In order to earn a higher salary in a company, a software developer has to do anything anyone else has to do. Be motivated, open minded, always learn, stay up to date, do a good job, be sociable and then collect good arguments and go to your superior to ask for a raise.
Good arguments include, but are not limited to:
Alternatively, try to change your position. It will give you new insights and you will gain valuable experience. It works especially well when you are still quite young and not completely specialized. When making a new contract, you will usually get a raise. But don't switch around too often. Stay for a few years and experience the job you have to do!