Wafer Scanning process Traveler
Wafers to Use
The wafers for process calibration are ordered from SVM (https://www.svmi.com/). Specification:
Resistivity: 1-30 ohm-cm
Thickness: 525 +/-25 microns
Particles: <=10 @ >=0.3 microns
These wafers have low LPD count (LPD= light particle detection, LPD<100).
The box with 25 wafers is stored in the cleanroom and staff use it only for process calibration (you can order same type of wafers for the same purpose). Wafers are handled very carefully, because every loading and unloading of wafers will add some particulates.
Surfscan 6200 (located in bay5) is used for scanning wafers. There are two standard recipes that could be used for scanning wafers: UCSBTEST1 (for scanning 8” wafers) and UCSBTEST2 (for scanning 4"wafers). We do not have cassettes for any other size of the wafers. You need to provide your own cassette and calibrate it. If you need to scan wafers pieces, you need to develop your own procedure how to scan it.
Scanning procedure for 4" Si wafers
Scan before process calibration
- Log in (access code is boss)
- Load wafers(face up) to the carrier that says " SURFSCAN" .
- Place the carrier with wafers to the right indexer.
- In the menu option select "CAS" (this will read all wafers that are in the carrier).
- Go to "Recipes"
- Select one of the recipes:
- UCSB Gain4 (measuring small particles 0.16-1.6um)
- UCSB Gain2 (measuring larger particles 1.6-28um)
- (Recipe "UCSBTEST2" is used as a template to create recipes UCSB Gain2 and UCSB Gain4)
- View the recipe and modify it if needed ( if recipe modified, select bin split/default).
- Select the wafer in catalog box you want to scan (you can select one wafer or you can scan all wafers).
- Select START.
- Wait until scan is finished.
- Record: LPD Cnt (sum of all particles #1- #8), particles #1(0.160-0.213)um, particles #8(1.20-1.60)um, haze region(%).
- Take a picture of the scan (by phone).
- Select "Home" so indexer moves up to loading/unloading position.
- Unload wafers.
- Log out.