CC1101: CC1101 burned out

Not sure what you mean by " IC burned out" and the picture does not show any details either?

Additional pictures. Top and bottom sides.

Ok, not that often I see pictures that shows that the IC has been so hot that the PCB is black... This is most likely due to a short, you should check the impedances on the board and see where it's close to 0. 

Also, from what I can see from the picture, the layout is not optimal. I hope this is more than 2 layers because chip ground is poorly connected on the button layer. The RF path toward the antenna is also poor. Follow the ref design and also look at http://www.ti.com/lit/ds/symlink/cc1101.pdf

Yeah, layout isn't optimal, I know...Additional detail: devices works fine for 1-3 weeks. I measured all possible impedances before and after CC1101 burning out event - its ok.

Is it just this board that have had this problem? 

Could the board been exposed for a ESD event? 

I have about 10 boards with that problem (and no one that works fine longer than 3 weeks).
Board is packed to the plastic case. So, it can be damaged by ESD event only via SMA antenna connector.

10 boards out of how many? It's not often a ESD is seen as a systematic error but we have sen cases with poorly grounded production lines that cause a large fall out due to ESD. 

What is the value of VCC in your design? 

I could also do a layout review to see if I see something that could potential cause this. For this I would need gerber files.