POST Verification / Inspection
Once the image has been written, we then have to inspect it for accuracy / quality / defects and flaws that can sometimes affect the final product.
Customers who have very specific requirements for geometry sizes, may specify critical dimensions (CD) and the acceptable variance from that target (the tolerance). If no tolerance is given, then we work to our own default values .
CDs are measured using a microscope during the processing of a mask, to determine process times and to make sure that the CD size is acceptable.
Once all processes are complete, and the mask has been cleaned and washed, we can offer you 3 different types of final inspection . By default, the STANDARD method of inspection will always be used unless you request otherwise.
Standard: We firstly inspect the piece by eye for flaws, design inaccuracies and contaminations. We also inspect a test coupon (placed in the bottom corner of the mask) for line width accuracy and edge definition. Next we measure the overall dimension of the mask, and record both of these measurements on our internal inspection records. Finally, we find the CD of the mask, measure that, record it, and also take a digital photo that is saved with the inspection log. We use Nikon MM40 at 900x magnification and an OGP ZIP 300 at 400 x magnifications for this
Certificate of Conformance: In addition to the standard inspection process described above, we will also supply a printed Certificate of Conformance.
Certificate of Measurement: By selecting this option during the ordering process, we will inspect upto 10 customer defined measurements, with customer supplied tolerances. You will need to send us a document, or a separate layer of the design, showing us where you want us to take the measurements from. There can be upto 10 positions defined by the customer. These dimensions are then programmed on the co-ordinate measuring system and the mask is compared to this unique program. A certificate of measurement /conformity is given if the mask passes the inspection process. Additional positions can be requested if required.
