Just use modifier S
(Shift) in your key binding. E.g.:
(global-set-key "\M-\S-c" 'foobar)
If there is nothing explicitly bound to the shifted key then Emacs automatically translates it to the unshifted key.
From the Elisp manual, node Key Sequence Input
:
If an input character is upper-case (or has the shift modifier) and has no key binding, but its lower-case equivalent has one, then
read-key-sequence' converts the character to lower case. Note that
lookup-key' does not perform case conversion in this way.