Standard PhotoLitography

AZ5214 Image reversal PR: 

Official datasheet AZ 5200 series 

Use as Positive PR

1. Wafer cleanning (Piranha or AMI clean depending on what layer on the wafer you're processing).

2. Optional: HMDS 2-min priming (total time is about 18 min 20 sec) - This is to improve the adhesion of the PR layer.  If you have small features on your mask, it is recommended. So that it won't be lifted off during dicing and any other process.

3. Spin-coating at 3000PRM for 30 sec - This will yield a 1.6-μm-thick AZ5214 layer on your substrate.

4. Prebake at 110°C for 50 sec on a hotplate (make sure you check the temperature properly before starting a prebake)

5. Expose:

   1. If you use MA8, set the exposed dose between 75 mJ/cm^2 to 100 mJ/cm^2 (You can open the folder-Zihuan Liu, and check the recipe accordingly)

6. Develop: AZ400K :  Water = 1 : 4 (50ml : 200 ml), 25 - 35 sec (may adjust the time until you see the pattern exposed and clear)

Image reversal

AZ 5214 can be used as a negative PR, this procedure is called image reversal

7. After exposure, and before development, using the ordinary process, post bake at 110-120 C for 45 sec

8. Flood expose using greater than 300 mJ  (this is not critical, just make sure you expose with enough energy)

Then develop (step 6)

SU8 Negative PR:

SU8 datasheet: KAM-SU-8-3000-Datasheet-7.10-final.pdf (kayakuam.com) 

Omnicoat datasheet: XP SU-8 Release Layer (kayakuam.com) 

1. Omnicoating, omnicoat enables effective SU8 removal

   1. 1000 RPM 40s

   2. bake after each coat at 200C for 1min

   3. coat 3 layers, each layer is around 17nm, 3 layers give you ~40 nm, good for SU8 removal

2. Note: between each step, let the wafer cool down to room temperature

   1. Spin coat Su8 3005: 4000 RPM 40s, yield ~3um, 1000 RPM 40s, yields ~10 um  

   2. Baking: at 95C, the duration depend on the thickness, for 3um, 3mins is good, for 10 um, 6mins is good

3. Expose: If you use MA8, exposure energy 100-200 mJ/cm^2 (you may use the recipe in the folder - Zihuan Liu)

At this point, you can't see the pattern, because the pattern will show up after the post-exposure bake process.

4. Post Exposure bake at 95C 3min, the pattern will reveal.

5. Develop using SU8 developer 1min

6. Rinse using IPA not DI water, dry with N2 gun

7. Use Oxford RIE (YS Omniremoval) 90s is enough for 3 layers, the recipe is 4min