Muslims do not worship the Qur'an. The Qur'an is a book, like the Bible, which Muslims believe was revealed to the prophet Muhammad by God so that the Arabs could have instructions from God in their own language.
Muslims worship God ('Allah' in Arabic) but respect the Qur'an as God's word. Because of this many Muslims will not place another book on top of the Qur'an. However, the Qur'an in sacred because of what's in it--the words and commands of God--but it is not God himself.