Dear Wensink,
1. Try not to dry the resist to much live it a bit flexible.
2. Try to use adhesion promoter ( like HMDS).
3. Before resist coating you have to make a surface treatment ( using 5%
ammonia or 5% HCL or 1:15 H2O:BHF for 20-30 sec.) follows by short rinse
in water and nitrogen dry.
Regards
Motti Vered