Silicon Nitride Market Worth $127 Million by 2023 - Exclusive Report by MarketsandMarkets™ (prnewswire.com)
If we are playing the guessing game, I would say that it is either Kyocera or CoorsTek....but just conjecture on my part....it could be any of these or none of these......but these are the leading fabricators of silicon nitride
The leading players in the fabrication of silicon nitride are 3M (US), CeramTec (Germany), Kyocera Fine Ceramics (Japan), Morgan Advanced Ceramics (UK), Toshiba (Japan), Rogers Corporation (US), and CoorsTek (US).