A golden wafer, golden unit or golden sample is a well-characterized reference item stored carefully and run through a metrology tool or tester on a schedule, after maintenance and during tool matching. Because the item itself should not change, any movement in its readings is the gauge drifting. Golden wafers do degrade, through native oxide growth, contamination or probe wear, so measurement sites rotate and backups get qualified ahead of time.
Ran the golden wafer after the source swap and it reads 0.6 nm thick against its baseline. Recal before we release the tool.
Also heard as
- golden unit
- golden sample
- reference wafer
- check standard
Related terms
Tool matching
Making several tools or chambers that run the same step produce the same results on the same material.
Bias
Systematic offset between the average of repeated measurements and the true or reference value.
MSA
Measurement systems analysis: the set of studies that prove a gauge is fit for the decisions its data will drive.
Drift
Slow, steady creep of a process or gauge reading in one direction as something wears, depletes or ages.