TikZ uses *.auxlock files to check if the main *.aux file is available. This is only used when using the external tikz library.
\tikzexternalize
When using TikZ & PGF with: `\usepackage{tikz} \usetikzlibrary{external} \tikzexternalize` It creates .dpth and .md5 files for the externalized tikzpictures.