Sailor Moon Question...again hehe

I use Sailor Moon to study japanese and I’ve been struggling with this sentence

そして 生きる しかばねとなった
臣下たちの中で
わらわは
独りで生きることにしたのだ

My problem is with ばねとなった, I guess is a derivation from naru, in the sense of become (and the subs mentions living corpses), but what is that ばね. I try to google it but no definition seem to match.
Thanks in advance for reading o replying to my post

しかばね is one word.

6 Likes