English is not my mother language, so sometimes I feel bad when I write English. I want to produce a research paper, do you have any recommendations for AI that help to fix grammar and words in order to more formal and scientific?
You can certainly use the tools listed above by Amer. Alternatively, you can ask someone with excellent English (native-speaker or not) to proofread your text.
A proofreader might be of greater help to you than an AI tool. Your research paper, in the process of using an AI tool, especially when used in free mode, can be plagiarised. So, I would recommend seeking the help of a proofreader instead.