There are two ways you can take to increase your salary further:
- Specialist way: Specialize your knowledge to a more specific field or branch - for example developing software for purposes in the aeronautic field (just an example).
- Generalist way: Gain leadership qualities and become project manager or department/team leader.
Since I am not a professional for long time (I have no more experience than one year after graduation), I cannot give you more detailed information, but at least this is what I understood, the options you have when you want to get more money in software development.