Well, he was resisting the process of becoming a hollow when he activated his shinigami powers to stop him becomming a hollow. Since Ichigo has hollow abilities it appears that he didn't turn shinigami quick enough and some of the hollow powers remained, turning him into a hybrid.

i doubt that urahara made Ichigo a hollow hybrid deliberately. Te pit method seems to be failry risky (they were ready to kill Ichigo if he turned hollow). I mean, if urahara created the ball-thingy in the first place, he'd probably be capable of making an other one. (Unless he was desperate, for resorces, being isolated from SS. Which, now that I think about it, does make some sense.)