Export L2A image with real BOA value

I have converted the S2 L1C data to L2A with sen2cor, and I want to transfer the BOA data to Geotiff format.
The problem is that the obtained GeoTiff has been re-sampled to int format. I wonder how I can reserve the real BOA values (0 to 1).

Thanks very much.

please have a look at this topic:

The values are stored as integers but interpreted as floats in SNAP using the QUANTIFICATION_VALUE variable in the metadata

Thanks very much for your help. It really solves my concern.