Taken from here:
You can use Notepad++ to accomplish this in three ways. Just so you know, Notepad++ is a more advanced version of Notepad, which supports syntax highlighting of different code files "out of the box" - PHP included!
Download & install it, fire it up, and load up your PHP file. You should automatically see it beautifully coloured (if not, because the file extension is something other than .php, go to Language -> PHP or Language -> P -> PHP).
If you need to change any of the colours, you can easily do so - just go to Settings -> Styler Configurator. From that menu, you can change the various highlighting and font options, to suit your needs - although the default usually suffices for most.
Then, go to Plugins -> NppExport. From there, you have three options you can consider:
Export to RTF Export to HTML Copy all formats to clipboard Start with the last one - "Copy all formats to clipboard" - which will copy the entire file with the highlighted syntax to the clipboard. Once you click it, then open Microsoft Word, and just hit paste! You should see the beautifully syntax-highlighted code. If something goes wrong, then you can try one of the other options (export to RTF/HTML), although I've never had a problem with the clipboard method.