Specific Process Knowledge/Lithography/5214E: Difference between revisions
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==Image reversal== | ==Image reversal== | ||
If 5214E is baked after exposure, the exposed resist will cross-link, making it insoluble in the developer. This is called the "Reversal bake", or sometimes the post-exposure bake. The reversal bake activates cross-linking of the exposed areas, which "reverses" the polarity of the design. | |||
If the substrate is flood exposed after the reversal bake, the previously unexposed areas become soluble, and will be removed in the subsequent development. The 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 resist sidewalls are desired. 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, | 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> | ||
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, 60-120s at 110°C is recommended (as well as a resist thickness above 2 µm), but if straight sidewalls are desired, 60-120s at 120°C can be used. | |||
The flood exposure, on the other hand, is uncritical, and 2-5 times the normal positive process dose is generally used. | |||
==Development== | ==Development== | ||
A 1.5-2.2µm AZ 5214E resist film is fully developed in 60s using TMAH (AZ 726). Depending on the exposure dose, thicker coatings may develop in 1 min, but it is probably better to aim for a similar development speed (2µm/min). | A 1.5-2.2µm AZ 5214E resist film is fully developed in 60s using TMAH (AZ 726). Depending on the exposure dose, thicker coatings may develop in 1 min, but it is probably better to aim for a similar development speed (2µm/min). | ||