Sentinel 3 data netcdf4 to geotiff in python

I am new to geodata processing. I need to convert Sentinel 3 slstr data of a single band to geotiff format. I am able to read the cartesian coordinates and band values into an numpy array using SNAPPY. I tried to convert into geotiff using rasterio affine transformation but am not able to get the correct coordinates in the geotiff image.