privileges to backup controlfiles

I want to set up an user so I can use him to backup the control files; beside granting "ALTER DATABASE" to this user, is there any other roles or privileges I can grant him so he can backup the control files. "ALTER DATABASE" and too powerful for this user.

thanks

you could create a procedure and give them execute on that procedure

Why do you want to allow this user to take backup controlfile??? & you say he is an ordinary user???

I dont see any point in doing this for an end user?