Message-ID:


Dear friends:
        I am a process engineer of photolithography. These days our
production wafers got some flatness problem. So we should find a way to
check  the flatness of our wafers. I wonder if there are any reference
materials about how to measure surface flatness. Further more I also want to
know the definition and measurement of LTV and TTV.

any suggestions will be appreciated.
thanks in advance.


Best regards,
Zhou Wenzhan
Engineer
Siemens Matsushita Components Pte Ltd
166, Kallang Way
Tel: 8457610
Fax: 8457693
Email: wenzhan.zhou@sgp3.siemens.com.sg