Wafer Testing: Find the Source of Measurement Noise — working record
Yenra | October 4, 2026
https://yenra.com/silicon-wafers/

Purpose: Plan a controlled investigation that separates device behavior from instrument, contact, cabling and environmental effects.

Instructions: Make a working copy. Fill the fields below with actual evidence and units. Record unavailable information as unknown, give it an owner, and resolve it before using the record for acceptance. Keep raw evidence by reference. Use the approved method, equipment limits and acceptance rules for your application. This blank record does not establish qualification.

1. Wafer, die, device, recipe revision and measurement question
   Response / evidence reference: ______________________________

2. Instrument, probe, cable and fixture identities; calibration status
   Response / evidence reference: ______________________________

3. Bias, range, integration time, filter, sample interval and compliance limits
   Response / evidence reference: ______________________________

4. Temperature, warm-up and settling times; approved reference and its impedance
   Response / evidence reference: ______________________________

5. Raw baseline file, duration, units, metric and bandwidth
   Response / evidence reference: ______________________________

6. One proposed change, mechanism and responsible equipment owner
   Response / evidence reference: ______________________________

7. Changed and restored runs; repeatability; mean and response-time effects
   Response / evidence reference: ______________________________

8. Conclusion, remaining uncertainty and acceptance evidence
   Response / evidence reference: ______________________________

Teaching example (fictional; not acceptance criteria):
Fictional troubleshooting example With identical range, integration, sample interval and 60-second windows, a reference trace has a standard deviation of 12 pA before an approved cable-route change and 8 pA afterward. The reduction is (12 − 8) / 12 × 100 = 33.3%. Repeat and reverse the change to test reproducibility. If the filtering also changed, the comparison would combine two causes.

Primary source context (consult for applicable method and scope):
Keithley Low Level Measurements Handbook
https://www.tek.com/en/documents/product-article/keithley-low-level-measurements-handbook---7th-edition

Review outcome: accepted / held / further evidence needed
Reviewer and date: __________________
Open actions, owner and due date: __________________