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Vacuum Bake/Vapor Prime Systems
YES-3TA, YES-5TA (Vacuum Bake/Vapor Prime)
YES-8TA, YES-10TA (Image Reversal)
YES-310TA, YES-58TA (Dual Function – Vacuum Bake/Vapor Prime Image Reversal)
YES builds vacuum bake/vapor prime, image reversal, and dual function systems. The vacuum bake/vapor prime process achieves strong silane/substrate bonds by combining heat with low pressure. Wafers are completely dehydrated—not only surface moisture, but the chemically bound water molecules as well. Once dehydrated, wafers are primed with HMDS vapor to strengthen photoresist adhesion. Properly treated wafers last for weeks with no change to surface adhesion.
In the image reversal process, the action of positive resist is reversed so negative images can be formed with the same resolution and processing ease of positive resist.
Image reversal advantages:
- Allows variations of the slope of the photoresist sidewall for higher resolution and improved lift off.
- Replaces use of harsh chemicals or plasma "metal etch” processes.
- Using image reversal on two or more layer resist levels can eliminate residual photoresist along the sidewalls, preventing "shorts" from level to level without reducing line width.
- Image reversal done with dark or light fields eliminates standing waves; this allows steep and straight profiles, repeatable results, and excellent chemical deposition uniformity.
- Image reversal achieves excellent results for rework problems; underlying substrate is protected (for a double metal process), so unwanted metal can be stripped away without "pitting" or eroding the underlying level.