 Companies offering SONOS-based products include Cypress Semiconductor, Macronix, Toshiba, United Microelectronics Corporation and Floadia.A SONOS memory cell is formed from a standard polysilicon N-channel MOSFET transistor with the addition of a small sliver of silicon nitride inserted inside the transistor's gate oxide.The sliver of nitride is non-conductive but contains a large number of charge trapping sites able to hold an electrostatic charge.