PIC12LF1572 too much current in sleep mode

Hi, I try to create a project with a PIC12LF1572 (XLP).
It is neccesary that the chip runs with less than 1 uA.
The PIC is normally in the sleep mode and I wake it up by a pinchange
interrupt. Everything works fine, but the chip allways consumes 7uA@3V3. The PIC is clocked
with 1MHz without PLL. The pullups are all deactivatet and the pins are fixed to high or low.
I searched in the datasheet and on the internet for a solution. Can you give me some
ideas what I can do to achive my target?
Thank you for your help.