http://www.engadget.com/2015/10/06/does-your-iphone-have-a-good-or-bad-a9-cpu/
https://itunes.apple.com/us/app/lirum-device-info-lite-system/id591660734?mt=8
このアプリで判別できるんだってさ
N66AP (6s plus) or N71AP (6s) - Samsung chip
N66MAP (6s plus) or N71MAP (6s) - TSMC chip