Yes you can, specify your desires on your will but this doesn't mean that if you die the father won't contest your will and fight for his rights as a father. If he does the court is likely to side with him and not with your mother unless he is a terrible person. If he doesn't want to be in your kid's life what you should do is get sole custody for yourself and seek to terminate his parental rights, which is unlikely to happen but at least get physical and legal custody for you and you alone.