudicated by the Traceability Committee during its 2009 Spring meeting the week of March 29, 2009 in San Jose.
Scope
This specification defines the content and location of a back surface bar code marking for silicon wafers. The code is variable in length from 7 to 18 characters which are user-definable. A character position is held constant for the checksum character, but all else is variable. No other information is encrypted into the code. This allows the performance requirements of related bar code reading equipment to be simplified. In addition, provision is made for an optional alphanumeric marking of the size specified in SEMI M12 to enable operator identification of wafers. This alphanumeric code is not intended to be machine readable.
This specification applies to flatted or notched silicon wafers of nominal diameter 125 mm and larger, as specified in SEMI M1.
The bar code can be read bi-directionally without impairing its decodability.
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