1. Weekly Report Renjie Chen

2. /6 Summary After Wednesday group meeting, I was trying to finish the last step EBL writing of Fin structure and do ICP dry etching. However, with the new design of Fin arrangement, the writing condition of HSQ needs to be adjusted, and the ICP etching condition also drifted. I’m starting with two new samples now. 2

3. /6 Problems with HSQ Writing 3 For the first sample, I was using the same writing condition as before: -- spin-coating: 5000rpm spin-coating, bake at 80’C for 4min -- EBL writing: 4 layers of pattern, dose 1200 uC/cm 2, step size 6 nm -- Developing: 80’C HSQ for 40s It shows that the near the Ni lines the HSQ is hard to be removed during developing. It might be due to under-develop, but the two narrow fins has already disappeared.

4. /64 For the 2nd sample: -- spin-coating: 5000rpm spin-coating, bake at 80’C for 4min -- EBL writing: 4 layers of pattern, dose 1200 uC/cm 2, step size 8 nm -- Developing: 80’C (?) HSQ for 60s Fin structure looks ok, but the the smallest fin was gone and there’s no protection on the Ni layer.

5. /6 Problems with the Cl-ICP Etching 5 I kept the same recipe as before and did conditioning before my real samples, but the etching condition was drifted. Previous etching time for 50nm InGaAs was 75-85 s, but this time even though I elongate it 150s there’re still residuals inside the Ni lines, and the HSQ layer has been damaged.

6. /6 Plan 1.I’ve been working on the neural probe devices for half a year, but still facing a lot of problems. I was wondering whether I can have all the documentary of Dr. Yoontae’s presentation and weekly report, so that I could learn from the tests he has already done and avoid some attempts he has already tried but didn’t work. 2.Can you please also share with me Daisy’s summary of HSQ test and the ICP etching? I’m afraid I may overlook some parameters that might be important for the processing. Thanks so much. 3.I’m starting with two batch of new samples, and will do HSQ writing test and ICP etching test. 6