The debt is still due upon your father and it will remain hanging until it is paid off on his behalf. This is due to the words of the Prophet (peace be upon him) who said:
“The soul of a (dead) believer remains suspended by his debt, until it is repaid on his behalf.”
This ruling stands except if the bank waives your father's debt. Therefore, you must start paying off the debt to the bank from your father's estate to absolve him from the debt.May Allah grant us success. May Peace be upon our Prophet, his family and Companions.