Patent ID: 6303444
Filing Date: 2001-10-16
Classification: H01L

Abstract:
A method for varying the threshold voltage of a device, said method comprising:providing a bulk material of a first conductivity type;forming source and drain regions within said bulk material, said source and drain regions being separated by a channel region, said source and drain regions having a second conductivity type;forming a gate over said channel region;forming a resistive well of said first conductivity type with an average dopant concentration of said first conductivity type chosen to provide a resistance per unit length in said resistive well within a desired range, said resistive well being positioned in said bulk material below said channel region;electrically coupling said bulk material to a first location in said resistive well;forming a well tie of said first conductivity type within said bulk material, said well tie being positioned beside one of said source or drain regions and outside said channel region;electrically coupling said well tie to a second location in said resistive well,wherein said first position in said resistive well and said second position in said resistive well are separated by a horizontal distance such that said resistive well provides a resistive path, thereby creating an equivalent resistor between said well tie and said bulk material.