Is it obligatory to fulfill a vow by paying the full current salary or the salary at the time of the vow, after the salary has doubled?

A conditional vow is disliked, but it must be fulfilled if the condition upon which it was made occurs. You must fulfill your vow and pay your entire salary to Allah if the condition upon which you made the vow occurs. If your intention when making the vow was the entire salary, then you are not obliged to pay anything beyond that afterwards. However, if you did not intend the entire salary when making the vow, then you are obliged to pay the entire salary you received, based on the literal meaning of the wording.