Table 6.
Pros and cons of different PDBC fabrication process flows discussed in this study.
| Process | Process sub-type | Different approaches | Pros | Cons |
|---|---|---|---|---|
| Process A (SU-8 process) |
Process A1 (Does not support BCL etch; SU-8 first process) |
A1-RIE | 1. SU-8 thickness control after photolithography. 2. SU-8 etch also clears photoresist in via region (better electrical contact). |
1. Dry etch (RIE-ICP) process step is required. 2. Higher SU-8 surface roughness (bad for certain applications). |
| A1-spin | 1. Fewer fabrication steps. 2. Dry etch is not necessary for thickness control but is possible. |
1. Contact photolithography is difficult on thinner SU-8 films especially for smaller features. | ||
| Process A2 (Supports BCL etch; metal point contact first process; better electrical contact than process A1) |
A2-no mask | 1. Relatively easy compared to A1-RIE because of the photomask-less metal point contact opening. | 1. Dry etch (RIE-ICP) step is required for metal point contact opening. | |
| A2-with mask | 1. Two photomasks are needed if a +ve photoresist is used for metal point contact fabrication. | 1. Photomask alignment to metal point contacts is difficult. | ||
| Process B (Evaporable dielectric process) |
Process B1 (No BCL etch) |
NA | 1. Dielectric deposition first process. So, less organic contamination on the device compared to the photoresist first process. | 1. Does not support BCL etch. 2. Applicable only for etchable dielectrics. |
| Process B2 (Supports BCL etch) |
NA | 1. Supports BCL etch. 2. Applicable for any evaporable dielectric. |
1. Photoresist lift-off after dielectric deposition may sometimes be challenging. | |