You only need a Bachelor's Degree in order to apply for a PhD in America. You do not need a Master's Degree. To get a fully funded PhD in America you need to do this:
3. Understand the funding offer. If you are admitted, most PhDs guarantee 4–6 years of full support. Some require teaching or research assistantships, but you’re paid while studying.
4. Accept your offer and get your I-20. Once you accept, the school will send you an I-20 form.
5. Apply for your visa. With your I-20 and passport, you can apply for an F-1 student visa.
🎓 School List: Here is a list of USA universities with a 100% scholarship for your PhD.