How to Prevent an Alert Dialog Getting Closed by Back Button

I have an alert dialog like this:

    AlertDialog.Builder oyunaBaslaDialog = new AlertDialog.Builder(this);
    oyunaBaslaDialog.setMessage("A Takımı");
    oyunaBaslaDialog.setNeutralButton("Başla!",
            new DialogInterface.OnClickListener() {
                public void onClick(DialogInterface arg0, int arg1) {
                    oyunOyna();
                }
            });
    oyunaBaslaDialog.show();

This dialog is shown in onCreate method. And I want it just to be closed by the button on it. But Hardware Back Button can also close this dialog without dialog's action performed.

I dont want the back button close this dialog, what can i do?