Hi, all,

I am working on a low-k material related project. The
following is my process flow chart. Cr was used for
etching mask for low-k material and BCB. But after
lift-off, Cr was cracked.

1. low-k substrate

2. PR spin and align (AZ5214E, 4000rpm/1Krps/45s, bake
90 degree C for 1 min, expose 3 sec, followed by flood
expose for 200s, develop in 300 MIF for 1 min)

3. E-beam evaporation of 120 nm thick Cr

4. lift-off, (find Cr cracked into pieces).

5. After lift-off, low-k material etch (Cr is designed
as etching mask)

6. BCB is spinned on Cr film and cured at 250 degree C

7. BCB etching  (Cr is designed as etching mask)


Anyone can check my flow chart and give me some
suggestions.  Thanks