How to make citations in a word document superscript?

The Word built-in reference tool has a style called "IEEE" which has similar citations except that the number is not in superscript. IEEE format

Inorder to make the citation in superscript, you should modify the style file which is in the %APPDATA%\Microsoft\Bibliography\Style folder.
Back up the IEEE2006OfficeOnline.xsl file, and find the string <xsl:template name="Citation">.
In this segment, you can find <body> and </body>, change these to <body><xsl:element name="sup"> and </xsl:element></body>.
Then the citation looks like this below. modified IEEE format