Texas Instruments Corporation

Dallas Semiconductor Corporation

Jack G Qian

Allan T Mitchell

Thomas E Harrington, Iii

Shanjen Pan

Doug Weiser

Roy Austin Hensley

Alan T Mitchell

Varun Singh

Tanmay Kumar

In one disclosed embodiment, a non-volatile memory cell is constructed using a floating gate transistor with a channel that includes a buried channel region interposed between two surface channel regions under a floating gate. The surface channel regions are formed using angled lightly-doped drain implantation at locations in the substrate so that a first surface channel region is located under a first end of the floating gate and a second surface channel region is located under a second end of the floating gate. In one embodiment, the floating gate transistor is a PMOS transistor, with the channel being formed in an n-well formed in a p-type substrate, with the buried channel region being formed using a Vtp implant, and with the surface channel regions being formed using angled NLDD implants. The surface channel regions increase the energy barrier along the channel and reduce off state current of the memory cell.

Programmable non-volatile memory with low off current

In an embodiment of the invention, a method of fabricating a floating-gate NMOSFET (n-type metal-oxide semiconductor field-effect transistor) is disclosed. A silicide blocking layer (e.g. oxide, nitride) is used not only to block areas from being silicided but to also form an insulator on top of a poly-silicon gate. The insulator along with a top electrode (control gate) forms a capacitor on top of the poly-silicon gate. The poly-silicon gate also serves as the bottom electrode of the capacitor. The capacitor can then be used to capacitively couple charge to the poly-silicon gate. Because the poly-silicon gate is surrounded by insulating material, the charge coupled to the poly-silicon gate may be stored for a long period of time after a programming operation.

N-channel erasable programmable non-volatile memory

A polysilicon resistor is formed using a late implant process. Low dopant concentrations on the order of 6&times;10,to 3.75&times;10,have shown good results. with a reduced post anneal temperature. Both the first and second order temperature coefficients (TC1 and TC2) can then be adjusted. Using electrical trimming resistors can be produced with highly linear temperature characteristics. By varying the geometries of the resistors, low trimming threshold current densities and voltages can be used to produce good results.

Method of making polysilicon resistor having adjustable temperature coefficients

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Plano, TX, United States of America

Jack G Qian