Specific Process Knowledge/Lithography/5214E: Difference between revisions
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If 5214E is baked after exposure, the exposed resist will cross-link, making it insoluble in the developer. This is called the "Reversal bake". The reversal bake activates cross-linking of the exposed areas, which "reverses" the polarity of the design. When the substrate is flood-exposed after the reversal bake, the previously unexposed areas become soluble, and will be removed in the subsequent development. The image reversal procedure effectively makes AZ 5214E a negative resist. | If 5214E is baked after exposure, the exposed resist will cross-link, making it insoluble in the developer. This is called the "Reversal bake". The reversal bake activates cross-linking of the exposed areas, which "reverses" the polarity of the design. When the substrate is flood-exposed after the reversal bake, the previously unexposed areas become soluble, and will be removed in the subsequent development. The image reversal procedure effectively makes AZ 5214E a negative resist. | ||
The image reversal process greatly increases the sensitivity of AZ 5214E, and the dose of the image exposure is a critical parameter, especially if negative angled resist sidewalls are desired.<br> | The image reversal process greatly increases the sensitivity of AZ 5214E, and the dose of the image exposure is a critical parameter, especially if negative angled resist sidewalls are desired. In coatings below 2 µm, it is difficult to achieve undercut.<br> | ||
Half dose of the normal, positive process is a good starting point for optimization. Similarly, the reversal bake is also a critical step, and must be tightly controlled in order to achieve consistent results. If negative sidewalls are desired, 60 - 120 s at 110°C is recommended (as well as a resist thickness above 2 µm), but if straight sidewalls are desired, 60 - 120 s at 120°C can be used. | Half dose of the normal, positive process is a good starting point for optimization. Similarly, the reversal bake is also a critical step, and must be tightly controlled in order to achieve consistent results. If negative sidewalls are desired, 60 - 120 s at 110°C is recommended (as well as a resist thickness above 2 µm), but if straight sidewalls are desired, 60 - 120 s at 120°C can be used. | ||