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Explain the difference Between Contact, Proximity and Projection Printing.
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written 16 months ago by
prajapatijaimin
• 3.1k
|
Solution:
| Contact | Proximity | Projection Printing. |
|---|---|---|
| Reduced mask life | Average mask life | Increased mask life |
| High detect density in the printed pattern | Poor Eliminates defect as there is no direct contact | Good No defects |
| A photomask containing a pattern for an entire wafer is brought into contact with the wafer to be patterned | A small gap of 10 to $25 \mathrm{um}$ is kept in between the wafer and mask | Avoids mask damage entirely An image of the mask is projected onto resist coated chafer |
| Misalignment at the edges w.r.t. Centre | Alignment accuracy is good | |
| Introduction of defects in the resist and mask | Increased diffraction effects and hence a limit on the min. feature size that can be printed. | wafer is separated from the mask by several cm steps of repeat pry system |
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