tex-directory

tex-directory is a variable defined in `tex-mode.el'.
Its value is

"."

Documentation:
Directory in which temporary files are written.
You can make this `/tmp' if your TEXINPUTS has no relative directories in it
and you don't try to apply M-x tex-region or M-x tex-buffer when there are
`\input' commands with relative directories.

You can customize this variable.