I am single and have no children. Both my parents are deceased. I have one sister and some half-brothers with whom I do not get along. Upon my death, will they have rights in my estate?

Yes. Your half-brothers are the children of one of your parents and are legally considered your siblings. Under French law, your estate will be divided equally between them and your sister. If you do not want them to inherit, you must make a will to exclude them.
(Articles 734 to 738 of the French Civil Code).