Well, that looks perfectly fine to me the way you posted it.
But perhaps you were trying to say that you used the HTML named entity ™? (If you're going to post HTML entities, you have to escape them properly.)
In any case, your document is encoded in UTF-8. So either put the character itself into the document, encoded in UTF-8, or use a character entity like ™. And by the way it doesn't make any difference that it's inside a CDATA section, the same character rules apply there as for everywhere else in the document.