Single product speckle filter error

when I want to apply speckle filter on my calibrated data I get this error?
A problem occurred during the target product processing.
Type: OperatorException
Message: Not able to write product file: ‘C:\Users\Benyamin\Desktop\S1B_IW_GRDH_1SDV_20181019T082701_20181019T082726_013219_0186F1_90C1_Vband_Cal_Spk.dim’

can any one help?

You may not have enough disk space available on C: