Wafer Scanning process Traveler
Wafers to Use
The wafers for process calibration are ordered from a wafer supplier that sells high grade, quality wafers. these are 4"Si wafers, with low particle count (Particles: <=10 @ >=0.3 microns). Wafers should be handled carefully, because every loading and unloading 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). The recipe UCSBTEST2 is used as a template to create other two standard recipes: "UCSB Gain4" (measuring small particles 0.16-1.6um) and "UCSB Gain2" (measuring larger particles 1.6-28um).
We have cassettes only for 4" and 8" wafers. If you plan to scan wafers that have different size, you need to provide your own cassette and calibrate it. If you need to scan wafer 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 cassette that says " SURFSCAN" .
- Place the cassette 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 to save changes).
- Select the wafer in catalog box you want to scan (you can select one wafer or you can scan all wafers-AUTO option).
- Select START.
- Wait until scan is finished.
- LPD Cnt (sum of all particles #1- #8), particles #1(0.160-0.213)um, particles #8(1.20-1.60)um
- Haze (region(%), average(ppm), peak(ppm)).
- Take a picture of the scan (by phone).
- Select "Home" so indexer moves up to loading/unloading position.
- Unload wafers.
- Log out.
Scan after process calibration
Repeat the same procedure as it was done before process calibration.