Unitary floating-gate electrode with both N-type and P-type gates

US8178915B1 · kind B1 · utility

Assignee

• TEXAS INSTRUMENTS INCORPORATED · US

Inventors

• Allan T. Mitchell · Rockwall, US
• Imran Khan · Richardson, US
• Michael Wu · Oakland, US

Key dates

• Filing date: Mar 23, 2011
• Grant date: May 15, 2012
• Expiry date: Mar 23, 2031

Classification

• Technology area (CPC H): Electricity
• CPC primary: H10D84/212

Abstract

An analog floating-gate electrode in an integrated circuit, and method of fabricating the same, in which trapped charge can be stored for long durations. The analog floating-gate electrode is formed in a polycrystalline silicon gate level, and includes n-type and p-type doped portions serving as gate electrodes of n-channel and p-channel MOS transistors, respectively; a plate of a metal-to-poly storage capacitor; and a plate of poly-to-active tunneling capacitors. Silicide-block silicon dioxide blocks the formation of silicide cladding on the electrode, while other polysilicon structures in the integrated circuit are silicide-clad. An opening at the surface of the analog floating-gate electrode, at the location at which n-type and p-type doped portions of the floating gate electrode abut, allow formation of silicide at that location, shorting the p-n junction.