I found this interesting item on SCOTUSBlog.
If one goes to the “Frequently Asked Questions” page of the Supreme Court website, there is this question: “Where can I find the papers of the Justices?” Indeed. And here is the answer tendered: “The Biographical Directory of Federal Judges, maintained by the Federal Judicial Center, provides location information for the Justices’ papers. Search by the name of the Justice and then click on the link to ‘Research Collections’ to see where the papers are available. Many collections of papers are located at the Library of Congress and at academic and research institutions throughout the country. Depending upon the institution, some material may be available online.”
My first search for Justice Scalia was a negative. But as the piece notes there are many federal judges who do have collections to be perused. So if you are interested in historical surfing, give it a try.