Force measurement sensor integrated on silicon, and a method of manufacture

Claim 1

A force measurement sensor integrated on silicon, comprising: a mono-crystalline silicon substrate having a first dopant and covered on at least a portion of its surface by a doped layer having a second dopant; a variable capacitor comprising a first moving plate including a flexible conducting blade having a free end which is deformable by bending, said plate having an "anchor portion applied to a localized zone of said doped layer, and which is mounted so as to have a cantilevered portion including a set of staircase steps, each staircase step being shorter than a critical sticking length and co-operating with a doped zone having a high concentration of impurities situated beneath said step and capable of being individually biased, and a fixed second plate including a conducting zone made on said doped layer, said conducting zone facing said first plate and separated therefrom by an empty space which is a few microns across; a first doped zone which is doped with a high concentration of said first dopant and which is situated in said doped layer, the anchor portion being located on said first doped zone in order to constitute the gate of a junction field effect transistor (JFET); second and third doped zones which are doped with a high concentration of said second dopant situated on either side of said first doped zone to constitute the drain and source zones of the JFET, the doped layer defining a zone having a low concentration of said second dopant situated beneath said first doped zone between said second and third doped zones in order to constitute the channel of said JFET whose gate is directly connected via the flexible blade to the moving plate of the variable capacitor; and means for detecting a signal representative of variations in the position of said flexible blade.