Note: Very personal preference here - If someone only promotes you to a section head because you tender your resignation and want to avoid a vacuum with your abscene and not because of your merits, you should really consider the impact on your career in such a company. If the company really recognizes your merits, why didnt this promotion happened before? If they did not recognize your merits now, will they later on? Or will you have to threaten with resignation again in the future to get your well deserved?

My personal preference has always been to find a company that recognizes and practices meritocracy. If a company can promote you for the wrong reasons, they can well promote others for the wrong reasons. Ultimately this makes the company run by people doing things for the wrong reasons and causes a lot of unnecessary problems.

Btw, if the current company is gonna pay you the same salary after promotion to a section head as a normal engineer in infeneon, dont you think you are underpaid?